Home Physical Sciences Antioxidant-rich Micromeria imbricata leaf extract as a medium for the eco-friendly preparation of silver-doped zinc oxide nanoparticles with antibacterial properties
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Antioxidant-rich Micromeria imbricata leaf extract as a medium for the eco-friendly preparation of silver-doped zinc oxide nanoparticles with antibacterial properties

  • Gadah A. Al-Hamoud , Musarat Amina EMAIL logo , Nawal M. Al Musayeib , Hanan M. Al-Yousef , Mohsin Ul Haq and Saeed Akhtar EMAIL logo
Published/Copyright: September 16, 2025
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Green Processing and Synthesis
From the journal Green Processing and Synthesis Volume 14 Issue 1

Abstract

This study explores the versatile features of eco-friendly green synthesized silver-doped zinc oxide nanoparticles (Ag/ZnO NPs) using a fresh leaf extract of Micromeria imbricata as both a reducing and a stabilizing agent. The work primarily evaluates the antibacterial and antioxidant properties of the pre-synthesized Ag/ZnO NPs and the plant extract. Structural and morphological characterization confirmed the hexagonal wurtzite structure of Ag/ZnO NPs via X-ray diffraction (XRD), with absorption peaks at 256 and 374 nm and a band gap of 3.17 eV. Fourier transform infrared analysis confirmed that phytoconstituents in the M. imbricata extract facilitated the synthesis, capping, and stabilization of Ag/ZnO NPs. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and transmission electron microscopy analyses showed spherical NPs with an average size of 28.12 nm. Antibacterial tests demonstrated that both ZnO NPs and Ag/ZnO NPs had strong bactericidal effects against tested strains, with Ag/ZnO NPs exhibiting superior performance. These NPs produced significant zones of inhibition and reduced the bacterial growth and viable cell counts. In comparison, the M. imbricata extract showed moderate antibacterial activity. However, antioxidant assays revealed that the extract had the highest efficacy (IC50 = 48.72 µg·mL−1), surpassing both ZnO NPs (76.41 µg·mL−1) and Ag/ZnO NPs (81.51 µg·mL−1). Overall, these Ag/ZnO NPs effectively inhibit the growth of various pathogens, underscoring their promise for applications in antimicrobial system design and medical device innovation.

Keywords: Micromeria imbricata ; silver-doped zinc oxide; nanoparticles; antibacterial; antioxidant

1 Introduction

Drug-resistant microorganisms have emerged as a result of increased rates of bacterial infections and antibiotic abuse over the past two decades, raising morbidity and mortality rates worldwide [1]. Treating these drug-resistant microbes or superbugs has become quite challenging due to the scarcity of antimicrobial drugs currently on the market [2]. Antimicrobial resistance is predicted to claim up to 10 million lives by 2050, if appropriate measures are not taken to resolve this problem, with over 4 million of those fatalities occurring in Asia alone [3]. In response to this growing threat, the World Health Organization (WHO) has called for intensified global efforts in the research and development of novel antimicrobial agents, particularly antibacterial drugs [4]. Consequently, advanced nanotechnological systems have been designed with diverse applications in agriculture, medicine, and other fields to combat antibiotic-resistant pathogens and improve food production efficiency to sustainably support the growing global population [5,6,7]. Nanotechnology serves as a fascinating emerging technology with applications across various domains, including biomedical sciences [8], consumer products [9], energy production [10], and nano-electronics [11].

The advancement of bio-based nanomaterials in agriculture and medicine offers sustainable alternatives to reduce the overuse and depletion of limited natural resources, thereby alleviating environmental pressure [12,13]. In particular, the fabrication of hybrid (composite or coated) nanosystems with multifunctional and tuneable properties holds great promise for innovative applications across multiple domains [14,15]. The design of their structure entails a combination of multiple nano-substances into arranged assemblies with two or more distinct nanoparticles (NPs) assembled in a functional nano-scale pattern [16]. The biological effects of these assemblies often surpass those achievable through a mixture of individual components [17]. In this regard, silver-doped zinc oxide nanoparticle (Ag/ZnO NPs) with improved chemical and mechanical features (such as optical, catalysis, semi-conduction, magnetic, thermal, and electric properties) have been prepared through chemical and phytogenic procedures [18,19,20,21]. However, chemically synthesized NPs are often hazardous and pricy [22]. This has motivated the scientists to create sophisticated, dependable, affordable, and non-toxic nanomaterials by utilizing herbal extracts [23]. Recently, the phytochemical approach to synthesizing metal/metal oxide/hybrid NPs has attracted significant attention due to its eco-friendliness, cost-effectiveness, non-toxicity to humans, simplicity of the process, and inspiration from biological systems. Plant-derived phytocompounds, including flavonoids, terpenoids, tannins, alkaloids, carotenoids, proteins, and chlorophyll, act as both reducing and capping agents in the green synthesis of zinc oxide NPs [24].

Plant-based hybrid NPs containing silver (Ag) are preferred for their low production costs, ecological compatibility, and strong antibacterial efficacy against certain drug-resistant Gram-positive and Gram-negative infections [25,26]. Ag NPs have gained prominence as effective antimicrobial agents, outperforming many other metals in this regard [27]. Additionally, the high surface energy of Ag NPs enhances their suitability for nanomaterial synthesis by supporting favourable surface chemistry [28]. Therefore, when Ag is combined with ZnO, it is expected that the resulting hybrid will exhibit enhanced antibacterial efficacy. ZnO is a renowned inorganic material widely used in daily applications and considered non-toxic, as it is classified as Generally Recognized As Safe (GRAS) by the Food and Drug Administration (FDA) [29]. Previous studies have shown that excellent biocompatibility of nanoscale ZnO makes it an effective material for diverse biological applications and drug delivery systems [30]. Notably, Ag coupled with ZnO NPs has exerted superior biomedical properties, especially the antimicrobial applications [31]. Moreover, doping or integrating ZnO NPs with other nanomaterials has been found to alleviate their activity by inducing oxidative stress in the bacterial cell, leading to membrane disruption and eventually cell death [32]. Numerous studies have successfully demonstrated the green synthesis of Ag-doped ZnO NPs using extracts from various plants, such as Averrhoa carambola fruit [33], Vitis vinifera leaves [34], Sansevieria trifasciata root [35], Azadirachta indica leaves, Hibiscus rosa-sinensis leaves, and Ocimum tenuiflorum leaves [36]. However, no study to date has reported the use of M. imbricata leaf extract for synthesizing Ag-doped ZnO nanocomposites via a green synthetic approach. The leaf extract of M. imbricata is abundant in flavonoids and phenolic compounds and also contains moderate levels of coumarins, anthocyanins, and terpenes [37]. Its diverse phytochemical profile highlights the presence of numerous bioactive compounds, suggesting promising avenues for further research into its medicinal and therapeutic applications, as well as its potential as a reducing agent. Moreover, previous research has demonstrated that M. imbricata extracts exhibit notable antioxidant, cytotoxic, and anti-obesity properties [37].

In this context, the present study explores the green biosynthesis of Ag/ZnO NPs using the fresh leaf extract of M. imbricata as a reducing and a capping agent in the fabrication process. The biosynthesis process was optimized with respect to temperature, reaction time, silver concentration, and pH. The pre-synthesized Ag/ZnO NPs were characterized by sophisticated spectroscopic (ultraviolet-visible [UV-vis], Fourier transform infrared [FTIR], and X-ray diffraction [XRD]) and microscopic (scanning electron microscopy [SEM], energy-dispersive X-ray [EDX] spectroscopy, and transmission electron microscopy [TEM]) techniques to evaluate their physicochemical properties. The biogenic Ag/ZnO NPs and the M. imbricata extract were evaluated for their antioxidant and antibacterial potency. Based on the available literature, no research investigated the antioxidant and antibacterial potency of leaf extracts of M. imbricata or Ag/ZnO NPs synthesized using the M. imbricata leaf extract.

2 Materials and methods

2.1 Materials

Analytical-grade metal salt precursors were used for the biosynthesis of ZnO NPs and Ag/ZnO NPs. Zinc acetate dihydrate [(CH3COO)2Zn·2H2O, 98%], silver nitrate (AgNO3, 98%), sodium hydroxide (NaOH, ≥98%, anhydrous) pellets, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals were procured from Sigma-Aldrich.

2.2 Botanical materials and preparation of the extract

Fresh leaves of Micromeria imbricata (Forssk.) were collected in August 2019 from the fertile Asir Mountains in the Abha region of southwestern Saudi Arabia. The harvested leaves were thoroughly rinsed with distilled water to eliminate dust and debris, then shade-dried for several days. After drying completely, the leaves were ground into a fine, consistent powder and stored in a dark place at room temperature until needed. About 25 g of powdered M. imbricata leaves was soaked in 250 mL of ethanol and extracted using a Soxhlet apparatus at 50°C for 8 h. The resulting crude extract was then cooled and filtered through Whatman No. 1 filter paper. The extraction procedure was repeated twice under the same conditions, each time using fresh solvent. The combined bio-extract was evaporated under reduced pressure at 45°C on a rotary evaporator. A dark green extract obtained was stored in a refrigerator at 4°C until needed.

2.3 Synthesis of ZnO and Ag/ZnO NPs

Biogenic ZnO and Ag/ZnO NPs were successfully synthesized using a simple, affordable, environmentally benign, and widely used green approach. The ZnO NPs were prepared utilizing the M. imbricata leaf extract as the media in accordance with previously published research with slight modifications [38]. Briefly, a defined proportion (2.25 g) of zinc acetate [(CH3COO)2Zn·2H2O] was dissolved in 100 mL of distilled water under constant magnetic stirring for 1 h to ensure complete solubilization. Around 80 mL of 0.1 M zinc acetate was added to 20 mL of freshly prepared ethanol leaf extract of M. imbricata (5.12 g dissolved in 50 mL MeOH), and the mixture was stirred continuously at 70°C. The initial reaction pH of 4.2 was adjusted to 12 by dropwise addition of 2 M NaOH solution. After stirring for 2 h, the mixture was centrifuged for 10 min at 5,000 rpm, and the resulting product was repeatedly rinsed with water and ethanol to eliminate impurities. The pre-synthesized ZnO NPs were then transferred to a crucible and dried at 60°C in a hot air oven.

A similar procedure was employed to synthesize the Ag/ZnO NPs by following the protocol of Ranjithkumar et al. [39], with minor modifications. In brief, 100 mL of 0.1 M (CH3COO)2Zn·2H2O (2.25 g) solution was mixed with 50 mL of 0.01 M AgNO3 (1.30 mg) solution and stirred for 10 min at ambient temperature. Subsequently, 20 mL of M. imbricata extract (prepared by dissolving 5.12 g in 50 mL MeOH) was poured into the reaction mixture, followed by dropwise addition of 2 M NaOH solution to adjust the pH to 7. The reaction was stirred for 2 h at 70°C, resulting in dark brown precipitates. These precipitates were collected by centrifugation (5,000 rpm for 10 min) and washed several times with distilled water to remove impurities. The resulting Ag/ZnO NPs were dried overnight at 60°C, then calcined at 500°C for 2 h using a Thermolyne benchtop muffle furnace (model: F48025-60; max. temperature: 1,200°C). Figure 1 illustrates the overall procedure for the green synthesis of Ag/ZnO NPs using the M. imbricata leaf extract. The formed biogenic Ag/ZnO NPs were investigated for structural, optical, and morphological characterization.

Figure 1 Schematic procedure for the green synthesis of Ag/ZnO NPs using the M. imbricata leaf extract.
Figure 1

Schematic procedure for the green synthesis of Ag/ZnO NPs using the M. imbricata leaf extract.

2.4 Characterization of Ag/ZnO NPs

XRD analysis was performed to investigate the crystalline structure and purity of formed Ag/ZnO NPs using an X-ray diffractometer (D8 Advance, BRUKER AXS, Germany) operated at 40 kV voltage and 30 mA current. The biosynthesized Ag/ZnO NPs were suspended in ethanol and applied onto a glass substrate for XRD analysis. The measurements were conducted over a 2θ range of 20°–80° using Cu Kα radiation (k = 1.5406Å). The nanomaterial was subjected to optical inspection using a Spectroquant® Prove 300 spectrophotometer (D-64293 Darmstadt, Merck KGaA, Germany) for UV-visible analysis. A spectrum was recorded using 3 mL of sample solution placed in a quartz cuvette with a 1 cm path length. The UV-vis spectrum of the prepared Ag/ZnO NPs was obtained within the 200–800 nm wavelength range to identify the maximum absorbance values. Tauc’s equation [αhv = C(hν – Eg) m] was applied to further compute the band gap energy of Ag/ZnO NPs. In this equation, α stands for the absorbance coefficient, h for Planck’s constant, ν for the photon frequency, C for the proportionality constant, Eg for the optical band gap, and m for direct band gap semiconductors. The functional groups and chemical bonds of the M. imbricata extract and complex nanomaterial were analysed using FTIR spectroscopy (Thermo Nicolet Avatar 370, Bio Surplus, San Diego, CA, USA) with the KBr pellet method. Each spectrum represents an average of 20 scans, recorded at a resolution of 4 cm−1 over the wavelength range of 4,000–400 cm−1 to enhance the signal-to-noise ratio. The dimensions and morphological features of the biosynthesized Ag/ZnO NPs were examined by SEM (JOEL, 222, Germany) with 100 kV maximum voltage. The sample was prepared by dispersing the Ag/ZnO NPs in 100% ethanol using ultrasonication. The resulting solution was deposited onto a glass slide and allowed to air dry, ensuring complete evaporation of the solvent. The dried sample was subsequently sputter-coated with a thin coating of gold, about 3 nm thick, using a vacuum sputter coater. The scanning electron microscope was equipped with an integrated energy-dispersive X-ray (EDX) spectrometer (XFlash® 6130 with Quantax 200) to determine the elemental content and their distribution on the surface of formed NPs. The shape, size, and crystallinity of pre-synthesized Ag/ZnO NPs were obtained by TEM micrographs using a JEOL-1011 microscope operating at an accelerating voltage of 200 kV. A formvar resin grid was used to prepare the samples. A suspension of the biosynthesized Ag/ZnO NPs (0.5% w/v) was deposited onto a TEM grid coated with formvar resin and allowed to air-dry for 10 min. The morphology of the NP aggregates was then examined and documented through photography.

2.5 Antibacterial potential of ZnO NPs and Ag/ZnO NPs

2.5.1 Test organism source and inoculum preparation

The antibacterial potency of M. imbricata extract, biogenic ZnO NPs, and Ag/ZnO NPs was examined against four pathogenic bacteria associated with food borne diseases. The study involved two strains of Gram-positive (Bacillus subtilis and Staphylococcus aureus) and two strains of Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. The bacterial test strains were sourced from the Microbiology Department at King Khalid Hospital, King Saud University, Riyadh, Saudi Arabia. Each test bacterial strain was inoculated in nutrient broth and incubated overnight at 37°C until the turbidity reached 0.5 McFarland standards, yielding a final inoculum concentration of 1.5 × 108 CFU/mL.

2.5.2 Antibacterial test of ZnO NPs and Ag/ZnO NPs

The disc diffusion method was employed to assess the antibacterial efficacy of M. imbricata extract, biogenic ZnO NPs and Ag/ZnO NPs [40]. Nutritional agar medium (15–20 mL) was prepared and sterilized before being poured into Petri plates for solidification. After solidification, a sterile swab was used to evenly spread each bacterial strain onto individual agar plates. After that, overnight cultures were then spread on the surface of nutrient agar (NA) plates using sterile cotton swabs, and the surface was set aside to dry for about 3 min. Prior to testing, the investigated samples (10 mg·mL−1) were re-dissolved in ethanol to prepare standardized stock solutions, ensuring uniformity and accuracy in the subsequent analyses. On homogeneous bacterial lawns, 15 µL of 100 µg·mL−1 test solutions were loaded onto filter discs of 8 mm diameter. Gentamicin (10 μg) disc was utilized as a standard antibiotic. The plates were incubated at 37°C for 24 h. The antibacterial efficacy of M. imbricata extract, ZnO NPs and Ag/ZnO NPs was assessed by observing the zones of inhibition (ZOIs), visible as clear areas surrounding the disc. Each experiment was conducted in triplicate, and the antibacterial activity was ascertained by calculating the average values of the inhibition zone.

The bacterial cell growth and growth kinetics were assessed following exposure to test samples at varying concentrations (200 and 400 µg·mL−1). The optical densities were examined using a spectrophotometer. Similarly, the growth curve for viable counts was determined using overnight bacterial cultures inoculated into fresh NA (108) containing test samples (400 µg·mL−1). Aliquots of 100 μL were incubated at 37°C for 0, 3, 6, 12, and 24 h, after which bacterial viability was assessed by plate counting.

2.6 Antioxidant activity

The DPPH radical assay was applied to test the antioxidant capability of the prepared M. imbricata extract biosynthesized ZnO NPs and Ag/ZnO NPs. The DPPH• radical, recognized for its stable purple hue and distinct absorbance at 517 nm, was employed as the substrate for this assay. Upon interaction with antioxidants in the sample, the DPPH solution exhibited a noticeable shift from purple to colourless, indicating radical scavenging activity. Briefly, 15 mg of test samples was dissolved in methanol to prepare a 50 mL diluted solution. This solution was applied as a base solution for preparing varied concentrations (50, 100, and 150 μg·mL−1) for the test. After that, about 5 mL of 0.1 mM methanolic solution of DPPH was poured into 1 mL solution from each test tube and placed in dark at ambient temperature for 30 min. Following the incubation time, the mixtures were examined for antioxidant potential at 517 nm wavelength using a UV-Vis spectrophotometer. Ascorbic acid was employed as a positive control and was prepared as above without the test sample. Data interpretation was performed by calculating the percentage inhibition of DPPH free radicals compared to the control, followed by the determination of IC50 values based on the decreasing order of absorbance readings from the test samples. This systematic methodology provided a comprehensive evaluation of the antioxidant properties of test samples and offered valuable insights into their ability to scavenge the free radial. Each experiment was conducted in triplicate and monitored. DPPH inhibition as a percentage was computed by applying the following formula:

Scavenged DPPH ( % ) = Control absorbance − Sample absorbance Control absorbance × 100

2.7 Statistical analysis

MS Excel 2007 was utilized to analyse the data and reported as mean ± SD from triplicate. To determine significant differences between groups, one-way analysis of variance (ANOVA) followed by Tukey’s post hoc test was conducted using the trial version of StatPlus 2009 Professional software. Differences with p <0.01 were considered statistically significant.

3 Results and discussion

3.1 Biosynthesis of M. imbricata-mediated Ag/ZnO NPs

In this study, Ag-doped ZnO NPs were biosynthesized using the M. imbricata leaf extract, which are rich in phytochemicals such as flavonoids, phenolic compounds, terpenes, coumarins, anthocyanins, aromatic compounds, and alkynes as main constituents [37]. After mixing the M. imbricata leaf extract with zinc acetate solution under alkaline conditions, the reaction mixture changed from green to yellow and turned dark brown after the subsequent addition of silver nitrate. This colour transition, resulting from surface plasmon resonance within the synthesized metal NPs, can serve as an indicator for the presence of ZnO NPs. The electron-donating groups in the M. imbricata leaf extract may have contributed to this colour transformation in the synthesized Ag/ZnO NPs.

3.2 Characterization

The XRD analytical technique was used to characterize the pre-synthesized Ag/ZnO NPs crystalline material and assess their crystal structure, orientation, and defects. Figure 2a illustrates the XRD spectrum of biosynthesized Ag/ZnO NPs using the M. imbricata extract. The emergence of diffraction peaks at 2θ values of 31.69°, 34.26°, 36.12°, 46.49°, 55.58°, 62.73°, 67.21°, 69.23°, and 77.84° was indexed to the (100), (002), (101), (102), (110), (103), (112), (201), and (202) Miller index planes, respectively. The distinct peaks observed in the XRD spectrum verified the wurtzite crystalline structure and the hexagonal phase of ZnO, aligning with the standard ZnO powder diffraction data (JCPSD card No: 036-1451) [41]. In contrast, the XRD spectrum of biogenic Ag-doped ZnO NPs revealed additional prominent peaks at 2θ values of 37.15°, 43.26°, 64.28°, and 78.23° attributed to the (111), (200), (220), and (311) crystal planes, respectively. These peaks align with the reference data (JCPDS card number 04-0783) for the face-centred cubic structure of Ag NPs [42]. In the XRD pattern of Ag-doped ZnO, a slight shift of the (111), (200), (220), and (311) diffraction peaks towards lower angles is observed. As the silver doping concentration increases, the intensity of these peaks decreases and peak broadening occurs, indicating a reduction in the crystalline nature of the synthesized NPs [20]. The shift in the (111), (200), (220), and (311) crystal planes suggests the substitution of Zn2+ ions by Ag+ ions within the crystal lattice. This peak shift is not directly proportional to the weight percentage of silver doping, likely due to the difference in ionic radii between silver and zinc, with silver ions being larger than zinc ions [43]. The substitution of Ag+ into Zn2+ lattice sites is challenging because of this size mismatch. Consequently, silver ions are more likely to be incorporated on the surface of ZnO NPs rather than into the crystal lattice, as also confirmed by TEM analysis. Moreover, the strong diffraction peak intensity of Ag/ZnO NPs suggested that they is highly crystalline in nature.

Figure 2 (a) XRD pattern, (b) UV-vis spectrum exhibiting two distinct peaks at 256 and 374 nm, and (c) band gap energy of biosynthesized Ag/ZnO NPs using the M. imbricata leaf extract.
Figure 2

(a) XRD pattern, (b) UV-vis spectrum exhibiting two distinct peaks at 256 and 374 nm, and (c) band gap energy of biosynthesized Ag/ZnO NPs using the M. imbricata leaf extract.

The crystallite size of the nanomaterial was employed to estimate Scherrer’s formula (D = 0.9λ/β cos θ), resulting in an average size of 21.89 nm. The absence of impurity peaks confirms the successful synthesis of Ag/ZnO NPs using the leaf extract from M. imbricata as media. Notably, the measured crystallite size was smaller than that reported by Islam et al. [44], suggesting that smaller size may enhance the surface chemistry. Therefore, the presence of phytoconstituents from the leaf extract likely plays a key role in improving the crystalline nature of Ag/ZnO NPs.

The biosynthesis of Ag/ZnO NPs through a bio-reduction process by the leaf extract M. imbricata was monitored by UV-vis spectrophotometry. The effect of Ag on the optical absorption of ZnO NPs in the pre-synthesized Ag/ZnO NPs was evaluated using UV-visible spectroscopy. The UV spectrum of Ag/ZnO NPs exerted two prominent peaks with varying intensities at 256 and 374 nm, respectively (Figure 2b). The appearance of these peaks is attributed to the localized surface plasmon resonance (LSPR) property of the NPs, which arises from the collective oscillation of conduction electrons on the NP surface when they resonate with the incident light wavelength. The electronic transition of ZnO was accountable for the first absorption peak, whereas the presence of Ag in Ag-doped ZnO NPs produced the second peak. The absorption spectrum of Ag NPs is related to a characteristic band gap transition in the visible region between 420 and 300 nm, due to localized surface plasmon resonance [45]. A strong interfacial electronic coupling between neighbouring ZnO and Ag NPs results in a distinctly broadened surface plasmon band in the Ag/ZnO NPs. The excitonic peak arises from the transition of electrons from the valence band to the conduction band. This plasmon oscillation enhances light scattering due to the interaction between incident light and Ag NPs, effectively increasing the optical path length and minimizing light energy loss [46]. The observed red shift indicates that the Ag/ZnO NPs exhibit heightened sensitivity to visible light. Studies have shown that Ag NPs of size between 10 and 50 nm, when embedded in ZnO NPs, significantly enhance photon scattering, thereby improving direct light absorption. The UV-vis spectra of Ag/ZnO NPs display a typical band gap transition in the visible region (approximately 350–450 nm), attributed to the silver surface plasmon [47]. This peak demonstrates clearly the successful integration and interaction between Ag and ZnO in the current investigation. The band gap energy was computed for Ag/ZnO NPs by plotting the graph between (αhυ)2 vs energy (E) and found to be 3.17 eV (Figure 2c). The obtained band gap value was consistent with that reported in a previous study, which utilized the leaf extract of M. citrifolia plant for the synthesis of Ag/ZnO NPs [48].

The functional moieties involved in the formation of NPs and their distribution on the biogenic Ag/ZnO NPs were identified with FTIR spectroscopy. Figure 3 presents the FTIR spectrum of M. imbricata plant extract and pre-synthesized Ag/ZnO NPs, recorded in the 4,000–400 cm−1 range. A distinctive absorption band at 3,411.36 cm−1 observed in FTIR spectra of Ag/ZnO NPs was likely due to the hydroxyl group (OH), indicating the presence of phenolic groups. A typical absorption band at 479 cm−1 was attributed to Zn–O bonds [49]. The absorption peak located at 2,935.66 cm−1 was assigned to the alkyne group (CH) present in the phytocomponents of M. imbricata leaf extract [50]. While peaks observed between 600 and 800 cm−1 was associated with Ag [51]. Specifically, appearance of smaller peaks at 637.60 and 774.72 cm−1 confirmed the blending of Ag NPs with the ZnO lattice [52]. Overall, the FTIR spectra of Ag/ZnO NPs suggested that biomolecules were successfully capped on the NP surface, providing stability to the synthesized NPs (Figure 3a). However, the FTIR spectra of the plant extract showed a vibrational band between 1,300 and 1,700 cm−1, corresponding to the functional groups of proteins (–CN and C═O). A characteristic IR band around 1,000 cm−1 was attributed to the stretching of O–H and C–O, indicating the presence of alcohols and phenols. Similarly, bands observed between 2,800 and 3,000 cm−1 suggested the presence of amines. However, bands in the 3,300–3,600 cm−1 range indicated hydroxyl and phenolic groups in the plant extract (Figure 3b). Comparing the FTIR spectra of Ag-doped ZnO NPs and the plant extract, it can be concluded that the components of plant extract coated the NPs, playing a significant role in their formation.

Figure 3 FTIR spectra of (a) biosynthesized Ag/ZnO NPs and (b) M. imbricata leaf extract, showing prominent absorption bands in the range of 4,000–400 cm⁻¹.
Figure 3

FTIR spectra of (a) biosynthesized Ag/ZnO NPs and (b) M. imbricata leaf extract, showing prominent absorption bands in the range of 4,000–400 cm⁻¹.

The morphological features of biogenic Ag/ZnO NPs were assessed by SEM, TEM, and EDX micrographs. The surface features were examined by SEM, and results revealed agglomerated spherical morphologies of Ag/ZnO NPs (Figure 4a). The observed agglomeration could be ascribed to the polarity and electrostatic interaction of ZnO NPs formed during green synthesis as well as high calcination temperature which increased the surface reactivity [53]. Although addition of Ag ions did not cause significant morphological changes to the ZnO NPs, some grain growth was noted. Moreover, the plant phytoconstituents from the plant extract facilitated the formation of mesocrystals during the self-assembly process [54]. The elemental content of Ag/ZnO NPs was evaluated by EDX analysis. The EDX spectrograph of formed Ag/ZnO NPs confirmed the presence of silver (Ag), zinc (Zn), oxygen (O), and carbon (C) peaks (Figure 4b), indicating the successful fabrication of impurity-free NPs. The corresponding weight percentages were 16.8% for Ag, 54.9% for Zn, 19.7% for O, and 8.6% for C. TEM images of phyto-mediated Ag/ZnO NPs revealed the crystalline nature and quality of the NPs. The majority of the NPs observed in TEM micrographs were spherical, with an average particle size of 28.12 nm (Figure 4c). This result validated the XRD analysis findings.

Figure 4 (a) SEM image at ×20,000 magnification, (b) EDX spectrum, (c) TEM image with 200 nm scale bar, and (d) distribution of particles of biosynthesized Ag/ZnO NPs using the M. imbricata leaf extract.
Figure 4

(a) SEM image at ×20,000 magnification, (b) EDX spectrum, (c) TEM image with 200 nm scale bar, and (d) distribution of particles of biosynthesized Ag/ZnO NPs using the M. imbricata leaf extract.

Elemental mapping of Ag/ZnO NPs, as shown in Figure 5a, demonstrated a uniform distribution of all constituent elements across the NP surface. The predominant elements in the deposited layer were Ag, O, and Zn, as illustrated in Figure 5c and d. The presence of other elements, such as carbon, is likely due to biocomponents from the plant extract used as a reducing agent.

Figure 5 Elemental mapping of (a) Ag/ZnO NPs with peaks of (b) C, (c) O, (d) Zn, and (e) Ag elements on biogenic Ag/ZnO NPs synthesized by using the M. imbricata leaf extract.
Figure 5

Elemental mapping of (a) Ag/ZnO NPs with peaks of (b) C, (c) O, (d) Zn, and (e) Ag elements on biogenic Ag/ZnO NPs synthesized by using the M. imbricata leaf extract.

3.3 Antibacterial activity

The antibacterial effect of M. imbricata extract, pre-synthesized ZnO NPs, and Ag/ZnO NPs was assessed towards four microbial strains through the disc diffusion method and compared with a standard drug, gentamicin. The antibacterial potency of plant extract and biosynthesized nanomaterials is recorded in Table 1 and illustrated in Figure 6. The results of disc diffusion assay demonstrated that both the biogenic NPs (ZnO NPs and Ag/ZnO NPs) effectively inhibited the growth of tested bacterial strains with variable potency. Both Gram-positive and Gram-negative microorganisms exhibited significant susceptibility to the biogenic ZnO NPs and Ag/ZnO NPs. As perceived by the inhibition zone depicted in Figure 6, Gram-negative bacteria generally exerted greater sensitivity compared to Gram-positive bacteria. Among the tested strains, E. coli displayed the highest inhibition zone (27.13 ± 0.04 mm), followed by P. aeruginosa (21.72 ± 0.14 mm) at 10 mg·mL−1 concentration of Ag/ZnO NPs. In contrast, treatment with ZnO NPs alone resulted in inhibition zones of 20.34 ± 0.12 mm for E. coli and 16.21 ± 0.06 mm for P. aeruginosa. For Gram-positive bacteria, Ag/ZnO NPs produced inhibition zones of 17.64 ± 0.02 mm for B. subtilis and 16.87 ± 0.12 mm for S. aureus. Meanwhile, ZnO NPs treated samples demonstrated inhibition zones of (14.37 ± 0.08 mm) and (12.84 ± 0.14 mm) for B. subtilis and S. aureus, respectively. These findings suggest that biosynthesized Ag/ZnO NPs were the most effective NPs in inhibiting the microbial growth of all examined pathogenic bacteria. Among them, E. coli and P. aeruginosa were the strains most vulnerable to ZnO NPs and Ag/ZnO NPs, respectively, while S. aureus showed the highest resistance, followed by B. subtilis. However, the M. imbricata extract showed moderate antibacterial effects towards all the tested bacterial strains. The antibacterial efficacy of both Ag/ZnO NPs and ZnO NPs was also evaluated against the standard antibiotic gentamicin (10 μg mL−1). The Ag/ZnO NPs exhibited antibacterial capabilities comparable to the standard gentamicin drug, highlighting their potential as effective agents against food borne pathogens, as depicted in Figure 6. The antibacterial effects of Ag/ZnO NPs were superior to those of ZnO NPs. These outcomes were anticipated as both silver (Ag) and zinc oxide (ZnO) are known for their antibacterial effects [55,56], and their synergistic combination with Ag/ZnO NPs appears to enhance this effect. In addition, Ag/ZnO NPs have a larger surface area for interacting with microorganisms, and their uniform spherical shape and smaller particle size compared to ZnO NPs, allow them to penetrate bacterial cell walls more effectively, resulting in enhanced antibacterial activity [57]. Similar findings have been documented in the literature, indicating that the addition of Ag into ZnO NPs enhances their antibacterial efficiency and accelerates the kinetics of bacterial eradication across different cell wall types [58–60]. Although some studies have reported lower antibacterial activity of green-synthesized ZnO-based NPs compared to conventional antibiotics [61], our findings reveal the opposite trend. In our study, the green-synthesized Ag/ZnO NPs demonstrated antibacterial activity comparable to that of the standard antibiotic gentamicin. This improved efficacy may be due to the smaller particle size (∼22 nm), which provides a larger surface area for interaction with microbial cells, thereby enhancing antimicrobial activity. It is well established that the antibacterial performance of Ag/ZnO NPs decreases as the particle size increases [62]. Moreover, a narrower energy band gap facilitates easier electron excitation from the valence band to the conduction band, increasing the electron mobility. This increased electron mobility enables NPs to interact more effectively with bacterial cells, leading to damage through multiple mechanisms [62]. Additionally, the literature indicates that green-synthesized Ag/ZnO NPs exhibit superior antibacterial performance compared to their chemically synthesized counterparts and even outperform the activity of simple or bare plant extracts [63].

Table 1

ZOI (mm) of M. imbricata extract, ZnO NPs and Ag/ZnO NPs against selected bacterial strains at 10 mg·mL−1 concentration

Samples ZOI (mm)
Gram (+ve) bacteria Gram (−ve) bacteria
B. subtilis S. aureus E. coli P. aeruginosa
M. imbricate extract 9.78 ± 0.17 8.57 ± 0.32 12.56 ± 0.40 10.24 ± 0.22
ZnO NPs 14.37 ± 0.08 12.84 ± 0.14 20.34 ± 0.12 16.21 ± 0.06
Ag/ZnO NPs 17.64 ± 0.02 16.87 ± 0.12 27.13 ± 0.04 21.72 ± 0.14
Gentamicin 21.46 ± 0.24 25.53 ± 0.18 29.12 ± 0.02 22.31 ± 0.05

Data were means of triplicates (n = 3) ± standard error.

Figure 6 Growth inhibition of Gram-positive (a,b) and Gram-negative (c,d) bacterial strains caused by the M. imbricata extract, ZnO NPs, and Ag/ZnO NPs.
Figure 6

Growth inhibition of Gram-positive (a,b) and Gram-negative (c,d) bacterial strains caused by the M. imbricata extract, ZnO NPs, and Ag/ZnO NPs.

The disc diffusion assay results also validated that both Gram-positive and Gram-negative microorganisms demonstrated antibacterial potential when exposed to NPs. However, Gram-positive bacteria can provide strong resistance to NP penetration because they comprised a thick coating of peptidoglycan with linear chains of polysaccharides with short peptides. On the other hand, the NPs may more readily penetrate the thin peptidoglycan coatings of Gram-negative bacteria and allowing them to exhibit superior antibacterial effect than Gram-positive bacteria [64]. Both ZnO and Ag-doped ZnO NPs can induce cytotoxic effects and disrupt multiple cellular functions, contributing to their effectiveness in inhibiting microbial growth. Their antibacterial activity mainly stems from the production of reactive oxygen species (ROS) and disruption of metalloprotein components. Although Ag/ZnO NPs demonstrate stronger antimicrobial effects compared to ZnO NPs, the exact mechanisms remain not fully elucidated. Proposed explanations include ROS generation, release of silver (Ag+) and zinc (Zn2+) ions, and direct interactions between the microbial cells and nanocomposites, with different microbes potentially affected via distinct pathways. The positively charged Zn2+ and Ag+ ions released from Ag/ZnO NPs can penetrate the cell membranes and electrostatically bind to the negatively charged bacterial surfaces. This NP penetration may disrupt DNA replication during cell division and impair cellular respiration [65]. Further, these interactions can induce cytotoxicity through ROS generation, ultimately leading to cells death [66]. Figure 7 depicts the proposed antibacterial mechanism triggered upon interaction with the NPs.

Figure 7 Proposed mechanism underlying the antibacterial activity of biosynthesized NPs.
Figure 7

Proposed mechanism underlying the antibacterial activity of biosynthesized NPs.

The antibacterial effect was further supported by growth kinetics analysis of the tested bacterial strains, assessed through changes in optical density (OD) in the presence of Ag/ZnO NPs and ZnO NPs. These NPs were tested at concentrations of 200 and 400 μg·mL−1. The results revealed that the growth inhibition pattern of all the tested bacteria was highly influenced by the concentration, size, and morphology of NPs. The proliferation of all the microorganism was reduced with the rise in concentration of pre-synthesized ZnO NPs from 200 and 400 μg·mL−1, as illustrated in Figure 8a and b, respectively. A comparable trend was noted for Ag/ZnO NPs, which showed limited suppression of growth at 200 μg·mL−1 (Figure 8c) and almost complete growth inhibition at 400 μg·mL−1 (Figure 8d). Thus, the inhibitory effects were more pronounced in Ag/ZnO NPs compared to ZnO NPs. The enhanced antibacterial performance of Ag/ZnO NPs compared to ZnO NPs was attributed to their larger surface area and greater facet reactivity, enabling effective interaction of spherical NPs with bacterial cells. These observations were consistent with previous studies reporting that high aspect hybrid nanostructures, such as bimetallic nanostructures [67], metal-doped nanostructures[68], and nanoflowers [69], exert membrane-disruptive effects on bacteria, leading to reduced OD. Furthermore, the superior antibacterial potential of Ag/ZnO NPs compared to ZnO NPs may be attributed to structural modifications in ZnO NPs upon coupling with Ag. The incorporation of Ag atoms on the ZnO NP surface creates lower electron states within the band gap, which trap the photogenerated charge carriers and increase the formation of electron–hole pairs. These pairs can interact with oxygen and water to generate ROS, crucial agents in inducing cell death. Additionally, the crystallographic properties of Ag/ZnO NPs, indicated by their higher XRD peak intensities compared to ZnO NPs (Figure 2a), support this enhanced effect.

Figure 8 Growth curves of bacterial strains treated with (a) 200 μg·mL−1 concentration of ZnO NPs, (b) 400 μg·mL−1 concentration of ZnO NPs, (c) 200 μg·mL−1 concentration of Ag/ZnO NPs, and (d) 400 μg·mL−1 concentration of Ag/ZnO NPs at different time intervals.
Figure 8

Growth curves of bacterial strains treated with (a) 200 μg·mL−1 concentration of ZnO NPs, (b) 400 μg·mL−1 concentration of ZnO NPs, (c) 200 μg·mL−1 concentration of Ag/ZnO NPs, and (d) 400 μg·mL−1 concentration of Ag/ZnO NPs at different time intervals.

These findings were substantiated by viable cell count analyses conducted at 400 μg·mL⁻¹ concentration for both NP types, as presented in Table 2. The result showed that Ag/ZnO NPs induced a bactericidal effect within 6 h, whereas ZnO NPs only caused a moderate reduction in CFU/mL after 24 h in all tested strains.

Table 2

Viable count growth measurements in CFU/mL in the presence of ZnO NPs and Ag/ZnO NPs for both Gram-positive and Gram-negative bacterial strains

Gram-positive bacteria
Time (h) B. subtilis S. aureus
Control ZnO NPs Ag/ZnO NPs Control ZnO NPs Ag/ZnO NPs
0 112 × 105 115 × 105 ± 10 113 × 105 ± 10 112 × 105 115 × 105 ± 10 115 × 105 ± 10
3 116 × 105 121 × 105 ± 10 105 × 105 ± 10 116 × 105 122 × 105 ± 10 108 × 105 ± 12
6 108 × 105 113 × 103 ± 15 No growth 118 × 105 108 × 104 ± 12 No growth
12 128 × 106 108 × 102 ± 15 No growth 108 × 106 118 × 103 ± 10 No growth
24 130 × 106 103 × 102 ± 15 No growth 102 × 106 102 × 103 ± 12 No growth
Gram-negative bacteria
Time (h) E. coli P. aeruginosa
Control ZnO NPs Ag/ZnO NPs Control ZnO NPs Ag/ZnO NPs
0 122 × 104 120 × 104 ± 10 112 × 105 ± 10 132 × 104 130 × 104 ± 10 120 × 105 ± 12
3 125 × 104 118 × 104 ± 10 102 × 105 ± 10 145 × 104 145 × 104 ± 10 116 × 105 ± 10
6 160 × 104 113 × 104 ± 15 No growth 150 × 105 140 × 104 ± 12 No growth
12 182 × 105 102 × 103 ± 10 No growth 190 × 106 122 × 103 ± 12 No growth
24 186 × 105 101 × 102 ± 10 No growth 180 × 106 116 × 102 ± 10 No growth

3.4 Antioxidant activity

DPPH radical scavenging activity of M. imbricata leaf extract, biogenic ZnO NPs, and Ag/ZnO NPs was assessed and compared with the reference standard ascorbic acid. The results of antioxidant potential of M. imbricata extract and pre-synthesized Ag/ZnO NPs are presented in Table 3. The results revealed that the M. imbricata extract exhibited strong free radical scavenging potential (78.36 ± 0.02) compared to biogenic Ag/ZnO NPs (59.31 ± 0.30). This study indicated a concentration-dependent increase in the percentage of free radical inhibition (Table 3). However, the standard (ascorbic acid), demonstrated DPPH radical scavenging capabilities that were noticeably greater than those of the M. imbricata extract and biogenic Ag/ZnO NPs. The concentration of the test samples required to scavenge 50% of DPPH free radicals (IC50) was also computed, and IC50 values for the M. imbricata extract and biogenic Ag/ZnO NPs were 48.72 and 81.48 μg·mL−1, respectively. Higher levels of antioxidant activity are indicated by lower IC50 values. Thus, the antioxidant potential of leaf extract was found to be higher than the biogenic Ag/ZnO NPs as well as ZnO NPs in this study.

Table 3

Antioxidant activity of M. imbricata extract, biogenic ZnO NPs, and Ag/ZnO NPs by using the DPPH assay

Sample Concentration (μg·mL−1) DPPH percentage inhibition (mean ± SD) IC50 (μg·mL−1)
M. imbricata extract 50 53.21 ± 0.48 48.72
100 62.45 ± 0.25
150 78.36* ± 0.02
ZnO NPs 50 29.27 ± 0.12 76.41
100 46.15 ± 0.24
150 61.27 ± 0.22
Ag/ZnO NPs 50 30.50 ± 0.32 81.51
100 42.26 ± 0.42
150 59.31* ± 0.03
Ascorbic acid 50 58.62 ± 0.45 32.52
100 76.45 ± 0.28
150 89.51* ± 0.12

Values indicated were mean ± standard deviation; *shows (p < 0.01) compared to positive control.

The strong antioxidant capability of plant extract can be attributed to the presence of a variety of chemical components (flavonoids, phenols, tannins, and terpenoids) in the extract [37,70]. However, the decrease in bioactive components, modification of the chemical structure, interaction with ZnO in ZnO NPs and Ag-doped ZnO NPs in Ag/ZnO NPs, and incompatibility of the formed NPs could be the reason for decline in the antioxidant potential of the formed ZnO NPs and Ag/ZnO NPs. The production of ZnO NPs and Ag/ZnO composite involves a number of chemical reactions that could degrade or alter the bioactive compounds responsible for antioxidant properties. Consequently, ZnO NPs and Ag/ZnO NPs may contain less amount of these compounds, which would reduce their antioxidant activity. Although the scavenging activity of standard ascorbic acid and the plant extract was significantly higher than that of Ag/ZnO NPs and ZnO NPs, their antioxidant activity improved with increasing concentrations. Consistent findings in the literature report that Ag/ZnO NPs and ZnO NPs synthesized using different plant extracts also demonstrate appreciable antioxidant potential [48,71]. The scavenging mechanism of ZnO NPs and Ag/ZnO NPs relies on their ability to neutralize free radicals and ROS [24]. This process involves the adsorption of free radicals and ROS onto the NP surface, followed by electron transfer from ZnO NPs and Ag/ZnO NPs to stabilize the radicals, leading to the formation of ZnO and silver oxide species that contribute to ROS scavenging.

4 Conclusions

The study demonstrated an efficient, simple, and environmentally benign green approach to synthesize Ag/ZnO NPs utilizing the leaf extract from M. imbricata as a mediating agent. The formation of Ag/ZnO NPs was confirmed by the structural and optical characterization results, which showed that the NPs were pure and entirely made up of nano-sized Ag and ZnO particles. The crystal structure of biogenic Ag/ZnO NPs was verified by XRD patterns, and the SEM/TEM images showed a spherical morphology with 28.12 nm average size. The formed Ag/ZnO NPs, ZnO NPs, and M. imbricata were evaluated for antibacterial and antioxidant potential. The antibacterial evaluation revealed that Ag/ZnO NPs exhibited strong activity against two human pathogenic bacteria, E. coli and P. aeruginosa, indicating their potential as environmentally friendly antimicrobial agents. The enhanced antibacterial efficacy is attributed to the synergistic effects of silver and zinc oxide, which induce membrane rupture, disrupt essential cellular functions, and generate ROS, ultimately leading to microbial cell death. This study contributes to the expanding field of hybrid NPs with superior antibacterial properties. The antioxidant assessment revealed that the leaf extract of M. imbricata exerted higher antioxidant potential with an IC50 value of 48.72 μg·mL−1 compared to as-synthesized ZnO NPs (ZnO NPs [IC50 = 76.41 μg·mL−1] and Ag/ZnO NPs [81.51 μg·mL−1]). In conclusion, the findings of this study underscore the potential of Ag/ZnO NPs synthesized using the M. imbricata extract as effective biological agents. These nanostructures present a promising alternative to conventional drugs in addressing multi-drug-resistant pathogens. Nevertheless, further investigations are essential to elucidate the underlying biochemical pathways and mechanisms responsible for their antibacterial and antioxidant activities. Future research should aim to optimize synthesis parameters to enhance their efficacy and explore broader biomedical and environmental applications, facilitating the development of advanced functional nanomaterials.

Acknowledgments

The authors gratefully acknowledge the support offered by the Scientific Research Unit, Inaya Medical Colleges, Saudi Arabia.

  1. Funding information: This research project was supported by the Ongoing Researchers Funding Program (ORF-2025-377), King Saud University, Riyadh, Saudi Arabia.

  2. Author contributions: G.A.A. contributed to conceptualization; M.A. and N.M.A. carried out formal analysis, visualization, and data curation; M.H. was responsible for figure preparation and validation; H.M.A. contributed to biological methodology, writing, review, and editing; S.A. contributed to writing, review, and editing. All authors have read and approved the final version of the manuscript.

  3. Conflict of interest: The authors state no conflict of interest.

  4. Data availability statement: All data generated or analysed during this study are included in this published article.

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Received: 2025-01-04
Accepted: 2025-08-05
Published Online: 2025-09-16

© 2025 the author(s), published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

  1. Research Articles
  2. Optimized green synthesis of silver nanoparticles from guarana seed skin extract with antibacterial potential
  3. Green adsorbents for water remediation: Removal of Cr(vi) and Ni(ii) using Prosopis glandulosa sawdust and biochar
  4. Green approach for the synthesis of zinc oxide nanoparticles from methanolic stem extract of Andrographis paniculata and evaluation of antidiabetic activity: In silico GSK-3β analysis
  5. Development of a green and rapid ethanol-based HPLC assay for aspirin tablets and feasibility evaluation of domestically produced bioethanol in Thailand as a sustainable mobile phase
  6. A facile biodegradation of polystyrene microplastic by Bacillus subtilis
  7. Enhanced synthesis of fly ash-derived hydrated sodium silicate adsorbents via low-temperature alkaline hydrothermal treatment for advanced environmental applications
  8. Impact of metal nanoparticles biosynthesized using camel milk on bacterial growth and copper removal from wastewater
  9. Preparation of Co/Cr-MOFs for efficient removal of fleroxacin and Rhodamine B
  10. Applying nanocarbon prepared from coal as an anode in lithium-ion batteries
  11. Improved electrochemical synthesis of Cu–Fe/brass foil alloy followed by combustion for high-efficiency photoelectrodes and hydrogen production in alkaline solutions
  12. Precipitation of terephthalic acid from post-consumer polyethylene terephthalate waste fractions
  13. Biosynthesized zinc oxide nanoparticles: Multifunctional potential applications in anticancer, antibacterial, and B. subtilis DNA gyrase docking
  14. Anticancer and antimicrobial effects of green-synthesized silver nanoparticles using Teucrium polium leaves extract
  15. Green synthesis of eco-friendly bioplastics from Chlorella and Lithothamnion algae for safe and sustainable solutions for food packaging
  16. Optimizing coal water slurry concentration via synergistic coal blending and particle size distribution
  17. Green synthesis of Ag@Cu and silver nanowire using Pterospermum heterophyllum extracts for surface-enhanced Raman scattering
  18. Green synthesis of copper oxide nanoparticles from Algerian propolis: Exploring biochemical, structural, antimicrobial, and anti-diabetic properties
  19. Simultaneous quantification of mefenamic acid and paracetamol in fixed-dose combination tablet dosage forms using the green HPTLC method
  20. Green synthesis of titanium dioxide nanoparticles using green tea (Camellia sinensis) extract: Characteristics and applications
  21. Pharmaceutical properties for green fabricated ZnO and Ag nanoparticle-mediated Borago officinalis: In silico predications study
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  24. Sustainable green synthesis of silver nanoparticles using walnut septum waste: Characterization and antibacterial properties
  25. Efficient electrocatalytic reduction of CO2 to CO over Ni/Y diatomic catalysts
  26. Greener and magnetic Fe3O4 nanoparticles as a recyclable catalyst for Knoevenagel condensation and degradation of industrial Congo red dye
  27. Recycling of HDPE-giant reed composites: Processability and performance
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  31. Green-synthesized chromium oxide nanoparticles using pomegranate husk extract: Multifunctional bioactivity in antioxidant potential, lipase and amylase inhibition, and cytotoxicity
  32. Therapeutic potential of sustainable zinc oxide nanoparticles biosynthesized using Tradescantia spathacea aqueous leaf extract
  33. Chitosan-coated superparamagnetic iron oxide nanoparticles synthesized using Carica papaya bark extract: Evaluation of antioxidant, antibacterial, and anticancer activity of HeLa cervical cancer cells
  34. Antioxidant potential of peptide fractions from tuna dark muscle protein isolate: A green enzymatic approach
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  36. Optimization of cellulose yield from oil palm trunks with deep eutectic solvents using response surface methodology
  37. Nitrogen-doped carbon dots from Brahmi (Bacopa monnieri): Metal-free probe for efficient detection of metal pollutants and methylene blue dye degradation
  38. High energy density pseudocapacitor based on a nanoporous tungsten(VI) oxide iodide/poly(2-amino-1-mercaptobenzene) composite
  39. Green synthesized Ag–Cu nanocomposites as an improved strategy to fight multidrug-resistant bacteria by inhibition of biofilm formation: In vitro and in silico assessment study
  40. In vitro evaluation of antibacterial activity and associated cytotoxicity of biogenic silver nanoparticles using various extracts of Tabernaemontana ventricosa
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  43. Kinetics and synthesis of formation of phosphate composites from low-grade phosphorites in the presence of phosphate–siliceous shales and oil sludge
  44. Removal of minocycline and terramycin by graphene oxide and Cr/Mn base metal–organic framework composites
  45. Microfluidic preparation of ceramide E liposomes and properties
  46. Therapeutic potential of Anamirta cocculus (L.) Wight & Arn. leaf aqueous extract-mediated biogenic gold nanoparticles
  47. Antioxidant-rich Micromeria imbricata leaf extract as a medium for the eco-friendly preparation of silver-doped zinc oxide nanoparticles with antibacterial properties
  48. Influence of different colors with light regime on Chlorella sp., biomass, pigments, and lipids quantity and quality
  49. Experimental vibrational analysis of natural fiber composite reinforced with waste materials for energy absorbing applications
  50. Green synthesis of sea buckthorn-mediated ZnO nanoparticles: Biological applications and acute nanotoxicity studies
  51. Production of liquid smoke by consecutive electroporation and microwave-assisted pyrolysis of empty fruit bunches
  52. Synthesis of MPAA based on polyacrylamide and gossypol resin and applications in the encapsulation of ammophos
  53. Application of iron-based catalysts in the microwave treatment of environmental pollutants
  54. Enhanced adsorption of Cu(ii) from wastewater using potassium humate-modified coconut husk biochar
  55. Adsorption of heavy metal ions from water by Fe3O4 nano-particles
  56. Green synthesis of parsley-derived silver nanoparticles and their enhanced antimicrobial and antioxidant effects against foodborne resistant bacteria
  57. Unwrapping the phytofabrication of bimetallic silver–selenium nanoparticles: Antibacterial, Anti-virulence (Targeting magA and toxA genes), anti-diabetic, antioxidant, anti-ovarian, and anti-prostate cancer activities
  58. Optimizing ultrasound-assisted extraction process of anti-inflammatory ingredients from Launaea sarmentosa: A novel approach
  59. Eggshell membranes as green carriers for Burkholderia cepacia lipase: A biocatalytic strategy for sustainable wastewater bioremediation
  60. Research progress of deep eutectic solvents in fuel desulfurization
  61. Enhanced electrochemical synthesis of Ni–Fe/brass foil alloy with subsequent combustion for high-performance photoelectrode and hydrogen production applications
  62. Valorization of baobab fruit shell as a filler fiber for enhanced polyethylene degradation and soil fertility
  63. Valorization of Agave durangensis bagasse for cardboard-type paper production circular economy approach
  64. Green priming strategies using seaweed extract and citric acid to improve early growth and antioxidant activity in lentil
  65. Review Article
  66. Sustainable innovations in garlic extraction: A comprehensive review and bibliometric analysis of green extraction methods
  67. Natural sustainable coatings for marine applications: advances, challenges, and future perspectives
  68. Integration of traditional medicinal plants with polymeric nanofibers for wound healing
  69. Rapid Communication
  70. In situ supported rhodium catalyst on mesoporous silica for chemoselective hydrogenation of nitriles to primary amines
  71. Special Issue: Valorisation of Biowaste to Nanomaterials for Environmental Applications
  72. Valorization of coconut husk into biochar for lead (Pb2+) adsorption
  73. Corrigendum
  74. Corrigendum to “An updated review on carbon nanomaterials: Types, synthesis, functionalization and applications, degradation and toxicity”
https://doi.org/10.1515/gps-2025-0003
Keywords for this article
Micromeria imbricata; silver-doped zinc oxide; nanoparticles; antibacterial; antioxidant
Creative Commons
BY 4.0

Articles in the same Issue

  1. Research Articles
  2. Optimized green synthesis of silver nanoparticles from guarana seed skin extract with antibacterial potential
  3. Green adsorbents for water remediation: Removal of Cr(vi) and Ni(ii) using Prosopis glandulosa sawdust and biochar
  4. Green approach for the synthesis of zinc oxide nanoparticles from methanolic stem extract of Andrographis paniculata and evaluation of antidiabetic activity: In silico GSK-3β analysis
  5. Development of a green and rapid ethanol-based HPLC assay for aspirin tablets and feasibility evaluation of domestically produced bioethanol in Thailand as a sustainable mobile phase
  6. A facile biodegradation of polystyrene microplastic by Bacillus subtilis
  7. Enhanced synthesis of fly ash-derived hydrated sodium silicate adsorbents via low-temperature alkaline hydrothermal treatment for advanced environmental applications
  8. Impact of metal nanoparticles biosynthesized using camel milk on bacterial growth and copper removal from wastewater
  9. Preparation of Co/Cr-MOFs for efficient removal of fleroxacin and Rhodamine B
  10. Applying nanocarbon prepared from coal as an anode in lithium-ion batteries
  11. Improved electrochemical synthesis of Cu–Fe/brass foil alloy followed by combustion for high-efficiency photoelectrodes and hydrogen production in alkaline solutions
  12. Precipitation of terephthalic acid from post-consumer polyethylene terephthalate waste fractions
  13. Biosynthesized zinc oxide nanoparticles: Multifunctional potential applications in anticancer, antibacterial, and B. subtilis DNA gyrase docking
  14. Anticancer and antimicrobial effects of green-synthesized silver nanoparticles using Teucrium polium leaves extract
  15. Green synthesis of eco-friendly bioplastics from Chlorella and Lithothamnion algae for safe and sustainable solutions for food packaging
  16. Optimizing coal water slurry concentration via synergistic coal blending and particle size distribution
  17. Green synthesis of Ag@Cu and silver nanowire using Pterospermum heterophyllum extracts for surface-enhanced Raman scattering
  18. Green synthesis of copper oxide nanoparticles from Algerian propolis: Exploring biochemical, structural, antimicrobial, and anti-diabetic properties
  19. Simultaneous quantification of mefenamic acid and paracetamol in fixed-dose combination tablet dosage forms using the green HPTLC method
  20. Green synthesis of titanium dioxide nanoparticles using green tea (Camellia sinensis) extract: Characteristics and applications
  21. Pharmaceutical properties for green fabricated ZnO and Ag nanoparticle-mediated Borago officinalis: In silico predications study
  22. Synthesis and optimization of gemcitabine-loaded nanoparticles by using Box–Behnken design for treating prostate cancer: In vitro characterization and in vivo pharmacokinetic study
  23. A comparative analysis of single-step and multi-step methods for producing magnetic activated carbon from palm kernel shells: Adsorption of methyl orange dye
  24. Sustainable green synthesis of silver nanoparticles using walnut septum waste: Characterization and antibacterial properties
  25. Efficient electrocatalytic reduction of CO2 to CO over Ni/Y diatomic catalysts
  26. Greener and magnetic Fe3O4 nanoparticles as a recyclable catalyst for Knoevenagel condensation and degradation of industrial Congo red dye
  27. Recycling of HDPE-giant reed composites: Processability and performance
  28. Fabrication of antibacterial chitosan/PVA nanofibers co-loaded with curcumin and cefadroxil for wound healing
  29. Cost-effective one-pot fabrication of iron(iii) oxychloride–iron(iii) oxide nanomaterials for supercapacitor charge storage
  30. Novel trimetallic (TiO2–MgO–Au) nanoparticles: Biosynthesis, characterization, antimicrobial, and anticancer activities
  31. Green-synthesized chromium oxide nanoparticles using pomegranate husk extract: Multifunctional bioactivity in antioxidant potential, lipase and amylase inhibition, and cytotoxicity
  32. Therapeutic potential of sustainable zinc oxide nanoparticles biosynthesized using Tradescantia spathacea aqueous leaf extract
  33. Chitosan-coated superparamagnetic iron oxide nanoparticles synthesized using Carica papaya bark extract: Evaluation of antioxidant, antibacterial, and anticancer activity of HeLa cervical cancer cells
  34. Antioxidant potential of peptide fractions from tuna dark muscle protein isolate: A green enzymatic approach
  35. Clerodendron phlomoides leaf extract-mediated synthesis of selenium nanoparticles for multi-applications
  36. Optimization of cellulose yield from oil palm trunks with deep eutectic solvents using response surface methodology
  37. Nitrogen-doped carbon dots from Brahmi (Bacopa monnieri): Metal-free probe for efficient detection of metal pollutants and methylene blue dye degradation
  38. High energy density pseudocapacitor based on a nanoporous tungsten(VI) oxide iodide/poly(2-amino-1-mercaptobenzene) composite
  39. Green synthesized Ag–Cu nanocomposites as an improved strategy to fight multidrug-resistant bacteria by inhibition of biofilm formation: In vitro and in silico assessment study
  40. In vitro evaluation of antibacterial activity and associated cytotoxicity of biogenic silver nanoparticles using various extracts of Tabernaemontana ventricosa
  41. Fabrication of novel composite materials by impregnating ZnO particles into bacterial cellulose nanofibers for antimicrobial applications
  42. Solidification floating organic drop for dispersive liquid–liquid microextraction estimation of copper in different water samples
  43. Kinetics and synthesis of formation of phosphate composites from low-grade phosphorites in the presence of phosphate–siliceous shales and oil sludge
  44. Removal of minocycline and terramycin by graphene oxide and Cr/Mn base metal–organic framework composites
  45. Microfluidic preparation of ceramide E liposomes and properties
  46. Therapeutic potential of Anamirta cocculus (L.) Wight & Arn. leaf aqueous extract-mediated biogenic gold nanoparticles
  47. Antioxidant-rich Micromeria imbricata leaf extract as a medium for the eco-friendly preparation of silver-doped zinc oxide nanoparticles with antibacterial properties
  48. Influence of different colors with light regime on Chlorella sp., biomass, pigments, and lipids quantity and quality
  49. Experimental vibrational analysis of natural fiber composite reinforced with waste materials for energy absorbing applications
  50. Green synthesis of sea buckthorn-mediated ZnO nanoparticles: Biological applications and acute nanotoxicity studies
  51. Production of liquid smoke by consecutive electroporation and microwave-assisted pyrolysis of empty fruit bunches
  52. Synthesis of MPAA based on polyacrylamide and gossypol resin and applications in the encapsulation of ammophos
  53. Application of iron-based catalysts in the microwave treatment of environmental pollutants
  54. Enhanced adsorption of Cu(ii) from wastewater using potassium humate-modified coconut husk biochar
  55. Adsorption of heavy metal ions from water by Fe3O4 nano-particles
  56. Green synthesis of parsley-derived silver nanoparticles and their enhanced antimicrobial and antioxidant effects against foodborne resistant bacteria
  57. Unwrapping the phytofabrication of bimetallic silver–selenium nanoparticles: Antibacterial, Anti-virulence (Targeting magA and toxA genes), anti-diabetic, antioxidant, anti-ovarian, and anti-prostate cancer activities
  58. Optimizing ultrasound-assisted extraction process of anti-inflammatory ingredients from Launaea sarmentosa: A novel approach
  59. Eggshell membranes as green carriers for Burkholderia cepacia lipase: A biocatalytic strategy for sustainable wastewater bioremediation
  60. Research progress of deep eutectic solvents in fuel desulfurization
  61. Enhanced electrochemical synthesis of Ni–Fe/brass foil alloy with subsequent combustion for high-performance photoelectrode and hydrogen production applications
  62. Valorization of baobab fruit shell as a filler fiber for enhanced polyethylene degradation and soil fertility
  63. Valorization of Agave durangensis bagasse for cardboard-type paper production circular economy approach
  64. Green priming strategies using seaweed extract and citric acid to improve early growth and antioxidant activity in lentil
  65. Review Article
  66. Sustainable innovations in garlic extraction: A comprehensive review and bibliometric analysis of green extraction methods
  67. Natural sustainable coatings for marine applications: advances, challenges, and future perspectives
  68. Integration of traditional medicinal plants with polymeric nanofibers for wound healing
  69. Rapid Communication
  70. In situ supported rhodium catalyst on mesoporous silica for chemoselective hydrogenation of nitriles to primary amines
  71. Special Issue: Valorisation of Biowaste to Nanomaterials for Environmental Applications
  72. Valorization of coconut husk into biochar for lead (Pb2+) adsorption
  73. Corrigendum
  74. Corrigendum to “An updated review on carbon nanomaterials: Types, synthesis, functionalization and applications, degradation and toxicity”
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