Biosynthesis of Ag/Cu nanocomposite mediated by Curcuma longa: Evaluation of its antibacterial properties against oral pathogens

Huanfang Yan; Li Wang; Yanfei Mu

doi:10.1515/chem-2024-0059

Article Open Access

Biosynthesis of Ag/Cu nanocomposite mediated by Curcuma longa: Evaluation of its antibacterial properties against oral pathogens

Huanfang Yan , Li Wang and Yanfei Mu

Published/Copyright: August 6, 2024

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From the journal Open Chemistry Volume 22 Issue 1

Abstract

Curcuma longa is a popular plant around the world with various applications in food and medicinal aspects. An investigation has been conducted on the formulation of Ag/Cu nanocomposite by C. longa as a natural stabilizing agent, without the use of any toxic or harmful reagents. This bio-inspired approach is focused on applicative, facile, and green chemical research. The study also explored the potential of Ag/Cu nanocomposite to prevent dental bacteria growth and prevent adherence in vitro. The biomediated Ag/Cu@ turmeric NCs were characterized by advanced physicochemical techniques. The FE-SEM imaging has established that Ag/Cu@ turmeric has a semi-spherical shape (60.92 nm). The crystallinity of nanocomposite has been confirmed by the XRD technique. Subsequently, the biological activity of the Ag/Cu nanocomposite functionalized with biomolecules was examined. The concentration of 1,000 µg/mL showed the most effective minimum inhibitory concentrations (MICs) against Porphyromonas gingivalis and Streptococcus mutans (MIC = 16 µg/mL) during the investigation. The addition of Ag/Cu nanocomposite (MIC = 32 µg/mL) significantly hindered the S. mutans in vitro adherence. According to the findings of this research, Ag/Cu nanocomposite could potentially serve as an effective oral hygiene agent for managing periodontopathic and dental caries conditions.

Keywords: oral bacteria; Curcuma longa ; silver/copper nanocomposite; Streptococcus mutans ; Porphyromonas gingivalis

1 Introduction

More than 700 distinct types of bacteria have been identified in the oral cavity, with the average person usually hosting between 34 and 72 species [1,2,3]. The vast majority of these bacteria pose no threat to our well-being, with some even aiding in the digestive process. Additionally, specific bacteria help in keeping our teeth and gums healthy [3,4,5,6,7]. Tooth decay and cavities develop when food particles rich in carbohydrates, such as sugar and starch found in candy, cakes, fruits, soft drinks, milk, cereal, or bread, are left on the teeth [8,9,10]. The food remnants present in the mouth are transformed into acid by the bacteria that inhabit it. This acid, along with saliva, bacteria, and food particles, combines to create plaque, which attaches itself to the teeth [11,12,13]. Tooth decay is mainly attributed to specific bacteria, notably Porphyromonas gingivalis and Streptococcus mutans [14,15,16,17]. S. mutans inhabits the oral cavity and feeds on sugars and starches. Although this is not directly harmful, the bacteria’s consumption of food results in acid formation in the mouth, ultimately causing erosion of the tooth enamel [15,16]. As a result, S. mutans is considered the main culprit behind tooth decay in humans. P. gingivalis typically does not inhabit the oral cavity, however, its presence can lead to periodontitis, an advanced and severe gum disease that harms the supporting tissues and bones of the teeth. This condition is extremely incapacitating, causing considerable discomfort for the individual and possibly resulting in tooth loss [16,17].

The existence of harmful streptococci species, like mutant streptococci, in the oral cavity may result in the formation of cavities and eventual costs for treatment or tooth extraction. Hence, it is essential to identify compounds that can diminish or eliminate these bacterial species [15,16]. Recently, there has been a big use of medicinal plants and herbal remedies based on local traditional wisdom for disease prevention and treatment [16,17]. The inclusion of herbal extracts in gums, toothpaste, and mouthwash is a significant aspect of this current trend. The surge in bacterial resistance, along with the beneficial effectiveness of ethno-medicinal plants in disease treatment, has led to the growing utilization of plant-based products and herbal nanoparticles [18,19]. The growing utilization of herbal nanoparticles in addressing health concerns can be attributed to their improved compatibility with the immune system and the increasing preference for natural resources among individuals [18,19,20]. Recent research has reported that plant nanoparticles possess much stronger antimicrobial efficacies than the plants they originate from, leading to a growing fascination with these nanoparticles [19,20].

Silver has been extensively utilized throughout various civilizations for a multitude of purposes [21]. Ag is widely recognized as an effective antimicrobial agent, capable of combating more than 650 microorganisms across various classes, including fungi, viruses, and bacteria [22]. Silver nanoparticles are being increasingly utilized, with ancient Ayurvedic texts highlighting silver’s medicinal properties for various ailments [21,22]. Among all the metals possessing antimicrobial characteristics, it has been discovered that silver exhibits the most potent antibacterial activity while being the least harmful to animal cells [21]. Ag is commonly utilized in the nitrate form to trigger antimicrobial efficacies. However, the utilization of silver nanoparticles results in a significant augmentation of the surface area accessible for the microbes to come into contact with. Silver nanoparticles produced through plant extracts sourced from various origins have been employed to assess their antimicrobial properties against a variety of microorganisms [18,19,20,21,22].

Curcuma plants have long been utilized in traditional medicine for their effectiveness in treating various immune-related conditions. Numerous scientific studies have been carried out to validate their immunomodulatory properties, supporting their traditional medicinal use. The Curcuma genus comprises six well-known species, including Curcuma longa, Curcuma zanthorrhiza, Curcuma mangga, Curcuma aeruginosa, and Curcuma amada [23]. Turmeric (C. longa) is a widely cultivated plant from the Zingiberaceae family, primarily found in regions of Africa and Asia such as Pakistan, India, China, and Bangladesh. The ground and dried root stocks of C. longa are commonly used as a colorant spice and additive in culinary preparations. Additionally, turmeric is utilized for dyeing fine leathers and silk fabrics due to its vibrant color properties [24,25]. The global popularity of turmeric stems from its diverse applications in cooking, cosmetics, and medicine. This tuberous species is valued for its role as a flavoring and coloring agent, along with its several pharmacological benefits, which include anti-inflammatory, anticancer, antioxidant, neuroprotective, dermatoprotective, antiasthmatic, antiviral, hypoglycemic, and antifungal properties [26,27,28,29]. Its primary bioactive component, curcumin acts as a natural nitrogen provider and active oxygen scavenger [30]. Curcumin, known chemically as diferuloylmethane, is a hydrophobic polyphenolic compound found in abundance in turmeric. It has been traditionally used in Southeast Asian countries for its therapeutic potential against various chronic diseases. Curcumin exhibits a wide range of pharmacological and biological properties, making it a promising candidate for diverse biomedical applications such as antioxidant therapies, anticancer treatments, antiviral interventions, drug delivery systems, and anti-inflammatory remedies. The rhizomes of turmeric varieties are rich in curcuminoids, the primary bioactive compounds, as well as other essential flavonoids and polyphenols like p-coumaric acids, catechins, sinapic acid, ferulic acid, cinnamic acid, and quercetin [31,32].

In the past decade, the green synthesis of metallic nanoparticles has been growing in comparison with the chemical method. The low cost, eco-friendly, and no toxic effects are the main reasons for this desire. An examination was carried out in this research to explore the production of Ag/Cu nanocomposite utilizing C. longa as a natural agent for reduction and stabilization, eliminating the need for any hazardous or harmful substances. This bio-inspired method emphasizes practical, straightforward, and environmentally friendly chemical investigation. Furthermore, because of the anti-inflammation properties of turmeric compared to other popular herbals, the research investigated the capability of Ag/Cu nanocomposite to hinder the growth of dental bacteria and prevent adhesion in a laboratory setting.

2 Experimental

2.1 Materials

Silver nitrate and copper nitrate were purchased from Merck with analytical grade. Mueller Hinton Agar and Mueller Hinton broth were purchased from Conda Prondisa.

2.2 Synthesis of Ag/Cu@ turmeric NCs

Turmeric was chopped to 2–10 mm species. Then, 5 g of turmeric was boiled in 100 mL of ultrapure water for 10 min. After cooling and filtration, 25 mL of turmeric extract was added to the solution of AgNO₃ (0.01 M, 10 mL) and Cu₂NO₃·4H₂O (0.01 M, 10 mL). The pH was adjusted at 8 using NaOH (10%). The reaction mixture was refluxed at 90°C for 75 min. The Ag/Cu@ turmeric NCs were formed as dark gray participants. After that time, the mixture was centrifuged for 10 min at 8,000 RPM to separate the NCs. Finally, Ag/Cu@ turmeric NCs were dried in an oven at 55°C for 3 h.

2.3 Growth inhibition zone (GIZ) of bacteria

Two types of oral bacteria, namely S. mutans and P. gingivalis, were employed in this study. Initially, a 0.5 McFarland turbidity standard was used to prepare the microbial suspension, which was then transferred to Mueller Hinton Agar for cultivation. Subsequently, 70 µL of different concentrations of Ag/Cu@ turmeric NCs were introduced into the disks and wells. In the latest experiment, distilled water was used as the negative control, whereas certain antibiotics were employed as positive controls. The GIZ was evaluated on both wells and disks.

2.4 Minimum inhibitory concentration (MIC) and MBC of bacteria

The MIC was determined using the macro broth dilution technique. Tubes were filled with different concentrations of Ag/Cu@ turmeric NCs, followed by the addition of 70 µL of bacterial suspensions for incubation. Two essential factors for determining the MIC are the absence of turbidity and the lowest concentration. To determine the MBC, 70 µL of the MIC and the four wells before it were plated on Agar. The MBC is determined as the lowest concentration at which no bacterial growth is seen [33].

2.5 Statistical analysis

The antibacterial activity study included analyzing the data with one-way ANOVA in SPSS-22 software. Following this, the mean values were compared using the least notable change approach, with computations carried out at a 1% confidence interval.

3 Results and discussion

The synthesis of Ag/Cu@ turmeric was optimized at different conditions including pHs (6–9), temperatures (70–100°C), and times (45–85). The amount of obtained yields was recorded for each step along with a comparison of the FT-IR spectra of the NPs. For those nanoparticles with the same FT-IR spectra, which showed the metallic bands, the maximum amount was chosen as the optimized conditions. According to the obtained data, the pH of 8, the temperature of 90°C, and the time of 75 min were selected as the best conditions for the green synthesis of Ag/Cu@ turmeric NCs.

3.1 Chemical characterization of Ag/Cu@ turmeric NCs

The FT-IR spectrum of Ag/Cu@ turmeric NCs is presented in Figure 1. The presence of various bands approves the successful synthesis of nanocomposite. The peaks at 459, 519, 571, and 585/cm are related to silver and copper bonds; these peaks are similar to previously reported peaks for the metal bonds [34,35]. The other bands for the organic compounds of turmeric extract that are linked to the surface of nanocomposite are found at 1,081/cm (for C–O bond), 1,530–1,717/cm (for double bonds of C═C, C═O), 2,981/cm (for C–H bond), and 3,335/cm (for O–H bond). In comparison with the FT-IR spectrum of turmeric extract, a little shift in the stretching vibrational bands of different functional groups can be observed. Furthermore, the presence of new bands related to metals corroborates the synthesis of Ag/Cu nanocomposite. The functional groups are abundant in the secondary metabolites of turmeric such as curcumin and other phenolic and flavonoid compounds.

Figure 1

The FT-IR spectra of Ag/Cu@ turmeric NCs and turmeric extract.

The Ag/Cu@ turmeric NC elemental analysis was evaluated by the EDS method. The data are exhibited in Figure 2. The presence of signals in the various energies confirms the existence of silver and copper in the green synthesized nanocomposite. The signals at 0.93, 8.05, and 8.92 keV are assigned for Cu Lα, Cu Kα, and Cu Kβ, respectively. Furthermore, the signals at 3.34 and 3.63 KeV are related to Ag Lα and Ag Lβ. Due to the linkage of organic compounds to the surface of the nanocomposite, the signals at 0.28 and 0.52 keV reveal the presence of oxygen and carbon in Ag/Cu@ turmeric NCs. Previous studies have reported similar signals for silver and copper in nanoparticles that are synthesized using plant extracts.

Figure 2

The EDS diagram of Ag/Cu@ turmeric NCs.

The XRD diagram of Ag/Cu@ turmeric NCs is shown in Figure 3. The technique is a common way to investigate the crystallinity of nanoparticles. The result revealed a crystal structure for Ag/Cu@ turmeric NCs. The presence of different signals at 2 theta values corresponds to Cu and Ag NPs with a little shift for each signal that approves the formation of silver/copper nanocomposite. The signals at 32.43 (110), 35.34 (11–1), 37.83 (111), 57.15 (202), and 67.84 (220) are much closer to data of JCDD PDF card no. 96-901-6327 for copper; while the signals at 37.83(111), 44.12 (200), 64.20 (220), and 76.31 (311) are compatible with JCPD card 04-0783 for silver. The signals are similar to previous reports for the green synthesized silver and copper nanoparticles [36,37].

Figure 3

The XRD pattern of Ag/Cu@ turmeric NCs.

The morphology of Ag/Cu@ turmeric NCs was investigated using FE-SEM and TEM imaging. The method is known as a powerful technique to screen the nanomaterial shape. Figure 4a and b indicates the TEM and FE-SEM images of Ag/Cu@ turmeric NCs. According to the results of both techniques, the particles are formed in a semi-spherical shape with an average size around 70 nm, which is a sufficient size for the material with a nano size. The nanometallic material, which is synthesized using plant extract, shows a tendency to aggregation [38,39,40,41]. It seems the organic compounds as the capping and reducing agents for the synthesis are responsible for these properties. According to previous studies, the stability of nanomaterials depend on the pHs and temperatures as the reaction conditions [42,43,44]. In the present study, both imaging techniques show an aggregate tendency for Ag/Cu@ turmeric NCs similar to the other metallic nanomaterial.

Figure 4

(a) The FE-SEM; (b) TEM images of Ag/Cu@ turmeric NCs.

3.2 Antibacterial efficacy of the Ag/Cu@ turmeric NCs on oral bacterial pathogens

According to the data shown in Tables 1–3, it is clear that there is no notable change (p ≤ 0.01) in the GIZ of the two bacteria when comparing standard antibiotics to Ag/Cu@ turmeric NCs. The maximum GIZ was noted at a concentration of 512 µg/mL in both agar well and disk diffusion assays. It is important to highlight that no inhibitory zone was detected for Ag/Cu@ turmeric NCs at levels of 1, 2, and 4 µg/mL against oral pathogens in the agar well diffusion test (p ≤ 0.01).

Table 1

The GIZ of oral pathogens in several dilutions of Ag/Cu@ turmeric NCs and Ag@ turmeric NPs (p ≤ 0.01)

Dilution (µg/mL)	GIZ in disk diffusion (mm)
Microorganism	S. mutans	P. gingivalis
Difloxacin (30)	34.33333 ± 1.527525^ab	37.66667 ± 1.527525^a
Chloramphenicol (30)	32.66667 ± 1.527525^ab	31 ± 1^ab
Oxytetracycline (30)	26.66667 ± 0.57735^b	37.66667 ± 1.527525^a
Amikacin (25)	28.66667 ± 0.57735^ab	28.66667 ± 1.527525^ab
Ag/Cu@ turmeric NCs (512)	37.33333 ± 2.081666^a	38.66667 ± 0.57735^a
Ag/Cu@ turmeric NCs (256)	35.66667 ± 1.527525^a	34 ± 2^ab
Ag/Cu@ turmeric NCs (128)	33 ± 1.732051^ab	35.33333 ± 1.527525^a
Ag/Cu@ turmeric NCs (64)	26.33333 ± 2.081666^b	31.33333 ± 1.527525^ab
Ag/Cu@ turmeric NCs (32)	25.66667 ± 1.527525^b	25.33333 ± 1.527525^b
Ag/Cu@ turmeric NCs (16)	19.66667 ± 1.527525^bc	19.66667 ± 1.527525^bc
Ag/Cu@ turmeric NCs (8)	15.33333 ± 0.57735^bc	15.66667 ± 2.081666^bc
Ag/Cu@ turmeric NCs (4)	11.33333 ± 1.527525^c	11.66667 ± 1.527525^c
Ag/Cu@ turmeric NCs (2)	9 ± 0^c	9.666667 ± 1.154701^c
Ag/Cu@ turmeric NCs (1)	8.666667 ± 0.57735^c	9.333333 ± 0.57735^c
Ag@ turmeric (512)	31.33333 ± 1.154701^ab	31 ± 1^ab
Ag@ turmeric (256)	24 ± 1^b	27.66667 ± 1.527525^ab
Ag@ turmeric (128)	21.66667 ± 1.527525^b	20.66667 ± 1.527525^b
Ag@ turmeric (64)	18 ± 1^bc	18.66667 ± 2.516611^bc
Ag@ turmeric (32)	13.66667 ± 0.57735^c	12.66667 ± 0.57735^c
Ag@ turmeric (16)	11.66667 ± 1.527525^c	11 ± 1^c
Ag@ turmeric (8)	10.33333 ± 1.154701^c	9.333333 ± 0.57735^c
Ag@ turmeric (4)	LIZ	LIZ
Ag@ turmeric (2)	LIZ	LIZ
Ag@ turmeric (1)	LIZ	LIZ

LIZ: lack of inhibitory zone. ^a,b,c The means with different letters are significantly different in each column.

Table 2

The GIZ of oral pathogens in several dilutions of Ag/Cu@ turmeric NCs and Ag@ turmeric NPs (p ≤ 0.01)

Dilution (µg/mL)	GIZ in well diffusion (mm)
Microorganism	S. mutans	P. gingivalis
Ag/Cu@ turmeric NCs (512)	32.66667 ± 1.527525^a	33.66667 ± 2.081666^a
Ag/Cu@ turmeric NCs (256)	30 ± 0^a	30.66667 ± 2.516611^a
Ag/Cu@ turmeric NCs (128)	27.33333 ± 1.527525^ab	26.66667 ± 0.57735^ab
Ag/Cu@ turmeric NCs (64)	23.66667 ± 1.527525^b	21.66667 ± 1.527525^b
Ag/Cu@ turmeric NCs (32)	18.66667 ± 0.57735^bc	14.33333 ± 1.527525^c
Ag/Cu@ turmeric NCs (16)	13.66667 ± 2.309401^c	11.66667 ± 0.57735^c
Ag/Cu@ turmeric NCs (8)	9.333333 ± 0.57735^c	9.666667 ± 0.57735^c
Ag/Cu@ turmeric NCs (4)	LIZ	LIZ
Ag/Cu@ turmeric NCs (2)	LIZ	LIZ
Ag/Cu@ turmeric NCs (1)	LIZ	LIZ
Ag@ turmeric (512)	21 ± 1^b	22 ± 1^b
Ag@ turmeric (256)	15.66667 ± 1.527525^bc	18.33333 ± 1.527525^bc
Ag@ turmeric (128)	11.66667 ± 0.57735^c	14.66667 ± 1.527525^c
Ag@ turmeric (64)	10.33333 ± 1.154701^c	12.33333 ± 0.57735^c
Ag@ turmeric (32)	LIZ	9.666667 ± 0.57735^c
Ag@ turmeric (16)	LIZ	LIZ
Ag@ turmeric (8)	LIZ	LIZ
Ag@ turmeric (4)	LIZ	LIZ
Ag@ turmeric (2)	LIZ	LIZ
Ag@ turmeric (1)	LIZ	LIZ

LIZ: lack of inhibitory zone. ^a,b,c The means with different letters are significantly different in each column.

Table 3

MBC and MIC of Ag/Cu@ turmeric NCs and Ag@ turmeric NPs against oral pathogens (p ≤ 0.01)

Microorganism	S. mutans	P. gingivalis
MIC_{Ag/Cu@ turmeric NCs} (µg/mL)	16 ± 0^a	16 ± 0^a
MBC_{Ag/Cu@ turmeric NCs} (µg/mL)	32 ± 0^A	32 ± 0^A
MIC_{Ag@ turmeric} (µg/mL)	64 ± 0^b	64 ± 0^b
MBC_{Ag@ turmeric} (µg/mL)	128 ± 0^B	128 ± 0^B

^a,b,A,B The means with different letters are significantly different in each column.

At 8 µg/mL, Ag/Cu nanocomposite inhibited the oral pathogen’s growth and effectively eliminated P. gingivalis and S. mutans at 32 µg/mL. Also, Ag@ turmeric NPs inhibited the oral pathogen’s growth at 64 µg/mL and effectively eliminated P. gingivalis and S. mutans at 128 µg/mL. The findings suggest that Ag/Cu nanocomposite possesses notable antibacterial characteristics against oral pathogens. Additionally, the Ag/Cu nanocomposite displayed the strongest antibacterial impact on P. gingivalis (p ≤ 0.01).

The precise mechanisms behind the antimicrobial or toxic activities of Ag NPs are currently under investigation and remain a topic of much debate. The positive charge carried by the silver ions is believed to have a crucial role in their antimicrobial effects. Silver must be in its ionized form to exhibit any antimicrobial properties. While in this state, silver is inactive; however, when exposed to moisture, it releases silver ions [45,46]. Silver ions (Ag⁺) can create complexes with nucleic acids and show a preference for interacting with nucleosides over the phosphate groups of nucleic acids. Consequently, any silver-based compounds that indicate antimicrobial characteristics are ultimately silver ions (Ag⁺) sources; the silver ions can be integrated into the material and gradually released over time, similar to Ag sulfadiazine. Alternatively, the Ag ions may originate from the ionization of the solid silver object surface, such as Ag NPs [47,48]. Some research has demonstrated the high potential of Ag NPs as effective bactericidal agents [45,46]. These nanoparticles have demonstrated the ability to gather within the membrane and subsequently infiltrate the cells, resulting in harm to the cell membranes or cell wall. It is believed that Ag atoms attach to thiol groups (single-bond SH) of enzymes, creating stable S single-bond Ag bonds with thiol-containing compounds. This, in turn, leads to the enzyme deactivation in the cell membrane that is involved in ion transport and transmembrane energy generation [49–56]. The suggestion was made that the silver(i) ion penetrates the cell and inserts itself between the pyrimidine and purine base pairs, causing a disruption in the hydrogen bonding and resulting in the denaturation of the DNA molecule. The antibacterial properties of bacterial cells may be attributed to cell lysis [48,49,50,51]. Nanoparticles alter the bacterial peptides’ phosphotyrosine profile, subsequently impacting signal transduction and hindering the microorganism’s growth. The antibacterial efficacy is contingent on the dosage and remains unaffected by the bacterial resistance development to antibiotics. The application of silver nanoparticles on Escherichia coli cells has been observed to lead to their accumulation in the bacterial membrane, consequently causing an elevation in permeability and ultimately resulting in cell death [50,51,52].

Gram-negative bacteria are more resistant to Ag⁺ compared to Gram-positive bacteria. This is attributed to the fact that the Gram-negative bacterial cell wall contains fewer peptidoglycan molecules than Gram-positive bacteria [46,47,48,49]. Due to Gram-positive bacteria’s thicker cell walls and the peptidoglycan negative charge, a greater amount of silver ions may become trapped by the peptidoglycan in Gram-positive bacteria compared to Gram-negative bacteria. The Gram-positive bacteria’s reduced susceptibility can also be attributed to the thicker cell wall they possess compared to Gram-negative bacteria [50,51,52,53]. Alternative pathways that entail the silver particles’ interaction with enzymes and DNA by an electron-release process or the generation of free radicals have also been suggested [48,49]. Some literature suggests that silver nanoparticles can induce the inhibition of protein and cell wall synthesis. Proteomic data supports this claim, showing evidence of the envelope protein precursor accumulation or outer membrane destabilization. Ultimately, this causes ATP leaking [50]. Nanosilver demonstrates high efficacy as a rapid-acting fungicide that targets Saccharomyces, Candida, and Aspergillus [51].

The ineffective management of multi-resistant pathogens, caused by antigenic drifts and/or shifts, poses a significant challenge to public health. Consequently, there is a pressing need to create novel virucides and bactericides to combat this resistance to medication. Silver has a rich historical background in its application as a disinfectant and antiseptic [52,53,54,55]. It possesses the ability to interact with the disulfide bonds found in the glycoprotein/protein components of microorganisms like fungi, bacteria, and viruses. This interaction can lead to alterations in the three-dimensional protein structure, thereby hindering the functional processes of the microorganism. Both Ag ions and Ag NPs have been found to have this effect [56,57,58]. The green synthesis route suggests many advantages over chemical and physical methods. First, it is a cost-effective approach that helps in reducing expenses. Second, it is environmentally friendly, contributing to the preservation of our ecosystem. Additionally, this method can be easily scaled up for large-scale synthesis, making it suitable for industrial applications. Moreover, it eliminates the requirement for highly toxic chemicals, temperature, pressure, and energy, ensuring a safer and healthier process [57,58,59,60,61]. The utilization of eco-friendly materials such as enzymes, plant extracts, fungi, and bacteria in the production of Ag NPs provides various advantages in terms of environmental sustainability and suitability for pharmaceutical and biomedical purposes because of the toxic chemicals absence in the synthesis process. The drawbacks necessitated the utilization of innovative and highly developed techniques that paved the way for investigating eco-friendly and sustainable approaches to produce nanoparticles.

4 Conclusion

In summary, a new nanocomposite of silver and copper was green synthesized using a familiar plant extract namely turmeric (C. longa). The nanocomposite was chemically characterized using various imaging and spectroscopic techniques. The XRD analysis revealed the formation of the composite with a crystallite structure with the presence of signals in different 2 theta values for both silver and copper. The FE-SEM images showed a semi-spherical morphology with 60.92 nm for the particles. The FT-IR and EDS analysis confirmed the copper and silver presence with a long of oxygen and carbon, which showed the linkage of plant extract secondary metabolites to the metallic nanocomposite surface. Furthermore, our research revealed that the inclusion of nanocomposite successfully hindered the attachment of S. mutans in a laboratory setting, exhibiting a MIC of 16 µg/mL. Notably, the most potent concentrations against both S. mutans and P. gingivalis were observed at 16 µg/mL. Nanoparticles show potential for a range of medical uses within the realm of pharmacology, especially in the creation of advanced formulations aimed at combating oral pathogens.

List of abbreviations

NCs: nanocomposites
NPs: nanoparticles
EDS: energy-dispersive X-ray spectroscopy
TEM: transmission electron microscopy
FE-SEM: field emission scanning electron microscopes
XRD: X-ray Diffraction
FT-IR: fourier transform infrared spectroscopy
MIC: minimum inhibitory concentration
MBC: minimum bactericidal concentration
GIZ: growth inhibition zone
LIZ: lack of inhibitory zone

Funding information: The authors state no funding involued.
Author contributions: Huanfang Yan: data curation and original draft. Li Wang: investigation, methodology. Yanfei Mu: conceptualization, review, visualization, and editing.
Conflict of interest: The authors state no conflict of interest.
Ethical approval: The conducted research is not related to either human or animal use.
Data availability statement: Data are available on request from the authors.

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Received: 2024-03-31

Revised: 2024-05-12

Accepted: 2024-06-14

Published Online: 2024-08-06

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

Articles in the same Issue

https://doi.org/10.1515/chem-2024-0059

Keywords for this article

oral bacteria; Curcuma longa; silver/copper nanocomposite; Streptococcus mutans; Porphyromonas gingivalis

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