Volume 97, Issue 3

Organic–inorganic composite antibacterial materials based on silver phthalocyanine-silver (AgPc/Ag) and aminosilane-modified silicate (Ormosil) were synthesized by sol-gel method and in-situ reduction method. The objective of this study was not only the synthesis of Pc-Ormosil and AgPc-Ormosil/Ag composites but also investigated the bacteriostatic ability of the Pc-Ormosil and AgPc-Ormosil/Ag modified fabrics and the relationship between the antibacterial property and the content of composites on non-woven fabric was discussed. Moreover, the laundering durability of the bacteriostatic of the AgPc-Ormosil/Ag-treated fabrics was also examined. The bacteriostatic ability of the Pc-Ormosil and AgPc-Ormosil/Ag modified fabrics against Gram-negative Pseudomonas aeruginosa , Escherichia coli and Gram-positive Staphylococcus aureus , Bacillus subtilis were confirmed by the zone of inhibition and the plate-counting method. The bacteriostatic ability remains even after one laundry cycle.

A rapid colorimetric assay for the dual detection of Fe 3+ and Cr 3+ using gold nanoparticles (AuNPs) capped with α-cyclodextrin was developed. The synthesized AuNPs produced a red wine color with a particle size of 8.60 ± 1.55 nm and were stable for 9 months. Detection of Fe 3+ and Cr 3+ changed the color of the AuNPs solution to bluish purple with a detection time of <1 and 10 min, respectively. Reaction of the AuNPs with Fe 3+ and Cr 3+ also increased the particle size of the AuNPs to 16.18 ± 2.28 nm and 17.33 ± 1.71 nm, respectively. Characterization of the AuNPs using Fourier-transform infrared spectroscopy and X-ray diffraction showed that the presence of Fe 3+ would damage the structure of the AuNPs, whereas Cr 3+ would not. This colorimetric sensor is sensitive toward Fe 3+ and Cr 3+ with limits of detection of 265.92 and 430.80 μg/L, respectively. The dual ion sensing ability of the AuNPs was also assessed by individually detecting Fe 3+ and Cr 3+ in tap water samples in South Tangerang, Banten, Indonesia.

Activated carbon was prepared at 300 °C and 600 °C, characterized by SEM, EDX and XRD, and was then used as an adsorbent for the removal of acidic dyes; acid yellow 25 and acid red 4. The activated carbon prepared at high temperature (600 °C) due to its high carbon contents and surface area was subsequently used as adsorbent for the selected dyes adsorption using batch adsorption approaches to estimate different adsorption parameters. For the estimation of kinetics and equilibrium parameters a number of kinetics and isotherm models were employed. Dyes were adsorbed on activated carbon surface at a high rate for the first 15 min, after which it began to diffuse into the micro pores and thus the process became steady. The rate constant was estimated for first and second order kinetics models. The maximum adsorption capacities recorded were 526.32 mg g −1 for acid red 4 and 555.55 mg g −1 for acid yellow 25. The enthalpy change values recorded were; 19.44 kJ mol −1 for acid yellow 25 adsorption and 16 kJ mol −1 for acid red 4 adsorption, meant that the process is endothermic. The negative values of Gibbs free energy change (−393.28, −1,515.48, −2,634.68 J mol −1 ) of acid red 4 and acid yellow 25 (−251.72, −1,058.06, −2,367.84 J mol −1 ) at tested temperatures, confirmed the feasibility and spontaneity of the adsorption processes. The adsorption of dyes on the carbon surface was diffusion-controlled process, as demonstrated by the linear graph of intraparticle diffusion model.

A smartphone-assisted microchemistry analyzer with an image-based colorimetric assay using ImageJ and a smartphone app detection method was successfully developed for the quantitative detection of melamine (MEL). The color changes of the MEL in the colloidal gold lateral flow immunoassay strip were captured and analyzed using a smartphone-controlled analyzer with an LED light source and a smartphone camera. The smartphone camera and light source were used to read the colorimetric signal from the strip, and a smartphone app was written and installed onto the smartphone. The quantitative analysis was validated with ImageJ and smartphone app colorimetric analysis. The limits of detection (LODs) for ImageJ and the smartphone app were calculated as 0.30 and 0.07 mg/L, respectively. The highly quantitative relationships between the MEL concentrations and the optical density and gray value of the ImageJ and smartphone app detection method. The designed image-based biosensor is successfully applied to detect MEL in solution of standard MEL and commercial milk samples.

Ti-6Al-4V metal is widely used as an implantable material due to its biocompatibility and corrosion resistance; however, it has low bioactive properties. The formation of nanotubes and a hydroxyapatite-polyvinyl alcohol-collagen composite coating on Ti-6Al-4V metal aims to enhance its biocompatibility and bioactivity. The nanotube oxide layer Ti-6Al-4V was formed by the anodization method. The composite’s infrared spectrum showed characteristic absorption bands from Hydroxyapatite (HAp), polyvinyl alcohol, and collagen. The composite-coated Ti-6Al-4V metal, both non-nanotube, and nanotube, showed a typical diffraction pattern of HAp and titanium element. The electron microscope image showed the uniform granular form of HAp. The corrosion test results showed that composite-coated nanotube Ti-6Al-4V metal could not improve corrosion resistance. It is also relevant to the in vitro test in a lactate ringer solution that showed the higher Ca 2+ ion of nanotube Ti-6Al-4V metal than that of non-nanotube Ti-6Al-4V metal.

Cacumen platyclade extracts were utilized as the reducing agent to prepare Au/Al 2 O 3 composites. XRD, BET, SEM, TEM were employed to characterize the properties of the catalyst. The catalytic activity of Au/Al 2 O 3 was studied by using NaBH 4 as the reducing agent and nitrophenol as the pollutant. The results showed that the Au/Al 2 O 3 catalyst, calcinated at 400 °C, exhibited the highest catalytic activity. With a catalyst dosage of 1 g L −1 , 2 mL NaBH 4 of 0.15 mol L −1 could degrade 96.5 % nitrophenol in 21 min at 298 K, with a reaction constant of 0.16 min −1 . Furthermore, the p -nitrophenol degradation ratio decreased by 0.8 % after ten cycles.

A nanocomposite scaffold was developed using gelzan, a natural extracellular polysaccharide, as the biopolymer matrix. Gelzan (GZ) was combined with Ag/Fe 2 ⁺ co-doped hydroxyapatite (HAp) particles to enhance the scaffold’s biological properties. The aim of incorporating Ag/Fe 2 ⁺ co-doped HAp was to utilize the combined antibacterial and bioactive properties of these components. The synthesized Ag/Fe 2 ⁺ co-doped HAp nanoparticles, along with the gelzan-based nanocomposite scaffold produced via freeze-drying, underwent comprehensive analyses. These included Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and biological assessments for antibacterial activity and bioactivity. The results demonstrated that the Ag/Fe 2 ⁺ co-doped HAp nanocomposite scaffold possessed favourable physicochemical properties. Furthermore, the integration of Ag and Fe 2 ⁺ co-doped HAp into the gelzan matrix was confirmed, revealing the scaffold’s structural and compositional characteristics. Tests of apatite formation in simulated body fluid (SBF) indicated the development of layered apatite precipitates after 7 days. The scaffold also exhibited significant antibacterial activity, with inhibition zones of 7.35 ± 0.70 mm and 5.54 ± 0.60 mm against Staphylococcus aureus and Escherichia coli , respectively. These findings suggest the scaffold’s promising potential as a biomaterial for bone tissue regeneration.