In situ synthesis of bio-green silver nanoparticles incorporated zeolite a using orthosiphon aristatus leaves extract for antibacterial wound healing

Silver in its various forms is well known to have a potent antibacterial property. Despite the high antibacterial activity and efficacy of silver nanoparticles (AgNP), its frequent use could lead to bacterial resistance. Without a proper release mechanism, the efficacy of AgNP is often questioned. Additionally, chemical and physical methods to synthesize AgNP pose threats to the environment and health. Thus, alternative approach using biological resources are desired. However, AgNP produced through this method still needs preclinical evaluation on toxicity and biocompatibility. Thus, a novel in situ biosynthesis of AgNP-incorporated synthesized zeolite A (AgNP-SZ) was developed. The AgNP-SZ was then assessed for their antibacterial activity, in vitro cytotoxicity and wound healing potency. Zeolite A (SZ) was synthesized from kaolinite through hydrothermal method whereas AgNP was produced from AgNO3 using Orthosiphon aristatus leaves extract as the green reducing and capping agent. The AgNP-SZ was synthesized using 0.4 mL 5 % O. aristatus leaf extract solution and mixed physically with Ag-SZ. The synthesized materials SZ, Ag-SZ and AgNP-SZ were characterized for their morphological and physicochemical properties. In the present study, the characterization results validated that the synthesized product was zeolite A. Characterization by Transmission Electron Microscope (TEM) showed AgNP with particle size of 20.01 nm in diameter and area of 381.61 nm2 was incorporated in the zeolite A. TEM analysis, surface and pore analysis (BET/BJH), thermogravimetric and differential temperature analysis (TGA-DTA), and inductively coupled plasma-optical emission spectrometry (ICP OES) were used to assess the synthesized products. These characterizations validated the O. aristatus leaves extract acted as natural reducing and capping agents with a timely release mechanism of AgNP from zeolite A. SZ, Ag-SZ and AgNP-SZ were assessed for antibacterial activity against E. coli and S. aureus using disc diffusion technique (DDT) and minimum inhibitory/bactericidal concentration (MIC/MBC), biofilm inhibition against P. aeruginosa, in vitro cytotoxicity against human skin fibroblast (HSF 1184) cells and wound healing potency through in vitro scratch assay. The powder form of the samples was pressed into pellets for DDT, whereas MIC/MBC and biofilm study utilized the powder form in both water and saline solution. Inhibition zones and bacterial growth inhibition were observed. The DDT showed clear zone of inhibitions for Ag-loaded materials on both bacteria, with E. coli was more susceptible than S. aureus in both water and saline solutions based on the MIC/MBC values. The AgNP-SZ also showed potential biofilm inhibition action against S. aureus compared to P. aeruginosa. SZ, Ag-SZ and AgNP-SZ at 0.5, 1.0, 1.5, and 2.0 mg/mL were tested for cytotoxicity. In vitro scratch assay determined the HSF 1184 cell migration rate after treatment with the synthesized products. The absence of cytotoxicity in all concentrations of AgNP-SZ proved that the material is biocompatible. Although cell migration rate by AgNP-SZ was slower compared to the SZ and control in in vitro scratch assay, the material did not hinder cell migration and proliferation. These findings show the potential of green synthesized AgNP-incorporated zeolite A using plant extract to substitute conventional methods, with good antibacterial application and sustainable production

Antibacterial, cytotoxicity, and wound healing studies of amine-functionalized zeolite y

The antibacterial activities, cytotoxicity, and wound healing of amine(3-aminopropyltriethoxysilane (APTES))-functionalised zeolite Y against normal human fibroblast cells were studied. The characterisation of unmodified and amine-functionalised zeolites Y (Z, ZA 0.04, ZA 0.4, and ZA 0.6) by Fourier transform infrared spectroscopy, X-ray powder diffraction, and energy dispersive X-ray analysis proved that the APTES molecules were grafted onto the zeolite Y surface without distorting its framework structure. All amine-functionalised zeolite Y samples possessed antibacterial activities against several ATCC bacteria that were correlated with the increased amount of APTES on the zeolite Y surface. Conversely, when a higher concentration of APTES was grafted on the zeolite Y, higher cytotoxicity was observed against the fibroblast cells. Although the ZA 0.6 sample (zeolite Y functionalised with 0.6 M of APTES) had higher antibacterial activity, it was cytotoxic to the cells. Therefore, the selection of an antibacterial agent for human treatment purposes must also consider its cytotoxicity effect against human cells to ensure it is biocompatible

Simultaneous action of surfactant modified clinoptilolite: adsorbent of dyes and antibacterial agent

In this study, the simultaneous action of surfactant modified clinoptilolite (SMC) as adsorbent for dyes and its antibacterial activity was investigated. Methylene blue (MB) and acid orange 7 (AO7) represent cationic and anionic dyes, respectively were used as adsorbate in this study and the antibacterial activity was studied against Gram-negative (Escherichia coli ATCC 11229) and Gram-positive bacteria (Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 2921). Initially, natural zeolite clinoptilolite was modified with 3 different concentrations (0.1, 1.0 and 4.0 mM) of cationic surfactant hexadecyltrimethyl ammonium bromide (HDTMA-Br). The SMC samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), amount of HDTMA adsorbed and dispersion behaviour. Result from XRD shows that the HDTMA-Br molecules caused no effect on primary structure of the clinoptilolite since the clinoptilolite structure remained the same after modification with HDTMA-Br. Compared to the unmodified clinoptilolite, FTIR spectra of the SMC shows peak corresponds to C-H stretches which proved the attachment of HDTMA onto the clinoptilolite surfaces. In the dispersion behaviour study, SMC samples were located at the adjacent phase between the water and oil mixture. The amount of HDTMA-Br adsorbed onto the clinoptilolite increased with the increasing concentrations of the surfactant. The use of SMC as adsorbent and antibacterial agent were further studied against the ionic dyes and bacteria simultaneously. The results show that the adsorption capacity of SMC towards both ionic dyes increase with the increasing HDTMA-Br concentration. While for the antibacterial activity, the number of colony forming unit of bacteria seem to be highly reduced at the highest concentration of the HDTMA (4.0 mM) attached on the clinoptilolite. Hence, this study had shown that SMC has high adsorption capacity towards the ionic dyes at the same time reducing the growth of both Gram positive and negative bacteria in aquoes solution

Antibacterial activity of copper exchanged zeolite Y synthesized from rice husk ash

Increasing problems with antibacterial agent primarily bacterial resistance and environmental pollution due to the high release of antibacterial agents in water necessitates the development of new and effective antibacterial agents. One of the techniques that can be used to overcome these problems is by immobilizing antibacterial compounds or any related compounds on the carrier system such as by using zeolite. In this study, zeolite Y was synthesized from rice husk ash as silica source by using hydrothermal technique and it was used as a carrier system for antibacterial copper (Cu) ions. A series of Cu-exchanged zeolite Y was then prepared by loading with different concentrations of Cu ions (100 ppm, 600 ppm and 900 ppm of the Cu(NO3)(2)) on the synthesized zeolite Y. The Cu-exchanged zeolite Y was characterized by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR). These characterization techniques showed that the zeolite Y was synthesized in pure phase and had a good degree of crystallinity. Whereas, from the characterization results, zeolite Y was successfully loaded with different concentrations of Cu ions and no structural changes happen after modification. The antibacterial activity of the samples was determined through disc diffusion technique (DDT) against Gram positive bacteria (Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 29212) and Gram negative bacteria (Escherichia coli ATCC 11229 and Pseudomonas aeruginosa ATCC 15442). Based on the antibacterial results, the synthesized zeolite Y loaded with 900 ppm of Cu2+ showed the highest antibacterial activity compared to that of loaded with 100 ppm and 600 ppm of Cu2+. The higher the Cu concentration on the zeolite Y resulted in the higher antibacterial activity against wide spectrum of bacteria. As a conclusion, synthesized zeolite Y from rice husk ash could be a carrier system for antibacterial Cu ions and it has the potential for the application as antibacterial agents