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

Microbiological analysis of drinking water from water vending machines

Commercial water vending machines are gaining popularity nowadays among the general public, probably due to the ease of obtaining clean drinking water. However, improper maintenance of the machines can lead to bacterial contamination. Hence, this study aimed to investigate and determine the microbiological characteristics of drinking water from Water Vending Machines (WVM) by isolating and characterizing culturable bacteria in the water and nozzle swab samples. The samples were obtained from WVM at eight different locations around Johor Bahru, Johor, Malaysia. Several unique bacterial isolates were found, from both Gram-positive and Gram-negative groups. Polymerase chain reaction amplification and 16S rRNA sequence analysis suggested that these isolates are from Pseudomonas, Bacillus, and Stenotrophomonas genera. In situ water quality tests which include pH, conductivity, and total dissolved solids were also conducted. Two samples from the inlet source have pH and conductivity values slightly above the reference values stipulated in drinking water regulations. The findings presented here suggest the importance of regular service maintenance of the WVM to ensure that the water samples meet the standard stipulated by the authority

Adsorption of gentamicin on surfactant-kaolinite and its antibacterial activity

Kaolinite is a common component of soil. Negatively-charged kaolinite can act as an adsorbent material and it has the ability to adsorb antimicrobial agents. In this study, local natural kaolinite was used to adsorb gentamicin and cationic surfactant molecules. Gentamicin-loaded surfactant-kaolinite (GSK) was prepared firstly by the attachment of cationic surfactant 4.0 mM hexadecyltrimethyl ammonium (HDTMA) on raw kaolinite to produce surfactant-kaolinite (SK), which was then loaded with gentamicin sulphate (50 and 200 mg/L) to yield GSK. Gentamicin-loaded kaolinite (GK) was also prepared and compared. All samples were characterised by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and CHNS elemental analysis. The characterisation results proved that the framework structure of kaolinite was not disrupted after modification with antimicrobial agents. The antibacterial activity of the samples was tested against Gram-negative Escherichia coli (ATCC 11229) and Gram-positive Enterococcus faecalis (ATCC 29212) through disc diffusion technique (DDT). Based on the technique, raw kaolinite did not exhibit antibacterial activity but showed antibacterial activity when HDTMA and/or gentamicin was loaded on kaolinite. In addition, GSK showed better antibacterial activity compared to GK and performed better on Gram-positive bacteria compared to Gram-negative bacteria. As a conclusion, immobilisation of HDTMA on kaolinite proved that kaolinite can act as an adsorbent to adsorb antibiotics and it has the potential to be developed as an enhanced antimicrobial agent

Preparation, characterization, and antibacterial activity of green-biosynthesised silver nanoparticles using Clinacanthus nutans extract

Plant leaf extract can be used as a reducing agent in the synthesis of silver nanoparticles (AgNP) in a green and safe way. As a result, this study describes the synthesis of AgNP using a Clinacanthus nutans plant extract. C. nutans is known as belalai gajah in Malaysia and is widely used as a medicinal herb. UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), and transmission electron microscope (TEM) were used to characterize the biosynthesized AgNP using C. nutans aqueous extract at pH 10, 70°C, and a reaction time of 48 hours. The UV-Vis spectra revealed a peak around 400 nm, while XRD confirmed AgNP's crystal structure, which had an average size of 20 to 30 nm, as shown in FESEM and TEM micrographs. The antibacterial activity of biosynthesized AgNP against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus was tested using the disc diffusion technique (DDT). Antibacterial activity was limited against Enterococcus faecalis and methicillin-resistant Staphylococcus aureus (MRSA). AgNP, which was synthesized using C. nutans leaf extract AgNP as a bioreducing agent, has antibacterial activity against a wide range of bacteria in general

Antibacterial silver nanoparticles using different organs of Ficus deltoidea Jack var. kunstleri (King) Corner

Biosynthesis of silver nanoparticles (AgNP) using plant extracts is considered as an advanced method of synthesising AgNP using the green method. Although the leaf and the root of Ficus deltoidea Jack var. kunstleri (King) Corner (Mas Cotek) are known to have medicinal benefits, the study on its organs (leaf, stem, fig and root) to synthesise AgNP is still scarce. Therefore, this study determined the optimal synthesising conditions for AgNP-Leaf, AgNP-Stem, AgNP-Fig, and AgNP-Root, involving the volumes of plant extracts (1.0, 1.0, 0.8 and 3.0 mL), reaction times (30, 21, 33 and 21 h), reaction temperatures (60, 90, 100 and 90 °C), and solution pH (10, 12, 10 and 12). Thermogravimetric analysis (TGA) discovered that AgNP-Stem had the highest organic decomposition. All biosynthesised AgNPs exhibited spherical and crystal structures, with the particle sizes in the order of AgNP-Root (15.4 ± 3.4 nm) < AgNP-Stem (20.5 ± 2.4 nm) < AgNP-Fig (21.3 ± 4.2 nm) < AgNP-Leaf (22.9 ± 4.3 nm), as measured by transmission electron microscope (TEM). Meanwhile, in the disc diffusion technique (DDT) and minimum inhibitory/bactericidal concentration (MIC/MBC) analyses, AgNP-Root exhibited more significant antibacterial activity against Escherichia coli (ATCC 11229) and Staphylococcus aureus (ATCC 6538) bacteria compared to other organs. Visible damage was found on the bacterial wall of S. aureus treated with AgNP-Stem when observed using field emission scanning electron microscopy (FESEM). Hence, the phytochemical compounds found in the F. deltoidea organs significantly influenced the characteristics of AgNP and subsequently impacted the antibacterial activity

Effect of different HDTMA loading on silver modified kaolinite on its antibacterial activity

A synergistic combination of organic and inorganic materials as a hybrid antibacterial agent aiming to combine two or more antibacterial compounds in a carrier system has been developed. This research aimed to study the physicochemical properties of silver loaded kaolinite attached with different amounts of cationic surfactant hexadecyltrimethylammonium (HDTMA) and its effect on Gram-positive and Gram-negative bacteria. Kaolinite was initially modified with silver ion and later, with different HDTMA concentrations (50, 75, and 100% of Cation Exchange Capacity (CEC) of the kaolinite). The materials were characterized using X-ray diffraction, Fourier transforms infrared spectroscopy and field emission scanning electron microscope equipped with energy dispersive X-ray analyzer. Antibacterial activity was evaluated using disc diffusion technique against Escherichia coli and Staphylococcus aureus. Characterization results showed that kaolinite was successfully modified with silver ion and HDTMA. For the antibacterial assay, S. aureus was more susceptible than E. coli due to differences in their peptidoglycan structure, whereas, surfactant-modified silver kaolinite was more effective in inhibiting bacterial growth than silver kaolinite. However, the different concentrations of HDTMA did not alter the existing inhibitory effects against these bacteria. Thus, the low concentration of HDTMA loaded on silver-kaolinite is suitable to be used as an antibacterial agent

Antibacterial, cytotoxicity and wound healing assessments of amine-functionalised 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

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