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

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