Preparation of antibacterial chlorhexidine/vermiculite and release study

Abstract

The antibacterial chlorhexidine/vermiculite (CA/Ver) was successfully prepared through the intercalation process and the stability of CA on the vermiculite matrix and was investigated by stirring in aqueous solutions under the influence of different pH and temperature. The content of CA was determined by total organic carbon (TOC) analysis before and after stability tests. The structure of all samples was characterized by X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The antibacterial activity of prepared CA/Ver samples was evaluated by finding a minimum inhibitory concentration (MIC) against Entero coccus faecalis, Staphylococcus aureus, Escherichia coil and Psetidomonas aeruginosa. The content of chlorhexidine ranged from 209 to 231.6 mg of CA in 1 g of the whole sample after the intercalation process. After stability study, only a slight outflow of CA from the Ver matrix (<5%) was noted. The antibacterial test confirmed that the outflow of CA was negligible.

After 30 min of exposition the MIC of organovermiculite samples before and after stability test were the same for Staphylococcus aureus and Escherichia coif with value 333 (%; w/v) and the MIC decreased to 0.014 (%; w/v) with longer time of exposition (120 h). A small difference was observed at Enterococcus faecalis where MIC was 10 (%; w/v) after 30 min of exposition for the sample after stability test in neutral pH. However, after 24 h of treatment the MIC value decreased to 0.014 (%; w/v). And finally, bacterial strain Pseudomonas aeruginosa showed a great resistance against antibacterial organovermiculite samples and MIC did not decreased under 10 (%; w/v) even after 5 days of exposition.