Híbridos de nerolidol ou digluconato de clorexidina com bentonita como agentes antibacterianos e híbridos de montmorillonitas/RNA

Abstract

Clays/clay minerals are versatile materials that can interact with organic compounds, changing their chemical properties. In the present work, montmorillonite was applied in the adsorption of RNA and a sodium bentonite was used for the incorporation of nerolidol and chlorhexidine digluconate. RNA/monoionic montmorillonites hybrids were obtained at different pHs and the reaction was followed by X-ray diffraction, thermogravimetry, infrared spectroscopy and 27Al, 31P and 13C solid state nuclear magnetic resonance. It was observed that the formation of the RNA/montmorillonite hybrid was pH dependent. In an acidic medium, the RNA molecules were intercalated in a flat conformation, with contribution of electrostatic interactions and hydrogen bonds. The presence of different cations such as Na+, Ca2+, Mg2+ and Sr2+ influenced the adsorption of the biomolecule. Sodium bentonite cetylammonium bentonite were used to incorporate nerolidol, whose antibacterial activities against Escherichia coli and Staphylococcus aureus were investigated. Low angle X-ray diffraction measurements suggested the formation of nerolidol intercalated hybrids in montmorillonite with a maximum basal spacing of 3.0 nm. The amount of nerolidol depended on the composition as indicated CHN results. Antibacterial activity was probably influenced effect of nerolidol release from solids. The formation of chlorhexidine/montmorillonite intercalated hybrids was followed by X-ray diffraction measurements resulting in basal spacings between 1.40-1.56 nm. The maximum incorporated amount of chlorhexidine was 689 mg g-1. The antibacterial activity of the hybrids was effective and directly proportional to the incorporated amount of chlorhexidine, achieving 100% inhibition against Escherichia coli and Staphylococcus aureus. The results indicated formation of intercalation hybrids of the organic molecules in montmorillonite were and that the antibacterial activity was dependent on the nature of the organic molecules and the composition, although all of the samples showed antibacterial activity for both evaluated bacteria.