Silica xerogels as novel streptomycin delivery platforms

Abstract

Streptomycin was encapsulated by sol-gel through acid-catalysed (SA) or base-catalysed (SB) gelation processes and the samples were evaluated for their antimicrobial activity against a spectrum of Gram-positive and Gram-negative bacteria. The xerogels were characterized using a set of techniques including N2 adsorption isotherms, SEM, DLS, XRD, FTIR and SAXS to investigate their structure, texture and morphology. Cell viability assay was conducted using MRC5 lung fibroblasts and erythrocytes in order to assess the cytotoxicity of the encapsulated samples. The positive electrostatic charge on the surface was identified as relevant factor for the SA sample, which was shown to be a more effective system than SB sample on inhibiting all bacterial strains tested. The best antimicrobial activity was observed with the encapsulated streptomycin prepared via the acid-catalysed gelation route, showing largest inhibitory zones against Listeria monocytogenes and Staphylococcus aureus. These SA materials caused no cytotoxic effect on mammalian cells.