Characterization of functionalized silica particles using linear solvation energy relationships

Abstract

The development of silica nanoparticles as carriers for drug delivery systems has increased exponentially during the last decade. The present work is focused on the characterization of functionalized silica particles using the linear solvation energy relationship model (LSER). Following different procedures, the bare silica was functionalized adding 3-glycidoxypropylsilane (Epoxy), an ibuprofen group and (3-aminopropyl)triethoxysilane (APTES). The resultant structures were analysed by FTIR. Thereafter, they were package and used as stationary phases. The retention of 17 solutes in supercritical fluid chromatography (SFC), with carbon dioxide modified with methanol as mobile phase, were evaluated using LSERs. It was observed that the retention and behaviour of the solutes have a correlation among different solute subgroups in all the selected columns. The results showed that polar compounds were more sensitive to the changes of pressure, temperature and modifier concentration, among which the modifier concentration affected the retention the most. The LSER coefficients, were obtained performing multilinear regressions with five descriptors. The analysis of significance showed that coefficients a and s, related to H-bond donor ability and dipolarity/polarizability capacity respectively, are the dominating solute descriptors. To obtain the trend with the diverse operational conditions, simplified regressions using a and s were performed. The results showed that the simplified model improved the sensitivity of the analysis. It was concluded that the LSER correlation provides information for the characterization of the functionalized silica particles, although the LSER model is should be improved to predict retention times accurately.