Lysozyme Adsorption and Release from Ordered Mesoporous Materials

Ordered mesoporous materials (OMMs) are interesting matrixes for nanomedicine applications such as innovative drug delivery systems. Here, we compare the behavior of the widely studied SBA-15 mesoporous silica with that of the less investigated MSE (a periodic mesoporous organosilica whose silicon atoms are alternatively connected by means of −Si−O−Si− and −Si−CH2−CH2−Si− groups) toward the adsorption (pH 7.0 and 9.6) and in vitro release (pH 7.4; T= 37 °C) of an antimicrobial protein (hen egg white lysozyme). Both OMMs have a hexagonal ordered mesoporous structure and texture, as confirmed by SAXS, TEM, and N2adsorption isotherms, but differ for the chemical composition and surface charge density, as determined by ATR-FTIR spectroscopy and potentiometric titrations, respectively. Rather than the structural and textural features, the different chemical composition of SBA-15 and MSE seems to be responsible for the different lysozyme loading and release and for the different stability toward the lixiviating action of the physiological medium (pH 7.4; T= 37 °C).