XPS and Raman study of zinc containing silica microparticles loaded with insulin

Zinc–silica microparticles obtained by sol–gel method solely or by combining sol–gel chemistry with freeze-drying and spray-drying procedures were explored as potential insulin drug delivery carriers for their improved loading efficiency. Zinc containing silica hosts of different specific surface area and mean pore volume loaded with insulin under similar conditions were investigated by X-ray photoelectron spectroscopy (XPS) and confocal micro-Raman spectroscopy in order to assess the insulin adherence to these matrices and the biologically active state of the insulin after embedding.