SURFACE-MODIFIED NANOCRYSTALLINE CERAMICS FOR DRUG-DELIVERY APPLICATIONS

Drug delivery systems comprised of various types of carriers have long been the object of pharmacological investigation. The search has been stimulated by the belief that carriers will lead to reduced drug toxi city, dosage requirements, enhanced cellular targeting and improved sh elf-life. Among the carriers investigated are complex polymeric carboh ydrates, synthetic proteins and liposomal structures. For the past fou r years, we have been experimenting with a radically new class of carr iers comprised of surface-modified nanocrystalline ceramics. While the ceramics provide the structural stability of a largely immutable soli d, the surface modification creates a glassy molecular stabilization f ilm to which pharmacological agents may be bound non-covalently from a n aqueous phase with minimal structural denaturation. As a consequence of maintained structural integrity and owing to concentration effects afforded by the surfaces of the nanocrystalline materials, drug activ ity following surface immobilization is preserved. We have used succes sfully surface-modified nanocrystalline ceramics to deliver viral anti gens for the purpose of evoking an immune response, oxygenated haemogl obin for cell respiration and insulin for carbohydrate metabolism. The theoretical principles, technical details and experimental results ar e reviewed. Surface-modified nanocrystalline materials offer an exciti ng new approach to the well-recognized challenges of drug delivery.