Functionalized bridged silsesquioxane-based nanostructured microspheres: ultrasound-assisted synthesis and in vitro cytotoxicity characterization

Different kinds of polymers have been employed in medicine as biomaterials for different purposes. In recent years, considerable attention has been focused on the development of new drug-delivery systems in order to increase bio-availability, sustain, localize and target drug action in the human body. The versatility of the sol–gel processing to synthesize nanostructured materials and the possibility of incorporating organic molecules into the matrix of the final hybrid material, represent a novel and attractive path to the synthesis of new functionalized hybrid biomaterials with advanced properties. In this work, acetylsalicylic acid (ASA)-functionalized hybrid microspheres based on bridged silsesquioxanes synthesized via ultrasound-assisted sol–gel processing, were characterized. An investigation concerning the cytotoxic response of these new microspheres on CHO-K1 cells was accomplished based on ISO 10993-5 standard (Biological Evaluation of Medical Devices). Microspheres incorporating ASA showed a cytotoxic effect when pure extracts of the microspheres were analyzed, however, they strongly diminished their cytotoxicity as the extracts were diluted. When a 10% concentration extract was employed, hybrid microspheres were shown to be non cytotoxic. These results are promising for considering these novel functionalized organic–inorganic microspheres as potential drug-carriers to be employed in drug delivery-related applications.