BIOENGINEERED POROUS SILICA DEVICES FOR BIOMEDICAL APPLICATIONS

This thesis summaries three years of research on the development of innovative porous silica based devices for biosensing and drug delivery purposes. Porous silicon (PSi), is one of most exploited nanostructured material in biomedicine. Due to its optical and electrical properties, high specific surface area, tailorable morphology and surface chemistry, PSi is an ideal transducer material for the realization of high sensitive and selective biosensors. In this work, different porous silica structures have been explored for the development of label-free oligonucleotide-biosensor realized by in situ synthesis of bioprobe on porous platform. Different functionalization strategies have been also explored in order to make PSi surface more chemically stable. The realization of label-free aptamer-PSi sensor, with great stability, fast response time, high sensitivity and specificity for the detection of human ?-thrombin, has been successfully demonstrated. Diatomite, an emerging natural porous silica material of sedimentary origin, with similar physiochemical properties of man-made porous silicon, has been also exploited as potential platform for biomedical applications. Its non-toxicity, biocompatibility, high specific surface area, tailorable surface chemistry, as well as thermal and chemical stability make diatomite a viable cheap surrogate to synthetic porous silica for realization of nano-based drug delivery system. In this thesis work the potentialities of diatomite nanoparticles (DNPs) as safe nanovectors for drug delivery in cancer cells have been successfully demonstrated. Since the silica surface of diatomite is covered by silanol groups, it can be easily modified with functional reactive groups for the conjugation of biomolecules (e.g., DNA, antibodies, enzymes) in order to realize advanced healthcare devices. Different approaches of functionalization based on covalent bond for preparation of bioengineered diatomite NPs for therapeutic molecules transport into cancer cells were developed. Preliminary in vitro and in vivo studies endorsed this cheap, natural and biocompatible nanomaterial for drug delivery applications.