Chapter 10 - Silicon Carbide-Based Nanowires for Biomedical Applications

This chapter presents an overview of the growth and optical properties (Section 10.2) and some in vitro applications of core-shell 3C-SiC-SiO2 NWs and bare SiC NWs. In Section 10.3 it was shown, by the analysis of cell proliferation, cell cycle progression, and oxidative stress, that the core-shell NWs are cytocompatible over a time of up to 10 days. They are effectively internalized by cells through the macropinocytosis mechanism (phagocytosis only in the THP-1 model) and sporadically by direct penetration. In all the cell lines, the intracellular presence of NWs induces the same molecular events: peroxidation of membrane lipids and oxidation of proteins. These effects are late and may be limited by the activation of protection systems, for instance the effect of ROS is not acute and effectively countered by the intracellular scavenger. Our results highlight that the core-shell 3C-SiC-SiO2 NWs do not elicit either midterm (72 h) or long-term (10 day) cytotoxic activity leading to irreversible cellular damages or death. In Section 10.4 it was shown that the hybrid nanosystem formed by core-shell NWs conjugated with an organic photosensitizer, a tetracarboxyphenyl porphyrin derivative, is an efficient source of singlet oxygen under 6 MV X-ray irradiation. Further, this nanosystem is effective for SLPDT tests in vitro on lung cancer cells cultured with the functionalized NWs and irradiated in a clinical linear accelerator for radiation therapy. The experimental results validate the nanosystem in view of nanomedicine applications aimed at the definition of more effective and synergic treatments of tumors deep inside the body. In Section 10.5 it was shown that core-shell 3C-SiC-SiO2 NWs and bare 3C-SiC NWs could be used as a biomimetic biomaterial for cell cultures, providing a biological interface that is biocompatible according to ISO 10993 standards. The blood compatibility of the NWs was also evaluated analyzing the interaction of the NW platforms with PRP, in agreement with ISO 10993-4 guidelines. The analysis of adhesion and activation of platelets on the NW bundles indicates that a higher platelet activation was induced by the core-shell structures compared to the bare ones. These data suggest that SiC-SiO2 NWs may be suitable for tissue regeneration, while SiC NWs may be exploited for implantable prosthetic devices.