Functionalization of SiC nanowires by supersonic molecular beams for photodynamic therapy

Photodynamic Therapy (PDT) is a therapeutical approach in the cancer treatment, which consists in the activation of a photosensitizer (phorphyrins) with visible light in order to produce singlet oxygen, to exert a cytotoxic activity towards cancer cells. The use of visible light limits the PDT application only to shallow deseases, for this reason we propose a new "X­Ray induced PDT" approach, using nanohybrid systems as photosensitizer, consisting in Silicon Carbide (SiC) nanowires (NWs) functionalized with organic molecules (fluorinated porphyrins). Modification of the inorganic semiconductor surface with organic or bio­molecules represents the route to activate processes at the interface and can be achieved by functionalizing the SiC NWs with porphyrins, that showing a good match between the organic absorption Q band and the 3C­SiC near­band­edge­optical emission. In fact SiC NWs have interesting light emission properties [1] so it is promising the idea to couple this light emission with an organic absorber showing strong fluorescence properties, a viable route to increase the optical emission efficiency as well as to promote the anchoring of biological groups. We demonstrated the functionalization of SiOx/SiC core shell NWs, grown by a carbothermal method, showing enhanced fluorescence, with fluorinated porphyrins H2TPP(F) by supersonic molecular beam deposition (SuMBD), an approach that can promote and activate chemical/physical processes at the interface by means of the organic precursor kinetics properties [2]. The H2TPP(F)/SiC­NWs system has been deeply investigated in­situ with surface photoelectron spectroscopy and ex­situ by Cathodoluminescence (CL) to clarify the growth kinetics at low coverages and the interface processes. Results concerning the core level (C1s, Si2p, N1s, F1s) analysis at different growth steps on planar oxidized surface and SiOx/SiC core shell NWs will be presented. The role of morphology of inorganic surfaces together with kinetic activation of H2TPP(F) molecules in molecular beams will be discussed.