CONICET | Buscador de Institutos y Recursos Humanos

Photoluminescent silicon nanoparticles of 1-2 nm size were synthesized by awet chemical procedure and derivatized with propylamine (NH 2 SiNP). SurfaceNH 2 groups were used as linkers for further poly (ethylene glycol) and folic acidattachment (PEG-NHSiNP and Fo-NHSiNP, respectively) in order to providethe particles with efficient targeting to tumors and inflammatory sites. Theparticles were characterized by TEM, FTIR, XPS,  potential, DLS, andtime-resolved anisotropy.The photophysical properties, photosensitizing capacity, and interaction withproteins were observed to depend on the nature of the attached molecules.While PEG attachment to NH 2 SiNP did not change the particles photophysicalbehavior, attached folic acid diminished the particles photoluminescence.Despite all the particles retained the capacity for 1 O 2 generation, the efficient 1 O 2quenching by the attached surface groups might be a drawback when usingthese particles as photosensitizers of 1 O 2 . In addition, attached folic acidprovided the particles with the capacity of superoxide radical anion, O 2 .- ,generation.The particles were capable of binding to bovine serum albumin (BSA) withinquenching distances to tryptophan residues. NH 2 SiNP and PEG-NHSiNPground state complexes with BSA showed binding constants of (3.1 ± 0.3)10 4and (1.3  0.4)10 3 M -1 , respectively. The lower value observed for PEG-NHSiNPcomplexes indicates that surface PEGylation effectively leads to a reduction inprotein absorption, as required for opsonization prevention. An increase in theparticles luminescence upon binding to BSA was observed and attributed to thehydrophobic environment provided by the protein. In addition, NH 2 SiNP-BSAcomplexes also showed capacity for resonance energy transfer.