1 research outputs found
Amine Modification of Thermally Carbonized Porous Silicon with Silane Coupling Chemistry
Thermally carbonized porous silicon (TCPSi) microparticles
were
chemically modified with organofunctional alkoxysilane molecules using
a silanization process. Before the silane coupling, the TCPSi surface
was activated by immersion in hydrofluoric acid (HF). Instead of regeneration
of the silicon hydride species, the HF immersion of silicon carbide
structure forms a silanol termination (Si–OH) on the surface
required for silanization. Subsequent functionalization with 3-aminopropyltriethoxysilane
provides the surface with an amine (−NH<sub>2</sub>) termination,
while the SiC-type layer significantly stabilizes the functionalized
structure both mechanically and chemically. The presence of terminal
amine groups was verified with FTIR, XPS, CHN analysis, and electrophoretic
mobility measurements. The overall effects of the silanization to
the morphological properties of the initial TCPSi were analyzed and
they were found to be very limited, making the treatment effects highly
predictable. The maximum obtained number of amine groups on the surface
was calculated to be 1.6 groups/nm<sup>2</sup>, corresponding to 79%
surface coverage. The availability of the amine groups for further
biofunctionalization was confirmed by successful biotinylation. The
isoelectric point (IEP) of amine-terminated TCPSi was measured to
be at pH 7.7, as opposed to pH 2.6 for untreated TCPSi. The effects
of the surface amine termination on the cell viability of Caco-2 and
HT-29 cells and on the in vitro fenofibrate release profiles were
also assessed. The results indicated that the surface modification
did not alter the loading of the drug inside the pores and also retained
the beneficial enhanced dissolution characteristics similar to TCPSi.
Cellular viability studies also showed that the surface modification
had only a limited effect on the biocompatibility of the PSi