Periodic mesoporous organosilica (PMO) containing bridged succinamic acid groups as a nanocarrier for sulfamerazine, sulfadiazine and famotidine: Adsorption and release study

Abstract

Periodic mesoporous organosilica (PMO) with a bridged amine framework and a pendant succinamic acid group (SA-PMO-5) was synthesised using a sol–gel and post modification process. The bridged amino functionality was introduced to the pore wall of the PMO (MA-PMO-5) using a silsesquioxane precursor, N,N-bis[3-(triethoxysilyl)propyl]amine (BTMSA), along with tetramethyl orthosilicate (TMOS). The succinamic acid functionality was tailored by the ring opening reaction of succinic anhydride with the bridged amine. The physico-chemical properties of SA-PMO-5 were determined by a range of spectroscopic analyses. X-ray diffraction, scanning electron microscopy and transmission electron microscopy showed that the MA-PMO-5 and SA-PMO-5 possessed mesoscopically ordered, hexagonal symmetry as well as well-defined morphologies. The N2 sorption experiment showed the MA-PMO-5 and SA-PMO-5 had a large surface area (704 and 623 m2 g−1), acceptable pore diameter (3.2 and 2.4 nm) and pore volume (0.56 and 0.47 cm3 g−1) to accommodate the guest molecules inside the pore channels. Organic functionalisation was determined successfully by Fourier transform infrared spectroscopy and 13C cross-polarisation magic angle spinning (CP-MAS) NMR spectroscopy. 29Si MAS NMR spectral analysis revealed the silicon environment of the final material. Sulfamerazine (SMR), sulfadiazine (SDZ) and famotidine (FAMO) adsorption as well as the release properties from the MA-PMO-5 and SA-PMO-5 were investigated at pH 4 and 7.4. The high adsorption and delayed release properties exhibited by SA-PMO-5 were attributed to the strong interaction between succinamic acid functionality with the drug molecules.