Effect of amino groups of mesoporous silica nanoparticles on CpG oligodexynucleotide delivery

In this study, we proposed to modify mesoporous silica nanoparticles (MSNs) with 3-aminopropyltriethoxysilane (NH₂-TES), aminoethylaminopropyltriethoxysilane (2NH₂-TES) and 3-[2-(2-aminoethylamino)ethylamino] propyl-trimethoxysilane (3NH₂-TES) for binding of cytosine-phosphate-guanosine oligodexynucleotides (CpG ODN), and investigated the effect of different amino groups of MSNs on the CpG ODN delivery. Serum stability, in vitro cytotoxicity, and cytokine interleukin-6 (IL-6) induction by MSN-NH₂/CpG, MSN-2NH₂/CpG and MSN-3NH₂/CpG complexes were investigated in detail. The results showed that three kinds of aminated-MSN-based CpG ODN delivery systems had no cytotoxicity to RAW264.7 cells, and binding of CpG ODN to MSN-NH₂, MSN-2NH₂ and MSN-3NH₂ nanoparticles enhanced the serum stability of CpG ODN due to protection by the nanoparticles. However, three aminated MSN-based CpG ODN delivery systems exhibited different CpG ODN delivery efficiency, and MSN-NH₂/CpG complexes had the highest ability to induce IL-6 secretion.