Optimization of MCM-41 type silica nanoparticles for biological applications: Control of size and absence of aggregation and cell cytotoxicity

Mesoporous silica nanoparticles were synthesized at high pH using CTAB as a template and TEOS as a silica precursor. It was shown that varying the NaOH concentration between Sand 27.5 mM allows the size, pore and silica structure of mesoporous nanoparticles to be precisely tuned. In particular, monodisperse nanoparticles with the MCM-41 structure with size ranging from 90 rim to 450 nm were obtained by increasing the NaOH concentration from 12.5 to 22.5 mM. It thus demonstrates that NaOH concentration must range between 12.5 and 15 mM in order to prepare MCM-41 silica nanoparticles with optimal size for nanovectorization. We also found that under usual conditions the aggregation of the obtained MSNs was due to the presence of carbonates and ethanol in the reaction mixture. Careful elimination of these species by using carbonate-free NaOH and purging with a N-2 flow allows a highly stable suspension of non-aggregated MSN-MCM-41 to be obtained. After a complete CTAB extraction which was confirmed by Raman spectroscopy, cytotoxicity assays carried out in SW480 cancer cells show that these nanoparticles are not toxic up to 100 mu g/mL. (c) 2014 Elsevier B.V. All rights reserved.