An Investigation of the Charge Effects on the Uptake and Release Capacity of Mesoporous Silica Nanoparticles as Vehicles for Short Oligonucleotides

An easy and cost-effective sol-gel procedure is described for the synthesis and co-modification of mesoporous silica nanoparticles (MSNs) with various metal ions and positive-charge inducing polymers including PEI and PEG, for the construction of a reliable gene delivery vehicle. All of the samples (denoted as PEI-MSN, M-MSN, PEI-M-MSN, and PEG-PEI-MSN, where, M= Fe2+, Fe3+, Co2+, Zn2+, Al3+), were unambiguously characterized by conventional techniques including FTIR, XRD, SEM, and BET. The adsorption capacity of siRNA was found to be more related to the zeta potential of the samples than their specific surface areas. The best adsorption result was obtained by using PEI-Fe(III)-MSN (48.8 µg of siRNA per mg of support). The release of siRNA from PEIFe(III)-MSN, was also good (91.5%), but a burst release profile was observed. Interestingly, when a layer of PEG was used as a co-modifier, a sustained release profile was achieved, and meanwhile, the released amount of siRNA was improved (93.2%). The whole combination showed noconsiderable cytotoxicity according to the MTT test.