Evaluation of colloidal properties of amino-functionalized mesoporous silica nanoparticles conjugated with the plasmid vector pEGFP-N3 and its influence on the pDNA delivery to HeLa cells

Abstract

Efforts are being made to develop gene therapy delivery systems capable of substituting the viral vectors with comparable efficiency but with fewer biosafety concerns, easier production on large-scale and improved shelf-stability. Among the potential delivery systems based on inorganic nanoparticles for plasmid DNA, mesoporous silica has been gaining significance due to its combination of biocompatibility with unique structural and chemical properties. In this study, mesoporous silica nanoparticles were grafted with different alkyl-amino groups to enable the formation of conjugates with the plasmid vector pEGFP-N3. The colloidal properties, cytotoxicity and transfection efficiency of conjugates to HeLa cells were evaluated. Spherical nanoparticles with around 90 nm of diameter were synthesized and then functionalized with propylamine, (2-aminoethyl)(ethyl)propylamine and 3-(diethylenetriamine)propyl groups. Dispersions prepared in different cell culture media and the zeta potential measurements revealed that their aggregation tendency was influenced by their functionalities. Besides, the structural integrity of the functionalized nanoparticles dispersed in Dulbecco's modified Eagle's medium was affected when sterilized in autoclave. The highest efficiency on the pEGFP-N3 conjugation was obtained with 3-(diethylenetriamine)propyl groups while the highest transfection efficiency was achieved with propyl amino groups onto the surface of mesoporous silica nanoparticles. The cytotoxicity of conjugates to HeLa cells was acceptable and the transfection efficiency was low possibly due to the aggregation observed in the cell culture medium.