Promising plasmid DNA vector based on APTES-modified silica nanoparticles

Abstract

Nanoparticles have an enormous potential for development in biomedical applications, such as gene or drug delivery. We developed and characterized aminopropyltriethoxysilane-functionalized silicon dioxide nanoparticles (APTES-SiNPs) for gene therapy. Lipofectamine(®) 2000, a commonly used agent, served as a contrast. We showed that APTES-SiNPs had a gene transfection efficiency almost equal to that of Lipofectamine 2000, but with lower cytotoxicity. Thus, these novel APTES-SiNPs can achieve highly efficient transfection of plasmid DNA, and to some extent reduce cytotoxicity, which might overcome the critical drawbacks in vivo of conventional carriers, such as viral vectors, organic polymers, and liposomes, and seem to be a promising nonviral gene therapy vector.

Keywords: Lipofectamine® 2000; aminopropyltriethoxysilane; gene therapy vector; nanomedicine; silicon dioxide nanoparticles.

Figure 1

Scanning electron microscopic images of amino-modified silicon nanoparticles. Note: Bars, 500 nm.

Figure 2

Agarose gel electrophoresis assay demonstrating APTES-SiNP-DNA complexation. A constant amount of DNA was complexed with nanoparticles at different ratios of 50:1, 30:1, 20:1, 10:1, and 1:1 (10 mM, pH 7.4). No 50:1 or 30:1 APTES-SiNP-DNA band is observed because of fluorescence quenching by nanoparticle complexation. Abbreviations: APTES, aminopropyltriethoxysilane; SiNP, silicon dioxide nanoparticle.

Figure 3

Cell viability assay. Cytotoxicity of Lipofectamine^® 2000 and APTES-SiNPs on human vascular smooth muscle cells. After 48 hours of incubation, cell viability was measured by flow cytometry. Silicon nanoparticles had negligible toxicity to human vascular smooth muscle cells compared with Lipofectamine 2000. Notes: *P < 0.05 for APTES-SiNPs versus control; ^§P < 0.05 for Lipofectamine 2000 versus APTES-SiNPs. Abbreviations: APTES, aminopropyltriethoxysilane; SiNPs, silicon dioxide nanoparticles.

Figure 4

Human vascular smooth muscle cells transfected with pEGFP delivered with APTES-SiNPs. A combined transmission and fluorescence image is shown. Fluorescence spectra of pEGFP taken in human vascular smooth muscle cells (magnification 400×). Abbreviations: APTES, aminopropyltriethoxysilane; SiNPs, silicon dioxide nanoparticles; pEGFP, plasmid encoding for enhanced green fluorescent protein.

Figure 5

Cell transfection efficiency. The percentage of pEGFP expression was determined by flow cytometry after APTES-SiNP transfection in human vascular smooth muscle cells. Notes: *P < 0.05 for APTES-SiNPs versus control; ^§P < 0.05 for Lipofectamine 2000 versus APTES-SiNPs. Abbreviations: APTES, aminopropyltriethoxysilane; SiNPs, silicon dioxide nanoparticles; pEGFP, plasmid encoding for enhanced green fluorescent protein.