Polyethyleneimine Coating Enhances the Cellular Uptake of Mesoporous Silica Nanoparticles and Allows Safe Delivery of siRNA and DNA Constructs

Abstract

Surface-functionalized mesoporous silica nanoparticles (MSNP) can be used as an efficient and safe carrier for bioactive molecules. In order to make the MSNP a more efficient delivery system, we modified the surface of the particles by a functional group that enhances cellular uptake and allows nucleic acid delivery in addition to traditional drug delivery. Non-covalent attachment of polyethyleneimine (PEI) polymers to the surface not only increases MSNP cellular uptake, but also generates a cationic surface to which DNA and siRNA constructs could be attached. While efficient for intracellular delivery of these nucleic acids, the 25 KD PEI polymer unfortunately changes the safety profile of the MSNP that is otherwise very safe. By experimenting with several different polymer molecular weights, it was possible to retain high cellular uptake and transfection efficiency while reducing or even eliminating cationic MSNP cytotoxicity. The particles coated with the 10 KD PEI polymer was particularly efficient for transducing HEPA-1 cells with a siRNA construct that was capable of knocking down GFP expression. Similarly, transfection of a GFP plasmid induced effective expression of the fluorescent protein in > 70% cells in the population. These outcomes were quantitatively assessed by confocal microscopy and flow cytometry. We also demonstrated that the enhanced cellular uptake of the non-toxic cationic MSNP enhance the delivery of the hydrophobic anticancer drug, paclitaxel, to pancreatic cancer cells. In summary, we demonstrate that by a careful selection of PEI size, it is possible to construct cationic MSNP that are capable of nucleotide and enhanced drug delivery with minimal or no cytotoxicity. This novel use of a cationic MSNP extends its therapeutic use potential.

Poly-l-lysine Functionalized Large Pore Cubic Mesostructured Silica Nanoparticles as Biocompatible Carriers for Gene Delivery

“…Silica is usually less toxic compared to polycations. 7 Porous silica materials have shown substantial benefits in terms of loading owing to their high porosity (i.e., high surface area and high pore volume), tunable pore size in the nanometer regime, and vast surface functionalization capabilities. 8,9 Previous studies in this area have shown the effectiveness of silica-based materials to transfer genes and anticancer drugs into target cells.…”

“…10 The major advantage of using porous silica materials compared to nonporous ones is the possibility to bind biomolecules either on the surface or within the pore and achieve much higher loadings, 7 with potential for codelivery. 11 Thus far, mesoporous silica materials with small pore size (<3 nm) were reported as potential carriers to deliver siRNA 7,11,12 and DNA. 7 In these approaches, due to the small pore size, the genes remain coated only on the external surface of the mesoporous silica materials.…”

“…11 Thus far, mesoporous silica materials with small pore size (<3 nm) were reported as potential carriers to deliver siRNA 7,11,12 and DNA. 7 In these approaches, due to the small pore size, the genes remain coated only on the external surface of the mesoporous silica materials. Recently, Li et al showed that large amount of double stranded salmon DNA (20À250 bp with an average chain length of 50 nm) could be adsorbed within the pore (2.7 nm) of magnetic mesoporous silica nanoparticles by optimizing adsorption conditions.…”

15 years on siRNA delivery: Beyond the State-of-the-Art on inorganic nanoparticles for RNAi therapeutics

“…PEI has been described using different kinds of nanoparticles directly adsorbed on negatively charged materials [74,92] or covalently attached by amination [93]. There are many examples of the functionalization of AuNPs [94,95], MNPs [54,[96][97][98], SiNPs [61,99,100], with PEI of different molecular weights [61,101] or even modified with labile bonds like acetal [102]. In relation to the PLL, this polymer has been used previously modified with a terminal cysteine for the direct attachment to AuNPs [103], conjugated to epoxysilanes [62] and as part of a layer-by-layer system with siRNA [104].…”

Highly efficient siRNA delivery from core–shell mesoporous silica nanoparticles with multifunctional polymer caps

“…However, due to the large molecular size of siRNA of approximately 2 × 8 nm and a hydrodynamic diameter of about 4.2 nm, sufficiently large pore entrances are necessary for an efficient uptake of siRNA molecules in the MSN pore system. Typical MSNs feature pore sizes at around 3 nm, and as a result such MSNs have been used to accommodate siRNA on their external surface, usually aided by large cationic polymers such as polyethyleneimine (PEI) [9][10][11] or poly(2-dimethylaminoethyl methacrylate) (PDMAEMA). 12 These polymers are known as endosomal escape agents, attributed to a proton-sponge effect, however, they are also known for their toxicity and are therefore sometimes used in combination with polyethylene glycol (PEG) to avoid these side effects.…”