Silica nanoparticles modified with aminosilanes as carriers for plasmid DNA

Abstract

We synthesised silica nanoparticles (SiNP) with covalently linked cationic surface modifications and demonstrated their ability to electrostatically bind, condense and protect plasmid DNA. These particles might be utilised as DNA carriers for gene delivery. All nanoparticles were sized between 10 and 100 nm and displayed surface charge potentials from +7 to +31 mV at pH 7.4. They were produced by modification of commercially available (IPAST) or in-house synthesised silica particles with either N-(2-aminoethyl)-3-aminopropyltrimethoxysilane or N-(6-aminohexyl)-3-aminopropyltrimethoxysilane. All particles formed complexes with pCMVbeta plasmid DNA as evidenced by ratio dependent retardation of DNA in the agarose gel and co-sedimentation of soluble DNA with nanoparticles. High salt and alkaline pH did inhibit complex formation. Absorption onto the particles also decreased the hydrodynamic dimensions of plasmid DNA as shown by photon correlation spectroscopy. Complexes formed in water at a w/w ratio of Si26H:DNA (pCMVbeta) of 300 were smallest with a mean hydrodynamic diameter of 83 nm. For effective condensation a w/w ratio of Si26H:DNA of 30 was sufficient. Further, the absorbed DNA was protected from enzymatic degradation by DNase I.

Preparation, purification, and characterization of aminopropyl-functionalized silica sol

“…The aqueous aminopropyl silica sol is stable at 4ºC for at least three months. becomes more and more negative by increasing the pH due to the dissociation of surface silanol groups in agreement with previous measurements [37][38][39]. The surface charge of the aminopropyl-modified silica nanoparticles becomes positive below pH 6.2 (isoelectric point) due to the protonation of surface amino groups.…”

Purification of Nucleic Acids in Microfluidic Devices

“…40 These nanoparticles were demonstrated to electro- statically bind plasmid DNA (10 ng/µL) in water, and this was subsequently verified by electrophoresis in agarose. These particles present another novel solid-phase matrix for plasmid DNA purification, with potential extrapolation to other NAs.…”

Organically modified silica nanoparticles: A nonviral vector for in vivo gene delivery and expression in the brain

“…The initiating event, which is the entrance of the genetic material into the cell without the use of a viral vector, is limited because of the need to supply the DNA to the surface of the cell in sufficient concentration to effect entrance (6). Ultrafine silica nanoparticles, functionalized with amino groups, have been shown to bind and protect plasmid DNA from enzymatic digestion and to effect cell transfection in vitro (7)(8)(9). Recent work by our group has established the feasibility of using amino-functionalized organically modified silica (ORMOSIL) nanoparticles as a nonviral vector for in vitro gene transfection (10).…”