Controlled DNA Delivery

Release of DNA in vivo takes place due to the increased acidic conditions inside living cells that result in the destabilization of the ORMOSIL-DNA complex. SiCVbased nanoparticles, in fact, do not release encapsulated biomolecules because of the strong hydrogen bonding between the biomolecule s polar centres and the silanols at the cage surface (as ORMOSIL-entrapped hydrophobic molecules are not leached in aqueous systems due to strong hydrophobic interactions).17 

Several patent applications have been granted to SGT covering its sol gel microencapsulation process and its implementation for 

Sailynoja, M. H. Raitavuo, M. H. Vaahtio, J. I. Salonen and A. U. O. Yli-Urpo, In vitro release of heparin from silica xerogels, Biomaterials, 2001, 22, 2163. 

Viitalaa, M. Jokinena and J. B. Rosenholma, Mechanistic studies on release of large and small molecules from biodegradable SiC 2, Int. J. Pharm., 2007, 336, 382. 

Compositions for controlled release of a biologically active agent, and the preparation thereof, US Pat., 7112339. 

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Balakirev, M., Schoehn, G. and Chroboczek, J. (2000) Lipoic acid-derived amphiphiles for redox-controlled DNA delivery. Chem. Biol., 7, 813-819. 

Kim YH, Gihm SH, Park CR et al (2001) Structural characteristics of size-controlled selfaggregates of deoxycholic acid-modified chitosan and their application as a DNA delivery carrier. Bioconjug Chem 12 932-938... 

Control over DNA delivery can be achieved by the formation of both synthetic and natural polymers in a variety of dosage forms such as matrix, reservoir, nano/microparticles. 

This method is extremely sensitive to pH changes which can lead to inconsistent transfection efficiencies, especially when using homebrew transfection buffers. To some extent, this sensitivity can be limited by the use of commercially available kits containing chemicals and buffers that have undergone quality control procedures, ensuring better reproducibility of results and less lot-to-lot variation. Although the costs per transfection for this method are unrivaled, the attractiveness of calcium phosphate precipitation has declined over the past 15 years, partly due to the trickiness of the method itself, the limited transfection efficiencies, and the narrow cell spectrum for which it is suitable, and partly because more modem and efficient DNA delivery methods have emerged. 

Koynova R, Wang L, Tarahovsky Y et al (2005) Lipid phase control of DNA delivery. Bioconjug Chem 16 1335-1339... 

Trentin D, Hubbell J, Hall H (2005) Non-viral gene delivery for local and controlled DNA release. J Control Release 102 263-275. 

Park JS, Oh YK, Yoon FI, et al. In situ gelling and mucoadhesive polymer vehicles for controlled intranasal delivery of plasmid DNA. / Biomed Mater Res 2002 59(1) 144-151. 

Luten J, Van Nostrum C, De Smedt S, Hennink W (2008) Biodegradable polymers as non-viral carriers for plasmid DNA delivery. I Control Release 126 97-110... 

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