title: Development and in vitro evaluation of a thiomer-based nanoparticulate gene delivery system.
abstract: Chitosan-thiobutylamidine was developed and evaluated as a novel tool for gene delivery. The conjugate, displaying 299.1+/-11.5 micromol free thiol groups per gram polymer, formed coacervates with pDNA at a mean size of 125 nm and a zeta potential of +9 mV. Thiol groups, being susceptible for oxidation, were immobilised on the polymeric backbone of chitosan in order to introduce the property of extracellular stability and intracellular pDNA release by forming reversible disulfide bonds. The integrity of the new particles was compared to unmodified chitosan under simulated physiological conditions. Within 10h, pDNA was completely released from chitosan-DNA particles while only 12% were released from the thiomer-based particles. At pH 7, the amount of thiol groups significantly (p<0.05) decreased by more than 25% within 6h. In contrast, in a reducing environment as found intracellularly, chitosan-thiobutylamidine-DNA nanoparticles dissociated continuously, liberating approximately 50% of pDNA within 3h. Transfection studies performed in a Caco2 cell culture evinced the highest efficiency for chitosan-thiobutylamidine-DNA nanoparticles in combination with a glycerol shock solution. The combination of improved stability, enhanced pDNA release under reducing conditions, and higher transfection efficiency identifies chitosan-thiobutylamidine as a promising new vector for gene delivery.
authors.affiliation: Department of Pharmaceutical Technology, Faculty of Chemistry and Pharmacy, Institute of Pharmacy, Leopold-Franzens-University Innsbruck, Innrain 52, A 6020 Innsbruck, Austria.
authors.forename: Thierry
authors.initials: T
authors.lastname: Schmitz
authors.forename: Irene
authors.initials: I
authors.lastname: Bravo-Osuna
authors.forename: Christine
authors.initials: C
authors.lastname: Vauthier
authors.forename: Gilles
authors.initials: G
authors.lastname: Ponchel
authors.forename: Brigitta
authors.initials: B
authors.lastname: Loretz
authors.forename: Andreas
authors.initials: A
authors.lastname: Bernkop-Schnürch
mesh_terms: D002082:Butylamines / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000295:instrumentation; D005822:Genetic Vectors; D008956:Models, Chemical; D008970:Molecular Weight; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D010957:Plasmids / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013997:Time Factors; D014162:Transfection
chemical_list: D002082:Butylamines; D013438:Sulfhydryl Compounds; D004247:DNA; D048271:Chitosan