Enhancement of efficiency of chitosan-based complexes for gene transfection with poly(γ-glutamic acid) by augmenting their cellular uptake and intracellular unpackage

As a cationic polysaccharide, chitosan (CS) has been identified for its potential use as a non-viral vector for exogenous gene transfection. However, owing to their electrostatic interactions, CS complexes may cause difficulties in gene release upon their arrival at the site of action, thus limiting their transfection efficiency. In this work, an attempt is made to facilitate the release of a gene by incorporating a negatively-charged poly(gamma-glutamic acid) (gamma PGA) into CS complexes in order to diminish their attractive interactions. The mechanisms of exploiting gamma PGA to enhance the transfection efficiency of CS complexes are elucidated. The feasibility of using this CS/gamma PGA-based system for DNA or siRNA transfer is explored as well. Additionally, potential of the CS/gamma PGA formulation to deliver disulfide bond-conjugated dual PEGylated siRNAs for multiple gene silencing is also examined. Moreover, the genetic use of pKillerRed-mem, delivered using complexes of CS and gamma PGA, to express a membrane-targeted KillerRed as an intrinsically generated photosensitizer for photodynamic therapy is described. (C) 2014 Elsevier B.V. All rights reserved.