Chemically Engineered Polyallylamine Nanoparticles: An Efficient Gene Delivery System

A. Pathak, A. Aggarwal, S. Patnaik, A. Swami, Y. Singh, S.P. Vyas#, P. Kumar and K.C. Gupta

Nucleic Acids Research Laboratory and Division of Allergy & Infectious Diseases, Institute of Genomics and Integrative Biology, Mall Road, Delhi University Campus, Delhi – 110 007, India. Tel: +91 11 2766 2491; Fax: +91 11 2766 7471; E.mail: kcgupta@igib.res.in #Department of Pharmaceutical Sciences, Dr. H.S. Gour University, Sagar – 470 003, India.

Abstract: Gene therapy is an emerging way of correcting genetic disorders at their molecular roots by redefining and revolutionizing the practice of medicine in near future. The clinical use of these novel therapeutic agents is severely hampered by lack of appropriate carrier system that helps DNA in reaching the target cells and in the subsequent intracellular trafficking. The naked DNA is not suitable for in vivo transport of genetic material into selected cell types due to its degradation by serum nucleases. Non-viral gene therapy involving cationic polymers provides flexibility to construct a carrier with broad range of properties increasingly making vector of choice over viral vectors. Polyallylamine (PAA) is a synthetic cationic pH-sensitive polymer, which contains ionizable groups as the cationic polyelectrolyte. Here, we explored novel PAA based nanoparticles for efficient intracellular gene delivery. The primary amines (10-90%) of PAA (MW 17 kDa) was substituted using buffering capacity enhancing agent. Modified PAA thus formed was crosslinked with Polyethyleneglycol (PEG). The prepared systems were further characterized for particles size, surface charge, DNA accessibility, buffering capacity, in vitro transfection in COS-1 cells (Simian virus 40 transformed kidney cells of an African green monkey), and cytotoxicity. The average size of PAA nanoparticles were in the range of 185-230nm, which increased slightly upon complexation with DNA. As the degree of substitution was increased the zeta potential decreased. The zeta potential of all the samples decreased on complexing with DNA, but still remained positive. PAA-IAA-PEG (PIP) nanoparticles interacted with negatively charged DNA and the compounds were evaluated for their transfer efficiency on COS-1 cells. An acid-based titration suggested that modification of PAA resulted in sufficient improvement in buffering capacity of system to cleave the endosome. Fabricated PIP nanoparticles have low cytotoxicity as well as improved gene delivery efficiency. The results suggest that these systems offer considerable potential as ideal candidate for in vivo gene delivery.

Extended Abstract Status: Not Uploaded