Novel cationic copolymers of a polyasparthylhydrazide: synthesis and characterization.

Alpha,beta-poly(asparthylhydrazide) (PAHy), a water soluble synthetic polymer, was functionalized by using EDCI chemistry with 3-(carboxypropyl)trimethyl-ammonium chloride (CPTACl) obtaining carboxypropyltrimethyl ammonium copolymers (PAHy-CPTA). Three PAHy-CPTA copolymers at increasing derivatization degrees (38%, 48%, 58%) were chosen for subsequent investigations. The capability of these copolymers to bind, neutralize, and protect DNA against degradation by DNase II was evalued by gel retardation assay and DNA degradation test at pH 5.5. Zeta potential measurements show that all studied polymers are able to neutralize the anionic charge of DNA at polymer/DNA weight ratio in the range of 0.8/1-5/1. Polyplex dimensional distribution analyses in bistilled water, saline solution NaCl 0.9%, and HEPES pH 7 show that polyplex size is strongly affected by both presence and type of electrolyte and with time incubation.