Sustainable DNA release from chitosan/protein based-DNA gel particles.

Chitosan lactate (CL) alone and in combination with protamine sulfate (PS) was used as an intrinsic biocompatible carrier to form DNA gel particles by interfacial diffusion. Protamine sulfate is highly positively charged, arginine-rich protein, which has been previosly used in the formation of mixed carriers for modulating DNA release. In view of the promising properties of oligosaccharides and the well-known cell-penetrating and nuclear localization capabilities of protamines, we presume that both structures could play a critical role in DNA delivery. The purpose of this study was to evaluate the capability of water-soluble, low molecular weight chitosan lactate to form DNA gel particles alone (binary system) and in combination with the protein protamine sulfate (ternary system). The particles were characterized with respect to the degree of DNA entrapment, the swelling and dissolution behavior, the secondary structure of DNA in the particles, and the kinetics and mechanisms of DNA release. We controlled the magnitude of DNA release and achieved controlled release by using mixed systems and changing the CL/PS ratio in the solution where the particles were formed. The Rose Bengal partition assay was applied for the first time to estimate the surface hydrophobicity of DNA gel particles. Both CL alone and in combination with PS promotes the formation of DNA gel particles that have an acute hydrophilic character, which may govern the posterior adsorption of plasma proteins and influence the bioavailability of the systems. The lack of hemolytic effect of these DNA gel particles suggests their potential application as long-term blood-contacting medical devices.