Novel Biocompatible DNA Gel Particles

Surfactants with the cationic functionality based on an amino acid structure have been used to prepare novel biocompatible devices for the controlled encapsulation and release of DNA. We report here the formation of DNA gel particles mixing DNA (either single- (ssDNA) or double-stranded (dsDNA)) with two different single-chain amino acid-based surfactants: arginine-N-lauroyl amide dihydrochloride (A LA) and N(alpha)-lauroyl-arginine-methyl ester hydrochloride (LAM). The degree of DNA entrapment, the swelling/deswelling behavior, and the DNA release kinetics have been studied as a function of both the number of charges in the polar head of the amino acid-based surfactant and the secondary structure of the nucleic acid. Analysis of the data indicates a stronger interaction of ALA with DNA, compared with LAM, mainly at to the double charge carried by the former surfactant compared to the singly charged headgroup of the latter species. The stronger interaction with amphiphiles for ssDNA compared with dsDNA suggests the important role of hydrophobic interactions in DNA. Data on the microstructure of the complexes obtained from small-angle X-ray scattering (SAXS) of the particles strongly suggests a hexagonal packing. It was found that, the shorter the lattice parameter, the stronger the surfactant-DNA in and the slower the DNA release kinetics. Complexation and neutralization of DNA on the DNA gel particles was confirmed by agarose gel electrophoresis measurements.