Hydrophilic and cationic latex particles for the specific extraction of nucleic acids.

The adsorption of BSA and RNA onto hydrophilic and thermosensitive poly(N-isopropyl-acrylamide) (NIPAM) latex particles was described as a function of pH, ionic strength and temperature. The hydrogel poly(NIPAM) latex was synthesized by precipitation polymerization in the presence of a cationic amino-containing monomer. The latex obtained was characterized in terms of particle size, and electrophoretic mobility as a function of pertinent variables: pH, temperature and ionic strength. The adsorption of BSA onto the latex was investigated to identify the conditions at which the adsorbed amount of BSA was negligible. The adsorption of RNA was studied to establish the conditions which give rise to maximal adsorption of RNA. In order to favor the desorption of RNA, desorption was investigated by changing the pH, ionic strength, and temperature. The adsorption of BSA was found to be lower at 20 than at 40 degrees C. However, the adsorption of RNA is drastically affected by the pH and the ionic strength of the medium. Maximal adsorbed amounts were obtained at acidic pH, 20 degrees C, and low ionic strength. The adsorption is shown to decrease when the pH, temperature and ionic strength increase, implying that the adsorption was mainly governed by electrostatic interactions. Maximal release of RNA molecules was obtained at high ionic strength and basic pH.