Temperature and magnetic dual responsive microparticles for DNA separation

The use of solid support in DNA separation from biological mixtures for diagnostics offers great potential for developing versatile separating tools. Although different polymer materials have been developed and studied for DNA separation, the application of such non-magnetic particles for DNA separation has remained limited. In this work, we describe the adsorption and desorption behavior of DNA on the temperature sensitive poly(N-isopropylacrylamide-co-aminoethylmethacrylate) (PNIPAM-co-AEMH) coated magnetic particles. Submicron sized temperature responsive magnetic/PDVB/P (NIPAM/AEMH/MBA) hybrid particles were prepared by a precipitation polymerization of NIPAM in the presence of previously prepared divinylbenzene (DVB) cross-linked magnetic particles as seed. Wherein, N,N-methylenebisacrylamide (MBA), aminoethylmethacrylate hydrochloride (AEMH) and 2,2'-azobis (2-methylpropionamidine) dihydrochloride (V-50) were used as a crosslinker, functional monomer and initiator respectively. The amino (-NH2) functional groups derived from AEMH and V-50 are able to be cationic charged (-NH3+) by being protonated and can interact electrostatically with negatively charged DNA. The adsorption and desorption behavior of Herring Sperm DNA onto these functional magnetic particles were investigated as a function of pH, temperature, time and ionic strength. Interestingly, it was found that there is a significant effect of temperature on the DNA adsorption onto these magnetic particles. The results obtained indicate that the maximum amount of DNA adsorption was found at lower salt concentration, acidic pH condition and below the volume phase transition temperature (VPTT) of the PNIPAM shell. The highest desorption was found at higher salt concentration in basic pH and above the vprr (40 degrees C) temperature. The temperature responsive magnetic particles and procedure described here can be used in microsystem separation technology for nucleic acid extraction, purification and concentration. (C) 2011 Elsevier B.V. All rights reserved.