Thermosensitive N-isopropylacrylamide-vinylphenyl boronic acid copolymer latex particles for nucleotide isolation

In this study, thermosensitive N-isopropylacrylamide-4-vinylphenylboronic acid copolymer latex, poly(NIPA-co-VPBA) particles were obtained by dispersion polymerization. A nucleotide isolation procedure was proposed by using the latex particles as the sorbent. As a model nucleotide, beta-nicotiamide adenine dinucleotide (beta-NAD) was adsorbed onto the latex particles at a low temperature (i.e. +4 degreesC) via the interaction between boronic acid groups of particles and diol groups of beta-NAD. The equilibrium beta-NAD adsorption capacities up to 40 mg/g were obtained by the proposed sorbent. The equilibrium beta-NAD adsorption capacity of the latex particles significantly decreased with increasing temperature and nearly zero nucleotide adsorption was observed at the temperatures higher than 30 degreesC. On the other hand, poly(NIPA-co-VPBA) latex particles forming a stable aqueous suspension in the temperature range of 4-25 degreesC exhibited a thermoflocculation behavior at the temperatures higher than 30 degreesC. The effects of temperature both on the beta-NAD adsorption capacity and the colloidal stability of the particles were used for beta-NAD recovery. After adsorption of beta-NAD onto the stable latex particles at +4 degreesC, the particles were flocculated by elevating the temperature to 37 degreesC and beta-NAD was desorbed from the flocculating particles simultaneously. Hence, beta-NAD was recovered in the clear supernatant. Therefore, the desorption of beta-NAD to a medium at any ionic strength and at any pH could be achieved by using temperature as an on-off switch controlling the adsorption/desorption behavior. (C) 2003 Elsevier B.V. All rights reserved.