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, β-nicotiamide adenine dinucleotide (β-NAD) was adsorbed onto the latex particles at a low temperature (i.e. +4 °C) via the interaction between boronic acid groups of particles and diol groups of β-NAD. The equilibrium β-NAD adsorption capacities up to 40 mg/g were obtained by the proposed sorbent. The equilibrium β-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 °C. On the other hand, poly(NIPA-co-VPBA) latex particles forming a stable aqueous suspension in the temperature range of 4–25 °C exhibited a thermoflocculation behavior at the temperatures higher than 30 °C. The effects of temperature both on the β-NAD adsorption capacity and the colloidal stability of the particles were used for β-NAD recovery. After adsorption of β-NAD onto the stable latex particles at +4 °C, the particles were flocculated by elevating the temperature to 37 °C and β-NAD was desorbed from the flocculating particles simultaneously. Hence, β-NAD was recovered in the clear supernatant. Therefore, the desorption of β-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.