Boronic acid-functionalized HEMA-based gels for nucleotide adsorption

A gel matrix that could be used as a sorbent for the specific adsorption of nucleotides was prepared by the radical copolymerization of 2-hydroxyethylmethacrylate (HEMA) with a relatively new boronic acid–functionalized monomer (4-vinylphenylboronic acid, VPBA). The synthesis of a gel could be achieved at a reasonably low temperature (+4°C) by using potassium persulfate and tetramethylethylenediamine as the redox system and methylenebisacrylamide (MBA) as the crosslinker. To increase the diol binding affinity of boronic acid–carrying gels, two different amine-containing monomers [N-3-(dimethylamino)propylmethacrylamide, DMAPM and 2-(dimethylamino)ethylmethacrylate, DMAEM) were also included in the gel-formation recipe. Then HEMA–VPBA–DMAPM and HEMA–VPBA–DMAEM terpolymer gels were obtained. The boronic acid–functionalized gel matrices with different swelling properties were produced by changing the feed concentrations of VPBA and of the amine-containing monomers (DMAPM and DMAEM). To test the usability of produced gels as a sorbent in the nucleotide adsorption, β-nicotinamide adenine dinucleotide (β-NAD) was selected as a model compound. The results of adsorption experiments indicated that the β -NAD adsorption capacity of HEMA-based gels increased with increasing VPBA feed concentration. Equilibrium adsorption capacities up to 33 mg β-NAD/g dry gel could be achieved with the DMAPM-containing boronic acid–functionalized HEMA-based gels. An increase in the feed concentration of DMAPM resulted in an increase in the β-NAD adsorption capacity of gels, while a decrease was observed with an increasing feed concentration of the other amine-containing monomer (DMAEM).