Hydrogen Bond-Dominated Hydrogel Copolymers for Selective Isolation and Purification of Microcystin-LR from Microcystis aeruginosa Lysate

The quality of microcystin-LR (MC-LR) standards is frequently low and varies considerably due to the quite complex and challenging isolation and purification of MC-LR from Microcystis aeruginosa lysates. To streamline the way of standard acquisition, we describe an approach that combines rational design and directed chemical evolution for discovering synthetic hydrogel copolymers, which are potential abiotic affinity materials for MC-LR. A small focused polymer library was engineered by incorporating various combinations and ratios of candidate N -acryloyl-( l )-amino acid monomers, including N -acryloyl-glycine (AGly), N -acryloyl- l -phenylalanine (APhe), and N -acryloyl- l -glutamic acid (AGlu), that were selected based on the analysis of structural and physicochemical properties of MC-LR. A hydrogel copolymer AGlu-NP13 (58% AGlu, 40% TBAm, and 2% BIS) that had a high and specific affinity to MC-LR was screened from the polymer library. The hydrogen bond interaction may dominate the AGlu-NP13– MC-LR binding. The external conditions that influence the hydrogen bond interaction, including pH and solvation environments, controlled the catch and release of MC-LR on AGlu-NP13 . The uptake of MC-LR is maximum under a saturated ethyl acetate (10%, v/v) solution at pH 3. The bound MC-LR can be completely desorbed from the hydrogel copolymer with a pH 9.5 and 70% methanol aqueous solution. The screened polymer affinity ligand was successfully applied for the isolation and purification of MC-LR from the lyophilized cell extracts of M. aeruginosa 905, providing a potential application of this material in standard preparation, sample pretreatment, and adsorption removal of MC-LR in complicated environmental and biological samples.