Insights from experiments and simulation of polydopamine modified carboxymethyl chitosan molecularly imprinted resins for adsorption of epicatechin in Rumex acetosa L.

In this study, a novel polydopamine modified carboxymethyl chitosan molecularly imprinted resin (CMCS-MIR) was synthetized for selectively adsorbed and separated epicatechin (EC) from Rumex acetosa L. The preparation process involved modifying the surface of DM-130 resin to form the polydopamine (PDA) layer firstly, which facilitated an increase in adsorption sites. Subsequently, carboxymethyl chitosan (CMCS), a green functional monomer, was utilized along with glutaraldehyde as a crosslinking agent and EC as a template molecule to synthesize the CMCS-MIR. The synthesized CMCS-MIR exhibited an adsorption capacity of 53.30 mg·g −1 within 6 h and exhibited excellent selectivity and affinity towards EC (IF = 3.31). Moreover, the CMCS-MIR maintained stable adsorption performance and reusability with the adsorption efficiency remaining above 90 % in the fifth cycle. What's more, the CMCS-MIR can be used as a novel column filler in solid-phase extraction (SPE) to separate EC from extracts of Rumex acetosa L. roots. The adsorption recovery rate of EC is 89.56 %, the desorption recovery rate reaches 88.02 %. The DFT simulation and NMR experiments indicated that the predominant adsorption mechanism was due to the strong hydrogen bonding interactions. This work offers significant insights into the development of green molecularly imprinted materials with excellent selectivity and recognition capabilities.