A novel microfluidic paper-based colorimetric sensor based on molecularly imprinted polymer membranes for highly selective and sensitive detection of bisphenol A

A novel microfluidic paper-based colorimetric sensor for the detection of bisphenol A (BPA) was developed based on the intrinsic peroxidase activity of ZnFe2O4 magnetic nanoparticles (ZnFe2O4 MNPs) and the adsorption capacity of molecularly imprinted polymer (MIP) membranes. In the process, ZnFe2O4 MNPs and cellulose fibers in paper were wrapped by MIP membranes (ZnFe2O4@MIP membranes) successfully. Novel MIP membranes for the recognition of BPA were prepared in polar solvent using acrylamide as the functional monomer and BPA as the template by bulk polymerization, which resulted in a new type of BPA imprinted polymer membranes. Adsorption isotherms model of MIP membranes was employed to describe the isotherms, and maximum adsorption capacity was evaluated. In the presence of 3,3′,5,5′-tetramethylbenzidine (TMB), the as-prepared ZnFe2O4 MNPs peroxidase mimetics was used to catalyze chromogenic reactions and showed the color with respective intensity. Under optimized conditions, the grey intensity was found to be proportional to the BPA concentrations in the range of 10 nM-1000 nM (R2 = 0.9945) with a detection limit of 6.18 nM. With the advantages of highly reproducible response, good selectivity and excellent regeneration, the colorimetric sensor holds great potential for portable detection of targets in environmental monitoring, security inspection and complicated matrices.