Optimization of enrofloxacin-imprinted polymers by computer-aided design

Recently, a series of computational and combinatorial approaches were employed to improve the efficiency of screening for optimal molecularly imprinted polymer (MIP) systems. In the present work, we investigated MIP systems based on enrofloxacin (ENRO) as the template molecule and either 2-vinyl-4,6-diamino-1,3,5-triazine (VDAT), 4-vinylpyridine (4-Vpy), acrylamide (AM), or trifluoromethacrylic acid (TFMAA) as the functional monomer. The optimized geometries of these systems, the optimal molar ratios of template to functional monomer, and the active sites in the systems were all identified using density functional theory (DFT) at the B3LYP/6-31G(d, p) level of theory. The imprinting mechanism was investigated by calculating the hydrogen nuclear magnetic resonance (H-1 NMR) spectra of the systems. The simulated results revealed that the MIP system corresponding to a 1: 7 complex of TFMAA and ENRO contained the most H-bonds and presented the lowest (i.e., most negative) binding energy and the strongest interactions. MIPs of ENRO with the four functional monomers were prepared based on the optimal molar ratios of template to functional monomer determined in the simulations. Adsorption experiments suggested that TFMAA has the highest affinity (saturated adsorption 30.25 mg/g) among the four monomers for the template. Thus, we determined the optimal monomer and imprinting ratio for ENRO-imprinted MIPs and predicted their adsorption characteristics.