Development of water compatible imprinted polymer beads for piezoelectric sensing of ultra-trace 5,6-dihydrouracil in biological fluids

Abstract

In this work, a novel water compatible molecularly imprinted polymer was synthesized in bead shape by the precipitation polymerization technique. Immobilization of such imprinted beads on the surface of quartz crystal microbalance (QCM) was made through Au-S links using the “surface-grafting to” approach. The imprinted beads revealed a superiority in terms of recapture ability of analyte in the large concentration range and sensitivity as compared to traditionally imprinted monolith films. The piezoelectric analysis of target analyte (5,6-dihydrouracil) with imprinted polymer beads was found to be highly selective and sensitive, without any cross-reactivity and false-positives, in real samples. A perfect linearity between the frequency shift and the analyte concentration was observed in the range 0.03–1.75μM, with detection limits varying between 0.003–0.006μM (S/N=3) [cf., imprinted film modified QCM: 0.04–1.32μM, limit of detection 0.01μM (S/N=3)]. The endogenous 5,6-dihydrouracil level was also obtained in the blood plasma sample which may help exploring concerned dihydropyrimidine dehydrogenase activity, on the basis of concentration ratio [dihydrouracil]/[uracil] in cancer patients undergoing chemotherapy with 5-fluorouracil supplementation.