Enantioselective sensor based on microgravimetric quartz crystal microbalance with molecularly imprinted polymer film

We report a novel quartz crystal microbalance sensor that provides enantios electivity to dansylphenylalanine enantiomers by using a molecularly imprin ted polymer film as a recognition element. The polymeric recognition thin f ilm, imprinted with chiral dansyl-l-phenylalanine, was immobilised on a gol d electrode modified with a photoactive precursor monolayer via a self-asse mbly process using photopolymerisation. The fabricated sensor was able to d iscriminate between l- and d-dansylphenylalanine enantiomers in solution ow ing to the enantioselectivity of the imprinted sites. The enantiomeric comp osition of l- and d-enantiomeric mixtures could be quantitatively determine d by the fabricated sensor. The detection limit is 5 mug mL(-1) with a resp onse range of 5-500 mug mL(-1) at pH 10.0. The influence of the template co ncentration on the sensitivity and selectivity of the synthesised polymer m embranes was investigated and optimised. The surface characteristics of the polymer coating were studied by varying the pH value of the buffer solutio n, and a convenient regeneration process was proposed to increase the repro ducibility and reusability of the sensor by flushing with pH 2.0 buffer. Th e selectivity and recognition mechanism of the imprinted polymer film were studied with compounds that are structurally related to the template. The m ethod presented in this work provides a novel means of preparing highly sel ective and sensitive chemical sensors via self-assembly and molecularly imp rinting techniques.