A Molecularly Imprinted Copolymer Designed for Enantioselective Recognition of Glutamic Acid

Authors


  • This project was supported by the National Science Funds for Distinguished Young Scholars (20325518) and Creative Research Groups (20521503), the Key Program (20535010) and Special Program (20745003) from the National Natural Science Foundation of China, and the Science Foundation of Jiangsu (BS2006006, BS2006074, BK2007570).

Abstract

A newly designed molecularly imprinted polymer (MIP) material was developed and successfully used as recognition element to fabricate a capacitive sensor for enantioselective recognition of glutamic acid (Glu). The MIP with a well-defined structure was synthesized on a gold electrode in one step by electrochemical copolymerization of o-phenylenediamine (o-PD) and dopamine (DA) in the presence of template molecule Glu. The resulting MIP material was characterized with a potentiostatic frequency scan method, cyclic voltammetry, capacitance measurements, atomic force microscopy, and X-ray photoelectron spectroscopy. The structure and recognition behaviour of the copolymer film to template molecule depended on its composition. The optimal composition was at the o-PD to DA molar ratio of 3:2. With a potentiostatic time scan method the copolymer displayed high enantioselectivity and sensitivity to the stereoselective rebinding of L- or D-Glu to their corresponding artificial receptor due to the exact definition of the imprint cavity. The capacitance response of the sensor for L-Glu or D-Glu was proportional to their concentration in the range of 16.7 to 250 μM. The enantiometric selectivity coefficients for L-Glu and D-Glu imprinted films against their respective enantiomers are 24 and 15, respectively. The resulting MIP capacitive sensors showed good reproducibility, stability and repeatability. This strategy opened a convenient way for preparation of enantioselective MIPs and recognition of enantiotropic molecules.

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