Molecularly imprinted polymer (MIP) based piezoelectric microgravimetry chemosensor for selective determination of adenine

An adenine-templated molecularly imprinted polymer (MIP) film, deposited on a poly(bithiophene) barrier film, served as the recognition element of a piezomicrogravimetric (acoustic) chemosensor. A 10 MHz AT-cut shear-thickness-mode bulk-acoustic-wave quartz crystal resonator with Pt film electrodes was used as the signal transducer. Adenine electrooxidation was prevented by the barrier film. The MIP film was deposited by electrochemical co-polymerization of two functional monomers of bis(bithiophene) derivatives, bearing either the 18-crown-6 or dioxaborinane substituent, in the presence of the adenine template. A strong base solution was then used to extract the template. Completeness of the template removal was substantiated by the UV-vis, XPS, DPV, and EIS measurements. The chemosensor performance was evaluated with the piezoelectric microgravimetry detection at QCM under FIA conditions using a carrier acetonitrile-water (1:1, v:v) mixed solvent solution. The linear dynamic concentration range extended from at least 0.1 to 1 mM for the 35 mu L/min flow rate, and 100 pi volume of the injected adenine solution. The chemosensor selectivity allowed for discrimination of the adenine analyte from structurally and functionally related interferants, such as 2-aminopurine, guanine, and ascorbic acid. The determined from the FIA kinetic studies stability constant of the MIP-adenine complex, (18 +/- 2.4) x 10(4) M-1, was much higher than that of the MIP-(2-aminopurine), (650 90)M-1, MIP-guanine, (122 +/- 11) M-1, and MIP-(ascorbic acid), (92 10) M-1, complexes. The concentration limit of detection was as low as 5 nM adenine for the 35 mu L/min flow rate, and 1 mL volume of the injected sample solution. (C) 2010 Elsevier B.V. All rights reserved.