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Development of a histamine acoustic sensor using film of molecularly imprinted polymer prepared by electrochemical co-polymerisation of bis(bithiophene) derivatives
|Agnieszka Pietrzyk 1, Wlodzimierz Kutner 1, Raghu Chitta 2, Francis D'Souza 2
1. Polish Academy of Sciences, Institute of Physical Chemistry, Kasprzaka 44/52, Warszawa 01-224, Poland
Preliminary results will be presented on application of a selective molecularly imprinted polymer (MIP) film for development of an acoustic histamine sensor. This MIP film and a 10-MHz quartz crystal resonator with Pt film electrodes of an electrochemical quartz crystal microbalance (EQCM) consists the recognition and transduction element of the sensor, respectively. Histamine was imprinted by electrochemical co-polymerisation of self-assembled complexes of this analyte, initially used as a template, and two bis(bithiophene) derivatives each bearing different reception site. The crown ether and dioxaborolane substituents of the bis(bithiophene) polymer subunits served as the respective reception sites. Accordingly, the bis(2,2'-bithienyl)-benzo-[18-crown-6] methane and bis(2,2'-bi-thie nyl)-4,4,5,5-tetramethyl-2-phenyl-[1,3,2]dioxaborolane methane monomers were used for electropolymerization in a 0.1 M (TBA)ClO4 solution of 1,2-dichlorobenzene or acetonitrile. Since the histamine molecule contains both a primary aliphatic amine site and an imidazole heteroaromatic ring, in our systematic studies, firstly, two different model analyte compounds were used to probe the histamine imprinting. That is, a phenethylamine model analyte served to test complexation of the protonated aliphatic amine group, –NH3+, and an imidazole probe to test reception of the nitrogen atom of its ring. In the pH range between pKa1 and pKa2 of histamine, its amine group is protonated and, therefore, can be complexed by the crown ether moiety. Moreover, the nitrogen atom of the imidazole ring can coordinate at this pH range to the boron atom of the borolane group. The most convenient way to release the histamine template from the polymer was to increase solution basicity to pH=12. Under these solution conditions, the boron atom changes its hybridization from sp2 to sp3 and the aliphatic amine group is deprotonated and, therefore, both the phenethylamine and imidazole probe is released. Binding of the imidazole, phenethylamine and histamine template in MIPs was characterized in situ under flow injection analysis (FIA) conditions by the simultaneous piezoelectric microgravimetry and chronoamperometry measurements at EQCM, as well as ex situ by the reflectance mode UV-vis and X-ray photoelectron spectroscopy measurements. Under FIA conditions, EQCM piezoelectric microgravimetry responses  of the resonant frequency and dynamic resistance changes after injection of the analyte solution samples were by over an order of magnitude larger for the derivatised bis(bithiophene) polymer films than those for the non-derivatised polymer films, used for comparison, indicating a pronounced analyte preconcentration in case of the former. The frequency change response to the imidazole and phenethylamine probe was linear over at least an order of the concentration magnitude in the range 10 mM to 1.0 M and 25 to 800 mM, respectively. Expectedly, the analyte preconcentration level in film was proportional to the film thicknesses.
1. A. Kochman, A. Krupka, J. Grissbach, W. Kutner, B. Gniewinska, and L. Nafalski, Electroanalysis 2006, 18, 2168.
Presentation: Poster at SMCBS'2007 International Workshop, by Agnieszka Pietrzyk
See On-line Journal of SMCBS'2007 International Workshop
Submitted: 2007-10-17 18:34 Revised: 2009-06-07 00:44