| Summary: | Biosensorsare systems that can perform a quantitative and/or qualitative analysis ofsubstances in a liquid or gas environment through their biological recognitionsites and transform the acquired data into detectable signals. Biosensors areable to detect physical changes (i.e. as density, mass concentration, etc.) bymeans of recognition sites and correlate them with electrical or opticalquantities (i.e. current, voltage and impedance). In this study, threemolecularly imprinted pencil graphite electrodes (PGE) with differing numbersof choline recognition sites, at E-1 M, E-3 M and E-5 M concentration, wereused as electrochemical biosensors. An increase in choline receptorconcentration on the electrode surface was expected to correlate with anincrease in PGE surface bound choline and thus lead to electrical changes. Thestudy was conducted in a three-electrode cell with Ag/AgCl as the referenceelectrode, platinum wire as the counter electrode and PGE as the workingelectrode. Cyclic voltammetry and electrochemical impedance measurements wereconducted in 10 mM phosphate buffer solution (PBS) containing 5mM K3[FeCN6]-3/-4redox pair. As expected, as increasing amount of choline was bound to thecomplementary recognition sites on choline imprinted PGEs, a correlating changein current, voltage and impedance on PGEs was observed. The dynamic detectionrange for choline expanded as the choline concentration imprinted on the PGEelectrode increased. Using the E-1 M PGE electrode, 72 pM limit of detection,up to 7.2 nM limit of linearity was attained.
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