Paper Title
Novel Biosensors and Sensor for Neurotransmitters Determination for Point-of-Care Testing

Abstract
In our previous work we have developed optical biosensor for detection of dopamine, where were used graphene quantum dots (GQDs) for a detection system. In such sensor dopamine molecules coated the GQD surface - as a result occurred quenching of fluorescence due to Resonance Energy Transfer (FRET). Changes in fluorescence corresponded to specific concentrations of the neurotransmitter in tested sample. Now we have constructed a new optical biosensor for epinephrine detection, which proved facile and convenient method for this neurotransmitter determination. Epinephrine does not possess any fluorescence properties in opposite to dopamine, so it was essential to prepare a new dye solution for detection system and carrier for epinephrine. The working Fe(II) solution was prepared freshly by mixing with the optimized alkaline buffer. To such prepared dye-solution were added epinephrine with different concentrations, and detected with LTCC-based sensor connected with immobilized biological active material. An outer platinum electrode was modified with semi-conductive polymer layer based on 2-([2,2'-bithiophene]-5-yl)-6-([2,3'-bithiophene]-5'-yl)-4-(5-hexylthiophene-2-yl)pyridine and laccase, as a basis for determination system of epinephrine. In result, constructed biosensor exhibits good performance, strong affinity between enzyme and catecholamine, fast response to the substrate and good linear range. Obtained results have shown that the developed system could be used in medical diagnostics for neurotransmitters detection. Keywords - Biosensor, Epinephrine, Laccase, Semi-Conductive Polymer