Electrochemical determination of L-tyrosine by a mediated banana peel tissue paper based biosensor modified with functionalized silica nanoparticles

L-tyrosine is known as essential amino acid. It is a vital constituent of proteins and establishing of a positive nitrogen balance [1]. In this paper, a novel and facile method was developed for determination of L-tyrosine by immobilization of the banana peel tissue tyrosinase at fiber matrices of the modified paper disc. The plants tissue as the source of enzymes has been applying at fiber matrices of the paper disc immobilized via physical adsorption recently [2]. In this study, the mediator potassium hexacyanoferrate was added to the enzymatic paper disc. For modification and increasing sensitivity, 3-mercaptopropyl trimethoxysilane- functionalized silica nanoparticles were added within the paper disc. This paper disc was placed on the top of the graphite screen printed electrode and was connected to potentiostat/ galvanostat electrochemical device. Characterization of synthesized nanostructure was down by scanning electron microscopy and Fourier transform infrared spectroscopy. Electrochemical characterization was studied by cyclic voltammetry and electrochemical impedance spectroscopy methods. After optimization of effective parameters, L-tyrosine measurements were done by differential pulse voltammetry. This biosensor showed a linear response for L-tyrosine in the wide concentration range of 0.05-600 µM with a detection limit about 0.03 µM and limit of quantification about 0.1 µM. The stability of this biosensor and its selectivity against some interferences biomolecules were evaluated. The practical applicability of this biosensor was established for the voltammetric determination of L-tyrosine in the heparinized blood plasma sample. The statistical tests showed usability of the proposed biosensor for voltammetric determination of L-tyrosine.