Imprinted electrochemical sensor of tyrosine based on chitosan/β-cyclodextrin/multi-walled carbon nanotubes composite film

Background: As a vital amino acid in the human body, tyrosine is indispensable in various biological processes, and therefore its accurate and simple determination is of crucial importance. In this work, a facile approach was developed to construct a molecularly imprinted sensor for tyrosine via co-electrodeposition of chitosan, β-cyclodextrin and tyrosine on the surface of indium tin oxide that was pre-coated with multi-walled carbon nanotubes (MWNTs). Methods: Benefitting from the excellent film-forming ability and the rich functional groups to form a hydrogen bond with target molecules, chitosan was utilized to form a recognition matrix. MWNTs and β-cyclodextrin were then introduced to enhance the selectivity and sensitivity to tyrosine, due to the subtle electronic, catalytic properties and possible π-π interaction of MWNTs with tyrosine, as well as recognition ability of β-cyclodextrin. The morphology of the imprinted films was characterized by a scanning electron microscope. The electrochemistry and tyrosine sensing performance were investigated in detail by cyclic voltammetry and chronoamperometry. Results: Amperometry results showed that the imprinted sensor exhibited a linear range of 1.0×10−6 to 1.0×10−4 M and 1.0×10−4 to 1.0×10−3 M for tyrosine determination, with a detection limit of 6.0 × 10−7 M (S/N=3). Moreover, a satisfactory recovery in the range of 99.0% to 105.1% was obtained with the application of the imprinted sensor in artificial urine samples analysis. Conclusion: The imprinted electrode is reusable with satisfactory reproducibility and stability in tyrosine determination.