Fabrication of a novel nanostructure electrochemical sensor for determination of tyrosine

Amino acids such as tyrosine are the major targets for radical’s attack. 4-Hydroxyphenylalanine or tyrosine (Tyr) is a nonessential amino acid and acts as a singlet oxygen quencher. Tyrosine plays an integral role in the synthesis of the neurotransmitter serotonin such as norepinephrine and dopamine (5-HT). Tyrosine and other amino acids play roles in inducing dementia such as Alzheimer s disease. The lack of tyrosine concentration in the body may cause albinism, alkaptonuria, depression, narcolepsy and other psychological diseases while a high level of tyrosine could cause the increase of sister chromatid exchange [1]. Therefore, it is significant to develop a simple, accurate, rapid and inexpensive sensor for the determination of tyrosine. Electrochemical analytical techniques have been a topic of interest to researchers in the biological and environmental analysis, due to simplicity, cost effectiveness, high sensitivity and the possibility of miniaturization. A screen-printed electrode (SPE) is an attractive alternative choice due to their miniaturized size, inexpensive, easy to fabricate, rapid responses and disposable, which makes them especially suitable for on-site analysis [2]. However, the signal to noise of bare electrode is insufficient to determine the trace level of tyrosine. One of the major strategies to enhance the electron exchange in electrochemical sensors and biosensors is to design new sensing layer by combining highly electrocatalytic materials with highly conductive substances. Metal oxide based nanocomposites have wide applications in 14th Annual Electrochemistry Seminar of Iran Materials and Energy Research Center (MERC), 12- 13 Dec, 2018 47 photocatalysis, gas-sensors, piezoelectric materials, and solar cells due to its features such as photosensitivity, non-toxic and low cost. The combination metals with metal oxide nanocomposites have a significant effect on the catalytic activity due to the interactions and surface reactivity [3]. A simple, selective and sensitive sensor based on La3+/Co3O4 nanoflowers modified screen printed electrode (La3+/Co3O4 NF/SPE) is introduced for electrochemical determination of tyrosine. Compared with the unmodified electrode, the oxidation peak current significantly improved. Under optimized experimental conditions, the oxidation peak current of tyrosine was linear over a concentration range of 5.0 × 10−7 to 7.0 × 10−4 M with a detection limit of 4.0×10−8 M. Moreover, the applicability of the method was demonstrated by the recovery tests of tyrosine in real samples.