A non-enzymatic sensor based poly(Histidine) for highly sensitive detection of Tyramine

Abstract

Rapid developments of the economy and society in the twenty-first century have exposed people's lifestyles to dietary hazards. Consequently, food quality and safety are critical concerns for consumers and public health all over the world.  It is necessary to ensure that food consumed is safe and free of potentially hazardous substances in large quantities. Biogenic amines (BAs) are food quality indicators for microbial contamination and processing conditions in both fresh and processed foods, as well as a crucial role in the physiological and toxicological effects on humans [1].  Tyramine is one of the most relevant biogenic amines which is found in fermented food, beverages and mainly in dairy products as cheeses [2].  It is an indirectly acting sympathomimetic that could be caused by the release of greater amounts of noradrenaline from sympathetic nerve terminals.  Hence, the excessive amounts of tyramine in food may cause adverse health risks such as headache, nausea, respiratory disorders, hypertension, brain haemorrhaging and cardiac failure [3].  Especially, patients who take monoamine oxidase inhibiting (MAOI) drugs for treatment of mental depression may lead to hypertensive crises, also referred to as the “cheese reaction” [4].  Moreover, tyramine-containing food is considered responsible for migraine attacks.  Because of its toxicity, the development of a practical analytical method for this BA monitoring is of clinical and food industrial significance.  The electrochemical technique turned out to be an alternative choice for tyramine determination due to its sensitivity, selectivity, rapidity and possibility of miniaturization.  Recently, various modifiers have been used for the development of tyramine sensors, such as carbon-based nanomaterials [5], composites between conducting polymer and nanoparticles [6] molecularly imprinted polymers (MIPs) [7] and enzyme-immobilization [8].  Even though the aforementioned sensors provide accurate and reliable performance, they are limited by the multiple modification steps and the use of complicated materials, which become the inability for on-site and real-time analysis.  Herein, a simple and highly sensitive electrochemical sensing platform for the quantification of tyramine is presented.  The proposed sensing was fabricated via electropolymerization of histidine for generating the poly (Histidine) film directly onto the screen-printed graphene electrode.  This produced film has the advantages of enhancing electrocatalytic activity, which in turn allows better sensitivity and simplicity of synthesis and deposition onto the electrode surfaces in a single step using
eco-friendly procedures.  The single modification step was performed by sweeping potential from -0.6 to +2.0 V for 20 cycles at a scan rate of 200 mV/s using cyclic voltammetry.  Subsequently, the amount of tyramine was successfully investigated by differential pulse voltammetry (DPV) using PBS (0.1 M, pH 7.4) as a supporting electrolyte.  All parameters concerning DPV technique were systematically optimized to obtain the optimal conditions.  The current response had a good linear correlation with tyramine concentrations (fig.1 [B]) in the ranges of 0.5-20 µM (R² = 0.9933) and 50-300 µM (R² = 0.9961) with the detection limit (3SD/slope) was found to be 0.065 µM.  Despite just using a poly (Histidine) modified electrode, the presented sensor exhibited not only high sensitivity but also excellent reproducibility (%RSD = 1.23) and good selectivity for tyramine detection.  The promising results show that the developed tyramine sensor could potentially be an alternative tool for analyzing tyramine levels in food and biological samples (fig.1 [A]).  Furthermore, the benefits of this electrochemical sensor include its ease of fabrication, portability, cost-effectiveness, rapid response and suitability for in-field detection.