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The content of amino acids in human body is closely related to human health and plays an important role in physiological regulation and medical function. In order to recognize a variety of amino acids, an electrochemical sensor array based on poly(3,4-ethylenedioxythiophene) (PEDOT) electrode was established by using two kinds of electropolymerizers, i.e., citrate and the mixture of citrate and potassium nitrate as sensing elements. Different electropolymerizers lead result in different amount of negative charge on PEDOT electrode, which leads to different adsorption capacity for positive charge amino acids and different repulsion capacity for negative charge amino acids, bringing about obvious changes in differential pulse voltammetry (DPV) current. The five amino acids were accurately identified by linear discriminant analysis (LDA), and the electrochemical sensor array was successfully applied in the differential detection of amino acids in milk. [Display omitted] • 1. An electrochemical sensor array based on poly(3,4-ethylenedioxythiophene) electrode was established. • Citrate and the mixture of citrate and potassium nitrate as sensing elements of the sensor array. • The five amino acids were accurately identified by linear discriminant analysis. • The sensor array was successfully applied in the discrimination of amino acids in human urine. [ABSTRACT FROM AUTHOR]

Nanozymes have been relatively well explored, and bimetal-doped nanozymes have attracted much exploration due to their superior catalytic activity. We developed bimetallic FeCu/NPCs and Cu/NPCs nanozymes, which have good catalytic properties due to the coordination of Fe and Cu with N and P. The nanozymes acted as sensing elements in a cascade reaction system to effectively recognize seven terpenoids, including menthol (Men), paeoniflorin (Pae), camphor (Cam), paclitaxel (Pac), andrographolide (Andro), ginkgolide A (Gin A), and piperone (Pip). Terpenoids act as inhibitors of acetylcholinesterase (AChE) and reduce the hydrolysis of acetylcholine (ATCh), providing insight into establishing a simple and distinct assay for terpenoids. Notably, the sensor array distinguished seven terpenoids with concentrations as low as 10 ng/mL and achieved high-precision detection of mixed samples with different molar ratios and 21 unknown samples. Finally, the sensor array successfully distinguished and identified multiple terpenoids in herbal samples. [Display omitted] • A bimetallic and multi-atom co-doped nanozyme was synthesized. Due to the coordination of metal and N, P, the peroxidase activity is much higher than other reported nanozymes. • A simple P doping strategy for pyrolysis of polymer spheres at high temperature was designed. P doping not only formed uniform pore structure, and achieve high coordination with the metal, significantly enhance the catalytic activity of the material • Based on the good activity of nanozymes, different terpenoids have different inhibitory effects on acetylcholinesterase. A colorimetric array sensor for seven terpenoids was constructed. • 4. The sensor array can distinguish 7 terpenoids with a concentration as low as 10 ng / mL in actual Chinese herbal medicine samples, and the discrimination degree reaches 100 %。 [ABSTRACT FROM AUTHOR]