RESUMO
Herein, we introduce a novel method for tryptophan detection via a reduction reaction facilitated by its interaction with a copper(II) phthalocyanine (CuPc) electrocatalytic electrode. This method addresses challenges associated with the susceptibility of the oxidation response to interference from various species when measuring tryptophan in bodily fluids. The reduction currents exhibit a linear increase with tryptophan concentrations in two ranges: 0.0013-0.10 mM and 0.10-1.20 mM, with the sensitivities of 14.7 ± 0.5 µA mM-1 and 3.5 ± 0.1 µA mM-1, respectively. The limit of detection (LOD, 3SB/m) is determined to be 0.39 µM. The sensor exhibits excellent reproducibility, with the relative standard deviation of <5%. Application of the sensor to authentic urine samples yields a % recovery of 101 ± 4%.
Assuntos
Técnicas Eletroquímicas , Eletrodos , Indóis , Limite de Detecção , Compostos Organometálicos , Triptofano , Triptofano/urina , Triptofano/química , Indóis/química , Humanos , Compostos Organometálicos/química , Catálise , Técnicas Eletroquímicas/métodos , Técnicas Eletroquímicas/instrumentação , Oxirredução , IsoindóisRESUMO
A highly sensitive and rapid electrochemical sensor was developed for detecting melatonin using a molecularly imprinted polymer (MIP) with methylene blue as the functional monomer and melatonin as the template. The MIP was synthesized via a simple electropolymerization process that did not require an initiating reagent. The sensor demonstrated good selectivity for melatonin against common interferences such as lactate, cytosine, cytidine, urea, ascorbic acid, creatine, creatinine, serotonin, and tryptophan. Melatonin detection was achieved at a potential of 0.60 V vs. Ag/AgCl with a sensitivity of 138.8 ± 4.7 µA µMâ1 in the linear range 0.097 - 200 µM and a limit of detection of 29 nM (3SB/m). The sensor exhibited excellent reproducibility and repeatability for both within (intra) and between (inter) electrodes (%RSD < 3% for n = 3). The sensor was applied to authentic urine and saliva samples with recoveries of 103 ± 1% and 102 ± 1%, respectively.