RESUMEN
The level control of biological active molecules in human body fluids is important for the surveillance of several human diseases. Dopamine (DA) and uric acid (UA) are two important biomarkers of neurological and bone diseases, respectively. Design of sensitive and cost-effective sensors for their detection is an effervescent research field. We report on the straightforward design of laser-induced graphene electrodes (LIGEs) from the laser ablation of a polyimide substrate and their modification by electrochemical deposition of gold nanoparticles (AuNPs/LIGE) and their uses as chemosensors. Electrochemical investigations showed that the presence of gold nanoclusters onto the electrode surface improved the electrochemical surface area (ECSA) and the heterogenous electron transfer (HET) rate. Furthermore, the AuNPs/LIGEs can be used to detect simultaneously low concentrations of DA and UA in presence of ascorbic acid (AA) as an potentially interfering substance at redox potentials of 300 mV, 230 mV and 450 mV and 91 mV, respectively, compared with the Ag/AgCl (3 M KCl) reference electrode in cyclic voltametric. The method displayed linear ranges varying from 2 to 20 µM and 5 to 50 µM, led to limits of detection of 0.37 µM and 0.71 µM for DA and UA, respectively. The AuNPs/LIGE was applied to simultaneously detect both analytes in scarcely diluted human serum with good recoveries. The data show that the recovery percentages ranged from 94% ± 2.1 to 102 % ± 0.5 and from 94% ±0.3 to 112% ± 1.4 for dopamine and uric acid, respectively. Thus, the AuNPs/LIGEs are promising candidates for the detection of other biologically active molecules such as drugs, pesticides, and metabolites.
Asunto(s)
Grafito , Nanopartículas del Metal , Humanos , Dopamina , Ácido Úrico , Oro , Rayos Láser , ElectrodosRESUMEN
CdTe quantum dots (CdTe QD) have been produced at different times of synthesis (1, 2, and 4 h) using thiols as capping agents: mercaptopropionic acid (MPA), mercaptosuccinic acid (MSA) and N-acetyl-l-cysteine (NAC) using water as a solvent. The produced CdTe QD were characterized by UV-vis and photoluminescence (PL) spectroscopy and showed a relationship among reflux time, size, and spectroscopic properties. CdTe QD were shown to interact with thimerosal (TM), an organic mercury compound, and the PL intensity was effectively quenched, characterizing an ON-OFF process. However, the NAC capped CdTe (CdTe-NAC) at 1 h presented the best sensitivity for TM determination. Under optimized conditions, a linear range from 0.1 to 1.0 µg mL-1 (0.25-2.5 µM) and a LOD of 26.6 µg L-1 (66.7 nM) were achieved. The influence of different mercuric species [Hg(II), methylmercury, ethylmercury, and phenylmercury], along with thiosalicylic acid (TSA), and other ionic species on the sensitivity of the method and the interaction mechanism between TM and CdTe-NAC have been discussed. The method was successfully applied for direct quantification of TM in vaccines, and the results were validated by cold vapor atomic fluorescence spectroscopy (CV AFS). Finally, the proposed method proved to be fast, sensitive, and simple for suitable use in vaccine quality control.