RESUMO
Cholesterol is an important steroid and hormone precursor, and its levels in the blood are associated with risk factors for cardiovascular diseases. In this work, a non-enzymatic methodology for cholesterol determination in serum samples is described. First, a working electrode was constructed using homemade ink and a plastic substrate by a simple dunking process. Next, the dunked electrode (DWE) was modified with nickel ions (Ni-DWE) and combined with a low-cost microfluidic platform, resulting in a thread-based electroanalytical device (µTED). The arrangement of µTED consists of two coupled electrodes (one reference in the inlet reservoir and an auxiliary electrode against the outlet reservoir) and a mobile support for facile working electrode exchange. After optimization of construction parameters, the system was applied for non-enzymatic determination of cholesterol under alkaline conditions using the redox pair Ni(II)/Ni(III) as a mediator. Under the best analytical conditions, a calibration curve was constructed with a linear dynamic range (LDR) from 0.25 to 25.0 µmol L-1, and the calculated limits of detection (LOD) and quantification (LOQ) were 0.074 and 0.24 µmol L-1, respectively. No effects of possible interferents on electrochemical response were found in the presence of ascorbic acid, uric acid, dopamine, cysteine, and glucose, suggesting that the proposed device can be used for the determination of cholesterol without significant matrix effects of human plasma. Finally, cholesterol analysis was carried out using spiked plasma samples, and good recovery values were achieved.
Assuntos
Técnicas Eletroquímicas , Glucose , Humanos , Técnicas Eletroquímicas/métodos , Glucose/análise , Eletrodos , Dispositivos Lab-On-A-Chip , ColesterolRESUMO
Microfluidic devices based on textile threads have interesting advantages when compared to systems made with traditional materials, such as polymers and inorganic substrates (especially silicon and glass). One of these significant advantages is the device fabrication process, made more cheap and simple, with little or no microfabrication apparatus. This review describes the fundamentals, applications, challenges, and prospects of microfluidic devices fabricated with textile threads. A wide range of applications is discussed, integrated with several analysis methods, such as electrochemical, colorimetric, electrophoretic, chromatographic, and fluorescence. Additionally, the integration of these devices with different substrates (e.g., 3D printed components or fabrics), other devices (e.g., smartphones), and microelectronics is described. These combinations have allowed the construction of fully portable devices and consequently the development of point-of-care and wearable analytical systems.