Napaporn Youngvises

Chronic kidney disease (CKD) is a progressive condition that affects more than 10% of the world’s population. Monitoring urine albumin-to-creatinine ratio (uACR) has become the gold standard for nephropathy diagnosis and control. The objective of the present study was to develop a simple, accurate, sensitive, and rapid point-of-care test (PoCT) device, MyACR, for uACR measurement, intended for use in community healthcare to screen for the risk and monitor the progress of CKD. Albumin and creatinine concentrations in urine samples were determined using spectrophotometric dye (tetrabromophenol blue)-binding and colorimetric Jaffe assay, respectively. Urine samples were diluted with distilled water (1:80) and mixed separately with albumin and creatinine reaction mixture. The creatinine reaction was incubated at room temperature (25 °C) for 30 min before analysis. Optical density (OD) was measured at the wavelengths of 625 nm (albumin) and 515 nm (creatinine). All calibration curves (0–60 mg/L and 0–2 mg/dL for albumin and creatinine) yielded linear relationships with correlation coefficients (R²) of >0.997. Good accuracy (% deviation of mean value (DMV) ≤ 5.42%) and precision (% coefficients of variation (CV) ≤ 12.69%) were observed from both the intra- and inter-day assays for the determination of albumin and creatinine using MyACR. The limit of quantification (LOQ) of albumin and creatinine in urine samples determined using MyACR and a laboratory spectrophotometer were 5 mg/L and 0.25 mg/dL, respectively, using 37.5 μL urine spiked samples (n = 5). The device was well-applied with clinical samples from 20 CKD patients. The median (range) of %DMV of the central (hospital) laboratory method (immune-based assay) was 3.48 (−17.05 to 21.64)%, with a high correlation coefficient (R² > 0.98). In conclusion, MyACR showed satisfactory test performance in terms of accuracy, reproducibility, and sensitivity. Cost-effectiveness and improvement in clinical decision making need to be proven in future multisite community and home studies.

A simple miniaturized system was fabricated in general laboratory from polydimethylsiloxane (PDMS) according to a prototype casting and molding process permitting the construction of three-dimensional (3D) microchannel (100 µm i.d.) with T-type network, together with an integrated optical sensor for on chip detection. The fabricated device has been successfully applied as a green chemistry-compatible miniaturized analytical system for the determination of zinc (II) in pharmaceutical samples taking the advantage of the colorimetric reaction of zinc (II) and xylenol orange in acetate buffer at pH 5.5. The microfluidic device is a convenient way to quantify zinc (II) over a wide dynamic range, 0.2–2.5 µg mL⁻¹, with good linearity (R² 0.9940).