Abstract:
A simple, low cost and portable microfluidic system for determination of urinary albumin and creatinine has been developed. Determination of microalbuminuria and creatinine was based on latex agglutination immunoassay and kinetic alkaline picrate reaction, respectively. Y-shaped microchannel (500-µm width and 100-µm depth) with two inlets for injection of reagent (100 µL) and urine sample (5 µL) was fabricated on the poly(dimethylsiloxane) (PDMS) microchip. The microfabricated arrowhead-shaped baffles within the microchannel were used to enhance the mixing efficiency of reagent and sample. A homemade flow cell detector (10 mm path length, total volume of 90 µL) made from a polystyrene cuvette was incorporated into the PDMS microchip at the detection zone. A miniature fiber optic spectrometer was used for monitoring the absorbance change at 500 nm and 510 nm, for latex agglutination and Jaffé reaction, respectively. For albumin assay, linear range was obtained at 0-10 mg/L (r2 =0.993), with a detection limit of 0.81 mg/L. Linear range for creatinine assay was found at 0-40 mg/L (r2 = 0.997), with a detection limit of 3.27 mg/L. For determination of albumin/creatinine ratio, the proposed method was highly correlated with the conventional methods when real urine samples from diabetes patients were evaluated (r2 = 0.985, n = 15).