Development of urinary albumin detection kit

Abstract

This work developed the colorimetric determination of bovine serum albumin (BSA) and creatinine in urine sample. The studied ranges are 0 – 30 mg/L for BSA and 0 – 3000 mg/L for creatinine. The layer-by-layer deposition technique (LbL) was used to modify the surface of cellulose acetate membrane (CA) for albumin and creatinine extraction via electrostatic interactions. The suitable polyelectrolyte pair used in this work was poly(diallyl dimethyl ammonium chloride (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS). For the albumin determination, BSA prepared in synthetic urine was diluted 4-fold with 5 mM pH 7 phosphate buffer and filtered through the modified membrane of which PDADMAC was the outermost layer. The adsorbed BSA on the membrane was eluted and detected with tetrabromophenol blue in Triton X-100 at pH 3, resulting in a change in the color of TBPB-BSA solution from yellow to green. The absorbance intensity was measured with a UV-Vis spectrophotometer at 625 nm. The relationship between the BSA concentration and the absorbance intensity was observed in the range of 2.5 – 7.5 mg/L with the detection limit of 0.47 mg/L. The recovery of albumin from samples was 81.2 – 106.9% and the relative standard deviation was 0.8 – 3.2%. For the creatinine determination, the modified membrane of which PSS was the outermost layer was used to extract creatinine. The adsorbed creatinine on membrane was detected with Jaffé reaction, forming a yellow-orange complex. The color intensity was monitored by Image J software. The linearity of this method was in the range of 0 – 100 mg/L and the limit of detection was found to be 3.53 mg/L. The recovery of creatinine from samples was found in the range of 102.2 – 103.3% and the relative standard deviation was less than 7.6%. Moreover, the color change from albumin and creatinine determination could be observed visually. Therefore, the proposed method could be applied to determine albumin and creatinine in urine samples by both colorimetric and naked eyes detection for the early diagnosis of kidney failure.