Screen-printed porous carbon electrode-based immunosensor for human serum albumin detection

• Main Authors: Yu-Feng, Lin, 林昱夆
• Other Authors: Jang-Zern Tsai
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/74143794410379232096

碩士 === 國立中央大學 === 電機工程學系 === 103 === Human serum albumin is the most abundant protein in human blood plasma. Albumin transports hormones, fatty acids, and other compounds, buffers pH, and maintains osmotic pressure. When the kidneys are working properly, albumin is not present in the urine. But when the kidneys are damaged, trace amount of albumin leaks into the urine, called albuminuria. If early kidney damage is not treated, large amount of albumin may leak into the urine and this can lead to chronic kidney disease (CKD). Therefore, the concentration of human serum albumin in human urine is an important indicator of a diagnosis of renal function. The clinical detection method of particle-enhanced turbidimetric inhibition immunoassay (PETINIA) instrument is very expensive. We want to create a low cost, easy-to-use biosensor for HSA detection to improve the modern measurement techniques. In this study, the porous carbon electrode with carboxylic surface was fabricated by screen-printing through uniform mixing of calcium carbonate (CaCO3) powder and stearic acid in the screen printing carbon paste. Then hydrochloric acid was used to dissolve the calcium carbonate powder to increase the surface area of the detection electrodes by porous structures. The obtained screen-printed porous carbon electrode (SPPCE) with carboxylic group surface was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). CV measurement showed the enhanced current response of SPPCE. Using EDC and sulfo-NHS crosslinking, anti-HSA antibodies were immobilized on SPPCE. In this study, we used anti-HSA/EDC+sulfo-NHS/ SPPCE immunosensor to measure HSA by chronoamperometry (CA) electrochemical technique. The electrochemical measurements of the urine samples with interferences demonstrated a high specificity and selectivity of this biosensor in detecting has. The Scanning Electron Microscope/Energy Dispersive Spectrometer (SEM/EDS) mapping was used to check every immobilization step. In optimal conditions, the immunosensor could detect HSA in a high linear range from 10 to 300 mg/L with a 1.68 μA mg-1 mL sensitivity. The calibration curve equation isI=2.10514-0.00175[HSA(mg/L)] with a high coefficient of determination (R2 = 0.99703). Finally, SPPCE based immunosensor was used to measure HSA in clinical urine samples from hospital. Measurement results showed a good correlation with clinical turbidimetric testing and error values were less than 12%. These results suggest that the HSA immunosensor is user-friendly, reliable, and highly specific for the detection of urinary albumin at the range of microalbuminuria.