Objective     To establish a novel methodology for simultaneous quantification of four trace proteins in urine with surface plasmon resonance (SPR) biosensor.      Methods     Monoclonal antibodies against Alpha-1 microglobulin (A1M)

Beta-2 microglobulin (B2M)

microalbumin (MA) and immunoglobulin G (IgG) were immobilized on the surface of biosensor chips

and then SPR was adopted to detect the corresponding antigens in standard solution containing the above-mentioned proteins. Calibrations of the 4 proteins were performed and the methodological evaluations we

re conducted to validate the sensitivity and specificity. Clinical urine samples from 125 inpatients were collected

and the contents of these 4 proteins were detected with SPR and immuno-turbidimetric assay at the same time. The results from the 2 methods were compared.     Results     The proposed SPR immunosensor had good signal-noise ratio and specificity. All the R

2

of the calibration curves were higher than 0.98. The sensitivity of A1M was 5 μg/L

B2M 7.3 μg/L

MA 11.5 μg/L

and IgG 22 μg/L. All the detection was finished in 20 min. This proposed method had good consistency when compared with traditional immuno-turbidimetric assay.      Conclusion     This proposed SPR immunosensor chip can accurately and simultaneously determine multiple trace proteins in urine

and can be a useful alternative to current methodology.