Detection of Kappa Light Chain Protein in Human Urine by Surface Plasmon Resonance

Abstract

Ingredients of urine proteins are complex, and different types of urinary proteins are usually associated with different diseases. Light chain proteins are related to neoplastic diseases, which might be misdiagnosed as nephropathia. Accurate detection of urine light chain proteins in urine is very important for early diagnosis of multiple myeloma and other diseases. Traditional methods for detecting urinary light chain proteins are of low sensitivities, complex processes and high costs. Surface plasmon resonance (SPR) is a sensitive, real-time and label-free method which is suitable for studying protein-molecule interactions. In this paper, SPR methods were used to detect kappa light chain proteins through direct assay method. Kappa light chain protein antibodies with a pH value of 5.0 were successfully immobilized to the sensor chip in one channel while another was used as a reference channel. Detection limit of kappa light chain proteins was estimated to be 0.1 μg/mL through direct assay method in standard solution. Healthy and patient human urine samples were also tested, which showed different SPR response signals. It indicated that SPR could be used as a fast and sensitive method in quantitative detection of urinary kappa proteins.