Reusable Surface Plasmon Resonance Immunosensor for Temporal Information of Protein Biomarkers

Monitoring temporal changes in antigen levels, such as disease-related markers in medical care or airborne allergens in environmental medicine, has been increasing in importance because it allows one to notice the level exceeding a threshold in real time, which helps the early detection or prevention of diseases. In this study, we have developed a reusable immunosensor that exploits surface plasmon resonance (SPR) and a pH-resistant protein, ORLA85, for rapid and repeated (semicontinuous) immunoassays. After the sensor development, a model experiment using mouse (mIgG) and anti-mouse (a-mIgG) antibodies was performed. In the experiment, the sensitivity of the developed SPR immunosensor was initially evaluated using various concentrations of a-mIgG. The limit of detection of the sensor for a-mIgG was 14.2 ng/mL (0.09 nM) and the dynamic range was 138-30000 ng/mL (0.86-187.5 nM). In 10 repeated measurements of a-mIgG, the sensor signals returned to the baseline after removing a-mIgG using an acidic solution with pH 1. The measurement time was 15 min and the coefficient of variation of the sensor outputs was 7.5%. These results indicated that the developed SPR immunosensor had potential for semicontinuous measurement, suggesting its application to monitoring systems for the early detection and prevention of diseases.

Automated summary

This study developed a reusable immunosensor utilizing SPR and a pH-resistant protein for rapid and repeated immunoassays. The sensor demonstrated a detection limit of 14.2 ng/mL for a-mIgG, a dynamic range of 138-30000 ng/mL, and potential for semicontinuous measurement, suggesting its application in monitoring systems for early disease detection and prevention.