Retroreflection-based nonspectroscopic optical immunosensing platform using retroreflective Janus particle

We developed a nonspectroscopic optical immunosensing platform employing retroreflection principle. To integrate the retroreflection principle and optical immunosensor, retroreflective Janus microparticle (RJP) was developed as a signaling probe. To analyze the retroreflection signal from RJPs, a highly simplified nonspectroscopic optical transducer was constructed using common polychromatic-light source and digital camera. In the developed immunosensor, retroreflection signals from RJPs are registered as shining dots on the digital camera. By counting numbers of RJPs on the immunosensing surface, we can quantify the target analyte concentration. To demonstrate the immunosensing performance of the developed immunosensor, a cardiac troponin I (cTnI) immunoassay was accomplished.