Water soluble silicon quantum dot based fluorescence immunoassay probe for C-reactive protein (CRP) detection

Silicon quantum dot (SiQD) based water soluble fluorescence immunoassay probe with aggregation induced emission features (AIE) was developed for the sensitive detection of C-reactive protein (CRP) biomarker. The solid state and solution phase photophysical properties of SiQD attributed from AIE effect was studied successfully. Later the ability of CRP antibody functionalized SiQD against the detection CRP antigen was evaluated systematically. The method relies on the decrease in fluorescence intensity of CRP antibody functionalized SiQD (CRPAb) upon the gradual addition of CRP antigen (CRPAg) via antigen-antibody interaction. The intensity of the antibody functionalized fluorophore quenched linearly by the addition of CRPAg within the concentration range of 50–150 nM and the limit of detection (LOD) was as sensitive as about 0.89 nM. Detection mechanism was assigned further by evaluating the interaction that exists between SiQD-CRPAb and CRPAg, which suggests that the effective complexation through a lock and key mechanism could be the plausible reason behind the fluorescence quenching of SiQD-CRPAb in presence of CRPAg. The solid state fluorescence features of SiQD arises from AIE phenomena which suggest that as a promising alternative to conventional QDs and organic fluorophores, integration of SiQD with lateral flow strips could result in powerful eco-friendly point-of-care device for in vitro diagnosis and the detection of other biomarkers.