Efficient, sensitive, and convenient quantum dots (QDs) fluorescent immunosensors have a wide range of applications in the field of in vitro diagnostics (IVD). However, traditional single-signal readout methods are susceptible to interference, have limited sensitivity, and involve time-consuming detection processes. These have become key bottlenecks restricting their use in point-of-care (POC) detection. Herein, we developed a novel immunosensor based on QDs ratiometric fluorescence (QRF) and magnetic driven technology for sensitive, rapid, accurate detection of C-reactive protein (CRP). High-quality magnetic-fluorescent QDs nanobeads (QBs) were prepared by efficiently and orderly layered loading of magnetic nanoparticles (MNP) and red QDs using mesoporous silica nanoparticles (MSN) as a template. The magnetic driven-QRF-immunosensor was constructed based on green QDs probes-functionalized microplate. The results showed that the linear range of magnetic-fluorescence probes for the detection of CRP was 0.1-1,000 ng/mL, with a sensitivity of up to 0.05 ng/mL. Compared to conventional QRF-immunosensor, the detection time was halved (within 30 min), and the sensitivity improved by approximately 5-fold. Recovery experiments and clinical sample analyses also demonstrated the good accuracy of this immunoassay. Therefore, the constructed novel magnetic driven-QRF-immunosensor shows great potential for clinical diagnosis and disease monitoring, and is expected to be applied in POC detection as a new generation of detection technology.

Semiconductor quantum dots (QDs), as promising fluorescent materials, have been widely applied in biomedical application due to their unique optical properties. Currently, the most intensively studied are Cd-containing QDs (Cd-based QDs), whose potential toxicity prevents their further commercialization. In recent years, the eco-friendly QDs with low toxicity and environmental friendliness have begun to be developed, showing great potential in biomedical applications. The high-quality synthesis of eco-friendly QDs and the appropriate surface modification are key to realize their applications. This review summarizes the progress of eco-friendly QDs for biomedical applications, including their designed preparation, optical properties, surface modification, toxicity, and their applications in bioimaging and diagnostics. Finally, the challenges of eco-friendly QDs for future bioimaging and diagnostics application were provided. We believe this review will provide important guidance for promoting the development of eco-friendly QDs in bioimaging and diagnostics.