Synthesis of uniform Pickering microspheres doped with quantum dot by microfluidic technology and its application in tumor marker

Tumor markers play a significant role in early cancer diagnosis, evaluation of the extent of the disease, and monitoring of therapy response. In this study, we described the Pickering emulsion polymerization method to synthesize uniform magnetic/fluorescent microspheres. A Pickering-structure composed of a lot silica nanoparticle closely covered onto the quantum dot-encoded magnetic microbeads is designed and synthesized. The uniform magnetic/fluorescent microspheres were prepared using a microfluidic device and the performance of the microspheres synthesized by the instruments was evaluated by flow cytometry. To avoid fluorescence quenching and intrinsic toxicity, CdSe/ZnS core-shell quantum dot and Fe₃O₄ nanoparticle were successfully encapsulated into MFM microspheres using the microfluidic technology. Using this structure enables the facile realization of a theoretical 4 × 4 barcoding matrix combining two colors and four fluorescence intensity levels. Then, different optical codes were prepared by simple changing the emission wavelength and the intensity of the quantum dots. The resulting microsphere are combined with flow cytometer using two lasers for decoding of multiplex tumor markers. Moreover, the stability testing of microspheres demonstrated good performance for further application in detection of tumor markers as well. When applied for the high-throughput ultrasensitive detection of three tumor markers (CEA, CA125 and CA199) in a single sample, the detection limits of 0.027 ng/mL for CEA, 1.48 KU/L for CA125 and 1.09 KU/L for CA199 are achieved, which exhibit superior detection performance. Thus, Pickering-structure magnetic/fluorescent microspheres are promising for application in tumor markers.