Multifunctional Manganese Carbonate Microspheres with Superparamagnetic and Fluorescent Properties: Synthesis and Biological Application

Multifunctional manganese carbonate microspheres with superparamagnetic and fluorescent properties were fabricated and used as biological labels. The Fe 3 O 4 @MnCO 3 microspheres were synthesized by direct co‐precipitation without any linker shell. The Fe 3 O 4 @MnCO 3 microspheres have uniform size distribution and rough surface, which provides a promising template for the assembly of polyelectrolytes (PEs) and CdTe quantum dots (QDs). A luminescent CdTe shell was observed in Fe 3 O 4 @MnCO 3 @PE‐CdTe spheres by confocal fluorescence imaging. With excellent solubility in water and rough surfaces, the multifunctional microsphere offers a friendly microenvironment for immobilization of α‐fetoprotein (AFP) antibodies (Ab 2 ) to fabricate Fe 3 O 4 @MnCO 3 @PE‐CdTe‐Ab 2 architecture. By using the Fe 3 O 4 @MnCO 3 @PEs‐CdTe‐Ab 2 bioconjugate as a label, a promising and versatile platform for fluorescence imaging and electrochemical immunosensing of cancer biomarker AFP was developed. The prepared electrochemical immunosensor shows high sensitivity and selectivity with a detection limit of 0.3 pg mL −1 .