Calcium Carbonate-Gold Nanocluster Hybrid Spheres: Synthesis and Versatile Application in Immunoassays

Fluorescent gold nanoclusters (AuNCs) were incorporated into porous calcium carbonate spheres through electrostatic interaction. The resulting CaCO3/AuNCs hybrid material exhibited interesting properties, such as porous structure, excellent biocompatibility, good water solubility, and degradability. These properties make the CaCO3/AuNCs hybrid material a promising template to assemble horseradish peroxidase/antibody conjugates (HRP-Ab2). By using CaCO3/AuNCs/HRP-Ab2 bioconjugates as probes, a versatile immunosensor was developed for fluorescent and electrochemical detection of the cancer biomarker neuron-specific enolase (NSE). The detection limits of the sensor were 2.0 and 0.1 pg?mL-1 for fluorescent and electrochemical detection, respectively. The immunosensor shows high sensitivity and offers an alternative strategy for the detection of other proteins and DNA.