Boronate ester bond-based potentiometric aptasensor for screening carcinoembryonic antigen-glycoprotein using nanometer-sized CaCO3 with ion-selective electrode.

Phenylboronic acid-functionalized nanometer-sized CaCO3 particles (PBA-CaCO3) were designed to determine the carcinoembryonic antigen (CEA) glycoprotein with a portable Ca2+ ion-selective electrode (Ca-ISE) through a typical boronate ester bond. CaCO3 nanospheres were conjugated to 3-aminophenylboronic acid by amine-epoxy reaction, whereas target CEA was captured into the aptasensing interface by the immobilized thiolated aptamer on gold substrate. Upon PBA-CaCO3 introduction, 3-aminophenylboronic acid labeled to CaCO3 microsphere specifically recognized with CEA glycoprotein based on sugar-boronic acid interaction to form a sandwiched complex. The carried CaCO3 was dissolved under acidic conditions to release Ca2+ ion with a portable Ca-ISE readout. Thanks to the specific boronate ester bond between PBA and 1,2-diols, the synthesized PBA-CaCO3 exhibited good conjugation properties for CEA glycoprotein. Under optimum conditions, Ca-ISE-based aptasensing platform exhibited good electrode potential response for evaluation of target CEA, and allowed detection of CEA at a concentration as low as 7.3 pg mL-1. Importantly, Ca-ISE-based aptasensing system is readily extended to detect other disease-related glycoproteins by controlling the corresponding aptamer.