Controllable preparation of silver-doped hollow carbon spheres and its application as electrochemical probes for determination of glycated hemoglobin.

Silver-doped hollow carbon spheres (Ag@HCS) were firstly introduced as electrochemical probes for glycated hemoglobin (HbA1c) sensing at a molecularly imprinted polymer (MIP)-based carbon cloth (CC) electrode. Herein, Ag@HCS was prepared using one-pot polymerization of resorcinol and formaldehyde with AgNO3 on the SiO2 template, subsequent carbonization, and template removal. Furthermore, poly-aminophenylboronic acid (PABA) as the MIP film was used as a sensing platform for recognition of HbA1c, which captured the Ag@HCS probe by binding of HbA1c with aptamer modified on the probe surface. Due to regular geometry, large specific surface area, superior electrical conductivity, and highly-dispersed Ag, the prepared Ag@HCS probe provided an amplified electrochemical signal based on the Ag oxidation. By use of the sandwich-type electrochemical sensor, the ultrahigh sensitivity of 4.365 μA (μg mL-1)-1 cm-2 and a wide detection range of 0.8-78.4 μg mL-1 for HbA1c detection with a low detection limit of 0.35 μg mL-1 were obtained. Excellent selectivity was obtained due to the specific binding between HbA1c and PABA-based MIP film. The fabricated electrochemical sensing platform was also implemented successfully for the determination of HbA1c concentrations in the serum of healthy individuals.