Electrochromic sensing platform based on steric hindrance effects for CEA detection

In this work, an electrochromic sensing platform with prussian blue (PB) as the indicator was proposed for signaling carcinoembryonic antigen (CEA) using the bipolar electrode (BPE) system. The CEA aptamer was pre-anchored on the anode pole of the BPE for capturing CEA through strong binding affinity. The presence of CEA induced the increase of steric hindrance and led to lower electrochemical currents. Due to the quantitative relationship between the two reactions occurring at both ends of the BPE, the amount of deposited PB in situ can be used as an indicator for reporting target protein concentration. Using CEA concentration in normal human serum as a reference (5 ng mL−1), this electrochromic sensing platform can be used for distinguishing persons with cancer from normal humans easily and quickly, which is very important for subsequent treatment of patients. This novel electrochromic platform has great selectivity for target tumor proteins and provides a fast, visual method for CEA detection. Finally, the proposed biosensor can be applied to detect CEA in human serum, which holds great potential for point-of-care diagnostics combined with the advantage of the closed BPE system.