Carcinoembryonic antigen imprinting by electropolymerization on a common conductive glass support and its determination in serum samples

This work reports a novel approach to monitor Carcinoembryonic antigen (CEA) biomarker with molecular-imprinting technology assembled on a conductive glass surface. For this purpose, the polymerization was achieved by electrical stimulus on fluorine doped tin oxide (FTO)-glass modified with a homemade carbon ink (hCCI). The biomimetic material was assembled on top of this surface, by moulding CEA at the molecular level around a polyaminophenol (PAP) polymeric matrix. The CEA biomarker was previously incubated in the presence or not of aminophenylboronic acid (APBA), to evaluate the effect of negative charges at the rebinding site. Then, aminophenol (AP) monomer was electropolymerized on the modified FTO glass, acting as working electrode. The template was removed by enzymatic action. Likewise, a control material having only PAP and no CEA was also prepared. The resulting sensing films were evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and the chemical modifications on these after each stage of the assembly process was followed by Fourier Transform Infrared (FTIR) and Raman spectroscopies. Imprinted devices displayed good linear responses to CEA in EIS assays from 2.5 ng/mL to 1.5 mu g/mL in phosphate buffer solution (PBS). A promising detection of CEA was, also, achieved in spiked foetal bovine serum (FBS) samples, with a limit of detection (LOD) of 3 ng/mL. Overall, the devices developed herein are promising tools for monitoring CEA in point-of-care (POC) applications, being able to detect lower concentrations than those in normal physiological levels. In addition, the biosensors offer low cost, high sensitivity and good selectivity, and may be used to couple to other reading devices.