Aptamer-Based Surface Plasmon Resonance for Carcinoembryonic Antigen Detection

Carcinoembryonic antigen (CEA) serves as a crucial biomarker associated with various cancers, making its early detection vital for timely intervention and improved patient outcomes. The conventional methods for CEA detection often entail time-consuming processes, hence hindering the prompt initiation of treatment. In response to this challenge, the present study demonstrates the potential of employing single-stranded (ss) DNA aptamers in Surface Plasmon Resonance (SPR) based assay for rapid CEA detection. Aptamers, being artificial recognition elements, offer a list of advantages over antibodies such as smaller size, easier artificial synthesis and modification, and better stability, allowing high selectivity during detection. Previously our research team selected CEA aptamers (Yunussova et al., 2022) that have high affinity and specificity towards CEA. These ssDNA aptamers underwent the following chemical modifications at the 5′-terminus with the addition of a thiol (-SH) C6 group, an 18-HEG spacer, and 5-T residues that served as molecular recognition elements. AuNPs-aptamer (8) conjugates were employed as a competitive reagent to enhance the response unit (RU) of the SPR aptasensor in the indirect competitive inhibition assay (ICIA) for the detection of CEA. This was accomplished by functionalizing AuNPs with a modified aptamer sequence (8) against the CEA. A streptavidin (SA) sensor chip surface in the ICIA functioned as a sensing platform following its first immobilization using the biotinylated aptamer (6) sequence. As a result, we have illustrated how novel CEA aptamer sequences can be used to develop a real-time SPR aptasensor to achieve rapid and specific CEA recognition, surpassing the limitations of traditional methodologies.