It has been reported that nearly 10 million deaths were caused by cancer in 2020. Focusing on early detection and treatment is highly recommended to reduce cancer mortality. Therefore, it is crucial to explore new technologies based on tumor markers that can be implemented in point-of-care tests for early diagnosis of the disease. One of these protein tumor biomarkers is a carcinoembryonic antigen (CEA), a glycoprotein whose concentration is a well-established sign of colorectal cancer, among others, and metastasis.<br/><br/>This study was focused on developing a nanoaptasensor based on gold nanotriangles (AuNT) functionalized with CEA hairpin-aptamer to produce the complex CEA-aptamer. The chemical pretreatment of this aptamer with tris (2-carboxyethyl) phosphine hydrochloride (TCEP) was studied to break possible disulfide bridges present (R-S-S-R) and ensure the interaction between the gold nanotriangles and the aptamer sulfur (Au-S). Additionally, two types of molecules were added as blocking agents to promote the stabilization of the AuNT while maximizing the interaction of the CEA and the aptamer. By using thiolated polyethylene glycol with a terminal methoxy group (HS -PEG(8)-OMe) as a blocking agent, the stability of the gold nanotriangles is enhanced since the PEG prevents them from agglomerating. In contrast, small molecules provide less stability to the AuNT than the PEG, but their presence may reduce the steric hindrance for the formation of the complex CEA-aptamer. By taking advantage of gold nanotriangles’ optical properties, promising results were obtained for detecting CEA by monitoring the LSPR band. In addition, it is possible to implement a colorimetric qualitative detection with the nanoaptasensor by a lateral flow assay (LFA).

Design and optimization of an optical nanoaptasensor based on gold nanotriangles modified with two blocking agents for the detection of carcinoembryonic antigen

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