Harnessing aptamers for the biosensing of cell surface glycans - A review

Cell surface glycans (CSGs) are essential for cell recognition, adhesion, and invasion, and they also serve as disease biomarkers. Traditional CSG recognition using lectins has limitations such as limited specificity, low stability, high cytotoxicity, and multivalent binding. Aptamers, known for their specific binding capacity to target molecules, are increasingly being employed in the biosensing of CSGs. Aptamers offer the advantage of high flexibility, small size, straightforward modification, and monovalent recognition, enabling their integration into the profiling of CSGs on living cells. In this review, we summarize representative examples of aptamer-based CSG biosensing and identify two strategies for harnessing aptamers in CSG detection: direct recognition based on aptamer-CSG binding and indirect recognition through protein localization. These strategies enable the generation of diverse signals including fluorescence, electrochemical, photoacoustic, and electrochemiluminescence signals for CSG detection. The advantages, challenges, and future perspectives of using aptamers for CSG biosensing are also discussed.