Aptamers in biosensing: biological characteristics and applications

Because of their peculiar characteristics, mainly deriving from their nucleic acid composition, aptamers have been identified as ideal ligands for bioanalytical applications. In addition, the current improvements of the SELEX method, allow the identification of unique RNA/DNA molecules from very large populations of random sequence oligomers, which bind to the target with very high affinity and specificity; the same advancements offer the opportunity of developing biosensing systems for the detection of analytes unlimited by size, toxicity and matrix effects. In this chapter, we will focus on the most challenging and up to date applications of aptamers in biosensing, starting from the biological characteristics, which make possible these unique functions: aptasensors for exosome isolation and detection will be considered together with their ambitious application to intracellular sensing.