Aptasensors: From fundamentals to new sensor concepts

Aptamers are synthetic single-stranded (ss) oligonucleotides that bind to a broad range of targets, including cells, proteins, small molecules, toxins, metal ions, etc. with high affinity and selectivity. Aptasensors utilizing ssDNA and RNA aptamers as recognition elements have attracted significant attention in biosensing as aptamers possess excellent chemical stability, commercial availability with high purity and ease of modification with functional groups. Labeling aptamers with signal transduction groups such as fluorophores and redox markers have been extensively studied in biosensing research. However, covalent labeling processes always require complicated organic reaction, tedious preparation and separation, and expensive reagents. Thus, over the last decade, label-free aptasensors characterized by methods such as electrochemical impedance spectroscopy (EIS), surface plasmon resonance (SPR), colorimetry and fluorescence and so on have been widely developed and investigated. These efforts providing for the design of novel aptasensors, however, the lack of knowledge in understanding widely studied platforms still limits their applicability. Thus, more work is  required to study the fundamentals of crucial aptasensoring platforms enabling better design, build-up and data analysis.