Current Trends in the Use of Semiconducting Materials for Electrochemical Aptasensing

Aptamers are synthetic single-stranded oligonucleotides that exhibit selective binding properties to specific targets, thereby providing a powerful basis for the development of selective and sensitive (bio)chemical assays. Electrochemical biosensors utilizing aptamers as biological recognition elements, namely aptasensors, are at the forefront of current research. They exploit the combination of the unique properties of aptamers with the advantages of electrochemical detection with the view to fabricate inexpensive and portable analytical platforms for rapid detection in point-of-care (POC) applications or for on-site monitoring. The immobilization of aptamers on suitable substrates is of paramount importance in order to preserve their functionality and optimize the sensors' sensitivity. This work describes different immobilization strategies for aptamers on the surface of semiconductor-based working electrodes, including metal oxides, conductive polymers, and carbon allotropes. These are presented as platforms with tunable band gaps and various surface morphologies for the preparation of low cost, highly versatile aptasensor devices in analytical chemistry. A survey of the current literature is provided, discussing each analytical method. Future trends are outlined which envisage aptamer-based biosensing using semiconductors.