Nanoelectrodes for intracellular and intercellular electrochemical detection: Working principles, fabrication techniques and applications

Electrochemical nanoelectrodes are emerging as suitable probes in chemical and biochemical molecules detection inside single cells. In-situ measurements, faster detection time and cost effectiveness are just some of the advantages of such technology. With this approach, the investigation of metabolic and single cell mechanisms gives accurate and meticulous results. The precise and localized estimation of different analytes concentration allows to predict in advance the progression of a particular disease. In the first part of the review, the scenario related to nanoelectrochemistry applications for intracellular and intercellular sensing is reported together with an overview of the most interesting analytes for intra and intercellular detection; moreover, main nanoelectrodes fabrication processes and electrochemical techniques are discussed and compared. In the second part, different examples are reported according to the detection mechanism employed, focusing on electroactive material stability in biological systems and methods to improve their selectivity. A discussion about their different working principles and electrode architectures/functionalizations highlights the most relevant benefits and drawbacks of each one. Moreover, a schematic summary pointing out the principal results at the state of the art is reported.