Electrochemical detection of proteins using nanoparticles: applications to diagnostics

The detection of proteins is of crucial importance in the nowadays' medicine for the early diagnosis of diseases. In this context, electrochemical immunoassays coupled with the recent advances in nanobiotechnology and nanomaterials (e.g. nanoparticles, NPs) offer new alternatives for clinical diagnostic procedures. Nanoparticles are being used for the electrochemical detection of proteins taking advantage of their versatility and electrochemistry inherent advantages.

This review describes the different ways of nanoparticles (NP) based approaches for the electrochemical detection of proteins of interest in medical diagnostics reported in the last five years. Furthermore, some examples of interesting methodologies optimised only for model proteins are also given because of their potential interest for future clinical applications.

NPs such as gold NPs (AuNPs) and quantum dots NPs (QDs) can be used as labels for protein biomarkers detection due to their excellent re-dox properties, electroacatalytic activity toward several substrates and easy preparation and bioconjugation capabilities. The versatility of NPs makes them suitable to act also as carriers of enzymatic labels, exerting the effect of amplifiers for enzymatic electrochemical signals. Finally, NPs can be used as modifiers of the electrotransducer surfaces, creating nanostructurated surfaces with improved electrochemical response coming either from the enhancement of the electron transference or the increased efficiency of biomolecules immobilization.

Although the developed nanoparticle based electrochemical immunosensors have shown high sensitivity and selectivity their implementation in clinical analysis still need a rigorous testing and control period so as to really evaluate these advantages in comparison to classical assays in terms of reproducibility, stability and cost while being applied for real sample analysis. Further developments of the stripping/disposable sensors including the sampling mode beside the development of simple electrochemical devices (i.e. pocket size such as glucosimeter) are necessary for future entrance in real sample diagnostics.