Different approaches to biosensing

Nowadays, the progress on nanotechnologhy enables the synthesis of nanoparticles (NPs) with customized physical, chemical, and/or biological activities. Recent works have underlined the modulation of semiconductor nanoparticles (SNPs) on determining their optical, electrochemical and photoelectrochemical response. The emission of light by these SNPs is explained by quantum effect. Hence, they are referred to as quantum dots (QDs). Here, I will present the last advances of the modulation of the shape of CdS QDs in aqueous reaction mixtures triggered by trace amount of analytes.

Firstly, it was showed photoelectrochemical detection of enzymatically grown CdS QDs applied to development of immunoassay. Secondly, It was demonstrated new optical and photoelectrochemical (PEC) immunoassay for detection of tumor biomarkers such as superoxide dismutase (SOD2). Finally, it was described modulation of growth of cysteine-capped CdS QDs with enzymatically produced H₂O₂ and reported modulating growth of CdS QDs with redox process catalyzed by copper ions (Cu²⁺).

These proposed analytical assays will be more sensitive than the previously published assays in which sulphide ions (S^2-) are generated in the presence of analytes. Instead of fluorescence spectroscopy, less pricey UV-vis spectroscopic, electrochemical and photoelectrochemical detection can be applied due to unique properties of CdS QDs formed in assay mixtures.