Multiplexed detection using quantum dots as photoluminescent sensing elements or optical labels

Multiplexed detection, seeking either the simultaneous assessment of multiple analytes in the same experiment or the multi-detection of a single analyte in a complex sample matrix replete of interfering species, has gained, in recent years, a noteworthy interest amidst the analytical community. Evolving from early immunoassays or ELISA tests, mostly devoted to research purposes rather than to applied analytical objectives, multiplexed detection has been able, both alone and coupled to chemometric models, to deliver reliable and efficient analytical tools for disease diagnostics, drug and contaminants screening and biodefense applications in fields as different as clinical, pharmaceutical, food and environmental analysis. The research on nanomaterials, in particular on photoluminescent quantum dots, has paved the way for the implementation of innovative and flexible multiplexed assays since their remarkable optical properties and tailored reactivity could be arranged in many configurations, combining different fluorophores and molecular recognition elements and providing the means for the establishment of definite reaction pathways and detection modes. This work aims at survey the optical multiplexed detection approaches using nanocrystalline materials as either PL active sensing elements or passive labels, examine the distinct roles they could play at the sensing platform, either alone or combined with other materials, and discuss their advantages, shortcomings, and application prospects.