(Invited) Ingenious Nanomaterials for Ultrasensitive ECL

The impact of nanotechnology and nanosystems on analytical science is hardly overlooked. In the search for ever-increasing sensitivity in biomedical sensors, nanoparticles have been playing a unique role as, e.g., ultrabright labels in clinical analysis (markers, tumor cells, and pharmaceuticals) and in the detection of pathogenic microorganisms, toxic agents, and pesticides in the environmental field and food products. Coupling such nanosystems with electrochemiluminescence (ECL), which naturally brings improved signal-to-noise ratio compared to photoluminescence, with minimized effects due to light scattering and luminescence background, has brought about new systems and strategies for analytes determination, even in very complex matrices, such as urine, blood or lysate. Among the several nanosystems, dye-doped silica nanoparticles (DDSNs) have proved as very promising and versatile nanomaterials in ECL-based bioanalytical platforms. The increase of the number of complexes active in the generation of the ECL signals together with an even larger increase in the signal stability, represents in fact a promising strategy towards ultrasensitive ECL. Approaches based on ECL generation on the nanoscale using luminophore-reporter-modified DNA-based nanoswitches (i.e., molecular beacon) has been additionally investigated and, in this context, the development of innovative amplification-free detection methods represents a significant breakthrough compared to existing PCR-based methodologies, allowing the integration of nucleic acid detection on portable and low-cost sensor devices, and enabling the massive diagnostic screening.