New nanoparticles for diagnostics and sensing Suitable fluorescent molecules are at the heart of labelling and sensing applications. EU-funded researchers explored different routes for successfully synthesising nano-structured silicon and carbon nanodots for use as labels or probes. Industrial Technologies © Shutterstock With typical sizes between 2 and 10 nm, quantum dots are semiconductor nanocrystals that are commonly used as fluorescence nanoparticles in bioimaging. However, some of the materials that make up quantum dots are rare and highly toxic. To overcome this issue, researchers in NANOLIGHT (Synthesis and characterization of nanostructured materials with luminescent properties for diagnostic and therapeutic applications) placed focus on silicon and carbon, which are amongst the most abundant materials on Earth and inherently non-toxic. Unlike their bulk structures, nano-structured silicon and carbon nanodots are strongly fluorescent, photostable and show adjustable luminescence from the red to the near-infrared region. Scientists made remarkable advances with regard to synthesising these luminescent nanoparticles following two different methods. The first one involved thermal processing of silsesquioxane – an organosilicon compound – to produce an encapsulating oxide matrix for the silicon nanocrystal. The second method involved laser pyrolysis of silicon precursors. Likewise, scientists used these two processes with carbon-containing precursors to produce carbon nanodots. The newly synthesised nanoparticles were successfully tested as selective ion probes for biological sensing, fluorescent labels for glioma cell imaging and photocatalysts in water decontamination. In general, NANOLIGHT fluorescent nanoparticles hold great potential for use as agents that combine diagnostic and therapeutic capabilities or sensors of organochlorine contaminants that pose a risk for human health. Given their abundance and the low cost of the raw starting precursors, these materials are also more cost competitive compared with quantum dots. Keywords Nanoparticles, diagnostics, sensing, nano-structured silicon, carbon nanodots, bioimaging
