Highly amino-functionalized fluorescent carbon nanoparticles (CNPs) were fabricated by hydrothermal carbonization of chitosan at a mild temperature. They were applied to bioimaging of human lung adenocarcinoma A549 cells, showing low cytotoxicity and excellent biocompatibility.

Self-quenching in the aggregation state is overcome, and tunable solid-state photoluminescence of carbon-dot powder is achieved. Furthermore, based on the controllable optical property in organic solvents, a novel concept, i.e., constructing dual-fluorescence morphologies from single luminescent species, is presented to realize white-light emission.

Highly blue-luminescent nitrogen-doped graphene quantum dots (N-GQDs) are obtained by hydrothermal treatment of graphene oxide in the presence of ammonia. The yield of N-GQDs is about 8.7% in weight. A high quantum yield of maximum 24.6% at an excitation wavelength of 340 nm is achieved. They are applied for bioimaging of HeLa cells, and showed bright luminescence and excellent biocompatibility.

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Stable solid-state red fluorescence from organosilane-functionalized carbon dots (CDs) with sizes around 3 nm is reported for the first time. Meanwhile, a novel method is also first reported for the efficient construction of dual-fluorescence morphologies. The quantum yield of these solid-state CDs and their aqueous solution is 9.60 and 50.7%, respectively. The fluorescence lifetime is 4.82 ns for solid-state CDs, and 15.57 ns for their aqueous solution. These CDs are detailedly studied how they can exhibit obvious photoluminescence overcoming the self-quenching in solid state. Luminescent materials are constructed with dual fluorescence based on as-prepared single emissive CDs (red emission) and nonfluorescence media (starch, Al O , and RnOCH COONa), with the characteristic peaks located at nearly 440 and 600 nm. Tunable photoluminescence can be successfully achieved by tuning the mass ratio of CDs to solid matrix (such as starch). These constructed dual-fluorescence CDs/starch composites can also be applied in white light-emitting diodes with UV chips (395 nm), and oxygen sensing.