Easy non-radiative decay property of long-lived triplet excitons in aqueous solution obstructs their applications in aquatic surroundings. Recently reported phosphorescence phenomena in aqueous solution have excited researchers enormously but achieving full-color water-soluble phosphorescent carbon nanodots (CNDs) is still a challenging issue. Herein, full-color phosphorescence of water-soluble CNDs has been demonstrated by triggering their triplet excitons through nanospace domain confinement, and Förster energy resonance transfer is used for further tuning phosphorescence range. The phosphorescence spans across most of the visible spectrum, ranging from 400 to 700 nm. In an aqueous solution, the CNDs exhibits blue, green, and red phosphorescence, lasting for approximately 6, 10, and 7 s, respectively. Correspondingly, the phosphorescence quantum yields are 11.85%, 8.6% and 3.56%, making them readily discernible to the naked eyes and laying a solid foundation for practical application. Furthermore, phosphorescence flexible optical display and bioimaging have been demonstrated by using the multicolor CNDs-based nanomaterials, showing distinct superiority for accuracy and complete display and imaging in complex emission background.

The spread of diseases caused by bacterial adhesion and immobilization in public places constitutes a serious threat to public health. Prevention of bacteria spread by the construction of an antibacterial surface takes precedence over post-infection treatment. Herein, we demonstrate an effective antibacterial surface with strong wear resistance by constructing cationic engineered nanodiamonds (C-NDs). The C-NDs with positive surface potentials interact effectively with bacteria through electrostatic interactions, where the C-NDs act on the phospholipid bilayer and lead to bacterial membrane collapse and rupture through hydrogen bonding and residual surface oxygen-containing reactive groups. In this case, bactericidal rate of 99.99% and bacterial biofilm inhibition rate of more than 80% can be achieved with the C-NDs concentration of 1 mg/mL. In addition, the C-NDs show outstanding antibacterial stability, retaining over 87% of the antibacterial effect after stimulation by adverse environments of heat, acid, and external abrasion. Therefore, an antibacterial surface with high wear resistance obtained by integrating C-NDs with commercial plastics has been demonstrated. The antibacterial surface with a mass fraction of 1 wt.% C-NDs improved abrasion resistance by 3981 times, with 99% killing of adherent bacteria. This work provides an effective strategy for highly efficient antibacterial wear-resistant surface, showing great practical applications in public health environments.

An unacceptable increase in antibacterial resistance has arisen due to the abuse of multiple classes of broad-spectrum antibiotics. Therefore, it is significant to develop new antibacterial agents, especially those that can accurately identify and kill specific bacteria. Herein, we demonstrate a kind of perilla-derived carbon nanodots (CNDs), integrating intrinsic advantages of luminescence and photodynamic, providing the opportunity to accurately identify and kill specific bacteria. The CNDs have an exotic-doped and π-conjugated core, vitalizing them near-infrared (NIR) absorption and emission properties with photoluminescence quantum yield of 21.1%; hydrophobic chains onto the surface of the CNDs make them to selectively stain Gram-positive bacteria by insertion into their membranes. Due to the strong absorption in NIR region, reactive oxygen species are in situ generated by the CNDs onto bacterial membranes under 660 nm irradiation, and 99.99% inactivation efficiency against Gram-positive bacteria within 5 min can be achieved. In vivo results demonstrate that the CNDs with photodynamic antibacterial property can eliminate the inflammation of the area affected by methicillin-resistant Staphylococcus aureus (MRSA), and enabling the wound to be cured quickly.

Phosphorescent carbon nanodots (CNDs) have various attractive properties and potential applications, but it remains a formidable challenge to achieve large-scale phosphorescent CNDs limited by current methods. Herein, a large-scale synthesis method for phosphorescent CNDs has been demonstrated via precursors’ self-exothermic reaction at room temperature. The as-prepared CNDs show fluorescence and phosphorescence property, which are comparable with that synthesized by solvothermal and microwave method. Experimental and computational studies indicate that exotic atom doped sp² hybridized carbon core works as an emissive center, which facilities the intersystem crossing from singlet state to triplet state. The CNDs show phosphorescence with tunable lifetimes from 193 ms to 1.13 s at different temperatures. The demonstration of large-scale synthesis of phosphorescent CNDs at room temperature opens up a new window for room temperature fabrication phosphorescent CNDs.

Room temperature phosphorescence (RTP) materials show potential applications in information security and optoelectronic devices, but it is still a challenge to achieve RTP in organic materials under water ambient due to the unstable property of triplet states. Herein, water-induced RTP has been demonstrated in the organic microrod (OMR). Noting that the RTP intensity of the as-prepared OMR is greatly enhanced when water is introduced, and the reason for the enhancement can be attributed to the formation of hydrogen-bonded networks inside the OMR. The hydrogen-bonded networks can confine the molecular motion effectively, leading to the stability of triplet states; thus the lifetime of the OMR can reach 1.64 s after introducing water. By virtue of the long lifetime of the OMR in the presence of water, multilevel data encryption based on the OMR has been demonstrated.