Cu2+-Cross-Linked Tannic Acid Carbon Dot Nanoparticles for Mold Inhibition

Mold has long been a priority because of its potential threat to human health and reduction in the value of wood. Most of the traditional mold inhibitors have toxic effects on the environment, so developing safe and nontoxic mold inhibitors remains a challenge. In this study, tannic acid carbon dots (TA-CDs) were obtained via a straightforward one-step hydrothermal process. Subsequently, Cu2+ cross-linked tannic acid carbon dot nanoparticles (TA-CDs-Cu2+) were synthesized by introducing Cu2+ to TA-CDs at room temperature. The TA-CDs-Cu2+ can be firmly anchored on the surface of Aspergillus niger spores, triggering the rapid release of Cu2+ and TA-CDs in the localized acidic environment. The released TA-CDs triggered the conversion of Cu2+ to Cu+, destroying the cell wall and cell membrane structure of A. niger and reducing cellular esterase activity. In addition, TA-CDs-Cu2+ has been demonstrated to diminish the biomass of biofilms markedly. The use of TA-CDs-Cu2+ on poplar and birch wood has achieved mold protection class 0 at 20 mg of Cu/mL, which were found to exhibit unparalleled advantages as a mold inhibitor. Meanwhile, the TA-CDs-Cu2+ has a warming effect and has opened up avenues for the design of mold inhibition therapeutic agents and photothermal synergistic mold inhibition.