Citral Encapsulated\ninto a Zeolite Imidazolate Framework-67\n(ZIF-67) Cage via Biomimetic Mineralization as an Efficient Preservative\nfor Long-Term Antimildew Efficacy of Bamboo

Natural mildew preventives, like\ncitral, have great potential\nto\nprotect bamboo from mildew, while their long-lasting antimildew performance\nis yet to be challenged owing to their oxidability and volatility.\nInspired by biomimetic mineralization, in this work, citral@ZIF-67\nparticles were synthesized by encapsulating citral into a zeolite\nimidazolate framework-67 (ZIF-67) cage and introduced into a bamboo\nstructure. Benefiting from the unique cage structure and large surface\narea of ZIF-67, it can encapsulate sufficient citral molecules. The\nencapsulation reduced the particle size of ZIF-67 due to the nucleation\nof citral. Furthermore, the surface area, pore size, and volume of\ncitral@ZIF-67 particles gradually decreased with the increase in loading\namounts of citral. ZIF-67 exhibited a certain antibacterial ability\nagainst E. coli and S. aureus. The encapsulation of citral can further\nenhance the antibacterial activity of ZIF-67. In addition, the citral@ZIF-67\nshowed slow-release performance that followed the <i>Fickian</i> diffusion mechanism. After the citral@ZIF-67 treatment, bamboo showed\nno mold spots on the surface with an infection grade of 0, which was\nretained, even though bamboo was conditioned at 50 °C and 85%\nrelative humidity for 10 days. This proposed method can effectively\nimprove the stability of natural mildew preventives and endow bamboo\nwith long-term antimildew properties with low cost and minimized environmental\nimpacts.