Enhancing wood preservatives from cultivated Chinese herbal medicines: A review of synergistic formulation, nano-modification, and smart release technologies

Traditional wood preservatives containing heavy metals (e.g., chromated copper arsenate, CCA) are increasingly restricted owing to their persistence and ecotoxicity. Botanical extracts derived from Chinese herbal medicines (CHMs) have emerged as promising green alternatives for wood protection. However, their industrial application is hindered by limitations such as leachability, environmental instability and moderate efficacy. This review examines three key enhancement strategies: synergistic formulation to boost antifungal efficacy; nanotechnology (e.g., TiO2, SiO2, carbon dots) to improve leaching resistance and durability via encapsulation; and stimuli-responsive systems for targeted, on-demand release, reducing overall dosage. Nevertheless, this review highlights that these technologies may introduce new challenges, including unclear mechanisms of combination, potential ecotoxicity of nanomaterials, and concerns regarding the reliability of stimuli-responsive release systems (e.g., pH-/enzyme-triggered) in real-world environments. Finally, it is emphasized that future research must transcend laboratory-scale performance optimization to incorporate holistic life cycle assessment (LCA) and ecotoxicological evaluations. The integration of emerging concepts, such as deep eutectic solvents (DES) for green extraction, is crucial for developing practical, sustainable, and efficient wood preservation systems derived from industrial crops. Overall, these advanced strategies demonstrate the potential of CHM-based preservatives as effective and sustainable alternatives, supporting the transition towards greener wood protection.