Bio-based Preservative using Methyl-β-cyclodextrin-Essential Oil Complexes for Wood Protection

Developing natural preservatives for wood protection is of great interest in sustainable construction and green building industries. This study was designed to determine the feasibility of using methyl-beta-cyclodextrin-essential oils (M beta CD-EOs) complexes as potential bio-based preservatives for wood protection. Four essential oils (EOs) with proven antifungal properties, eugenol (EG), trans-cinnamaldehyde (CN), thymol (TM) and carvacrol (CV), were complexed with methyl-beta-cyclodextrin (M beta CD) by a co-precipitation method. The inclusion of EOs in M beta CD and the corresponding inclusion yield of the M beta CD-EOs complexes were determined by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and ultraviolet-visible spectroscopy (UV/ Vis), respectively. The maximum inclusion yields in M beta CD-EG, M beta CD-CN, M beta CD-CV, and M beta CD-TM were estimated to be almost 100%. M beta CD-EOs complexes were impregnated into southern pine wood blocks and exposed to two brown rot fungi, Gloeophyllum trabeum and Portia placenta, following procedures described in AWPA Standard E22 and E10. The penetration of M beta CD-EOs complexes in wood was confirmed by fluorescence microscopic analysis after the selective dyeing of EOs encapsulated in M beta CD. In comparison to the control wood samples, M beta CD-EOs complexes treated wood exhibited a significant reduction in the mass loss from 16-36% to 2-18%, accompanied by improvement in radial compression strength loss from 81-92% to 29-67% after four-week fungi exposure. (C) 2020 Elsevier B.V. All rights reserved.