A multidisciplinary research team, led by Prof. Xiaoming Tao, Chair Professor of Hong Kong Polytechnic University, made a discovery in 2016 that a degradable polylactide/ poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fiber derived from renewable biomass possesses effective antibacterial and antifugal properties without any addition of reactive chemicals. (Textile Research Journal, 87(20), 2464-2474, 2016)
Following up the first surprising discovery, the team separated and extracted several components through precipitation and column chromatography, and conducted antimicrobial tests to confirm the efficacy of the extracted components. The chemical structure of the antimicrobial constituents was revealed by FTIR, NMR and HPLC-MS. The polyhydroxybutyrate (PHB) oligomer with a few degrees of polymerization was identified to be responsible for the effective antimicrobial properties of the fiber. Then the team produced pure PHB oligomer in the laboratory by ring‐opening polymerization of β‐butyrolactone. (Macromolecular Bioscience, 19(5), 1970014, 2019)
The identification of effective antimicrobial ingredient provided guidance for the fiber producing company to successfully improve its manufacturing process of anti-microbial PHBV/PLA fibers in terms of the quality and consistence. Containing sufficient amount of PHB oligomers, the bio-based PLA/PHBV fibers possess advantages of both natural and man-made antimicrobial fiber. , i.e. biodegradable and eco-friendly property, as well as effective antimicrobial property. Another important advantage is the oligomer is biodegradable thus have no threats to health and safety of human and environments, as there is no added antimicrobial agents, such as Ag, Cu, ZnO etc., for man-made fibers.
Next step was to make textile products from the new antimicrobial fibers. Working with companies, filament yarns, staple blend yarns, knitted and woven fabrics, socks, compression stockings, shoe uppers, and bandage were developed. The test results of the products showed the excellent antimicrobial properties and high textile quality in terms of mechanical properties, surface, comfort and coloration. The antimicrobial effects of the textile products were durable even after 100 washing cycles.
An even more exciting discovery recently made by the team showed the fact that the PHB oligomer is highly effective against Methicillin-resistant Staphylococcus aureus (MRSA), one of the most intractable pathogenic bacteria in hospitals, for 47 generations now while the tests are still on going. Encouraged by all the positive results, the team is continuing work with nursing homes and hospitals with a high hope to help patients, medical personnel and elderly in their battles fighting against bacteria infection.