Chakrit SirisinhaWeerapen SittichokchuchaiMahidol UniversityThe Institute of Science and Technology for Research and Development, Mahidol University2018-09-072018-09-072001-06-24Journal of Applied Polymer Science. Vol.80, No.13 (2001), 2495-2501002189952-s2.0-0035942953https://repository.li.mahidol.ac.th/handle/20.500.14594/26510The effect of the molecular weight of chitosan on antimicrobial activity was investigated using three chitosans of different molecular weights [1800 (water soluble), 100,000, and 210,000] and similar degrees of deacetylation (86-89%). Cotton fabrics were treated with chitosan by the pad-dry-cure method. The molecular weight dependence of the antimicrobial activity of chitosan was more pronounced at a low treatment concentration. Chitosans with molecular weight of 100,000 and 210,000 effectively inhibited Staphylococcus aureus at a 0.5% treatment concentration. Chitosan with a molecular weight of 1800 was effective against S. aureus at a 1.0% treatment concentration. Escherichia coli was effectively inhibited by chitosan with a molecular weight of 210,000 at a 0.3% treatment concentration and by chitosans with a molecular weight of 1800 and 100,000 at a 1.0% treatment concentration. Proteus vulgaris was effectively inhibited by chitosans with molecular weight of 100,000 and 210,000 at a 0.3% treatment concentration and by chitosan with a molecular weight of 1800 at a 0.5% treatment concentration. None of the chitosans significantly inhibited Klebsiella pneumoniae and Pseudomonas aeruginosa below a 1.0% treatment concentration. Chitosans with high molecular weights were more effective in inhibiting bacterial growth than chitosans with low molecular weights. © 2001 John Wiley & Sons, Inc.Mahidol UniversityChemistryMaterials ScienceArticleSCOPUS10.1002/app.1357