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Open AccessArticle

The Bio-Tribological Effect of Poly-Gamma-Glutamic Acid in the Lysozyme-Ionic Contact Lens System

Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608, Taiwan
Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou. No. 5, Fuxing St., Taoyuan 333, Taiwan
College of Medicine, Chang Gung University, No.259, Wenhua 1st Rd., Taoyuan 333, Taiwan
Anton Paar TriTec SA, Les Vernets 6, 2035 Corcelles-Cormondrèche, Switzerland
Graduate Institute of Biomedical Materials and Tissue Engineering, College of Biomedical Engineering, Taipei Medical University, No. 250, Wu-Hsing St., Taipei 110, Taiwan
Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, No. 35, Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan
Author to whom correspondence should be addressed.
These authors contributed to this work equally.
Polymers 2020, 12(1), 156; (registering DOI)
Received: 16 December 2019 / Revised: 2 January 2020 / Accepted: 3 January 2020 / Published: 7 January 2020
(This article belongs to the Special Issue Tribology of Polymers)
Feeling comfortable is an important issue for contact lens wearers as contact lenses are worn for an extensive period of time. It has been shown that the in vitro friction coefficient of contact lenses is correlated to the degree of in vivo comfort, thus many studies focus on establishing friction testing methods for investigating the friction coefficient of contact lenses or contact lens care solution. We have previously demonstrated the lubricating property of poly-gamma-glutamic acid (γ-PGA)-containing care solution, and it could reduce the high friction coefficient caused by lysozyme. However, the mechanism of how γ-PGA-containing care solution reduces the lysozyme-induced friction coefficient of contact lenses is unclear. We investigated the bio-tribological effect of γ-PGA on ionic contact lenses in the presence of lysozyme by testing load and velocity variations. The ability to remove lysozyme deposition by γ-PGA and viscosity analysis of γ-PGA-containing care solutions were also investigated to understand the potential mechanism. Our results showed that the friction coefficient of γ-PGA-containing care solution with lysozyme was the lowest in both load and velocity variations, and γ-PGA functions distinctly in the lysozyme-ionic contact lens system. We proposed a model of how γ-PGA could reduce the friction coefficient in these two conditions. View Full-Text
Keywords: bio-tribology; poly-gamma-glutamic acid; lysozyme; ionic contact lens bio-tribology; poly-gamma-glutamic acid; lysozyme; ionic contact lens
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MDPI and ACS Style

Su, C.-Y.; Yeh, L.-K.; Lai, C.-C.; Dubuisson, M.; Tsao, Y.-F.; Tseng, C.-L.; Fang, H.-W. The Bio-Tribological Effect of Poly-Gamma-Glutamic Acid in the Lysozyme-Ionic Contact Lens System. Polymers 2020, 12, 156.

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