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Zhu Q, Guan J, Tian B, Wang P. Rational design of antibiotic-free antimicrobial contact lenses: Trade-offs between antimicrobial performance and biocompatibility. BIOMATERIALS ADVANCES 2024; 164:213990. [PMID: 39154560 DOI: 10.1016/j.bioadv.2024.213990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 07/20/2024] [Accepted: 08/05/2024] [Indexed: 08/20/2024]
Abstract
Microbial keratitis associated with contact lenses (CLs) wear remains a significant clinical concern. Antibiotic therapy is the current standard of care. However, the emergence of multidrug-resistant pathogens necessitates the investigation of alternative strategies. Antibiotic-free antimicrobial contact lenses (AFAMCLs) represent a promising approach in this regard. The effectiveness of CLs constructed with a variety of antibiotic-free antimicrobial strategies against microorganisms has been demonstrated. However, the impact of these antimicrobial strategies on CLs biocompatibility remains unclear. In the design and development of AFAMCLs, striking a balance between robust antimicrobial performance and optimal biocompatibility, including safety and wearing comfort, is a key issue. This review provides a comprehensive overview of recent advancements in AFAMCLs technology. The focus is on the antimicrobial efficacy and safety of various strategies employed in AFAMCLs construction. Furthermore, this review investigates the potential impact of these strategies on CLs parameters related to wearer comfort. This review aims to contribute to the continuous improvement of AFAMCLs and provide a reference for the trade-off between resistance to microorganisms and wearing comfort. In addition, it is hoped that this review can also provide a reference for the antimicrobial design of other medical devices.
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Affiliation(s)
- Qiang Zhu
- School of Pharmacy, Jiangsu Key Laboratory of Inflammation and Molecular Drug Targets, Nantong University, Nantong 226001, China.
| | - Jian Guan
- School of Pharmacy, Shenyang Key Laboratory of Intelligent Mucosal Drug Delivery Systems, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Bin Tian
- Department of Pharmaceutical Sciences, School of Biomedical and Pharmaceutical Sciences, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Puxiu Wang
- Department of Pharmacy, The First Hospital of China Medical University, Shenyang 110001, China.
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2
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Kiani P, Soozanipour A, Rezayat A, Taheri-Kafrani A. Lysozyme-immobilized bandage contact lens inhibits the growth and biofilm formation of common eye pathogens in vitro. Exp Eye Res 2023; 234:109601. [PMID: 37488008 DOI: 10.1016/j.exer.2023.109601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 07/18/2023] [Accepted: 07/21/2023] [Indexed: 07/26/2023]
Abstract
Bandage contact lenses have an increased affinity to accumulate tear film proteins and bacteria during wear. Among the wide variety of tear film proteins, lysozyme has attracted the most attention for several reasons, including the fact that it is found at a high concentration in the tear film, has exceptional antibacterial and antibiofilm properties, and its significant deposits onto contact lenses. This study aims to evaluate the effect of lysozyme on bacterial biofilm formation on bandage contact lenses. For this purpose, several methods, including microtiter plate test and Colony Forming Unit (CFU) assay have been used to determine antibacterial and antibiofilm characteristics of lysozyme against the two most frequent contact lens-induced bacterial ocular infections, Staphylococcus aureus, and Pseudomonas aeruginosa. The results of these assays demonstrate lysozyme potential to inhibit 57.9% and 80.7% of the growth of S. aureus and P. aeruginosa, respectively. In addition, biofilm formations of P. aeruginosa and S. aureus reduced by 38.3% and 62.7%, respectively due to the antibiofilm effect of lysozyme. SEM and AFM imaging were utilized to visualize lysozyme antibacterial activity and topography changes of the contact lens surface, respectively, in the presence/absence of lysozyme. The results indicated that lysozyme can efficiently attack both gram-positive and gram-negative bacteria and consequently lysozyme-functionalized bandage contact lenses can reduce the risk of ocular infection after eye surgery.
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Affiliation(s)
- Pardis Kiani
- Department of Biotechnology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, 81746-73441, Iran
| | - Asieh Soozanipour
- Department of Biotechnology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, 81746-73441, Iran
| | - Azam Rezayat
- Department of Biotechnology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, 81746-73441, Iran; Department of Chemistry, Faculty of Science, Lorestan University, Khorramabad, Iran
| | - Asghar Taheri-Kafrani
- Department of Biotechnology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, 81746-73441, Iran.
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3
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Kalaiselvan P, Dutta D, Konda NV, Sharma S, Kumar N, Stapleton F, Willcox MDP. Effect of Deposition and Protease Digestion on the Ex Vivo Activity of Antimicrobial Peptide-Coated Contact Lenses. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:349. [PMID: 36678102 PMCID: PMC9863661 DOI: 10.3390/nano13020349] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 06/17/2023]
Abstract
A clinical study of antimicrobial contact lenses containing the cationic peptide Mel4 was conducted. The few adverse events that occurred with this lens occurred on or after 13 nights of wear. The current study examined whether the Mel4 contact lenses lost activity during wear and the mechanism of this loss. Participants wore contact lenses for up to 13 nights. Lenses were tested for their ability to reduce the adhesion of Pseudomonas aeruginosa and Staphylococcus aureus. The amount of protein and lipid extracted from lenses was measured. The ability of trypsin to affect the antimicrobial activity of Mel4-coated contact lenses was measured. Mel4-coated contact lenses lost their antimicrobial activity at six nights of wear for both bacteria. The amount of lipids (13 ± 11 vs. 21 ± 14 μg/lens at 13 nights wear) and proteins (8 ± 4 vs. 10 ± 3 mg/lens at 13 nights of wear) extracted from lenses was not different between Mel4-coated and uncoated lenses, and was not different after three nights when antimicrobial activity was maintained and thirteen nights when they had lost activity (lipid: 25 ± 17 vs. 13 ± 11, p = 0.2; protein: 8 ± 1 vs. 8 ± 4 mg/lens, p = 0.4). Trypsin digestion eliminated the antimicrobial activity of Mel4-coated lenses. In summary, Mel4-coated contact lenses lost antibacterial activity at six nights of wear, and the most likely reason was proteolytic digestion of the peptide. Future studies will design and test proteolytically stable peptide mimics as coatings for contact lenses.
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Affiliation(s)
| | - Debarun Dutta
- School of Optometry and Vision Science, UNSW Sydney, Sydney, NSW 2052, Australia
- School of Optometry, Aston University, Birmingham B4 7ET, UK
| | - Nagaraju V. Konda
- School of Optometry and Vision Science, UNSW Sydney, Sydney, NSW 2052, Australia
- School of Medical Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India
| | - Savitri Sharma
- Jhaveri Microbiology Centre, L. V. Prasad Eye Institute, Hyderabad 500034, Telangana, India
| | - Naresh Kumar
- School of Chemistry, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Fiona Stapleton
- School of Optometry and Vision Science, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Mark D. P. Willcox
- School of Optometry and Vision Science, UNSW Sydney, Sydney, NSW 2052, Australia
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4
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Huang TY, Chang CH, Baskaran N, Wei Y. Correlation between surface friction and the hydrophobicity of structure-related side-chain exposure of albumin on contact lens. Colloids Surf B Biointerfaces 2021; 209:112152. [PMID: 34655983 DOI: 10.1016/j.colsurfb.2021.112152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 10/01/2021] [Accepted: 10/05/2021] [Indexed: 10/20/2022]
Abstract
The management of contact lens discomfort remains a challenge leading to the increased contact lens dropout rates. Tear protein accumulates on the lens surfaces with different configurations observed are correlated to the lens friction, with the improved comfort experienced by reduced surface friction in the eye. However, protein adsorption is a complex process with the combined protein-protein interactions (PPI) and protein-surface interactions (PSI) involved, which is difficult to explain the complicated tribological behavior in terms of protein structural shifts alone on lens surfaces. On the other hand, the type of solvent-exposed side chains from specific protein conformations on lens surfaces should be more important to the lens friction involved. We aim to investigate the correlation between the structure-related side-chain exposure and corresponding lens friction of adsorbed tear proteins on lens surfaces under varied PPI and PSI. Albumin was the model protein adsorbed onto the conventional lens material. Such as polymethylmethacrylate (PMMA) or the poly-2-hydroxyethyl methacrylate (PHEMA) surfaces applied here. Adsorption was conducted under varying protein solution concentrations to saturate the model surface to change the PPI effects over a wide range. Our results indicate that PPI effects help stabilize protein structures on both surfaces. When PPI is minimized, a distinct correlation was observed between the surface friction and the hydrophobicity of structure-related side-chain exposure of albumin on lens surfaces depending on the different PSI involved. At a fundamental understanding, our results would provide insights for developing new lens materials or the lens care solution designs to reduce the lens discomfort.
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Affiliation(s)
- Tzu-Yin Huang
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608, Taiwan
| | - Chia-Hua Chang
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608, Taiwan
| | - Nareshkumar Baskaran
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608, Taiwan
| | - Yang Wei
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608, Taiwan.
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Chan VWY, Phan CM, Ngo W, Jones L. Lysozyme Deposition on Contact Lenses in an In Vitro Blink-Simulation Eye Model Versus a Static Vial Deposition Model. Eye Contact Lens 2021; 47:388-393. [PMID: 33840748 DOI: 10.1097/icl.0000000000000784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate active lysozyme deposition on daily disposable (DD) contact lenses (CL) using a novel in vitro blink model. METHODS Three conventional hydrogel DD CL materials (etafilcon A, omafilcon A, nelfilcon A) and three silicone hydrogel DD CL materials (delefilcon A, senofilcon A, somofilcon A) were tested. The device blink rate was set to 6 blinks/min with a tear flow rate of 1 μL/min using an artificial tear solution (ATS) containing lysozyme and other typical tear film components. After incubation at 2, 4, or 8 hr, lenses were removed, and lysozyme activity was measured. A separate experiment was conducted with lenses incubated in a static vial containing 480 μL of ATS. RESULTS Etafilcon A deposited significantly higher amounts of active lysozyme (402±102 μg/lens) than other lens materials after 8 hr (P<0.0001). Etafilcon A had a higher amount of active lysozyme using the blink model compared with the static vial (P=0.0435), whereas somofilcon A (P=0.0076) and senofilcon A (P=0.0019) had a higher amount of lysozyme activity in the vial compared with the blink model. CONCLUSION The blink model can be tuned to provide quantitative data that closely mimics ex vivo studies and can be used to model deposition of lysozyme on CL materials.
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Affiliation(s)
- Vivian W Y Chan
- Centre for Ocular Research and Education (CORE) (V.W.Y.C., C.-M.P., W.N., L.J.), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada ; and Centre for Eye and Vision Research (CEVR) (C.-M.P., W.N., L.J.), Hong Kong, China
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Walther H, Lorentz H, Heynen M, Kay L, Jones LW. The Impact of Incubation Conditions on In Vitro Phosphatidylcholine Deposition on Contact Lens Materials. Optom Vis Sci 2021; 98:341-349. [PMID: 33828039 DOI: 10.1097/opx.0000000000001680] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
SIGNIFICANCE Previous in vitro measurements of contact lenses commonly investigate the impact of nonpolar tear film lipids (i.e., sterols). Polar lipids, however, are equally important stabilizing components of the tear film. This research explores and presents further knowledge about various aspects of polar lipid uptake that may impact contact lens performance. PURPOSE This study evaluated the impact of incubation time, lipid concentration, and replenishment of an artificial tear solution (ATS) on the uptake of phosphatidylcholine (PC) onto conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials. METHODS Four SHs and two CH lens materials (n = 4) were soaked in a complex ATS containing radioactive 14C-PC as a probe molecule. Phosphatidylcholine uptake was monitored at various incubation time points (1, 3, 7, 14, and 28 days), with different ATS lipid concentrations (0.5×, 1×, 2×) and with and without regular replenishment of the ATS. Phosphatidylcholine was extracted from the lenses, processed, and counted by a β counter, and accumulated PC (μg/lens) was extrapolated from standard lipid calibration curves. RESULTS All materials exhibited increasing PC deposition over time. Conventional hydrogel materials showed significantly lower PC uptake rates (P < .001) than any of the SH materials. Increasing lipid concentration in the ATS resulted in increased PC binding onto the contact lens materials (P < .001). Replenishing the ATS every other day, however, impacted the PC deposition differently, showing increased binding (P < .001) on CHs and reduced PC deposition for SH materials (P < .001). CONCLUSIONS Length of incubation, lipid concentration in the ATS, and renewal of the incubation solution all influenced the amount of PC that sorbed onto various lens materials and therefore need to be considered when conducting future in vitro deposition studies.
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Affiliation(s)
| | | | - Miriam Heynen
- Centre for Ocular Research & Education, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Lise Kay
- Centre for Ocular Research & Education, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
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7
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Mirzapour P, McCanna DJ, Jones L. In vitro analysis of the interaction of tear film inflammatory markers with contemporary contact lens materials. Cont Lens Anterior Eye 2021; 44:101430. [PMID: 33771440 DOI: 10.1016/j.clae.2021.02.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 02/01/2021] [Accepted: 02/12/2021] [Indexed: 11/17/2022]
Abstract
PURPOSE Several clinical studies have suggested that reusable silicone hydrogel contact lens materials exhibit a two-times increased rate of corneal infiltrative events compared to reusable hydrogels. One potential factor contributing to this complication relates to the differential uptake of tear film-based pro-inflammatory cytokines. The purpose of this study was to use an in vitro assay to investigate whether four pro-inflammatory cytokines differed in their uptake onto six contemporary contact lens materials. METHODS Conventional hydrogel (etafilcon A, omafilcon A) and silicone hydrogel (balafilcon A, comfilcon A, senofilcon A, somofilcon A) contact lens materials were soaked in solutions containing pro-inflammatory cytokines IL-1β, IL-6, IL-8 and TNF-α. Samples of the soaking solutions were collected over various time points and analyzed using the Meso Scale Discovery system, which served as a measurement of cytokine uptake onto the contact lens materials. RESULTS Both conventional hydrogels (etafilcon A, omafilcon A) and two of the four silicone hydrogels tested (balafilcon A, comfilcon A), exhibited some uptake of IL-1β, IL-8 or TNF-α (p < 0.05). Senofilcon A and somofilcon A did not exhibit uptake of any of these cytokines (p > 0.05). There was no uptake of IL-6 onto any of the contact lens materials investigated (p > 0.05). CONCLUSION The contact lens materials tested did not exhibit any uptake of IL-6 and furthermore, did not exhibit more than 10 ± 3 % to 25 ± 12 % uptake of IL-1β, IL-8 or TNF-α. Numerous factors could contribute to the reported increase in corneal infiltrative events with reusable silicone hydrogel materials, however, based on these results, it appears that uptake of these four cytokines are unlikely to contribute to this finding.
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Affiliation(s)
- Parisa Mirzapour
- Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
| | - David J McCanna
- Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Lyndon Jones
- Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada; Centre for Eye & Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong
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Drolle E, Ngo W, Leonenko Z, Subbaraman L, Jones L. Nanoscale Characteristics of Ocular Lipid Thin Films Using Kelvin Probe Force Microscopy. Transl Vis Sci Technol 2020; 9:41. [PMID: 32832246 PMCID: PMC7414624 DOI: 10.1167/tvst.9.7.41] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 05/05/2020] [Indexed: 02/02/2023] Open
Abstract
Purpose To describe the use of Kelvin probe force microscopy (KPFM) to investigate the electrical surface potential of human meibum and to demonstrate successful use of this instrument on both human meibum and a meibum model system (six-lipid stock [6LS]) to elucidate nanoscale surface chemistry and self-assembly characteristics. Materials and Methods 6LS and meibum were analyzed in this study. Mica-supported thin films were created using the Langmuir-Blodgett trough. Topography and electrical surface potential were quantified using simultaneous atomic force microscopy/KPFM imaging. Results Both lipid mixtures formed thin film patches on the surface of the mica substrate, with large aggregates resting atop. The 6LS had aggregate heights ranging from 41 to 153 nm. The range in surface potential was 33.0 to 125.9 mV. The meibum thin films at P = 5 mN/m had aggregates of 170 to 459 nm in height and surface potential ranging from 15.9 to 76.1 mV, while thin films at P = 10 mN/m showed an aggregate size range of 147 to 407 nm and a surface potential range of 11.5 to 255.1 mV. Conclusions This study showed imaging of the differences in electrical surface potential of meibum via KPFM and showed similarities in nanoscale topography. 6LS was also successfully analyzed, showing the capabilities of this method for use in both in vitro and ex vivo ocular research. Translational Relevance This study describes the use of KPFM for the study of ocular surface lipids for the first time and outlines possibilities for future studies to be carried out using this concept.
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Affiliation(s)
- Elizabeth Drolle
- Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - William Ngo
- Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Zoya Leonenko
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada.,Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Lakshman Subbaraman
- Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Lyndon Jones
- Centre for Ocular Research & Education (CORE), School of Optometry & Vision Science, University of Waterloo, Waterloo, Ontario, Canada.,Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, Canada.,Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
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9
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Cheung S, Subbaraman LN, Ngo W, Jay GD, Schmidt TA, Jones L. Localization of full-length recombinant human proteoglycan-4 in commercial contact lenses using confocal microscopy. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2019; 31:110-122. [PMID: 31594478 DOI: 10.1080/09205063.2019.1678454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The aim of this study was to determine the sorption location of full-length recombinant human proteoglycan 4 (rhPRG4) tagged with fluorescein isothiocyanate (FITC) to four silicone hydrogel contact lenses [balafilcon A (PureVision, Bausch + Lomb), senofilcon A (Acuvue Oasys, Johnson & Johnson), comfilcon A (Biofinity, CooperVision), lotrafilcon B (Air Optix, Alcon)] and one conventional hydrogel lens [etafilcon A (Acuvue 2, Johnson & Johnson)], using confocal laser scanning microscopy (CLSM). Lenses (n = 3 each) were incubated under two conditions: (1) FITC-rhPRG4 solution at 300 μg/mL and (2) phosphate-buffered saline, for 1 h at 37 °C in darkness with gentle shaking. The central 4 mm of each lens was removed and viewed with the Zeiss 510 CLSM using an argon laser at 488 nm (FITC excitation 495 nm, emission 521 nm). Depth scans were taken at 1 μm intervals to a maximum depth of 100 μm. All lens materials demonstrated sorption of rhPRG4. Both senofilcon A and balafilcon A revealed FITC-rhPRG4 penetration into the bulk of the lens, generally favoring the surface. rhPRG4 was observed exclusively on the surface of lotrafilcon B, with no presence within the bulk of the lens. rhPRG4 was evenly distributed throughout the bulk of the lens, as well as on the surface, for comfilcon A and etafilcon A. The sorption profile of FITC-rhPRG4 was successfully visualized using CLSM in various contact lens materials. The polymer composition, surface treatment and pore size of the material can influence the sorption of rhPRG4.
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Affiliation(s)
- Steven Cheung
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Lakshman N Subbaraman
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - William Ngo
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
| | - Gregory D Jay
- Department of Emergency Medicine, Alpert Medical School & School of Engineering, Brown University, Providence, Rhode Island, USA
| | - Tannin A Schmidt
- Faculty of Kinesiology & Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada.,Biomedical Engineering Department, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Lyndon Jones
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada
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Phan CM, Walther H, Qiao H, Shinde R, Jones L. Development of an Eye Model With a Physiological Blink Mechanism. Transl Vis Sci Technol 2019; 8:1. [PMID: 31534830 PMCID: PMC6727780 DOI: 10.1167/tvst.8.5.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/04/2019] [Indexed: 01/26/2023] Open
Abstract
Purpose To develop an eye model with a physiological blink mechanism. Methods All parts of the eye model were designed using computer-aided design software. The eyelid consisted of a unique 3D printed structure containing teeth to physically secure a flexible membrane. Both the eyeball and eyelid membrane were synthesized using polyvinyl alcohol (PVA). Four molecular weights of PVA (89–98, 85–124, 130, and 146–186 kDa) were tested at a range of concentrations between 5% and 30% weight/volume. The wettability and water content of these materials were compared with the bovine cornea and sclera. The model was connected to a microfluidic pump, which delivers artificial tear solution (ATS) to the eyelid. A corneal topographer was used to evaluate the tear break-up and tear film regeneration. Results The eyelid flexes and slides across the eyeball during each blink, which ensures direct contact between the two surfaces. When loaded with an ATS, this mechanism evenly spreads the solution over the eyeball to generate an artificial tear film. The artificial tear film in this eye model had a tear break-up time (TBUT) of 5.13 ± 0.09 seconds at 1.4 μL/min flow rate, 6 blinks/min, and <25% humidity. Conclusions This model simulates a physiological blink actuation and an artificial tear film layer. Future studies will examine variations in flow rates and ATS composition to simulate clinical values of TBUT. Translational Relevance The eye model could be used to study in vitro TBUT, tear deposition, and simple drug delivery.
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Affiliation(s)
- Chau-Min Phan
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Hendri Walther
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Ha Qiao
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Ra Shinde
- Manipal Academy of Higher Education, Manipal Institute of Technology, Madhav Nagar, Manipal, Karnataka, India
| | - Lyndo Jones
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
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11
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Walther H, Subbaraman LN, Jones L. Novel in vitro method to determine pre-lens tear break-up time of hydrogel and silicone hydrogel contact lenses. Cont Lens Anterior Eye 2018; 42:178-184. [PMID: 30442514 DOI: 10.1016/j.clae.2018.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 10/10/2018] [Accepted: 11/04/2018] [Indexed: 10/27/2022]
Abstract
PURPOSE To develop an in vitro model to determine pre-lens non-invasive break-up time (NIBUT) and to subsequently use this method to compare the NIBUT over contemporary daily disposable (DD) contact lenses (CL). METHODS Three silicone hydrogel (SH) and two conventional hydrogel (CH) DD CLs were incubated in an artificial tear solution (ATS). A model blink cell (MBC) was utilised to mimic intermittent air exposure. CLs were repeatedly submerged for 3 seconds (s) and exposed to air for 10 s over periods of 2, 6, 12, and 16 hours (h). NIBUTs (n = 4) were determined out of the blister pack (T0) and at the end of each incubation period. RESULTS Overall, nesofilcon A showed the longest NIBUTs (p < 0.001). At T0, CHs revealed significantly longer NIBUTs (p ≤ 0.001) than SHs. After 2 h, nesofilcon A showed the longest NIBUT, however, this was only statistically significant compared with delefilcon A (p ≤ 0.001). After 6 h, nesofilcon A NIBUT was significantly longer than all other CLs (p ≤ 0.001). Etafilcon A showed a significantly longer NIBUT (p ≤ 0.001) after 12 h and delefilcon A had the longest NIBUT (p ≤ 0.001) after 16 h. Statistically significant (p ≤ 0.05) changes of NIBUT within the lens materials varied between time points. After 16 h, all CLs showed significant reductions in NIBUTs (p ≤ 0.001) in comparison to T0. CONCLUSION NIBUT values reduced gradually over time and varying levels of deposition impacted measured pre-lens NIBUTs. While NIBUT of CH materials are longer immediately out of the blister pack, after tear film exposure, the NIBUTs obtained using this methodology became very similar.
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Affiliation(s)
- Hendrik Walther
- Centre for Ocular Research & Education (CORE, formerly CCLR), School of Optometry and Vision Science, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.
| | - Lakshman N Subbaraman
- Centre for Ocular Research & Education (CORE, formerly CCLR), School of Optometry and Vision Science, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Lyndon Jones
- Centre for Ocular Research & Education (CORE, formerly CCLR), School of Optometry and Vision Science, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
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12
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Efficacy of Contact Lens Care Solutions in Removing Cholesterol Deposits From Silicone Hydrogel Contact Lenses. Eye Contact Lens 2018; 45:105-111. [PMID: 30199424 DOI: 10.1097/icl.0000000000000547] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine the efficacy of multipurpose solutions (MPSs) on the removal of cholesterol deposits from silicone hydrogel (SH) contact lens materials using an in vitro model. MATERIALS AND METHODS Five SH lens materials: senofilcon A, comfilcon A, balafilcon A, lotrafilcon A, and lotrafilcon B were removed from the blister pack (n=4 for each lens type), incubated for 7 days at 37°C in an artificial tear solution containing C radiolabeled cholesterol. Thereafter, lenses were stored in a preserved saline solution control (Sensitive Eyes Saline Plus) or cleaned with 1 of the 5 MPSs incorporating different preservatives (POLYQUAD/ALDOX, polyquaternium-1/alexidine, polyquaternium-1/PHMB, and 2 based on PHMB alone) using a rub and rinse technique, according to the manufacturer's recommendations, and stored in the MPS for a minimum of 6 hr. Lenses were then extracted with 2:1 chloroform:methanol, analyzed in a beta counter, and μg/lens of cholesterol was determined. RESULTS Balafilcon A and senofilcon A lens materials showed the highest amounts of accumulated cholesterol (0.93±0.02 μg/lens; 0.95±0.01 μg/lens, respectively), whereas lotrafilcon A and lotrafilcon B deposited the lowest amounts (0.37±0.03 μg/lens; 0.47±0.12 μg/lens, respectively). For all lens materials, the MPS preserved with POLYQUAD/ALDOX removed more deposited cholesterol than any other test solution; however, the amount of removed cholesterol contamination from the individual contact lenses was only statistically significant for balafilcon A and senofilcon A (P=0.006 and P=0.042, respectively). Sensitive eyes and the other evaluated MPSs showed no significant effect on cholesterol removal (P>0.05). CONCLUSION Cholesterol-removal efficacy varies depending on the combination of lens material and solution. Only 1 MPS showed a statistically significant reduction of cholesterol deposit for only 2 of the 5 tested lens materials.
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Omali NB, Subbaraman LN, Heynen M, Ng A, Coles-Brennan C, Fadli Z, Jones L. Surface versus bulk activity of lysozyme deposited on hydrogel contact lens materials in vitro. Cont Lens Anterior Eye 2018; 41:329-334. [DOI: 10.1016/j.clae.2018.03.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 12/15/2017] [Accepted: 03/18/2018] [Indexed: 01/12/2023]
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Bayazidi P, Almasi H, Asl AK. Immobilization of lysozyme on bacterial cellulose nanofibers: Characteristics, antimicrobial activity and morphological properties. Int J Biol Macromol 2017; 107:2544-2551. [PMID: 29079438 DOI: 10.1016/j.ijbiomac.2017.10.137] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/13/2017] [Accepted: 10/22/2017] [Indexed: 11/18/2022]
Abstract
The aim of this study was to immobilize of lysozyme onto bacterial cellulose nanofibers (BCNF) using physical absorption method. Antimicrobial activity and other properties of immobilized lysozyme and also morphological characteristics of BCNF were studied. Activity of lysozyme was decreased about 12% after immobilization. The lysozyme concentration of 1mg/ml was chosen for next studies on immobilized enzyme. The optimum pH and temperature were recorded as 7 and 45°C, respectively for immobilized enzyme. Storage stability was increased and immobilized lysozyme exhibited more than 70% of its initial activity after 9 cycles. Kinetic parameters of Km and Vmax were 31.18μg/ml and 112.35 ΔOD/min, respectively for immobilized enzyme. Antimicrobial activity of lysozyme against Staphylococcus aureus, Escherichia coli, Listeria monocytogenes, Yersinia entrocolitica, Aspergillus niger and Saccharomyces serviseae was increased after immobilization. The XRD analyses showed a decrease in diffraction intensities and crystallinity index of BCNF after immobilization of lysozyme. According to the results of scanning electron microscopy (SEM), the diameter of nanofibers was increased by lysozyme incorporation. This study demonstrates the potential for the use of BCNF as carrier for lysozyme immobilization.
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Affiliation(s)
- Pashew Bayazidi
- Department of Food Science and Technology, Faculty of Agriculture, Saba Higher Education Institute, Urmia, Iran
| | - Hadi Almasi
- Department of Food Science and Technology, Faculty of Agriculture, Urmia University, Urmia, Iran.
| | - Asghar Khosrowshahi Asl
- Department of Food Science and Technology, Faculty of Agriculture, Urmia University, Urmia, Iran
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In Vitro Effect of Lysozyme on Albumin Deposition to Hydrogel Contact Lens Materials. Optom Vis Sci 2017; 94:1047-1051. [PMID: 29040199 DOI: 10.1097/opx.0000000000001137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
SIGNIFICANCE Albumin deposition on contact lenses could be detrimental to contact lens (CL) wear because this may increase the risk of bacterial binding and reduce comfort. Lysozyme deposition on selected lens materials would reduce albumin deposition on lenses. PURPOSE This study aims to determine if lysozyme deposition on CLs could act as a barrier against subsequent albumin adsorption, using an in vitro model. METHODS Six hydrogel CL materials (etafilcon A, polymacon, nelfilcon A, omafilcon A, ocufilcon B, and nesofilcon A) were evaluated. Four CLs of each type were soaked in lysozyme solution for 16 hours at 37°C. Lysozyme-coated lenses were then placed in vials with 1.5 mL of artificial tear solution containing I-labeled albumin for 16 hours at 37°C with shaking. Four uncoated lenses of each type were used as controls. Lenses soaked in radiolabeled albumin were rinsed in a phosphate-buffered saline solution, and radioactive counts were measured directly on lenses using a gamma counter. Albumin uptake on lenses was measured using a calibration curve by plotting radioactive counts versus protein concentration. RESULTS Results are reported as mean ± SD. Lysozyme-coated etafilcon A lenses exhibited lower levels of deposited albumin than uncoated etafilcon A lenses (58 ± 12 vs. 84 ± 5 ng/lens; P < .05). There were no differences in albumin adsorption between control (uncoated) and lysozyme-coated polymacon (105 ± 10 vs. 110 ± 34 ng/lens), nelfilcon A (51 ± 7 vs. 42 ± 20 ng/lens), omafilcon A (90 ± 20 vs. 80 ± 38 ng/lens), ocufilcon B (87 ± 20 vs. 115 ± 50 ng/lens), and nesofilcon A (170 ± 29 vs. 161 ± 10 ng/lens) lens materials (P > .05). Uncoated nesofilcon A lenses deposited the highest amount of albumin when compared with other uncoated lenses (P < .05). CONCLUSIONS This study demonstrates that lysozyme deposited onto etafilcon A resists the deposition of albumin, which may potentially be beneficial to CL wearers.
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Boost M, Cho P, Wang Z. Disturbing the balance: effect of contact lens use on the ocular proteome and microbiome. Clin Exp Optom 2017; 100:459-472. [PMID: 28771841 DOI: 10.1111/cxo.12582] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 05/29/2017] [Accepted: 06/05/2017] [Indexed: 12/17/2022] Open
Abstract
Contact lens wear is a popular, convenient and effective method for vision correction. In recent years, contact lens practice has expanded to include new paradigms, including orthokeratology; however, their use is not entirely without risk, as the incidence of infection has consistently been reported to be higher in contact lens wearers. The explanations for this increased susceptibility have largely focused on physical damage, especially to the cornea, due to a combination of hypoxia, mechanical trauma, deposits and solution cytotoxicity, as well as poor compliance with care routines leading to introduction of pathogens into the ocular environment. However, in recent years, with the increasing availability and reduced cost of molecular techniques, the ocular environment has received greater attention with in-depth studies of proteins and other components. Numerous proteins were found to be present in the tears and their functions and interactions indicate that the tears are far more complex than formerly presumed. In addition, the concept of a sterile or limited microbial population on the ocular surface has been challenged by analysis of the microbiome. Ocular microbiome was not considered as one of the key sites for the Human Microbiome Project, as it was thought to be limited compared to other body sites. This was proven to be fallacious, as a wide variety of micro-organisms were identified in the analyses of human tears. Thus, the ocular environment is now recognised to be more complicated and interference with this ecological balance may lead to adverse effects. The use of contact lenses clearly changes the situation at the ocular surface, which may result in consequences which disturb the balance in the healthy eye.
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Affiliation(s)
- Maureen Boost
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong.,Squina International Centre for Infection Control, Hong Kong
| | - Pauline Cho
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong.,Squina International Centre for Infection Control, Hong Kong
| | - Zhaoran Wang
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong
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Jiang MF, Hu MJ, Ren HH, Wang L. Molecular Cloning and Characterization of a New C-type Lysozyme Gene from Yak Mammary Tissue. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2015; 28:1774-83. [PMID: 26580446 PMCID: PMC4647087 DOI: 10.5713/ajas.15.0125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 03/29/2015] [Accepted: 05/11/2015] [Indexed: 11/27/2022]
Abstract
Milk lysozyme is the ubiquitous enzyme in milk of mammals. In this study, the cDNA sequence of a new chicken-type (c-type) milk lysozyme gene (YML), was cloned from yak mammary gland tissue. A 444 bp open reading frames, which encodes 148 amino acids (16.54 kDa) with a signal peptide of 18 amino acids, was sequenced. Further analysis indicated that the nucleic acid and amino acid sequences identities between yak and cow milk lysozyme were 89.04% and 80.41%, respectively. Recombinant yak milk lysozyme (rYML) was produced by Escherichia coli BL21 and Pichia pastoris X33. The highest lysozyme activity was detected for heterologous protein rYML5 (M = 1,864.24 U/mg, SD = 25.75) which was expressed in P. pastoris with expression vector pPICZαA and it clearly inhibited growth of Staphylococcus aureus. Result of the YML gene expression using quantitative polymerase chain reaction showed that the YML gene was up-regulated to maximum at 30 day postpartum, that is, comparatively high YML can be found in initial milk production. The phylogenetic tree indicated that the amino acid sequence was similar to cow kidney lysozyme, which implied that the YML may have diverged from a different ancestor gene such as cow mammary glands. In our study, we suggest that YML be a new c-type lysozyme expressed in yak mammary glands that plays a role as host immunity.
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Affiliation(s)
- Ming Feng Jiang
- College of Life Science and Technology, Southwest University for Nationalities, Chengdu, Sichuan 610041, China
| | - Ming Jun Hu
- College of Life Science and Technology, Southwest University for Nationalities, Chengdu, Sichuan 610041, China ; Key Laboratory of Animal Genetics & Breeding, Southwest University for Nationalities, State Ethnic Affairs Commission and Ministry of Education, Chengdu, Sichuan 610041, China
| | - Hong Hui Ren
- College of Life Science and Technology, Southwest University for Nationalities, Chengdu, Sichuan 610041, China ; Key Laboratory of Animal Genetics & Breeding, Southwest University for Nationalities, State Ethnic Affairs Commission and Ministry of Education, Chengdu, Sichuan 610041, China
| | - Li Wang
- Key Laboratory of Animal Genetics & Breeding, Southwest University for Nationalities, State Ethnic Affairs Commission and Ministry of Education, Chengdu, Sichuan 610041, China
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Hall B, Heynen M, Jones LW, Forrest JA. Analysis of Using I125Radiolabeling for Quantifying Protein on Contact Lenses. Curr Eye Res 2015; 41:456-65. [DOI: 10.3109/02713683.2015.1031350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Hall B, Jones L, Forrest JA. Kinetics of Competitive Adsorption between Lysozyme and Lactoferrin on Silicone Hydrogel Contact Lenses and the Effect on Lysozyme Activity. Curr Eye Res 2014; 40:622-31. [PMID: 25251834 DOI: 10.3109/02713683.2014.946518] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To determine the effect of competitive adsorption between lysozyme and lactoferrin on silicone hydrogel contact lenses and the effect on lysozyme activity. METHODS Three commercially available silicone hydrogel contact lens materials (senofilcon A, lotrafilcon B and balafilcon A) were examined, for time points ranging from 10 s to 2 h. Total protein deposition was determined by I(125) radiolabeling of lysozyme and lactoferrin, while the activity of lysozyme was determined by a micrococcal activity assay. RESULTS Senofilcon A and balafilcon A did not show any relevant competitive adsorption between lysozyme and lactoferrin. Lotrafilcon B showed reduced protein deposition due to competitive adsorption for lactoferrin at all time points and lysozyme after 7.5 min. Co-adsorption of lactoferrin and lysozyme decreased the activity of lysozyme in solution for senofilcon A and lotrafilcon B, but co-adsorption had no effect on the surface activity of lysozyme for all lens types investigated. CONCLUSIONS Competition between lysozyme and lactoferrin is material specific. Co-adsorption of lysozyme and lactoferrin does not affect the activity of surface-bound lysozyme but can reduce the activity of subsequently desorbed lysozyme.
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Affiliation(s)
- Brad Hall
- Centre for Contact Lens Research, School of Optometry and Vision Science , Waterloo, Ontario , Canada and
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Hall B, Phan CM, Subbaraman L, Jones LW, Forrest J. Extraction versus In Situ Techniques for Measuring Surface-Adsorbed Lysozyme. Optom Vis Sci 2014; 91:1062-70. [DOI: 10.1097/opx.0000000000000354] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Elkins CM, Qi QM, Fuller GG. Corneal cell adhesion to contact lens hydrogel materials enhanced via tear film protein deposition. PLoS One 2014; 9:e105512. [PMID: 25144576 PMCID: PMC4140805 DOI: 10.1371/journal.pone.0105512] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/21/2014] [Indexed: 12/03/2022] Open
Abstract
Tear film protein deposition on contact lens hydrogels has been well characterized from the perspective of bacterial adhesion and viability. However, the effect of protein deposition on lens interactions with the corneal epithelium remains largely unexplored. The current study employs a live cell rheometer to quantify human corneal epithelial cell adhesion to soft contact lenses fouled with the tear film protein lysozyme. PureVision balafilcon A and AirOptix lotrafilcon B lenses were soaked for five days in either phosphate buffered saline (PBS), borate buffered saline (BBS), or Sensitive Eyes Plus Saline Solution (Sensitive Eyes), either pure or in the presence of lysozyme. Treated contact lenses were then contacted to a live monolayer of corneal epithelial cells for two hours, after which the contact lens was sheared laterally. The apparent cell monolayer relaxation modulus was then used to quantify the extent of cell adhesion to the contact lens surface. For both lens types, lysozyme increased corneal cell adhesion to the contact lens, with the apparent cell monolayer relaxation modulus increasing up to an order of magnitude in the presence of protein. The magnitude of this increase depended on the identity of the soaking solution: lenses soaked in borate-buffered solutions (BBS, Sensitive Eyes) exhibited a much greater increase in cell attachment upon protein addition than those soaked in PBS. Significantly, all measurements were conducted while subjecting the cells to moderate surface pressures and shear rates, similar to those experienced by corneal cells in vivo.
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Affiliation(s)
- Claire M. Elkins
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
- * E-mail:
| | - Qin M. Qi
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
| | - Gerald G. Fuller
- Department of Chemical Engineering, Stanford University, Stanford, California, United States of America
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Ng A, Heynen M, Luensmann D, Subbaraman LN, Jones L. Impact of tear film components on the conformational state of lysozyme deposited on contact lenses. J Biomed Mater Res B Appl Biomater 2013; 101:1172-81. [PMID: 23564739 DOI: 10.1002/jbm.b.32927] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 12/06/2012] [Accepted: 01/30/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Alan Ng
- Centre for Contact Lens Research; School of Optometry and Vision Science; University of Waterloo; 200 University Avenue West Waterloo Ontario N2L 3G1 Canada
| | - Miriam Heynen
- Centre for Contact Lens Research; School of Optometry and Vision Science; University of Waterloo; 200 University Avenue West Waterloo Ontario N2L 3G1 Canada
| | - Doerte Luensmann
- Centre for Contact Lens Research; School of Optometry and Vision Science; University of Waterloo; 200 University Avenue West Waterloo Ontario N2L 3G1 Canada
| | - Lakshman N. Subbaraman
- Centre for Contact Lens Research; School of Optometry and Vision Science; University of Waterloo; 200 University Avenue West Waterloo Ontario N2L 3G1 Canada
| | - Lyndon Jones
- Centre for Contact Lens Research; School of Optometry and Vision Science; University of Waterloo; 200 University Avenue West Waterloo Ontario N2L 3G1 Canada
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Ng A, Heynen M, Luensmann D, Subbaraman LN, Jones L. Optimization of a fluorescence-based lysozyme activity assay for contact lens studies. Curr Eye Res 2013; 38:252-9. [PMID: 23373676 DOI: 10.3109/02713683.2012.757324] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To optimize a fluorescence-based lysozyme activity assay to investigate the conformational state of lysozyme in solution and to determine the impact of extraction and evaporation procedures and the possible interference of contact lens materials on lysozyme activity. METHODS The fluorescence-based lysozyme activity assay, Enzchek (Molecular Probes Inc, Eugene, OR) which utilizes fluorescently quenched Micrococcus lysodeikticus, was compared to the gold standard, classical lysozyme turbidity assay, using four differently concentrated lysozyme samples (20, 10, 5.0 and 2.0 ng/µL). Furthermore, six differently concentrated lysozyme samples (2.0, 1.0, 0.5, 0.25, 0.125 and 0.01 µg/µL) were quantified using the fluorescence-based assay in the presence of extraction solvents consisting of 0.2% and 0.02% trifluroacetic acid/acetonitrile and following evaporation procedures. RESULTS A standard curve was generated by the fluorescence-based assay ranging from 2 to 150 ng. The total active lysozyme quantified in the four lysozyme samples was not significantly different between the two assays (p > 0.05) and the concordance correlation coefficient was determined to be 0.995. However an average discrepancy between the two assays was found to be 0.474 ng, with the turbidity assay typically reporting higher active lysozyme measurements. The sensitivity of the fluorescence-based assay was higher than the classical turbidity assay when quantifying 20 ng or less active lysozyme. Following the extraction and evaporation procedures and the addition of lens extracts, the total active lysozyme recovered was 95% or greater. CONCLUSIONS In comparison to the classical turbidity assay, the fluorescence-based assay is a very sensitive method, making it a favorable technique, particularly when studying contact lens materials that deposit relatively low levels of lysozyme.
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Affiliation(s)
- Alan Ng
- Centre for Contact Lens Research, School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada.
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