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Zhao N, Yu Z, Huang J, Liu Y, Zhao Y, Fu X, Yang P, Liu K. Non-invasive monitoring of biochemicals in hydrogel-assisted microfluidic chips. Nanoscale 2023; 15:6179-6186. [PMID: 36912469 DOI: 10.1039/d2nr06042f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Microfluidic chips are prevailingly utilized in biochemical monitoring and clinical diagnostics due to their capability of manipulating minuscule amounts of liquids in a highly integrated manner. Fabrication of microchannels on chips is commonly based on glass or polydimethylsiloxane, and sensing of the fluids and biochemicals within them relies on invasive embedded sensing accessories in the channels. In this study, we propose a hydrogel-assisted microfluidic chip for non-invasive monitoring of chemicals in microfluidics. A nanoporous hydrogel acts as a perfect sealing film on top of a microchannel to encapsulate liquid, and allows for the delivery of target biochemicals to its surface, leaving an open window for non-invasive analysis. This functionally "open" microchannel can be integrated with various electrical, electrochemical, and optical methods to realize accurate detection of biochemicals, suggesting the potential of hydrogel microfluidic chips for non-invasive clinical diagnostics and smart healthcare.
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Affiliation(s)
- Na Zhao
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China.
| | - Zehua Yu
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China.
| | - Jun Huang
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China.
| | - Yuxi Liu
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China.
| | - Yifan Zhao
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China.
| | - Xiangqian Fu
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China.
| | - Peihua Yang
- Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Kang Liu
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China.
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Kim YH, Nguyen T, Lin MC, Peng CC, Radke CJ. Protection against corneal hyperosmolarity with soft-contact-lens wear. Prog Retin Eye Res 2021;:101012. [PMID: 34597771 DOI: 10.1016/j.preteyeres.2021.101012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 09/18/2021] [Accepted: 09/21/2021] [Indexed: 01/03/2023]
Abstract
Hyperosmotic tear stimulates human corneal nerve endings, activates ocular immune response, and elicits dry-eye symptoms. A soft contact lens (SCL) covers the cornea preventing it from experiencing direct tear evaporation and the resulting blink-periodic salinity increases. For the cornea to experience hyperosmolarity due to tear evaporation, salt must transport across the SCL to the post-lens tear film (PoLTF) bathing the cornea. Consequently, limited salt transport across a SCL potentially protects the ocular surface from hyperosmotic tear. In addition, despite lens-wear discomfort sharing common sensations to dry eye, no correlation is available between measured tear hyperosmolarity and SCL-wear discomfort. Lack of documentation is likely because clinical measurements of tear osmolarity during lens wear do not interrogate the tear osmolarity of the PoLTF that actually overlays the cornea. Rather, tear osmolarity is clinically measured in the tear meniscus. For the first time, we mathematically quantify tear osmolarity in the PoLTF and show that it differs significantly from the clinically measured tear-meniscus osmolarity. We show further that aqueous-deficient dry eye and evaporative dry eye both exacerbate the hyperosmolarity of the PoLTF. Nevertheless, depending on lens salt-transport properties (i.e., diffusivity, partition coefficient, and thickness), a SCL can indeed protect against corneal hyperosmolarity by reducing PoLTF salinity to below that of the ocular surface during no-lens wear. Importantly, PoLTF osmolarity for dry-eye patients can be reduced to that of normal eyes with no-lens wear provided that the lens exhibits a low lens-salt diffusivity. Infrequent blinking increases PoLTF osmolarity consistent with lens-wear discomfort. Judicious design of SCL material salt-transport properties can ameliorate corneal hyperosmolarity. Our results confirm the importance of PoLTF osmolarity during SCL wear and indicate a possible relation between PoLTF osmolarity and contact-lens discomfort.
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Anderson DM, Corsaro M, Horton J, Reid T, Seshaiyer P. Tear film dynamics with blinking and contact lens motion. Math Med Biol 2021; 38:355-395. [PMID: 34286343 DOI: 10.1093/imammb/dqab010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 05/17/2021] [Accepted: 06/28/2021] [Indexed: 11/13/2022]
Abstract
We develop a lubrication theory-based mathematical model that describes the dynamics of a tear film during blinking and contact lens (CL) wear. The model extends previous work on pre-corneal tear film dynamics during blinking by coupling the partial differential equation for tear film thickness to a dynamic model for CL motion. We explore different models for eyelid motion and also account for possible voluntary and involuntary globe (eyeball) rotation that may accompany blinking. Boundary conditions for mass flux at the eyelids are also adapted to account for the presence and motion of the CL. Our predictions for CL motion compare reasonably with existing data. Away from the eyelids the pre-lens tear film (PrLTF) is shifted, relative to its pre-corneal counterpart, in the direction of CL motion. Near the eyelids, the inflow/outflow of fluid under the eyelids also influences the PrLTF profile. We also compare our PrLTF dynamics to existing in vivo tear film thickness measurements.
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Affiliation(s)
- Daniel M Anderson
- Department of Mathematical Sciences, George Mason University, Fairfax, VA 22030, USA
| | - Maria Corsaro
- Department of Mathematics, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Jonathan Horton
- Department of Mathematical Sciences, George Mason University, Fairfax, VA 22030, USA
| | - Tim Reid
- Department of Mathematical Sciences, George Mason University, Fairfax, VA 22030, USA
| | - Padmanabhan Seshaiyer
- Department of Mathematical Sciences, George Mason University, Fairfax, VA 22030, USA
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Kapoor Y, Dixon P, Sekar P, Chauhan A. Incorporation of drug particles for extended release of Cyclosporine A from poly-hydroxyethyl methacrylate hydrogels. Eur J Pharm Biopharm 2017; 120:73-79. [DOI: 10.1016/j.ejpb.2017.08.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/06/2017] [Accepted: 08/14/2017] [Indexed: 10/19/2022]
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Gavara R, Compañ V. Oxygen, water, and sodium chloride transport in soft contact lenses materials. J Biomed Mater Res B Appl Biomater 2016; 105:2218-2231. [DOI: 10.1002/jbm.b.33762] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 06/22/2016] [Accepted: 07/11/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Rafael Gavara
- Packaging Group, Instituto de Agroquímica y Tecnología de Alimentos; Consejo Superior de Investigaciones Científicas (IATA-CSIC), Avda, Agustín Escardino; 46980 Paterna Spain
| | - Vicente Compañ
- Escuela Técnica Superior de Ingenieros Industriales, Departamento de Termodinámica Aplicada; Universidad Politécnica de Valencia, Camino de vera s/n; 46020 Valencia Spain
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Su G, Zhou T, Zhang Y, Liu X, Zhang A. Microdynamics mechanism of D2O absorption of the poly(2-hydroxyethyl methacrylate)-based contact lens hydrogel studied by two-dimensional correlation ATR-FTIR spectroscopy. Soft Matter 2016; 12:1145-1157. [PMID: 26577131 DOI: 10.1039/c5sm02542g] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A good understanding of the microdynamics of the water absorption of poly(2-hydroxyethyl methacrylate) (PHEMA)-based contact lens is significant for scientific investigation and commercial applications. In this study, time-dependent ATR-FTIR spectroscopy combined with the perturbation correlation moving-window two-dimensional (PCMW2D) technique and 2D correlation analysis was used to study the microdynamics mechanism. PCMW2D revealed that D2O took 3.4 min to penetrate into the contact lens. PCMW2D also found the PHEMA-based contact lens underwent two processes (I and II) during D2O absorption, and the time regions of processes I and II are 3.4-12.4 min and 12.4-57.0 min. According to 2D correlation analysis, it was proved that process I has 5 steps, and process II has 3 steps. For process I, the first step is D2O hydrogen-bonding with "free" C[double bond, length as m-dash]O in the side chains. The second step is the hydrogen bond generation of the O-HO-D structure between D2O and "free" O-H groups in the side chain ends. The third step is the hydrogen bond generation of D2O and the "free" C[double bond, length as m-dash]O groups close to the crosslinking points in the contact lens. The fourth and the fifth steps are the hydration of -CH3 and -CH2- groups by D2O, respectively. For process II, the first step is the same as that of process I. The second step is the hydrogen bonds breaking of bonded O-H groups and the deuterium exchange between D2O and O-H groups in the side chain ends. The third step is also related to the deuterium exchange, which is the hydrogen bonds regeneration between the dissociated C[double bond, length as m-dash]O groups and the new O-D.
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Affiliation(s)
- Gehong Su
- State Key Laboratory of Polymer Materials Engineering of China, Polymer Research Institute, Sichuan University, Chengdu 610065, China.
| | - Tao Zhou
- State Key Laboratory of Polymer Materials Engineering of China, Polymer Research Institute, Sichuan University, Chengdu 610065, China.
| | - Yanyan Zhang
- State Key Laboratory of Polymer Materials Engineering of China, Polymer Research Institute, Sichuan University, Chengdu 610065, China.
| | - Xifei Liu
- State Key Laboratory of Polymer Materials Engineering of China, Polymer Research Institute, Sichuan University, Chengdu 610065, China.
| | - Aiming Zhang
- State Key Laboratory of Polymer Materials Engineering of China, Polymer Research Institute, Sichuan University, Chengdu 610065, China.
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Liu DE, Kotsmar C, Nguyen F, Sells T, Taylor NO, Prausnitz JM, Radke CJ. Macromolecule Sorption and Diffusion in HEMA/MAA Hydrogels. Ind Eng Chem Res 2013. [DOI: 10.1021/ie402148u] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- D. E. Liu
- Department
of Chemical and Biomolecular Engineering and ‡Vision Science Group, University of California, Berkeley, Berkeley, California, 94720-1462, United States
| | - C. Kotsmar
- Department
of Chemical and Biomolecular Engineering and ‡Vision Science Group, University of California, Berkeley, Berkeley, California, 94720-1462, United States
| | - F. Nguyen
- Department
of Chemical and Biomolecular Engineering and ‡Vision Science Group, University of California, Berkeley, Berkeley, California, 94720-1462, United States
| | - T. Sells
- Department
of Chemical and Biomolecular Engineering and ‡Vision Science Group, University of California, Berkeley, Berkeley, California, 94720-1462, United States
| | - N. O. Taylor
- Department
of Chemical and Biomolecular Engineering and ‡Vision Science Group, University of California, Berkeley, Berkeley, California, 94720-1462, United States
| | - J. M. Prausnitz
- Department
of Chemical and Biomolecular Engineering and ‡Vision Science Group, University of California, Berkeley, Berkeley, California, 94720-1462, United States
| | - C. J. Radke
- Department
of Chemical and Biomolecular Engineering and ‡Vision Science Group, University of California, Berkeley, Berkeley, California, 94720-1462, United States
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Cerretani C, Peng C, Chauhan A, Radke C. Aqueous salt transport through soft contact lenses: An osmotic-withdrawal mechanism for prevention of adherence. Cont Lens Anterior Eye 2012; 35:260-5. [DOI: 10.1016/j.clae.2012.07.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 06/04/2012] [Accepted: 07/03/2012] [Indexed: 11/22/2022]
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Abstract
Wear of low-oxygen-transmissible soft contact lenses swells the cornea significantly, even during open eye. Although oxygen-deficient corneal edema is well-documented, a self-consistent quantitative prediction based on the underlying metabolic reactions is not available. We present a biochemical description of the human cornea that quantifies hypoxic swelling through the coupled transport of water, salt, and respiratory metabolites. Aerobic and anaerobic consumption of glucose, as well as acidosis and pH buffering, are incorporated in a seven-layer corneal model (anterior chamber, endothelium, stroma, epithelium, postlens tear film, contact lens, and prelens tear film). Corneal swelling is predicted from coupled transport of water, dissolved salts, and especially metabolites, along with membrane-transport resistances at the endothelium and epithelium. At the endothelium, the Na+/K+ - ATPase electrogenic channel actively transports bicarbonate ion from the stroma into the anterior chamber. As captured by the Kedem-Katchalsky membrane-transport formalism, the active bicarbonate-ion flux provides the driving force for corneal fluid pump-out needed to match the leak-in tendency of the stroma. Increased lactate-ion production during hypoxia osmotically lowers the pump-out rate requiring the stroma to swell to higher water content. Concentration profiles are predicted for glucose, water, oxygen, carbon dioxide, and hydronium, lactate, bicarbonate, sodium, and chloride ions, along with electrostatic potential and pressure profiles. Although the active bicarbonate-ion pump at the endothelium drives bicarbonate into the aqueous humor, we find a net flux of bicarbonate ion into the cornea that safeguards against acidosis. For the first time, we predict corneal swelling upon soft-contact-lens wear from fundamental biophysico-chemical principles. We also successfully predict that hypertonic tear alleviates contact-lens-induced edema.
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Affiliation(s)
- B K Leung
- Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA 94720, USA
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Gupta C, Chauhan A. Drug transport in HEMA conjunctival inserts containing precipitated drug particles. J Colloid Interface Sci 2010; 347:31-42. [DOI: 10.1016/j.jcis.2010.03.037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/16/2010] [Accepted: 03/17/2010] [Indexed: 11/19/2022]
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Lee SJ, Bourne GR, Chen X, Sawyer WG, Sarntinoranont M. Mechanical characterization of contact lenses by microindentation: Constant velocity and relaxation testing. Acta Biomater 2008; 4:1560-8. [PMID: 18406673 DOI: 10.1016/j.actbio.2008.02.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2007] [Revised: 02/12/2008] [Accepted: 02/19/2008] [Indexed: 11/16/2022]
Abstract
Non-destructive methods for testing material properties allow for multiple tests to be performed on the same sample, which will speed up the design and testing process for hydrogel contact lenses. The mechanical properties of contact lenses were investigated by microindentation testing. Indenter force responses were recorded for two modes of testing: constant velocity and relaxation indentation. From these tests, we characterized the biphasic properties of a hydrogel contact lens: Young's modulus of the solid matrix and hydraulic permeability. Measured indenter force response was fit to finite element (FE) simulation results over a range of Young's modulus (E) and hydraulic permeability (k) over a short testing time scale (2s). Estimated hydraulic permeability, 1-5x10(-15)m(4) (Ns)(-1), was similar to previously measured values for Etafilcon A. However, values determined for Young's modulus, 50-60kPa, were lower than previously measured.
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Affiliation(s)
- Sung Jin Lee
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA
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Pishko GL, Lee SJ, Wanakule P, Sarntinoranont M. Hydraulic permeability of a hydrogel-based contact lens membrane for low flow rates. J Appl Polym Sci 2007. [DOI: 10.1002/app.25860] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Abstract
PURPOSE Tear exchange under a soft contact lens is directly related to the amount of lateral and transverse lens motion. Hydrodynamic modeling suggests that channels placed on the back surface of a soft lens will reduce fluid resistance and increase transverse lens movement. This study measured the effect of posterior lens surface scalloped channels on tear exchange. METHODS Tear exchange in the postlens tear film (PoLTF) was estimated using a fluorometer to measure the exponential depletion of high-MW fluorescein under the lens expressed as the time to deplete 95% of dye (T95). A total of 32 subjects wore two pairs of identical lenses except that the experimental lens had 12 scalloped channels placed radially in the midperiphery of the posterior lens surface, whereas lenses without channels served as controls. RESULTS The mean +/- standard error T95 values for the channel lenses was 28 +/- 2 minutes compared with 32 +/- 2 minutes for the control lenses (p = 0.107). There was a marginally significant difference in T95 between two lens groups in Asian eyes (p = 0.054). CONCLUSION Placing scallop-shaped channels on high-H2O content soft lenses improved the postlens tear pumping in Asian eyes.
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Affiliation(s)
- Meng C Lin
- Clinical Research Center, University of California, Berkeley, California 94720-2020, USA.
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Abstract
The stiffness and hydraulic permeability of soft contact lenses may influence its clinical performance, e.g., on-eye movement, fitting, and wettability, and may be related to the occurrence of complications; e.g., lesions. It is therefore important to determine these properties in the design of comfortable contact lenses. Micro-indentation provides a nondestructive means of measuring mechanical properties of soft, hydrated contact lenses. However, certain geometrical and material considerations must be taken into account when analyzing output force-displacement (F-D) data. Rather than solely having a solid response, mechanical behavior of hydrogel contact lenses can be described as the coupled interaction between fluid transport through pores and solid matrix deformation. In addition, indentation of thin membranes (∼100μm) requires special consideration of boundary conditions at lens surfaces and at the indenter contact region. In this study, a biphasic finite element model was developed to simulate the micro-indentation of a hydrogel contact lens. The model accounts for a curved, thin hydrogel membrane supported on an impermeable mold. A time-varying boundary condition was implemented to model the contact interface between the impermeable spherical indenter and the lens. Parametric studies varying the indentation velocities and hydraulic permeability show F-D curves have a sensitive region outside of which the force response reaches asymptotic limits governed by either the solid matrix (slow indentation velocity, large permeability) or the fluid transport (high indentation velocity, low permeability). Using these results, biphasic properties (Young’s modulus and hydraulic permeability) were estimated by fitting model results to F-D curves obtained at multiple indentation velocities (1.2 and 20μm∕s). Fitting to micro-indentation tests of Etafilcon A resulted in an estimated permeability range of 1.0×10−15 to 5.0×10−15m4∕Ns and Young’s modulus range of 130to170kPa.
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Affiliation(s)
- Xiaoming Chen
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA
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