Evaluation of plasma polymer‐coated contact lenses by electrochemical impedance spectroscopy

Weikart, Christopher M.; Mori, Yasuo; Winterton, Lynn; Yasuda, H.

doi:10.1002/1097-4636(20010315)54:4<597::aid-jbm170>3.3.co;2-j

Cited by 23 publications

(36 citation statements)

References 4 publications

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“…[22,28,51] The membrane capacity C mem can be estimated from the maximum of the semicircle at the frequency x max in the Nyquist plot, because x max C mem R mem = 1. [70] Adsorption of cells at a titanium surface leads to a decrease of the measured capacitance. [1,3] At low frequencies the capacity increases with confluence of the cells on polystyrene gold electrodes.…”

Section: Capacitance Measurementsmentioning

confidence: 99%

Biomaterial Interface Investigated by Electrochemical Impedance Spectroscopy

2008

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Electrochemical impedance spectroscopyElectrochemical impedance spectroscopy is an easy applicable sensitive technique. It is used to get information about the adsorption behaviour and the interactions of biomolecules with the electrode surface in a short measurement duration. Electrochemical processes can be modelled by an equivalent circuit and various parameters reflecting certain properties of the interface can be determined. The electrochemical properties of the interface are influenced by proteins and cells adsorbing at the surface. Different modified surfaces can be analyzed before, during, and after cell contact, respectively. Applying bias potentials also changes the behaviour of attaching cells and proteins. Changes in the medium composition have an influence on the electrochemically detectable surface properties.Biosensors are developed consecutively to detect biomolecules. Enzymes, lipids and membranes can be analyzed and the adsorption behaviour of DNA and antigens at modified electrode surfaces can be determined. Different technologies using microchips were constructed to allow a fast screening of electrochemical properties and discrimination of biological molecules or cells. ApplicationElectrochemical impedance spectroscopy serves not only for determination of the capacity of new battery materials or corrosion behaviour and long term stability of diverse alloys and oxide layers, it can also be used to gain information about biomolecules. The adsorption behaviour of cells [1][2][3] and proteins, [4] the amount of adsorbed proteins, [4][5][6][7] surface charge densities [4][5][6] and adsorption coefficients [5] can be determined. Interactions of implant surfaces with biological devices, changes in the polarizability of functional groups, the transport of ions or dipoles through polymer layers and mineralization processes, for instance of bone tissue can be assessed. The change of the Gibbs free energy and the entropy due to protein binding to the surface can be calculated [4,6,8] and the affinity of biomolecules to the surface can be estimated. [4] Electrochemical techniques are introduced as biosensors. Antigens, ssDNA or enzymes are immobilized at the surface and according antibodies, DNA and distinct proteins can be ADVANCED ENGINEERING MATERIALS 2008, 10, No. 10

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Section: Capacitance Measurementsmentioning

confidence: 99%

Biomaterial Interface Investigated by Electrochemical Impedance Spectroscopy

2008

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“…Plasma nanocoatings have attracted interest as a biocompatible material because they can be deposited onto many medical devices or implants, highly conformal and pinhole free [29–31], and have excellent adhesion to their substrates even after exposure to mineral-rich physiological medium [32]. With respect to stenting, plasma nanocoatings impart improved corrosion characteristics of the underlying substrate, potentially minimizing inflammation [33].…”

Section: Introductionmentioning

confidence: 99%

A chemical stability study of trimethylsilane plasma nanocoatings for coronary stents

Jones

Chen

2016

Journal of Biomaterials Science, Polymer Edition

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In this study, trimethylsilane (TMS) plasma nanocoatings were deposited onto 316L stainless steel coupons in direct current (DC) and radio frequency (RF) glow discharges and additional NH3/O2 plasma treatment to tailor the coating surface properties. The chemical stability of the plasma nanocoatings were evaluated after 12 week (~3 month) storage under dry condition (25 °C) and immersion in simulated body fluid (SBF) at 37 °C. It was found that nanocoatings did not impact surface roughness of underlying stainless steel substrates. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used to characterize surface chemistry and compositions. Both DC and RF TMS plasma nanocoatings had Si– and C– rich composition; and the O– and N– contents on the surfaces were substantially increased after NH3/O2 plasma treatment. Contact angle measurements showed that DC TMS nanocoating with NH3/O2 treatment generated very hydrophilic surfaces. DC TMS nanocoatings with NH3/O2 treatment showed minimal surface chemistry change after 12 week immersion in SBF. However, nitrogen functionalities on RF-TMS coating with NH3/O2 post treatment were not as stable as in DC case. Cell culture studies revealed that the surfaces with DC coating and NH3/O2 post treatment demonstrated substantially improved proliferation of endothelial cells over the 12 week storage period at both dry and wet conditions, as compared to other coated surfaces. Therefore, DC nanocoatings with NH3/O2 post treatment may be chemically stable for long-term properties, including shelf-life storage and exposure to the bloodstream for coronary stent applications.

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“…The clinical performance of the resultant polysaccharide-coated lenses displayed equivalent surface wettabilityldrying compared with hydrogel lenses and the additional advantage of better oxygen permeability. The influence of ultra-thin carbon tetrafluoride (CF4) plasma polymerized coatings on siloxane-based hydrogel contact lenses has been investigated by electrochemical impedance spectroscopy (EIS) [141]. The coatings were found to affect the extent of hydration and salt intrusion of the lenses in a measurable manner -although there was significant modification in the surface characteristics, the O2 and ion permeability was maintained and therefore deemed a viable method for modifying the surface characteristics of hydrogels.…”

Section: Applications For Contact Lensesmentioning

confidence: 99%