scholarly journals Controlling the Friction of Gels by Regulating Interfacial Oxygen During Polymerization

2021 ◽  
Vol 69 (3) ◽  
Author(s):  
Rok Simič ◽  
Nicholas D. Spencer
Keyword(s):  
Transdermal Drug Delivery ◽  
Contact Lenses ◽  
Distinct Pattern ◽  
Polymerization Reaction ◽  
Spatial Control ◽  
Oxygen Inhibition ◽  
Frictional Properties ◽  
Cell Scaffolds ◽  
Interfacial Oxygen ◽  
Potential Use

AbstractHydrogel surfaces are of great interest in applications ranging from cell scaffolds and transdermal drug-delivery patches to catheter coatings and contact lenses. In this work, we propose a method to control the surface structure of hydrogels, thereby tailoring their frictional properties. The method is based on oxygen inhibition of the free-radical polymerization reaction during synthesis and enables (i) control of friction over more than an order in magnitude and (ii) spatial control of friction as either a continuous gradient or a distinct pattern. The presented method has successfully been applied to acrylamide-, diacrylate- and methacrylate-based gels, illustrating the universality of the presented method, and its potential use in the above-mentioned applications. Graphical Abstract

scholarly journals Controlling the Friction of Gels by Regulating Interfacial Oxygen During Polymerization

2021 ◽  
Author(s):  
Rok Simič ◽  
Nicholas D. Spencer
Keyword(s):  
Transdermal Drug Delivery ◽  
Contact Lenses ◽  
Distinct Pattern ◽  
Polymerization Reaction ◽  
Spatial Control ◽  
Oxygen Inhibition ◽  
Frictional Properties ◽  
Cell Scaffolds ◽  
Interfacial Oxygen ◽  
Potential Use

Abstract Hydrogel surfaces are of great interest in applications ranging from cell scaffolds and transdermal drug-delivery patches to catheter coatings and contact lenses. In this work we propose a method to control the surface structure of hydrogels, thereby tailoring their frictional properties. The method is based on oxygen inhibition of the free-radical polymerization reaction during synthesis and enables (i) control of friction over more than an order in magnitude and (ii) spatial control of friction as either a continuous gradient or a distinct pattern. The presented method has successfully been applied to acrylamide-, diacrylate- and methacrylate-based gels, illustrating the universality of the presented method, and its potential use in the above-mentioned applications.

A study of the frictional properties of senofilcon-A contact lenses

2011 ◽  
Vol 4 (7) ◽  
pp. 1336-1342 ◽  
Author(s):  
Bo Zhou ◽  
Yuanting Li ◽  
Nicholas X. Randall ◽  
Lei Li
Keyword(s):  
Contact Lenses ◽  
Frictional Properties

Synthesis and characterization of a solvent-based acrylate pressure adhesive for transdermal drug delivery

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Fang Sun ◽  
Guoqiang. Zhu ◽  
Shunlai Li ◽  
Hongguang Du
Keyword(s):  
Drug Delivery ◽  
Drug Release ◽  
Transdermal Drug Delivery ◽  
Experimental Methodology ◽  
Polymerization Reaction ◽  
System Component ◽  
Release Behavior ◽  
Drug Release Behavior ◽  
Transdermal Drug Delivery Systems ◽  
Peel Adhesion

AbstractThe present investigation was directed towards the synthesis of a copolymer of vinyl acetate, butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid and acrylamide to be exploited as a pressure sensitive adhesive (PSA) in transdermal drug delivery systems. The experimental methodology involved the optimization of reaction conditions for the polymer synthesis. The optimal synthesis conditions of PSA were determined as that polymerization reaction of PSA in ethyl acetate with BPO of 0.5% w/w of reactants at 75 oC throughout the whole process with polymerization reaction time of eight hours. The copolymer was then characterized by FTIR, 1H-NMR, 13C-NMR and DSC. The PSA was also evaluated for residual monomer content, viscosity, tack, peel adhesion and drug release behavior. The synthesized PSA’s tack is 21#; peel adhesion is 1.39 N/mm. And the residual monomers content in the copolymer after polymerizing for eight hours are VAc 2.98%, BA 0.004%. The PSA also exhibited excellent drug release behavior. Membranes containing oxybutynin were capable of releasing in zero order fashion. It was found that the release velocity depended on the concentration of modified monomer. Drug release from those membranes could be easily tailored by changing the content of the modified monomers. It was found suitable for use in transdermals and could be further exploited either as an adhesive or as a system component in the area of transdermal drug delivery.

scholarly journals Liquid Crystal Elastomers for Biological Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 813
Author(s):  
Mariam Hussain ◽  
Ethan I. L. Jull ◽  
Richard J. Mandle ◽  
Thomas Raistrick ◽  
Peter J. Hine ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Stimuli Responsive ◽  
Absorption Properties ◽  
Liquid Crystal Elastomer ◽  
Cell Scaffolds ◽  
Artificial Tissue ◽  
Recent Developments ◽  
Liquid Crystal Elastomers ◽  
Potential Use

The term liquid crystal elastomer (LCE) describes a class of materials that combine the elastic entropy behaviour associated with conventional elastomers with the stimuli responsive properties of anisotropic liquid crystals. LCEs consequently exhibit attributes of both elastomers and liquid crystals, but additionally have unique properties not found in either. Recent developments in LCE synthesis, as well as the understanding of the behaviour of liquid crystal elastomers—namely their mechanical, optical and responsive properties—is of significant relevance to biology and biomedicine. LCEs are abundant in nature, highlighting the potential use of LCEs in biomimetics. Their exceptional tensile properties and biocompatibility have led to research exploring their applications in artificial tissue, biological sensors and cell scaffolds by exploiting their actuation and shock absorption properties. There has also been significant recent interest in using LCEs as a model for morphogenesis. This review provides an overview of some aspects of LCEs which are of relevance in different branches of biology and biomedicine, as well as discussing how recent LCE advances could impact future applications.

scholarly journals Oxygen inhibition of free-radical polymerization is the dominant mechanism behind the “mold effect” on hydrogels

Soft Matter ◽  
2021 ◽  
Author(s):  
Rok Simic ◽  
Joydeb Mandal ◽  
Kaihuan Zhang ◽  
Nicholas D. Spencer
Keyword(s):  
Free Radical ◽  
Cell Growth ◽  
Radical Polymerization ◽  
Contact Lenses ◽  
Free Radical Polymerization ◽  
Common Method ◽  
Dominant Mechanism ◽  
Oxygen Inhibition ◽  
Growth Studies

Hydrogel surfaces are of great importance in numerous applications ranging from cell-growth studies and hydrogel-patch adhesion to catheter coatings and contact lenses. A common method to control the structure and...

Complications associated with the wearing of contact lenses

JAMA ◽  
1966 ◽  
Vol 195 (11) ◽  
pp. 901-903 ◽  
Author(s):  
J. M. Dixon
Keyword(s):  
Contact Lenses

The growth of mica polytypes as studied by conventional and high-resolution TEM

1983 ◽  
Vol 41 ◽  
pp. 174-177
Author(s):  
A. Baronnet ◽  
M. Amouric
Keyword(s):  
Water Pressure ◽  
Point Of View ◽  
Temperature Fields ◽  
Natural Occurrence ◽  
Growth Mechanisms ◽  
Long Period ◽  
High Resolution Tem ◽  
Layer Stacking ◽  
Experimental Works ◽  
Potential Use

The origin of mica polytypes has long been a challenging problem for crystal- lographers, mineralogists and petrologists. From the petrological point of view, interest in this field arose from the potential use of layer stacking data to furnish further informations about equilibrium and/or kinetic conditions prevailing during the crystallization of the widespread mica-bearing rocks. From the compilation of previous experimental works dealing with the occurrence domains of the various mica "polymorphs" (1Mr, 1M, 2M1, 2M2 and 3T) within water-pressure vs temperature fields, it became clear that most of these modifications should be considered as metastable for a fixed mica species. Furthermore, the natural occurrence of long-period (or complex) polytypes could not be accounted for by phase considerations. This highlighted the need of a more detailed kinetic approach of the problem and, in particular, of the role growth mechanisms of basal faces could play in this crystallographic phenomenon.

An atomic-resolution microscope study of Al contracts on GaAs

1986 ◽  
Vol 44 ◽  
pp. 726-727
Author(s):  
Z. Liliental-Weber ◽  
C. Nelson ◽  
R. Ludeke ◽  
R. Gronsky ◽  
J. Washburn
Keyword(s):  
High Speed ◽  
Schottky Contacts ◽  
Detailed Knowledge ◽  
The Past ◽  
Semiconductor Interfaces ◽  
Deposited Metal ◽  
Microwave Applications ◽  
Free Interfaces ◽  
Potential Use

The properties of metal/semiconductor interfaces have received considerable attention over the past few years, and the Al/GaAs system is of special interest because of its potential use in high-speed logic integrated optics, and microwave applications. For such materials a detailed knowledge of the geometric and electronic structure of the interface is fundamental to an understanding of the electrical properties of the contact. It is well known that the properties of Schottky contacts are established within a few atomic layers of the deposited metal. Therefore surface contamination can play a significant role. A method for fabricating contamination-free interfaces is absolutely necessary for reproducible properties, and molecularbeam epitaxy (MBE) offers such advantages for in-situ metal deposition under UHV conditions

Dual stain kit for the microscopic gram classification of ocular infection bacteria

1993 ◽  
Vol 51 ◽  
pp. 248-249
Author(s):  
Jacob S. Hanker ◽  
Dale N. Holdren ◽  
Kenneth L. Cohen ◽  
Beverly L. Giammara
Keyword(s):  
Contact Lenses ◽  
Ocular Infection ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Gram Staining ◽  
Ocular Infections ◽  
Different Types ◽  
Culture Positive ◽  
Increased Susceptibility

Keratitis and conjunctivitis (infections of the cornea or conjunctiva) are ocular infections caused by various bacteria, fungi, viruses or parasites; bacteria, however, are usually prominent. Systemic conditions such as alcoholism, diabetes, debilitating disease, AIDS and immunosuppressive therapy can lead to increased susceptibility but trauma and contact lens use are very important factors. Gram-negative bacteria are most frequently cultured in these situations and Pseudomonas aeruginosa is most usually isolated from culture-positive ulcers of patients using contact lenses. Smears for staining can be obtained with a special swab or spatula and Gram staining frequently guides choice of a therapeutic rinse prior to the report of the culture results upon which specific antibiotic therapy is based. In some cases staining of the direct smear may be diagnostic in situations where the culture will not grow. In these cases different types of stains occasionally assist in guiding therapy.

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