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Polymers 2017, 9(11), 558; https://doi.org/10.3390/polym9110558

A pH-Indicating Colorimetric Tough Hydrogel Patch towards Applications in a Substrate for Smart Wound Dressings

1
Department of Chemical and Materials Engineering, University of Alberta, 116 Street and 85 Avenue, Edmonton, AB T6G 2V4, Canada
2
Department of Chemical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
*
Author to whom correspondence should be addressed.
Received: 10 October 2017 / Revised: 22 October 2017 / Accepted: 23 October 2017 / Published: 26 October 2017
(This article belongs to the Special Issue Polymer-Based Flexible Printed Electronics and Sensors)
View Full-Text   |   Download PDF [3090 KB, uploaded 26 October 2017]   |  

Abstract

The physiological milieu of healthy skin is slightly acidic, with a pH value between 4 and 6, whereas for skin with chronic or infected wounds, the pH value is above 7.3. As testing pH value is an effective way to monitor the status of wounds, a novel smart hydrogel wound patch incorporating modified pH indicator dyes was developed in this study. Phenol red (PR), the dye molecule, was successfully modified with methacrylate (MA) to allow a copolymerization with the alginate/polyacrylamide (PAAm) hydrogel matrix. This covalent attachment prevented the dye from leaching out of the matrix. The prepared pH-responsive hydrogel patch exhibited a porous internal structure, excellent mechanical property, and high swelling ratio, as well as an appropriate water vapour transmission rate. Mechanical responses of alginate/P(AAm-MAPR) hydrogel patches under different calcium and water contents were also investigated to consider the case of exudate accumulation into hydrogels. Results showed that increased calcium amount and reduced water content significantly improved the Young’s modulus and elongation at break of the hydrogels. These characteristics indicated the suitability of hydrogels as wound dressing materials. When pH increased, the color of the hydrogel patches underwent a transition from yellow (pH 5, 6 and 7) to orange (7.4 and 8), and finally to red (pH 9). This range of color change matches the clinically-meaningful pH range of chronic or infected wounds. Therefore, our developed hydrogels could be applied as promising wound dressing materials to monitor the wound healing process by a simple colorimetric display, thus providing a desirable substrate for printed electronics for smart wound dressing. View Full-Text
Keywords: smart hydrogels; pH responsive dye; molecular modification; mechanical testing; stretchable substrates smart hydrogels; pH responsive dye; molecular modification; mechanical testing; stretchable substrates
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Liu, L.; Li, X.; Nagao, M.; Elias, A.L.; Narain, R.; Chung, H.-J. A pH-Indicating Colorimetric Tough Hydrogel Patch towards Applications in a Substrate for Smart Wound Dressings. Polymers 2017, 9, 558.

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