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Wound management represents a well-known continuous challenge and concern of the global healthcare systems worldwide. The challenge is on the one hand related to the accurate diagnosis, and on the other hand to establishing an effective treatment plan and choosing appropriate wound care products in order to maximize the healing outcome and minimize the financial cost. The market of wound dressings is a dynamic field which grows and evolves continuously as a result of extensive research on developing versatile formulations with innovative properties. Hydrogels are one of the most attractive wound care products which, in many aspects, are considered ideal for wound treatment and are widely exploited for extension of their advantages in healing process. Smart hydrogels (SHs) offer the opportunities of the modulation physico-chemical properties of hydrogels in response to external stimuli (light, pressure, pH variations, magnetic/electric field, etc.) in order to achieve innovative behavior of their three-dimensional matrix (gel–sol transitions, self-healing and self-adapting abilities, controlled release of drugs). The SHs response to different triggers depends on their composition, cross-linking method, and manufacturing process approach. Both native or functionalized natural and synthetic polymers may be used to develop stimuli-responsive matrices, while the mandatory characteristics of hydrogels (biocompatibility, water permeability, bioadhesion) are preserved. In this review, we briefly present the physiopathology and healing mechanisms of chronic wounds, as well as current therapeutic approaches. The rational of using traditional hydrogels and SHs in wound healing, as well as the current research directions for developing SHs with innovative features, are addressed and discussed along with their limitations and perspectives in industrial-scale manufacturing. [ABSTRACT FROM AUTHOR]

Materials with excellent biocompatibility and targeting can be widely used in the biomedical field. Hydrogels are an excellent biomedical material, which are similar to living tissue and cannot affect the metabolic process of living organisms. Moreover, the three-dimensional network structure of hydrogel is conducive to the storage and slow release of drugs. Compared to the traditional hydrogel preparation technologies, ionizing radiation technology has high efficiency, is green, and has environmental protection. This technology can easily adjust mechanical properties, swelling, and so on. This review provides a classification of hydrogels and different preparation methods and highlights the advantages of ionizing radiation technology in smart hydrogels used for biomedical applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Smart hydrogels are promising materials for actuators and sensors, as they can respond to small changes in their environment with a large property change. Hydrogels can respond to a variety of stimuli, for example temperature, pH, metal ions, etc. In this article, the synthesis and characterization of polyampholyte hydrogels based on open chain ligands showing pH and metal ion sensitivity are described. Copolymer and terpolymer gels using different mixtures of monomers i.e., N-[2-(dimethylaminoethyl)acrylamide] (DMAEAAm), N,N-dimethylacrylamide (DMAAm), acrylic acid (AA) and 2-acrylamido-2-methyl-1-propanesulphonic acid (AMPS), have been synthesized. The effect of copolymer composition, i.e., the ratio and amount of ionic monomers and the degree of crosslinking on the swelling characteristics, was evaluated as a function of pH. On this basis, metal ion sensitivity measurements were performed at selected pH values. The metal ion sensitivity was measured by varying the concentration of Cu2+, Zn2+ and Ag+ ions under acidic pH conditions. [ABSTRACT FROM AUTHOR]