Photo-responsive hydrogels for potential responsive release applications

Smart Polymeric Hydrogels for Cartilage Tissue Engineering: A Review on the Chemistry and Biological Functions

“…24 For example, photosensitive chromophores such as azobenzenes (and its derivatives) exhibit cis−trans photoisomerization upon UV irradiation, inducing reversible volume changes in the hydrogel network. 95 Photodimerization processes based on coumarin, 96 nitrocinnamate, 97 anthracene, 98 and poly(cinnamic acid) 70 have been applied for the formation of photoresponsive hydrogels. Moreover, photocleavable groups, such as triphenylmethane leuco derivatives, can dissociate into ion pairs by UV light leading to light-induced swelling of the hydrogels.…”

“…There are three classes of light-induced reactions, including photoisomerization, photocleavage, and photodimerization . For example, photosensitive chromophores such as azobenzenes (and its derivatives) exhibit cis – trans photoisomerization upon UV irradiation, inducing reversible volume changes in the hydrogel network . Photodimerization processes based on coumarin, nitrocinnamate, anthracene, and poly­(cinnamic acid) have been applied for the formation of photoresponsive hydrogels.…”

Smart hydrogels as functional biomimetic systems

“…Most of the initial studies have utilized the ability of light-sensitive chromophores such as azobenzenes to undergo reversible cistrans isomerization in the presence of UV light to create lightresponsive hydrogels. 49,50 The inter-conversion of the immobilized azobenzene groups between the two photoisomers induces macroscopic, reversible volume changes of the hydrogel network. In addition to isomerization, studies have employed light-activated dimerization to also create responsive hydrogels.…”

Novel dual‐responsive semi‐interpenetrating polymer network hydrogels for controlled release of anticancer drugs

“…During the past two decades, great attention has been focused on the synthesis of smart or stimuli‐responsive hydrogels due to their special and distinctive properties and the potential applications in biomedical and pharmaceutical fields (Koetting, Peters, Steichen, & Peppas, ; Sood, Bhardwaj, Mehta, & Mehta, ). Stimuli‐responsive hydrogels are able to change their swelling behavior and undergo a reversible phase transition in response to slight change in the environmental stimuli, like temperature (Gong et al, ; Klouda, ; Li & Guan, ), pH (Gupta, Vermani, & Garg, ; Rizwan et al, ; Wang, Fu, Chen, Gao, & Dong, ), light (Cui & Del Campo, ; Tomer & Florence, ; Wang, Zhang, Liu, Hu, & Liu, ), enzyme (Koetting, Guido, Gupta, Zhang, & Peppas, ), ionic strength (Lai & Li, ), electric field (Spizzirri et al, ), and magnetic field (Lima‐Tenório et al, ). Among all the above stimuli, temperature and pH have been applied more widely because of the fact that these two parameters are directly related to the human body.…”