Combination hydrogel system

Harada and coworkers reported forming a photoresponsive hydrogel system by combination of a-cyclodextrin, dodecyl-modified poly(acrylic acid), and a photoresponsive competitive guest, 4,4 -azodibenzoic acid. An aqueous solution of dodecyl-modified poly(acrylic acid) exhibits a gel-like behavior, because polymer chains form a network structure via hydrophobic associations of Ci2 side chains. When a-cyclodextrin is added to the gel-like aqueous solution, the gel is converted to a sol mixture because hydrophobic interactions of Ci2 side chains are dissociated by the formation of inclusion complexes of a-cyclodextrin with the C12 side chains. Upon addition of 4,4 -azodibenzoic acid to the binary sol mixture of the modified poly(acrylic acid) and a-cyclodextrin, the cyclodextrin interacts predominantly with 4,4 -azodibenzoic acid ... 

Ferrocene is one of the most widely explored redox-responsive moieties that has been incorporated into a number of polymers to produce redox-responsive polymers and drug carriers, e.g., poly(ferrocenylsilane) (PFS) chains, which are composed of alternating ferrocene and silane units and can be reversibly oxidized and reduced by chemical and electrochemical means [90]. There are many other examples, including end-decorated homopolymer poly( -caprolactone)-ferrocene threaded onto a )8-cyclodextrin [91], redox-responsible hydrogel system synthesized by combination of / -cyclodextrin (/ -CD), dodecyl-modified poly(acrylic acid) [p(AA/Ci2)]. and ferrocenecarboxylic acid (FCA) [92], nanocapsules composed of a poly(vinylferrocene)-h/oc/c-poly(methyl methacrylate) shell [93] and amphiphilic block copolymers consisting of a hydrophilic poly(ethylene oxide)... 

Hydrogels are used ia the refining of edible oils to adsorb phosphohpids, trace metals, and soaps (103). The adsorption capacity depends on the ease of hydration of the adsorbates, so best performance demands careful control of moisture content ia the system (104). Sihca hydrogel ia combination with alumiaa has beea fouad to be useful for purifyiag used cooking oils ia order to extead their life and enhance the quahty of the fried food (105). 

In swelling-controlled systems, glassy hydrogels ia particular, the release process is a combination of the diffusion of water iato the system and dmg from the system. Empirically, release from these systems may be expressed as (83) ... 

Schiraldi et al. [64] have developed this kind of material by combining silica particles and pHEMA. pHEMA is a biocompatible hydrogel that has been widely studied in the past decades due to its chemical-physical structure and mechanical properties. It has been widely used in ophthalmic prostheses (contact or intraocular lenses), vascular prostheses, drug delivery systems and soft-tissue replacement [65]. These authors have shown that by incorporating silica nanoparticles, the resulting hybrid material is highly biocompatible and promotes bone cell adhesion and proliferation of bone cells seeded on it.1 ... 

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