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ABSTRACT The micellization of three tailor-made triblock copolymers, such as PB100-P2VP100-PEO104, PB185-P2VP108-PEO154, and PB37-P2VP115-PEO241, having similar total molecular weights and constant poly(2-vinylpyridine) (P2VP) sequence lengths, was investigated as a function of pH and sodium dodecyl sulfate (SDS) concentration. At pH 7 the formation of intermicellar aggregates was observed, especially for copolymers of low poly(ethylene oxide) (PEO) content. A pH decrease from 7 to 3 leads to a particle size increase due to the electrostatic repulsion of the protonated P2VP chains. The influence of the PEO sequence length was also observed for zeta potential values. At pH 3, in the absence of SDS, core-shell-corona micelles are formed whereas in the presence of small amount of SDS (degree of neutralization DN = 0%-50%), a complex is formed between SDS and the protonated P2VP which leads to the shrinkage of the shell and thus to a decrease of the micellar sizes. For higher DN values, the micellar sizes increase due to the formation of large agglomerates and a transition occurs from a monomodal to a bimodal size distribution. Furthermore, it turned out that secondary aggregation, such as intermicellar aggregation, can completely be avoided if the degree of polymerization (DPn) of the water-soluble block is significantly higher than the DPn of the water-insoluble sequence. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45313. [ABSTRACT FROM AUTHOR]

Curcumin has antibacterial and anti-inflammatory activity, and in topical applications, it was successfully used to treat rashes and skin infections. The hydrogel films based on gellan/albumin (BSA) with β-cyclodextrin/curcumin inclusion complex incorporated were prepared at pH = 7.8 by ionic cross-linking with magnesium acetate, to improve the curcumin stability and bioavailability. The films thus obtained were polyelectrolyte complexed with 1% pectin solution pH=3.5. BSA was used in this study due to its therapeutic effects that can lead to improved biocompatibility of the hydrogel film. The films were characterized by swelling degree, SEM, FT-IR, TGA, mechanical tests, cytoxicity, and the antioxidant activity was evaluated. The release kinetics of curcumin from films was performed in two different media: at pH=5.5 and pH=7.4, and a higher release efficiency was found at pH=7.4. The results confirm the biopolymer matrix protective role and the possibility of using the hydrogel obtained in biomedical applications. [ABSTRACT FROM AUTHOR]

The chitosan used was of medium molecular weight, with a 75% deacetylation degree. Crosslinking to obtain hydrogels was performed with partially oxidized carboxymethyl cellulose (CMC-Ox) with NaIO4, to form aldehyde groups by cleaving the C2-C3 bond and the oxidation degree of 45%. The films were obtained by cross-linking as a result of the reaction between the chitosan amine groups with CMC-Ox dialdehyde groups, working at different molar ratios -NH2/-CH=O. The amine groups amount that didn't participate at cross-linking (determined by the ninhydrin test) and the swelling degree value in different mediums decreases as the CMC-Ox amount increases as a result of cross-linking degree. The CMC-Ox and hydrogel films were characterized by SEM, FT-IR and NMR spectroscopy. CMC-Ox could constitute an appropriate cross-linking agent for chitosan having the advantage to avoid the use of another covalent cross-linker, usually toxic and the hydrogel obtained could be used as support for curcumin immobilization. [ABSTRACT FROM AUTHOR]

Adding carbonyl groups into the hydrogel matrix improves the stability and biocompatibility of the hydrogels, making them suitable for different biomedical applications. In this review article, we will discuss the use of hydrogels based on polysaccharides modified by oxidation, with particular attention paid to the introduction of carbonyl groups. These hydrogels have been developed for several applications in tissue engineering, drug delivery, and wound healing. The review article discusses the mechanism by which oxidized polysaccharides can introduce carbonyl groups, leading to the development of hydrogels through cross-linking with proteins. These hydrogels have tunable mechanical properties and improved biocompatibility. Hydrogels have dynamic properties that make them promising biomaterials for various biomedical applications. This paper comprehensively analyzes hydrogels based on cross-linked proteins with carbonyl groups derived from oxidized polysaccharides, including microparticles, nanoparticles, and films. The applications of these hydrogels in tissue engineering, drug delivery, and wound healing are also discussed.