Q103831733
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Aqueous solutions of some polymers exhibit a lower critical solution temperature (LCST); that is, they form phase-separated aggregates when heated above a threshold temperature. Such polymers found many promising (bio)medical applications, including in situ thermogelling with controlled drug release, polymer-supported radiotherapy (brachytherapy), immunotherapy, and wound dressing, among others. Yet, despite the extensive research on medicinal applications of thermoresponsive polymers, their biodistribution and fate after administration remained unknown. Thus, herein, they studied the pharmacokinetics of four different thermoresponsive polyacrylamides after intramuscular administration in mice. In vivo, these thermoresponsive polymers formed depots that subsequently dissolved with a two-phase kinetics (depot maturation, slow redissolution) with half-lives 2 weeks to 5 months, as depot vitrification prolonged their half-lives. Additionally, the decrease of TCP of a polymer solution increased the density of the intramuscular depot. Moreover, they detected secondary polymer depots in the kidneys and liver; these secondary depots also followed two-phase kinetics (depot maturation and slow dissolution), with half-lives 8 to 38 days (kidneys) and 15 to 22 days (liver). Overall, these findings may be used to tailor the properties of thermoresponsive polymers to meet the demands of their medicinal applications. Their methods may become a benchmark for future studies of polymer biodistribution.
- MeSH
- myši MeSH
- polymery * MeSH
- teplota MeSH
- tkáňová distribuce MeSH
- uvolňování léčiv MeSH
- voda * MeSH
- zvířata MeSH
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- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Herein, it is reported for the first time that when mixed with choline chloride, itaconic acid (IA), normally a low-reactive vinyl monomer, undergoes initiator-free radical polymerization under normal daylight. Furthermore, the process results in the formation of abnormally high-molecular-weight poly(itaconic acid) derivatives with Mw greater than ≈800 000 g mol-1 . Detailed 1D/2D NMR studies indicate that the polymers have two types of ionizable moieties, that is, anionic carboxylic and cationic choline ester groups in an average molar ratio of 12:1. Potentiometric titration shows polyampholyte behavior of the polymers. Tentative mechanistic studies reveal that the daylight-induced polymerization is initiated by species generated via interactions of near UV light with IA. However, EPR findings show that choline also participates in secondary radical reactions. The obtained polyampholytes are useful bio-based materials for fast and straightforward fabrication of polymer-clay nanocomposite hydrogels with excellent mechanical properties.
Ultra-high molecular weight polyethylene (UHMWPE) is used as a bearing material in total joint replacements. These joint replacements are in contact with the body fluids during their lifetime, resulting in material degradation. Due to the limited flow behaviour and the large number of physical entanglements of UHMWPE, some measurements (rheological measurements, determination of the gel content and extractable fraction, etc.) cannot be properly evaluated. Therefore, we have focused on accelerated aging of high density polyethylene (HDPE) in the hydrogen peroxide oxidation environment, allowing complete evaluation of degradation damage by monitoring mechanical, rheological, thermal and spectroscopic changes of the material. Perspective amine antioxidants (HALS) and the classical phenolic stabilizer α-tocopherol were used for HDPE stabilization and their effects compared. The aim of the work was to find an effective and rapid method of evaluating the antioxidant effect of newly developed stabilizers for UHMWPE using accelerated aging tests of lower molecular weight analogues. The results have shown that radiation crosslinking of HDPE leads to materials with higher sensitivity to oxidation. All tested stabilizers effectively inhibited the oxidation of HDPE. Moreover, after irradiation and subsequent aging, the branching of HALS stabilizer-containing HDPE chains took place which resulted in increased material resistance.
