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Novel conceptualization of double-network injectable hydrogels, from naturally occurring polymers
Project status: Ongoing
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The following is a condensed version of the actions that were completed during the stage 1 implementation period:

Stage 1:

  • Four types of cellulose were chemically functionalized by means of selective oxidation reactions: microcrystalline cellulose, α-cellulose, cotton linters, and viscose, using the "one-pot" oxidation process, which involves the simultaneous use of N-hydroxyphthalimide (NHPI), sodium hypochlorite (NaOCl), sodium bromide (NaBr), and sodium periodate (NaIO4). The oxidized form of cellulose(Ox-C), will serve as the foundation (the essential component) upon which injectable hydrogels will be built. After going through the oxidation process, we were able to extract tricarboxylated cellulose fractions, which are soluble in water.
  • Hydroxypropylcellulose (Ox-HPC) was chemically functionalized by oxidation processes, with sodium hypochlorite serving as the oxidizing agent. Sodium hypochlorite is a common chemical agent that is not only affordable but also safe for the environment. After the oxidation procedure, ketone groups were incorporated into the structure of the hydroxypropylcellulose, and the resulting samples of oxidized hydroxypropylcellulose had varying degrees of substitution.
  • Materials that have been chemically functionalized provide a significant number of functional groups (carboxylic, aldehydic, and ketone) that are able to operate as active sites in future transformations.
  • The "project execution plan" was successful in every way, as measured by the following indicators: 1 paper that was accepted for publication, participation in scientific meetings (including 2 oral communication and 2 poster presentations), and the establishment of a website for the project.

Stage 2:

  • The physicochemical and morphological characterization of oxidized cellulose and oxidized hydroxypropyl cellulose was carried out, demonstrating the successful oxidation of hydroxyl groups in the polysaccharide structure. The structure of the materials was confirmed by FTIR, NMR, X-ray, SEM, XPS, and titration methods. The oxidized materials represent the polysaccharide component of the hydrogel structure.
  • The phenomenon of degradation of the cellulose chain during the oxidation reaction has been studied in order to capture the factors contributing to the depolymerization processes.
  • Both natural polymers (oxidized polysaccharides) and proteins (gelatin) were successfully methacrylated, as demonstrated by FTIR and NMR techniques.
  • Several protocols for the preparation of hydrogels based on methacrylate components were tested, and a suitable protocol for their preparation was established. All the indicators set out in the "project realization plan" were achieved.
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