Synthesis of highly swellable hydrogels of water-soluble carboxymethyl chitosan and poly(ethylene glycol)

Abstract

Highly swellable hydrogels were produced by crosslinking of high molecular weight carboxymethylated chitosan (CmCHT) with poly(ethylene glycol) (PEG) oligomers. The hydrogel swelling capacity could be controlled via the crosslinking density and ranged from 900% to 5600%. The hydrogels showed good homogeneity with a high interconnected porosity in the swollen state and with nanodomains rich in CmCHT and others rich in PEG diglycidyl ether. Oscillatory frequency sweep analysis showed a storage modulus of 27 kPa for the hydrogel with the highest crosslinking density, which together with the exhibited enzyme degradability with lysozyme at 59 days indicate that these hydrogels have potential use in delivery systems or soft tissue regeneration. Rheological properties of the hydrogelsAn oscillatory frequency sweep was carried out to determine the mechanical properties of the hydrogels. Measurements of the shear modulus (G ′ ) were only possible for CmCHT-79 and CMCHT-58 because the other hydrogel samples were too fragile and disintegrated at the beginning of the test. The G ′ values for both samples (Fig. 7(a)) demonstrated that the hydrogel with the highest crosslinking density presented a higher storage modulus value (G ′ = 27 ± 9 kPa for CmCHT-58 and G ′ = 13 ± 6 kPa for CmCHT-79 at 1 Hz). No noticeable changes were observed in G ′ at all sweep frequencies for any sample. The values of the loss modulus (G ′′ ) were lower than G ′ .

Wet-electrospun PHBV nanofiber reinforced carboxymethyl chitosan-silk hydrogel composite scaffolds for articular cartilage repair

“…Gámiz-González et al. 21 also reported that the swelling ratio of the CMCht hydrogel scaffolds decreased as the PEGDE concentration increased.…”

“…It was seen that after cross-linking at 40°C overnight, liquid CMCht-SF solutions were converted to gel state through the ring-opening reaction of the epoxy groups in PEGDE with the amine and hydroxyl groups in carboxymethyl chitosan. 13,21…”

“…Besides, formation of new O–H bonds slightly increased the intensity of the broad band at 3400–3200 cm −1 with respect to the band at 1595 cm −1 . 21 As SF could not be cross-linked with PEGDE, methanol treatment was applied in order to immobilize the SF in the hydrogel. The methanol treatment resulted in the formation of insoluble β-sheet structure with bands at 1625 ± 10 cm −1 (amide I) and 1525 ± 10 cm −1 (amide II).…”

“…In the literature, the main degradation steps of CMCht and PEGDE took place between 210–310°C and 325–425°C, respectively. 21 Besides, the onset decomposition temperature of the SF was given as 281°C. 35 Accordingly, the first exothermic peak could be ascribed to the breakdown of the main polysaccharide chain of CMCht and the cleavage of the peptide bonds of SF.…”

In-Situ Ionic Imprinted Membrane (IIM) Synthesis Based on Acetic Polyeugenoxy Acetyl Tiophen Methanolate for Gold(III) Metal Ion Transports

“…The IIR FTIR spectra showed that the absorption area of the -OH group was widening; this indicates the increasing number of hydrogen interactions that made the vibration of the -OH group weaker [17]. In the IIM the CS group wave number (702.9 cm -1 ) also shifted to a larger wavenumber (848.68 cm -1 ), this is likely due to the presence of PEGDE as a crosslinker agent and PVA as a plasticizer on the membrane that experience interaction with PEATM-Au which influences the shift of vibrational wavenumber of CS bonds [17][18]. Based on the plank equation theory, which is the basis in the FTIR analysis, explains that energy is directly proportional to the wavenumber (E = h ѵ), the greater the vibrational energy, the greater the peak of the wavenumber [19].…”