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Elastic-Plastic Transformation of Polyelectrolyte Complex Hydrogels from Chitosan and Sodium Hyaluronate.

ABSTRACT: Hydrogels formed by polyelectrolyte complexation (PEC) of oppositely charged biopolymers, free of any chemical additives, are promising biomaterials. In this work, the mechanical behavior of hydrogels consisting of positively charged chitosan and negatively charged sodium hyaluronate (HA) at balanced charge composition is investigated. These hydrogels exhibit strong tensile strain and strain rate dependence. They are elastic-like, independent of the strain rate at small strain, but exhibit plastic-like behavior above the yield point by showing a monotonous decrease of the stress. The cyclic tensile test demonstrates that these hydrogels exhibit small and quickly recoverable hysteresis in the elastic-like region, but large and partially recoverable hysteresis above the yield point. The stress relaxation experiment shows a plateau in the reduced stress followed by an abrupt fracture, and the time-to-failure decreases exponentially with increasing applied step-strain. Such elastic-to-plastic-like transformation of the biopolymer PEC gels is quite different from the behaviors of PEC hydrogels formed by oppositely charged vinyl-type synthetic polyelectrolytes due to the difference in flexibility, charge density, and ionic bond strength of these polymers.

SUBMITTER: Shi R

PROVIDER: S-EPMC6449056 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Elastic-Plastic Transformation of Polyelectrolyte Complex Hydrogels from Chitosan and Sodium Hyaluronate.

Shi Ran R Sun Tao Lin TL Luo Feng F Nakajima Tasuku T Kurokawa Takayuki T Bin Yue Zhen YZ Rubinstein Michael M Gong Jian Ping JP

Macromolecules 20181031 21

Hydrogels formed by polyelectrolyte complexation (PEC) of oppositely charged biopolymers, free of any chemical additives, are promising biomaterials. In this work, the mechanical behavior of hydrogels consisting of positively charged chitosan and negatively charged sodium hyaluronate (HA) at balanced charge composition is investigated. These hydrogels exhibit strong tensile strain and strain rate dependence. They are elastic-like, independent of the strain rate at small strain, but exhibit plast ...[more]

PMID: 30956354

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Project description:BackgroundRecent artificial tear preparations have provided 0.2% concentration of sodium hyaluronate. However, no published data exist on their potential superiority against 0.1% in alleviating dry-eye-disease symptoms in cataract extraction surgery.MethodsA total of 180 patients that underwent cataract extraction surgery were randomly divided into 2 groups according to their postoperative regime: Study group (SG) received fixed combination of tobramycin and dexamethasone (FCTD) quid for 3 weeks, and additionally 0.2% sodium hyaluronate provided in the COMOD® device quid for 6 weeks. Control group (CG) received fixed combination of tobramycin and dexamethasone (FCTD) quid for 3 weeks, and additionally 0.1% sodium hyaluronate provided in the COMOD® device quid for 6 weeks. The following indexes were evaluated at 3 postoperative checkpoints: 1) Surface discomfort index (SDI) which was derived by four direct 10-scale Likert-type questions that were addressed to the patient and pertained to: a) foreign body sensation (FBS), b) blinking discomfort (BD), c) stinging sensation (SS), d) tearing sensation (TS), 2) Tear break-up time (TBUT), 3) Schirmer's test, 4) Central corneal thickness (CCT), and 4) Central Corneal Sensitivity (CCS).ResultsBoth groups showed reduced CCS values at all postoperative examination points; however, SG participants had significantly better CCS (all p < 0.05). SG had better TBUT than CG at the 3rd (p = 0.03) and 6th examination points (p = 0.04). Moreover, SG had better SDI scores at the 3rd (SDI = 9.26 ± 0.55) and 6th weeks (SDI = 9.47 ± 0.48) vs. CG participants (p = 0.03 and p < 0.01, respectively).ConclusionThe increased 0.2% sodium hyaluronate concentration in the artificial tears provided in the COMOD® device seems to address dry-eye-disease symptoms better in patients who underwent phacoemulsification surgery than the 0.1% concentration.Trial registrationClinicalTrials.gov Identifier: NCT03705949 Oct 15, 2018, retrospectively registered.

Project description:Neo-tissue formation and host tissue regeneration determine the success of cardiac tissue engineering where functional hydrogel scaffolds act as cardiac (extracellular matrix) ECM mimic. Translationally, the hydrogel templates promoting neo-cardiac tissue formation are currently limited; however, they are highly demanding in cardiac tissue engineering. The current study focused on the development of a panel of four chitosan-based polyelectrolyte hydrogels as cardiac scaffolds facilitating neo-cardiac tissue formation to promote cardiac regeneration. Chitosan-PEG (CP), gelatin-chitosan-PEG (GCP), hyaluronic acid-chitosan-PEG (HACP), and combined CP (CoCP) polyelectrolyte hydrogels were engineered by solvent casting and assessed for physiochemical, thermal, electrical, biodegradable, mechanical, and biological properties. The CP, GCP, HACP, and CoCP hydrogels exhibited excellent porosity (4.24 ± 0.18, 13.089 ± 1.13, 12.53 ± 1.30 and 15.88 ± 1.10 for CP, GCP, HACP and CoCP, respectively), water profile, mechanical strength, and amphiphilicity suitable for cardiac tissue engineering. The hydrogels were hemocompatible as evident from the negligible hemolysis and RBC aggregation and increased adsorption of plasma albumin. The hydrogels were cytocompatible as evident from the increased viability by MTT (>94% for all the four hydrogels) assay and direct contact assay. Also, the hydrogels supported the adhesion, growth, spreading, and proliferation of H9c2 cells as unveiled by rhodamine staining. The hydrogels promoted neo-tissue formation that was proven using rat and swine myocardial tissue explant culture. Compared to GCP and CoCP, CP and HACP were superior owing to the cell viability, hemocompatibility, and conductance, resulting in the highest degree of cytoskeletal organization and neo-tissue formation. The physiochemical and biological performance of these hydrogels supported neo-cardiac tissue formation. Overall, the CP, GCP, HACP, and CoCP hydrogel systems promise novel translational opportunities in regenerative cardiology.

Project description:BackgroundGingivitis is driven by plaque accumulation and, if left untreated, can progress to irreversible periodontitis. For many, the mechanical action of toothbrushing does not achieve adequate plaque control. The aim of this study was to investigate whether twice-daily use of a toothpaste containing 0.2% high molecular weight (HMW) sodium hyaluronate with 67% sodium bicarbonate and 0.221% sodium fluoride (experimental toothpaste) could improve gingival health compared with a regular fluoride toothpaste (negative control). The study also assessed whether the experimental toothpaste could provide additive gingival health benefit over a toothpaste containing only 67% sodium bicarbonate and 0.221% sodium fluoride (positive control).MethodsThis was a single-center, examiner-blinded, randomized, clinical study in healthy adults with mild-to-moderate gingivitis. At baseline, after abstaining from toothbrushing for 12 h, prospective participants underwent oral soft tissue (OST) and oral hard tissue examination followed by assessments for gingival inflammation (Modified Gingival Index [MGI]), gingival bleeding (Bleeding Index [BI]), and supra-gingival plaque (Turesky Plaque Index [TPI]). Eligible participants were stratified by gender and baseline number of bleeding sites (low: <45; high: ≥45 bleeding sites). Following randomization, participants underwent prophylactic dental treatment. Participants received a full OST examination, MGI, BI and TPI assessments after 3 days, 1, 2 and 6 weeks of product use.ResultsIn total, 110 participants were screened for study entry and all were randomized to receive one of three toothpastes (experimental: sodium hyaluronate, sodium bicarbonate, sodium fluoride; positive control: sodium bicarbonate, sodium fluoride; negative control: regular fluoride toothpaste). For all measures, significant improvements were observed in participants receiving either sodium bicarbonate-containing toothpaste (experimental or positive control) compared with the regular fluoride toothpaste (negative control) at week 6. No significant difference was observed in any assessment or visit comparing the experimental toothpaste with the positive control.ConclusionsBoth the experimental and the positive control toothpastes demonstrated clinically relevant improvements in gingival health compared with a regular fluoride toothpaste (negative control). However, no additional gingival health improvement was observed for the experimental toothpaste compared with the positive control, therefore, no additional gingival health benefit can be attributed to the inclusion of sodium hyaluronate in this formulation.Trial registrationClinicalTrials.gov Identifier: NCT04737538 (04/02/2021).

Dataset Information

Elastic-Plastic Transformation of Polyelectrolyte Complex Hydrogels from Chitosan and Sodium Hyaluronate.

Publications

Elastic-Plastic Transformation of Polyelectrolyte Complex Hydrogels from Chitosan and Sodium Hyaluronate.

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