Degradation Behavior Of Hydrogels Research Articles

Reinforcement of hydrogel scaffold using oxidized-guar gum incorporated with curcumin-loaded zein nanoparticles to improve biological performance

Newly, the use of biocompatible injectable hydrogel with appropriate features for application in the tissue engineering area as a perfect wound dressing has been more attracted. For this purpose, the curcumin loaded Zein nanoparticles/aldehyde-modified guar gum/silk fibroin (Cur-NPs/OGG/SF) hydrogel networks were successfully developed to increase the Cur bioavailability during the wound treatment procedure. Fabricated hydrogels were assessed for their morphological, thermal stability, degradation, and mechanical features. By varying the OGG/SF weight ratios, the physicochemical features of hydrogels without or with Cur-loaded Zein NPs were studied. The results showed that with enhancing the OGG content, the degradation behavior of hydrogels were improved. Besides, Cur-NPs/OGG/SF hydrogels increased the cell proliferation without any cytotoxic effect on mouse embryonic fibroblast (NIH-3T3) cells. The Cur-NPs/OGG/SF hydrogel exposed inhibition activity against Bacillus (15.26 ± 1.09 mm) and E. coli (11.54± 1.36 mm) bacteria. These achieved results recommended that the novel developed hydrogel could be suitable for wound healing application.

Oxaliplatin-loaded chemically cross-linked hydrogels for prevention of postoperative abdominal adhesion and colorectal cancer therapy

Colorectal cancer (CRC) is the third most commonly diagnosed cancer among both men and women worldwide. New therapeutic strategies involving cytoreductive surgery and intra-peritoneal chemotherapy could lead to a definitive cure in some cases. However, postoperative intra-abdominal adhesion can cause further complications. In this study, hyaluronic acid (HA)- and carboxymethyl cellulose sodium (CMCNa)-based novel cross-linked hydrogels (HC hydrogels) were synthesized and fully characterized. We demonstrated that varied compositions of HA and CMCNa altered the microstructure, rheology, and degradation behavior of hydrogels. Pre-constructed hydrogels were further loaded with oxaliplatin to prevent intra-abdominal adhesion following chemotherapy. Sustained release of oxaliplatin was observed from hydrogels compared that from solutions, which release drugs through diffusion, following the Higuchi and Korsmeyer-Peppas models. Moreover, low adhesion scores in an in vivo SD rat model demonstrated inhibition of intra-peritoneal adhesion in response to HC hydrogels. Therefore, HC hydrogels offer a novel formulation strategy for providing an intra-abdominal anti-adhesion barrier after cytoreductive surgery and intra-peritoneal chemotherapy for CRC treatment.

Control of Degradation Properties of Polymer Gel

Degradation behavior of hydrogel can be divided into two types, surface degradation that degrades from the surface of hydrogel and bulk degradation that degrades homogeneously. Most hydrogel show bulk degradation, but there are many scenes where surface degradation is more useful. This is because surface degradation does not press the surroundings more than bulk degradation. However, it is still unknown what conditions control bulk degradation and surface degradation. Whether the gel undergoes bulk degradation or surface degradation depends on the balance between the simultaneous phenomena of hydrolysis occurring at the hydrolysis site in the polymer constituting the gel and swelling of the gel. As for gel swelling, it is determined by the relationship between the elastic pressure of the gel and the osmotic pressure generated by the presence of polymer concentration difference inside and outside the gel. In this study, in order to change the elastic pressure, polymer concentration was changed. External solvent at the time of degradation was changed in order to control the hydrolysis rate and osmotic pressure. The effect of these parameters on degradation behavior was examined. A polymer having a degradation site was synthesized as follows. Polyethylene glycol (3000 mg, 1 mol) was dried for 3 hours under reduced pressure, and then 40 mL of THF, 1.5 mL of potassium naphthalene / THF solution (0.15 mM) and 7.2 mL of succinic anhydride / THF solution (0.3 M) were added. The mixture was stirred for 24 h at room temperature. After the reaction, THF was removed with an evaporator. 100 mL of chloroform was added to the obtained residue, and the washing out was carried out using 160 mL of hydrochloric acid (0.5 N). Thereafter, sodium sulfate was added for dehydration, and chloroform was removed using an evaporator. Benzene was added to the resulting residue until dissolved, and polymer was recovered by a freeze-drying technique. Furthermore, 40 mL of methacrylic anhydride was added to the obtained polymer. The reaction temperature and time were 60 ℃and 24 hours. After cooling to room temperature, the macromers formed were precipitated in excess of ether and filtered. They were further purified by dissolution and reprecipitation with dichloromethane and ether, respectively. The polymer synthesis was confirmed by 1 H NMR spectrum and IR spectrum. The obtained polymer was dissolved in acetonitrile(30,40 and 50 %(w/v)). The solution was deoxygenated by purging with Ar gas for 20 min. Gel was prepared by photo-crosslinking. For the crosslinking agent, 2,2-dimethoxy-2-phenylacetophenone was used. In order to investigate the degradation of the gel, the gel was immersed in an external solvent temperature-controlled by thermostat, and the volume change was measured. For the external solvent, mixed solvent of phosphate buffer (pH 7.4) and acetonitrile (phosphate buffer: acetonitrile = 10:0, 8:2, 5:5, 2:8 and 0:10) was used to investigate the influence on gel degradation behavior. Samples with different polymer concentrations during the process of gelation all showed surface degradation and it was found that it is difficult to control the type of degradation by changing the elastic pressure. In the evaluation of effect of external solvent, the results showed that the larger the ratio of acetonitrile, the longer time it took for the gel to degrade and the maximum volume of swelling was larger. Furthermore, when the ratio of phosphate buffer to acetonitrile was 2:8, the type of degradation switched from surface degradation to bulk degradation. This is because the rate of hydrolysis decreases as the amount of acetonitrile increases in the external solution, and as a result, the time to degrade becomes longer, the maximum volume of swelling becomes larger, and the whole gel is degrade to cause bulk degradation.

The use of clay nanoplatelets to improve hydrogels for tissue engineering applications

Event Abstract Back to Event The use of clay nanoplatelets to improve hydrogels for tissue engineering applications Lyndon Charles1, Sara E. Strecker1, Shimon A. Unterman1, Adar Oren1, 2, Michael Philbrook3, Gloria L. Matthews3, Elazer R. Edelman1, 4 and Natalie Artzi1, 5 1 MIT, Institute for Medical Engineering and Science, United States 2 ORT Braude College, Department of Biotechnology Engineering, Israel 3 Genzyme, a Sanofi Company, Orthopaedic Research, United States 4 Brigham and Women's Hospital, Cardiovascular Division, United States 5 Brigham and Women's Hospital, Department of Anesthesiology, United States Introduction: Hydrogels are widely used in tissue regeneration including bone and cartilage, but their tunability is challenged by their hydrophilicity which presents limits in degradation control, mechanical stability, and drug release which strongly influence regenerative outcomes. Hydrogels of polyamidoamine (PAMAM) dendrimer and dextran-aldehyde offer excellent biocompatibility, tunability, and in situ gelation[1]. Here we show the ability of clay nanoplatelets (cNPs) to improve hydrogel degradation and drug release to add further tunability. cNPs also modify the rheological properties[2] of hydrogel precursor solutions and has been optimized by our lab to create easily injectable hydrogels to improve use in minimally invasive procedures. Different sized clays, montmorillonite and laponite, were selected for improved mechanical and rheological properties. The ability to tune these properties using cNPs to create an injectable, biocompatible, drug delivery hydrogel represents a significant improvement over current hydrogels. Tunable clay hydrogels are a suitable candidate for use in tissue regeneration to address common challenges. Materials and Methods: PAMAM dendrimer was purchased from Dedritech, Inc and 10 kDa Dextran (Sigma Aldrich) was oxidized by reacting with sodium periodate. Clays were obtained from Southern Clay Products, Inc. Degradation studies were done in phosphate buffered saline and mass recorded daily. Mouse mesenchymal cells (MSC) were used for in vitro cell studies. Toxicity studies were performed by placing hydrogels in direct contact with C3H10T1/2 cells and imaged using live/dead cell staining kit (Life Technologies). Hydrogels were introduced to cell environment by transwell assay in cell growth and alkaline phosphatase assays (ALP) assays. For ALP, 16 mg simvastatin was loaded into each hydrogel and W20-17 cell line was used. PrestoBlue (Life Technologies) reagent was used to assay cell growth and ALP kit (Sigma Aldrich) was used for ALP expression. Results and Discussion: Degradation behavior of hydrogels was measured by mass loss. Results (Fig1A) show the ability of cNPs to retard hydrogel degradation. While hydrogels show a 20% loss in mass, clay hydrogels lose only 5% of mass over 21 days. Due to their large surface area and charge density, cNPs may add stability by forming networks of clay-clay and clay-polymer interactions, in addition to polymer-polymer interactions. Clay hydrogels also improve biocompatibility and acute toxicity. Early effect on cell growth is reversed with the addition of cNPs (Fig1B) and clay hydrogels mitigate the local, acute toxicity of MSCs (Fig1C) seen adjacent to the hydrogel (Fig1C). Clay addition may enhance polymer interactions and prevent the early release of unbound polymer into the media. Use of hydrogels as drug delivery vehicles is important in tissue regeneration. When added to hydrogels loaded with the osteogenic drug simvastatin, cNPs lead to increased ALP expression in MSCs (Fig1D). This is likely due to increase in simvastatin release from the hydrogel driven by the interruption of the polymer network by cNPs. Conclusion: Here we show that cNPs can modify hydrogel properties to control drug release and improve cell compatibility. This ability to tune hydrogel behavior by addition of cNPs, as well as improving injectability, can enhance their flexibility for use in variable environments and tissue engineering applications.

Controlled gelation temperature, pore diameter and degradation of a highly porous chitosan-based hydrogel

In this study, highly porous chitosan–α,β-glycerophosphate hydrogels were prepared by changing the chitosan/α,β-glycerophosphate ratio. The gelation temperatures of these gels determined from rheological analysis indicated that the gelation temperature decreased by increasing α,β-glycerophosphate content. The chemical structures and morphology of the hydrogels were examined by FTIR and SEM, respectively. The SEM images showed a highly porous 3D chitosan–α,β-glycerophosphate hydrogel structure with interconnected pores and the pore diameters depended on the chitosan/α,β-glycerophosphate ratio. The swelling and degradation experiments indicated that the degradation behaviors of these hydrogels via bulk erosion relied heavily on the chitosan/α,β-glycerophosphate ratio. This study suggested that the gelation temperature, pore diameter and degradation behaviors of chitosan-based porous hydrogels can be controlled by changing the ratio of chitosan and α,β-glycerophosphate.

Degradation behavior of hydrogels from poly(vinyl alcohol)‐graft‐[poly(rac‐lactide)/poly(rac‐lactide‐co‐glycolide)]: Influence of the structure and composition on the material's stability

AbstractThe swellability and mass loss of poly(vinyl alcohol)‐graft‐[poly(rac‐lactide)/poly(rac‐lactide‐co‐glycolide)] hydrogels upon hydrolysis are strongly affected by the composition of the hydrogels. Hydrophobic hydrogels remain at a relatively constant mass for a couple of weeks, and the mass decreases dramatically thereafter, whereas more hydrophilic hydrogels lose mass right from the beginning. All hydrogels display water uptake values between 90 and 280% within 8 weeks. For longer periods of degradation, the water uptake increases up to a maximum of about 900%. Studies of the thermal properties of samples upon degradation and their IR measurements have shown that the degradation rate is related to the physical and chemical structure of the hydrogels and hence to the hydrophobic/hydrophilic balance; that is, the degradation increases with the increasing hydrophilicity of the material. As a result, degradation can be engineered through the variation of the composition and structure of the material. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Manipulations in Hydrogel Degradation Behavior Enhance Osteoblast Function and Mineralized Tissue Formation

Manipulations in Hydrogel Degradation Behavior Enhance Osteoblast Function and Mineralized Tissue Formation

Flow through diffusion cell method: A novel approach to studyin vitro enzymatic degradation of a starch-based ternary semi-interpenetrating network for gastrointestinal drug delivery

A ter-polymeric semi-IPN has been synthesized by aqueous polymerization of methacrylamide in the presence of polyethylene glycol (PEG) and natural polysaccharides starch, and its enzymatic degradation has been studied in the phosphate buffer medium of pH 6.8 at the physiological temperature 37°C. With the increase in content of enzyme in the external solution and starch in the hydrogel, the degradation is enhanced while the extent of degradation is lowered with the increase in the amount of PEG in the hydrogel. The initial water content also affects the degradability of the polymer matrix. The degradation follows Michaelis–Menten kinetics and KM was found to be 3.92 × 10−5 mol dm−3. The hydrogel exhibits different degradation behavior when studied by “traditional degradation method” (TDM) and “flow through diffusion cell” (FTDC) method. The degradability is suppressed in FTDC method because of the absorption of amylase molecules onto filler particles. Finally the nature and size of the filler particles also affects the degradation behavior of hydrogels. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2975–2984, 2006