Wennan Zeng

Effect of Chemical Cross-linking on Properties of Gelatin/Hyaluronic Acid Composite Hydrogels

A composite hydrogel was fabricated by introducing hyaluronic acid (HA) into gelatin (Gel) using 1-ethyl-(3-3-dimethylaminopropyl) carbodiimide (EDC) as a cross-linker. The effects of cross-linking, including cross-linker content and cross-linking time, on the morphology, swelling ratio, compressive strength and cytotoxicity in vitro of the Gel/HA hydrogel were investigated. The results showed that the pore size of the Gel/HA hydrogel decreased with increasing cross-linker content. Further, the swelling ratio of the Gel/HA hydrogel also decreased with increasing cross-linker content and cross-linking time. However, the compressive strength increased with increasing EDC content and cross-linking time. The hydrogel extracts with various contents of EDC were not toxic, due to easy removal of excess EDC by washing with dilute acid or water.

Degradation behaviour and biological properties of gelatin/hyaluronic acid composite scaffolds

Abstract Hydrogels, based on natural polymers, are gaining attention as possible cell scaffolding materials for the regeneration of a variety of tissues. In this work, gelatin (Gel) and hyaluronic acid (HA) were used to fabricate novel scaffold materials using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a cross-linker. The degradation behaviours of Gel/HA scaffolds in phosphate buffered saline (PBS) and PBS solution containing lysozyme were investigated respectively. The biological properties including haemolytic activity and acute systemic toxicity were also studied. The results showed that the scaffold had an interconnected pore structure with an average pore size of about 100–500 μm. The degradation of Gel/HA scaffolds in PBS solution containing lysozyme was faster than that in PBS solution. The haemolytic ratio of 0·340–0·781% indicated that the Gel/HA scaffolds have a good blood compatibility. The acute systemic toxicity test showed that Gel/HA extracts have no acute systemic toxicity.

Morphological and Functional Expression of Fibroblast on Poly(lactide-co-glycolide)/β-Tricalcium Phosphate/Nature Bone

The in-vitro biocompatibility of degradable and bioactive composites consisting of poly(lactide-co-glycolide) (PLGA), β-tricalcium phosphate (β-TCP), and nature bone (NB) was investigated by culturing fibroblasts on the PLGA/β-TCP/NB substrates, and the cell morphology, proliferation, alkaline phosphatase (ALP) activity, and von Kossa mineralization were evaluated. The results showed that the incorporation of β-TCP and NB benefited fibroblasts attachment and the fibroblasts cultured on the PLGA/β-TCP/NB composite substrates spread better as compared to those on the pure PLGA after culturing for different times. MTT assay showed that the fibroblasts cultured on the PLGA/β-TCP/NB extraction revealed a higher proliferation rate than those on the pure PLGA extraction. ALP and von Kossa assay indicated that β-TCP and NB could promote biomineralization in vitro. All of the results showed that the addition of β-TCP and NB into PLGA could stimulate fibroblasts to proliferate and differentiate.

Characterization of Biocompatible Scaffolds Based on Gelatin and Hyaluronic Acid for Fibroblasts Culture

Gelatin/hyaluronic acid (Gel/HA) scaffolds were prepared by using the freeze-drying method after crosslinking with 1-ethyl-(3-3-dimethylaminopropyl) carbodiimide (EDC). The porous structure was characterized by scanning electron microscopy (SEM), and the wettability of Gel/HA film was also studied by measuring their contact angle. The biological behaviour of the scaffolds was analyzed by studying the cell behaviour using a fibroblast cell line and standard biological MTT test. The results showed that the scaffold had an inter-connected pore structure with a sufficient pore size for use as a support for the growth of fibroblasts. The contact angle decreased with increasing HA content, whereas the cell attachment and proliferation improved with decreasing HA content. Confocal laser scanning microscopy (CLSM) demonstrated a normal cell distribution and proliferation on the porous Gel/HA scaffolds.

Preparation and Characterization of Hyaluronic Acid Hydrogel Blends with Gelatin

Porous hydrogel blends composed of various weight ratios of hyaluronic acid (HA) and gelatin (Gel) were fabricated by a freeze-drying method. The 1-ethyl-3(3-dimethylaminopropyl) carbodiimide (EDC) was used as a crosslinker to improve their biostability. The effect of the component and crosslinker content on the morphology, swelling ratio (SR), and mechanical properties were investigated. The results indicated that after chemical crosslinking the hydrogel showed a smoother and denser surface with less pores and a crosssection with smaller pores than that without crosslinking. The crosssection morphologies of the HA/Gel hydrogels changed from a sheet-like appearance to a fiber-like appearance with increasing HA content. The addition of HA improved the swelling property, but reduced the compressive strength. As the crosslinker content increased, the SR decreased; however, the compressive strength of the HA/Gel hydrogels increased. All these results suggest that HA/Gel hydrogel crosslinked by EDC is a potential candidate for tissue engineering scaffolds.

Fabrication and Characterization of Gelatin/Chitosan Microspheres for Drug Release

Gelatin/chitosan (Gel/Cs) microspheres were fabricated through an emulsification-solvent evaporation technique using saturated glutaraldehyde as a cross-linking reagent. The influences of the concentration of the emulsifier, stirring speed, and water/oil ratio on particle size and surface morphology were investigated. The experimental results indicated that the particle size of the microspheres decreased with increasing concentration of the emulsifier; however, the microsphere size did not change when the concentration of the emulsifier exceeded 0.016 g·mL−1. The particle diameter of the microspheres decreased with increasing stirring speed and increased with increasing water/oil ratio. The concentration of an acetone/water solution had an obvious effect on the morphologies of the Gel/Cs microspheres during the course of dehydration; the surface of the microspheres became smooth when dehydrated by an acetone solution with a volume ratio of 3:1.

Fabrication and characterisation of gelatin-hyaluronic acid/nanobioactive glass hybrid scaffolds for tissue engineering

Abstract Nanobioactive glass (NBG) particles were synthesised via sol–gel method and characterised by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The new composite biomaterial based on gelatin (Gel) conjugated with hyaluronic acid (HA) and NBG in the ternary SiO2–CaO–P2O5 system was prepared through freeze drying method. The composite scaffold was characterised by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermal analyses. Mechanical properties and swelling behaviour of this composite are compared with properties of Gel-HA/NBG composite of similar material without NBG. The TEM results indicated that the prepared NBG particle size was ∼100 nm. The SEM studies showed that the NBG were homogenously distributed within the Gel/HA matrix and the composite scaffolds showed interconnected pores with a size varied from 50 to 200 μm. The Gel-HA/NBG composite scaffold showed higher compressive strength and better stability than the Gel/HA scaffold. These results indicate that composite scaffolds developed using NBG disseminated Gel/HA matrix as potential scaffolds for tissue engineering applications.

Biological Assessment of Composite Materials Based on Poly-L-lactide and Bovine Bone

Biodegradable polymers and bioactive fillers are being combined in a variety of composite materials for biomedical application. Biological properties in vivo of poly-L-lactide (PLLA) matrix containing bovine bone were investigated by using acute systemic toxicity in vivo, blood biocompatibility, sensitivity, pyrogen, and genetic toxicity testing methods. The results indicated that there were no toxic and death cases observed in the acute systemic toxicity test. The PLLA/bovine bone composite showed no genetic toxicity, pyrogen, or sensitizing response and the hemolytic index was 0.29%. The results from these studies demonstrated that PLLA/bovine bone has a good biocompatibility and good biological safety. Therefore, PLLA/bovine bone composite materials can be promising biomedical materials for bone tissue engineering.

Effect of Surface Modification of Bioactive Glass on Properties of Poly-L-lactide Composite Materials

The 3-aminopropyltrimethoxysilane (APS) surface modification of sol-gel bioactive glass (BG) was performed to improve the phase compatibility between poly-L-lactide (PLLA) and BG. The composite based on PLLA and modified BG was fabricated by using hot pressing methods. The effects of APS modification on the morphology of BG and mechanical properties of the PLLA/BG composite were investigated. The results indicated that uniformly dispersed BG particles, without agglomeration, were obtained after surface modification. Furthermore, the bending strength, bending modulus, and shearing strength of PLLA/BG-APS composites were all higher than those of unmodified composites. However, the bending strength and shearing strength of PLLA/BG-APS composites significantly decreased with increasing BG content for all, whereas the bending modulus increased.

Study on Controlled Release of 5-Fluorouracil from Gelatin/Chitosan Microspheres

The microspheres based on gelatin (Gel) and chitosan (Cs) were prepared by a water-in-oil (W/O) emulsion crosslinking method using glutaraldehyde (GA) as a crosslinker. 5-Fluorouracil (5-FU), as an anticancer drug, was successfully loaded into the Gel/Cs microspheres. The release behavior of 5-FU was investigated with the microspheres acting as carriers for controlled release. Scanning electron microscopy (SEM) showed the formation of the microspheres is spherical with the size around 300 μm. The release patterns depend on the composition of Gel/Cs microspheres, content of crosslinker and drug content in the microspheres. The cumulative drug release of 5-FU from the microspheres decreased with increasing GA content; however, the cumulative drug release increased with increasing Gel mass ratio and 5-FU content in the microspheres. The results of 5-FU release kinetics for Gel/Cs microspheres indicated Fickian diffusion.