Dafu Cao

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.

Fabrication and Physical Properties of Gelatin/Sodium Alginate/Hyaluronic Acid Composite Wound Dressing Hydrogel

Gelatin (Gel), sodium alginate (SA) and hyaluronic acid (HA) based various hydrogels for biomedical applications were prepared by freezing-drying method using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) as a crosslinker. The physical properties including morphology, water vapor transmission rate and hydrophilicity were investigated. The result showed the Gel/SA/HA composite hydrogels were successfully crosslinked by the crosslinking agent. All the Gel/SA/HA composite hydrogels with different compositions had highly homogeneous and interconnected pores, and the compositions had no significant effect on the surface and cross-section morphologies of the Gel/SA/HA hydrogels. The incorporation of sodium alginate enhanced the water vapor transmission capacity of the hydrogel; however, there were no significant differences between the water vapor transmission rates of all the Gel/SA/HA hydrogels. Gelatin had a low hydrophilic behavior, while sodium alginate exhibited relatively high hydrophilic behavior. The results indicate that the Gel/SA/HA hydrogel cross-linked via EDC is a potential wound dressing material capable of the adequate provision of moist environment for comfortable wound healing.

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.

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 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.

Influence of Nano-Bioactive Glass (NBG) Content on Properties of Gelatin-Hyaluronic Acid/NBG Composite Scaffolds

The development of three-dimensional (3-D) scaffolds with highly open porous structure is one of the most important issues in tissue engineering. A novel nanocomposite scaffold of gelatin (Gel), hyaluronic acid (HA), and nano-bioactive glass (NBG) was prepared by blending NBG with a Gel and HA solution followed by lyophilization. The effects of NBG content on the properties of the Gel-HA/NBG composite scaffolds, including the morphologies, porosity, compressive strength, swelling behavior, cell viability and alkaline phosphatase (ALP) activity, were investigated. Porous composite scaffolds with interconnected pores were obtained and the pores became cylindrical with increasing NBG content. The porosity percent and swelling ability decreased with increasing NBG content; however, the compressive strength, cell viability and ALP activity were enhanced. All the results showed the addition of NBG particles can improve the physicochemical and biological properties and the Gel-HA/NBG composite scaffolds exhibited good potential for tissue engineering applications.

Fabrication and Properties of Gelatin/Chitosan Microspheres Loaded with 5-Fluorouracil

The use of microspheres as drug delivery vehicles for anticancer therapeutics has great potential to revolutionize the future of cancer therapy. The present paper describes the influence of process variables on the encapsulation and loading efficiency of 5-Fluorouracil (5-FU) in gelatin/chitosan (Gel/Cs) microspheres. The influences of preparation parameters, including the contents of the emulsifier Span-80, the cross-linking agent and 5-FU, and the stirring speed, on drug loading and encapsulation efficiency of the microspheres were investigated. The experimental results indicated that drug loading and encapsulation efficiency of microspheres increased with increasing concentration of the cross-linking agent; and then decreased when the concentration of the cross-linking agent was higher than 0.3 ml·g−1 of Gel/Cs. Drug loading and encapsulation efficiency increased with increasing concentration of Span-80; they reached the maximum value when the concentration of the emulsifier was 0.012 g·ml−1. The loading and encapsulation efficiency of the microspheres also increased with increasing stirring speed. In addition, drug loading and encapsulation efficiency increased with increasing concentration of 5-FU; however, the encapsulation efficiency decreased when the concentration of 5-FU was higher than 40 mg·ml−1.

Evaluation of Biological Properties In-Vivo of Poly(L-Lactide-Coglycolide) Composites Containing Bioactive Glass

To evaluate the biological safety of composite materials based on poly(L-lactide-co-glycolide) (PLGA) and bioactive glass (BG), which have a potential application in tissue engineering, the in-vivo biological properties were investigated by applying the micronucleus test, acute systemic toxicity test, haemolytic test and pyrogen measurement. The results indicated that the PLGA/BG composite showed no genetic toxicity; there was no toxicosis or death observed in the acute systemic toxicity test. The haemolytic test suggested that the PLGA/BG composite, with a haemolytic index of 0.281%, did not have an obvious haemolytic reaction. In addition, the PLGA/BG composite materials showed no pyrogen reaction. Therefore, PLGA/BG composite materials could be promising candidate biomedical materials for bone tissue engineering.

Morphology and size control of gelatin/hyaluronic acid composite microsphere for drug delivery

Composite microspheres based on gelatin (Gel) and hyaluronic acid (HA) were prepared by an emulsion–coagulation method with glutaraldehyde as a crosslinker. The influences of stirring speed, crosslinker concentration, HA content and water/oil ratio on the particle size and surface morphology were investigated. The Fourier transform infrared spectra characterisation indicated that Gel and HA were crosslinked successfully by the glutaraldehyde. The in vitro release behaviours of 5-fluorouracil (5-FU) from Gel/HA microspheres were also studied. The results showed that the adhesion and agglomeration phenomena were apparent when the HA content reached 10.0 wt-%. The particle diameter of the microspheres decreased greatly with increasing stirring speed; however, the adhesion of smaller microspheres could be observed when the stirring speed reached 800 rev min− 1. The effect of crosslinker concentration on the particle size was not significant, but the dispersion degree of the Gel/HA microspheres decreased with decreasing crosslinker content. The particle size of the microspheres gradually became uniform with the increase of the water/oil ratios. The dispersion and surface smoothness level could be improved by optimising the experimental conditions. The cumulative drug release of 5-FU from the microspheres decreased with increasing glutaraldehyde content. The results of 5-FU release kinetics from Gel/HA microspheres indicated Fickian diffusion.