An Injectable Composite Gelatin Hydrogel with pH Response Properties

Baoguo Chen,Xiaohong Hu

doi:10.1155/2017/5139609

Baoguo Chen, Xiaohong Hu

Open Access

https://doi.org/10.1155/2017/5139609

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Abstract

On account of minimally invasive procedure and of filling irregular defects of tissues, injectable hydrogels are increasingly attractive in biomedical fields. However, traditional hydrogel formed by simple physical interaction or in situ crosslinking had inevitably some drawbacks such as low mechanical strength and lack of multifunctional properties. Though many investigations had successfully modified traditional injectable hydrogel to obtain both mechanical and functional properties, an acetalated β-cyclodextrin (Ac-β-CD) nanoparticle composite injectable hydrogel designed in the research was another effective and efficient choice to solve the drawbacks. First of all, gelatin derivative (G-AA) and Ac-β-CD were synthesized to prepare hydrogel and nanoparticle, respectively. In order to ensure good compatibility between nanoparticle and macromonomer and provide crosslink points between nanoparticle and macromonomer, G-AA was simultaneously functionalized onto the surface of Ac-β-CD nanoparticle during the fabrication of Ac-β-CD nanoparticle using one-step method. Finally, injectable composite hydrogel was obtained by photoinitiated polymerization in situ. Hydrogel properties like gelation time and swelling ratio were investigated. The viscoelastic behavior of hydrogels confirmed that typical characteristics of crosslinked elastomer for all hydrogel and nanoparticle in hydrogel could improve the mechanical property of hydrogel. Moreover, the transparency with time had verified obvious acid-response properties of hydrogels.

Highlights

On account of minimally invasive procedure and of filling irregular defects of tissues, injectable hydrogels are increasingly attractive in biomedical fields [1, 2]
In the 1HNMR spectrum of gelatin derivative (G-acrylic acid (AA)) (Figure 1(a)), the chemical shifts from 0.6 ppm to 1.7 ppm belong to the protons of methyl residues and the chemical shifts from 2.5 ppm to 3.7 ppm are assigned to the protons of methylene residues, while δ = 5.6 (a) and δ = 5.4 (b) are typical chemical shifts belonging to the protons of H2C=C, which confirms the successful modification of gelatin by AA
The 1H NMR spectrum of Acetalated β-cyclodextrin (Ac-β-CD) (Figure 1(b)) is analyzed as follows: the chemical shifts at 3, 4, 5, and 6 positions are, respectively, attributed to the protons of pyranose ring, constructed units of β-CD, the chemical shifts from 1.0 ppm to 2.0 ppm belong to the protons of CH3-C at 1 and 1󸀠 positions, and δ = 3.0 ppm is assigned to the protons of CH3-O at 2 position

Summary

Introduction

On account of minimally invasive procedure and of filling irregular defects of tissues, injectable hydrogels are increasingly attractive in biomedical fields [1, 2]. Many natural macromolecules such as collagen, gelatin, chitosan, alginate, and hyaluronic acid (HA) are fabricated into the injectable hydrogels [5,6,7,8,9,10,11] Among these materials, gelatin is a hydrolysis product of collagen and contains bioactive sequences, which lead to its widespread applications in tissue engineering and drug delivery [5, 6, 8]. Gelatin is a hydrolysis product of collagen and contains bioactive sequences, which lead to its widespread applications in tissue engineering and drug delivery [5, 6, 8] Despite these merits, injectable gelatin cannot be formed by only interactions between molecules or simple crosslinking, which is a common drawback of natural polymers. An injectable composite gelatin hydrogel was obtained by compounding of the hydrogel with Ac-β-CD nanoparticles, aiming at providing pH response properties for hydrogel and improving the hydrogel mechanical strength

Experimental Section

Results

Conclusions