Abstract
Dual adhesiveness to tissue and implant biomaterials and bioactivity to stimulate tissue regeneration are interesting properties for developing new generations of tissue-repairing hydrogels with potential new clinical applications. In this study, we developed a unique bioglass (BG)/oxidized sodium alginate (OSA) composite hydrogel with adipic acid dihydrazide (ADH)-modified γ-polyglutamic acid (γ-PGA) as the cross-linking agent, in which the BG plays a multifunctional role to endow the hydrogel with both dual-adhesive and bioactive properties. On one hand, the BG could improve the tissue-bonding strength by providing an alkaline microenvironment to stimulate the bond formation between OSA and the amino groups on the surrounding tissues. On the other hand, BG endows the hydrogel with adhesiveness to implantable materials by releasing Ca ions, which might chelate with the carboxyl groups of the hydrogel matrix. In addition, the composite hydrogel showed excellent bioactivity to promote vascularization and accelerate tissue regeneration. This study demonstrates that a multifunctional hydrogel can be designed by utilizing the multifunctional ions released from silicate BG, and the BG/OSA hydrogel shows good potential as an adhesive and bioactive material for wound-healing applications.
Highlights
Hydrogels are polymeric materials with threedimensional cross-linked networks that could act as a barrier to prevent bacterial infection and create a suitable microenvironment for tissue regeneration[1,2,3]
Preparation of the BG/oxidized sodium alginate (OSA) hydrogels As shown in Fig. 1a, the homogeneous composite hydrogels were obtained with different amounts of BG
Considering that the regulation of adhesiveness of hydrogels to materials might be regulated by the chelation between Ca ions and the carboxyl groups of the polymer chains of the hydrogels, we further explored the possible mechanisms by comparing the adhesiveness of the BG/OSA hydrogel with the CA/OSA composite hydrogel, sodium carbonate/OSA composite hydrogel, and the hydrogel prepared with CaCl2/OSA, which showed similar adhesiveness to the pure OSA hydrogel (Supplementary Fig. S2)
Summary
Hydrogels are polymeric materials with threedimensional cross-linked networks that could act as a barrier to prevent bacterial infection and create a suitable microenvironment for tissue regeneration[1,2,3]. Hydrogels with high adhesiveness to tissues may bind tissues together and prevent the scar tissue formation that is induced by conventional sutures[4]. Because there are a large number of amino groups on the surface of tissues, an amide linkage is one of the most commonly used linkages between adhesive materials and tissue when the hydrogel contains aldehyde groups, which can link with the amino groups on the surrounding tissues[4,10]. It is known that the formation of amide and imine bonds between adhesive hydrogels and tissues requires an alkaline environment[11,12]. A weak alkaline environment is of great importance for the improvement of the adhesive strength of amide linkage-based adhesive hydrogels to tissues. The adhesion strength of the hydrogels to materials may be affected by some factors[5,15,16], and an improvement in the viscosity of the hydrogels may result in stronger adhesion to the materials[17]
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