Mechanical properties andin vitrobehavior of nanofiber–hydrogel composites for tissue engineering applications

Abstract

Hydrogel-based biomaterial systems have great potential for tissue reconstruction by serving as temporary scaffolds and cell delivery vehicles for tissue engineering (TE). Hydrogels have poor mechanical properties and their rapid degradation limits the development and application of hydrogels in TE. In this study, nanofiber reinforced composite hydrogels were fabricated by incorporating electrospun poly(ε-caprolactone) (PCL)/gelatin 'blend' or 'coaxial' nanofibers into gelatin hydrogels. The morphological, mechanical, swelling and biodegradation properties of the nanocomposite hydrogels were evaluated and the results indicated that the moduli and compressive strengths of the nanofiber reinforced hydrogels were remarkably higher than those of pure gelatin hydrogels. By increasing the amount of incorporated nanofibers into the hydrogel, the Young's modulus of the composite hydrogels increased from 3.29 ± 1.02 kPa to 20.30 ± 1.79 kPa, while the strain at break decreased from 66.0 ± 1.1% to 52.0 ± 3.0%. Compared to composite hydrogels with coaxial nanofibers, those with blend nanofibers showed higher compressive strength and strain at break, but with lower modulus and energy dissipation properties. Biocompatibility evaluations of the nanofiber reinforced hydrogels were carried out using bone marrow mesenchymal stem cells (BM-MSCs) by cell proliferation assay and immunostaining analysis. The nanocomposite hydrogel with 25 mg ml(-1) PCL/gelatin 'blend' nanofibers (PGB25) was found to enhance cell proliferation, indicating that the 'nanocomposite hydrogels' might provide the necessary mechanical support and could be promising cell delivery systems for tissue regeneration.

Introduction to cell–hydrogel mechanosensing

“…Cells may be influenced by these materials either through contact or ingestion. The incorporation of electrospun nanofibres into hydrogels should increase the bulk elastic modulus and strength of these hydrogels [160,161] and can be used to dictate cell orientation and matrix production [160,162]. Nanofibres can be spun into aligned sheets that are then encapsulated by the cell-seeded hydrogels forming a nanofibre-cell-hydrogel composite.…”

Protein-based injectable hydrogels towards the regeneration of articular cartilage

“…However, significant reinforcement of the injectable gelatin was obtained when the electrospinning milled fibers were used to fabricate the composites (Figure 3-4b), as is noticeable by the change in the slope, which becomes higher with the increasing fiber content. A similar enhancement of the mechanical properties has been reported by other authors in systems that combine hydrogels and fibers [147], [150], [179]- [182], although the novel side to our system is the use of short fibers capable of being dispersed in an injectable hydrogel solution. The agglomeration of the high turbulent obtained fibers in the injectable gelatin solution prior to crosslinking may be causing the null reinforcement found here.…”

Rotary jet spinning review – a potential high yield future for polymer nanofibers

“…121 However, it has been shown that such fibers can be effective as reinforcements for biomedical engineering purposes when combined with hydrogels. 124 . Manufacturing fibers in the nano scale is of great interest for composites, as these fibers have a high aspect ratio and large available fiber surface area, potentially leading to high in the design of tissue engineering scaffolds is to mimic the natural interfaces that interact selectively with a specific cell type through biomolecular recognition.…”