Fabrication and Evaluation of Alginate/Bacterial Cellulose Nanocrystals–Chitosan–Gelatin Composite Scaffolds

Abstract

It is common knowledge that pure alginate hydrogel is more likely to have weak mechanical strength, a lack of cell recognition sites, extensive swelling and uncontrolled degradation, and thus be unable to satisfy the demands of the ideal scaffold. To address these problems, we attempted to fabricate alginate/bacterial cellulose nanocrystals-chitosan-gelatin (Alg/BCNs-CS-GT) composite scaffolds using the combined method involving the incorporation of BCNs in the alginate matrix, internal gelation through the hydroxyapatite-d-glucono-δ-lactone (HAP-GDL) complex, and layer-by-layer (LBL) electrostatic assembly of polyelectrolytes. Meanwhile, the effect of various contents of BCNs on the scaffold morphology, porosity, mechanical properties, and swelling and degradation behavior was investigated. The experimental results showed that the fabricated Alg/BCNs-CS-GT composite scaffolds exhibited regular 3D morphologies and well-developed pore structures. With the increase in BCNs content, the pore size of Alg/BCNs-CS-GT composite scaffolds was gradually reduced from 200 μm to 70 μm. Furthermore, BCNs were fully embedded in the alginate matrix through the intermolecular hydrogen bond with alginate. Moreover, the addition of BCNs could effectively control the swelling and biodegradation of the Alg/BCNs-CS-GT composite scaffolds. Furthermore, the in vitro cytotoxicity studies indicated that the porous fiber network of BCNs could fully mimic the extracellular matrix structure, which promoted the adhesion and spreading of MG63 cells and MC3T3-E1 cells on the Alg/BCNs-CS-GT composite scaffolds. In addition, these cells could grow in the 3D-porous structure of composite scaffolds, which exhibited good proliferative viability. Based on the effect of BCNs on the cytocompatibility of composite scaffolds, the optimum BCNs content for the Alg/BCNs-CS-GT composite scaffolds was 0.2% (w/v). On the basis of good merits, such as regular 3D morphology, well-developed pore structure, controlled swelling and biodegradation behavior, and good cytocompatibility, the Alg/BCNs-CS-GT composite scaffolds may exhibit great potential as the ideal scaffold in the bone tissue engineering field.

Comparative Study of Physicochemical Properties of Alginate Composite Hydrogels Prepared by the Physical Blending and Electrostatic Assembly Methods

“…The homogeneous alginate composite hydrogels were fabricated via physical blending and alternating electrostatic assembly technology with the HAP/GDL complex as the endogenous cross-linking agent according to our previous method [ 29 , 30 ]. In the ion cross-linking of alginate, the cross-linking rate is the key factor to control the gel uniformity and strength.…”

“…Composite hydrogels prepared by electrostatic assembly and physical blending of biomacromolecules could significantly inhibit the swelling property of ALG Gel, enhancing its stability in saline solution. It was found that Alg-CS-GT had the best control of the swelling behavior, which was due to the formation of a dense polyelectrolyte complex during the electrostatic assembly process, which effectively restrained the swelling of composite hydrogels [ 30 ]. However, when the composite hydrogel was immersed in PBS for more than 12 h, ALG/GT-CS exhibited higher swelling due to the strong hydrophilicity of GT, which resulted in the continuous swelling of the material.…”

“…However, the OD value of alginate composite hydrogels was higher than that of the control because of their good 3D morphology and porous structure, which could provide space for the three-dimensional proliferation of cells [ 37 ]. The low proliferative activity of ALG Gel may be related to its lack of cell-specific binding sites [ 30 ]. However, during the preparation of ALG/GT-CS, GT was mechanically embedded in the alginate hydrogel, which resulted in lower proliferation activity of cells than Alg-GT and Alg-CS-GT.…”

Bacterial Polyglucuronic Acid/Alginate/Carbon Nanofibers Hydrogel Nanocomposite as a Potential Scaffold for Bone Tissue Engineering

“…Alg, like chitin and chitosan, is frequently employed for bone tissue engineering [ 16 ]; for example Alg hydrogels are employed as fillers and carriers of osteoinductive factors [ 17 , 18 ]. This is due to the fact that Alg has several desirable characteristics, including water solubility, biocompatibility, low toxicity, low cost, extended active agent release and moderate and quick hydrogelation when divalent cations, such as Ca 2+ , are added [ 18 , 19 , 20 , 21 ]. However, natural polymers such as Alg have limits due to mechanical qualities that are insufficient to be used in bone tissue engineering [ 17 , 18 , 20 , 21 ].…”

“…This is due to the fact that Alg has several desirable characteristics, including water solubility, biocompatibility, low toxicity, low cost, extended active agent release and moderate and quick hydrogelation when divalent cations, such as Ca 2+ , are added [ 18 , 19 , 20 , 21 ]. However, natural polymers such as Alg have limits due to mechanical qualities that are insufficient to be used in bone tissue engineering [ 17 , 18 , 20 , 21 ]. To address these issues, a variety of materials, such as nanomaterials, have been mixed into the alginate structure, resulting in strong composite materials [ 22 , 23 , 24 ].…”