This review provides a report on recent advances in the field of chitosan (CTS) and silk fibroin (SF) biopolymer blends as new biomaterials. Chitosan and silk fibroin are widely used to obtain biomaterials. However, the materials based on the blends of these two biopolymers have not been summarized in a review paper yet. As these materials can attract both academic and industrial attention, we propose this review paper to showcase the latest achievements in this area. In this review, the latest literature regarding the preparation and properties of chitosan and silk fibroin and their blends has been reviewed.

In this work, the biological properties of three-dimensional scaffolds based on a blend of nanohydroxyapatite (nHA), silk fibroin (SF), and chitosan (CTS), were prepared using a lyophilization technique with various weight ratios: 10:45:45, 15:15:70, 15:70:15, 20:40:40, 40:30:30, and 70:15:15 nHA:SF:CTS, respectively. The basic 3D scaffolds were obtained from 5% (w/w) chitosan and 5% silk fibroin solutions and then nHA was added. The morphology and physicochemical properties of scaffolds were studied and compared. A biological test was performed to study the growth and osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs). It was found that the addition of chitosan increases the resistance properties and extends the degradation time of materials. In vitro studies with human mesenchymal stem cells found a high degree of biotolerance for the materials produced, especially for the 20:40:40 and 15:70:15 (nHa:SF:CTS) ratios. The presence of silk fibroin and the elongated shape of the pores positively influenced the differentiation of cells into osteogenic cells. By taking advantage of the differentiation/proliferation cues offered by individual components, the composites based on the nanohydroxyapatite, silk fibroin, and chitosan scaffold may be suitable for bone tissue engineering, and possibly offer an alternative to the widespread use of collagen materials.

Fibroin–chitosan composites, especially those containing nanohydroxyapatite, show potential for bone tissue regeneration. The physicochemical properties of these biocomposites depend on the compatibility between their components. In this study, the intermolecular interactions of fibroin and chitosan were analyzed using a molecular dynamics approach. Two types of systems were investigated: one containing acetic acid and the other containing calcium (Ca²⁺) and hydrogen phosphate (HPO₄²⁻) ions mimicking hydroxyapatite conditions. After obtaining the optimal equilibrium structures, the distributions of several types of interactions, including hydrogen bonds, ionic contacts, and hydrophobic contacts, along with structural and energetical features, were examined. The calculated binding energy values for the fibroin–chitosan complexes confirm their remarkable stability. The high affinity of fibroin for chitosan can be explained by the formation of a dense network of interactions between the considered biopolymers. These interactions were found to primarily be hydrogen bonds and ionic contacts involving ALA, ARG, ASN, ASP, GLN, GLU, GLY, LEU, PRO, SER, THR, TYR, and VAL residues. As established, the complexation of fibroin with chitosan maintains the β-sheet conformation of the peptide. β-Sheet fragments in fibroin are involved in the formation of a significant number of hydrogen bonds and ionic contacts with chitosan.

The present study compares two scaffold cross-linking strategies, EDC/NHS and pentasodium triphosphate (TPP), applied to nanohydroxyapatite/silk fibroin/chitosan (nHA/SF/CTS) scaffolds. The effects of the cross-linking strategy on scaffold morphology, ATR-FTIR profile, swelling, in vitro degradation, and compressive properties were evaluated. In addition, the biological response of selected 20:40:40 and 15:70:15 (w/w) scaffold variants was assessed using SaOS-2 cells. The IR spectra of TPP- and EDC/NHS-cross-linked materials were qualitatively similar, and no distinct bands attributable to residual EDC or NHS were observed after washing. SEM observations indicated that the TPP-cross-linked scaffolds tended to have smaller and more spherical pores, whereas the EDC/NHS-cross-linked materials showed a more elongated pore morphology. These qualitative morphological differences were accompanied by differences in swelling, degradation, and low-strain mechanical response. The 20:40:40 formulation cross-linked with EDC/NHS showed the most favorable low-strain response, whereas PBS swelling markedly reduced the early compressive response of all scaffolds. Biological assessment showed that the 20:40:40 scaffolds supported viable SaOS-2 populations and maintained osteogenic activity, although cell colonization remained lower than on the control surfaces. The 15:70:15 variant performed less favorably, particularly after TPP cross-linking. These findings indicate that both cross-linking strategies can be used to obtain nHA/SF/CTS scaffolds, but their effects depend strongly on scaffold composition and on the property being considered.

Fibroin-chitosan composites, especially those containing nanohydroxyapatite, show potential for bone tissue regeneration. The physicochemical properties of these biocomposites depend on the compatibility between their components. In this study, the intermolecular interactions of fibroin and chitosan were analyzed using a molecular dynamics approach. Two types of systems were investigated: one containing acetic acid and the other containing calcium (Ca²⁺) and hydrogen phosphate (HPO₄²⁻) ions mimicking hydroxyapatite conditions. After obtaining the optimal equilibrium structures, the distributions of several types of interactions including hydrogen bonds, ionic contacts, and hydrophobic contacts along with the structural and energetical features were examined. The calculated binding energy values for the fibroin-chitosan complexes confirm their remarkable stability. The high affinity of fibroin for chitosan can be explained by the formation of a dense network of interactions between considered biopolymers. These interactions were found to be primarily hydrogen bonds and ionic contacts involving ALA, ARG, ASN, ASP, GLN, GLU, GLY, LEU, PRO, SER, THR, TYR, and VAL residues. As it was established, the complexation of fibroin with chitosan maintains the β-sheet conformation of the peptide. β-Sheet fragments in fibroin are involved in the formation of significant amount of hydrogen bonds and ionic contacts with chitosan.