Visible light-based 3D bioprinted composite scaffolds of κ-carrageenan for bone tissue engineering applications.

Three-dimensional (3D) printing of bone scaffolds using digital light processing (DLP) bioprinting technology empowers the treatment of patients suffering from bone disorders and defects through the fabrication of cell-laden patient-specific scaffolds. Here, we demonstrate the visible-light-induced photo-crosslinking of methacrylate-κ-carrageenan (MA-κ-CA) mixed with bioactive silica nanoparticles (BSNPs) to fabricate 3D composite hydrogels using digital light processing (DLP) printing. The 3D printing of complex bone structures, such as the gyroid, was demonstrated with high precision and resolution. DLP-printed 3D composite hydrogels of MA-κ-CA-BSNP were prepared and systematically assessed for their macroporous structure, swelling, and degradation characteristics. The viscosity, rheological, and mechanical properties were also investigated for the influence of nanoparticle incorporation in the MA-κ-CA hydrogels. The in vitro study performed with MC3T3-E1 pre-osteoblast-laden scaffolds of MA-κ-CA-BSNP revealed high cell viability, no cytotoxicity, and proliferation over 21 days with markedly enhanced osteogenic differentiation compared to neat polymeric scaffolds. Furthermore, no inflammation was observed in the 21-day study involving the in vivo examination of DLP-printed 3D composite scaffolds in a Wistar rat model. Overall, the observed results for the DLP-printed 3D composite scaffolds of MA-κ-CA and BSNP demonstrate their biocompatibility and suitability for bone tissue engineering.

Injectable Adhesive Hydrogels for Soft tissue Reconstruction: A Materials Chemistry Perspective.

Injectable bioadhesives offer several advantages over conventional staples and sutures in surgery to seal and close incisions or wounds. Despite the growing research in recent years few injectable bioadhesives are available for clinical use. This review summarizes the key chemical features that enable the development and improvements in the use of polymeric injectable hydrogels as bioadhesives or sealants, their design requirements, the gelation mechanism, synthesis routes, and the role of adhesion mechanisms and strategies in different biomedical applications. It is envisaged that developing a deep understanding of the underlying materials chemistry principles will enable researchers to effectively translate bioadhesive technologies into clinically-relevant products.

Injectable and self-healing double network polysaccharide hydrogel as a minimally-invasive delivery platform.

Injectable hydrogels exhibiting self-healing ability are promising carriers for controlled and sustained delivery in a minimally-invasive format for biomedical applications. We designed a polysaccharide-based double network hydrogel by mixing solutions of aldehyde-alginate (aAlg) and acrylic acid-chitosan (aCS) in the presence of adipic acid dihydrazide and FeCl2 that resulted in dual crosslinking mediated by Schiff base and ionic interactions. The hydrogel exhibited excellent thixotropic and self-healing properties with a high compressive fracture strength of ≈ 48 kPa. Encapsulated cells were viable within the hydrogel, and after their release from the degraded gel. The controlled release of Doxorubicin and Ciprofloxacin from the hydrogels established the gel as a delivery platform. The released drugs were effective in killing cancer cells or arresting the growth of both bacteria. This work presents a self-healing and injectable degradable hydrogel that may be used as a minimally-invasive platform for the delivery of drugs and cells.

Digital light processing-based 3D bioprinting of κ-carrageenan hydrogels for engineering cell-loaded tissue scaffolds.

The demand to regenerate biological tissues and organs in patients as an alternative to transplants has motivated the tissue engineering field. Digital light processing (DLP)-based three-dimensional (3D) bioprinting technology enables the rapid fabrication of complex 3D cell-laden scaffolds for tissue engineering applications. Herein, we demonstrate the outstanding printability of photocurable methacrylate-κ-carrageenan (MA-κ-CA) using DLP 3D printing. 3D printed hydrogels with varying concentrations (1-5% w/v) of MA-κ-CA were thoroughly characterized for their swelling, degradation, mechanical, and rheological properties, and suitability for bioprinting with living cells. Viscosity and shear thinning behavior of MA-κ-CA faithfully recapitulate the biomechanical properties of soft human tissues. Encapsulated NIH-3T3 cells show high viability and good proliferation over several days. Furthermore, highly complex 3D hydrogel scaffolds of MA-κ-CA were printed to recapitulate the biological complexity of tissues and organs. This work presents a polysaccharide bioink for preparing tissue scaffolds by DLP 3D bioprinting.

Light-based 3D bioprinting of bone tissue scaffolds with tunable mechanical properties and architecture from photocurable silk fibroin.

Three-dimensional (3D) bioprinting based on digital light processing (DLP) offers unique opportunities to prepare scaffolds that mimic the architecture and biomechanical properties of human tissues. Limited availability of biocompatible and biodegradable bioinks amenable for DLP-bioprinting is an impediment in this field. This study presents a bioink prepared from silk fibroin (SF) tailored for DLP bioprinting. Photocurable methacrylated-SF (SF-MA) was synthesized with 67.3% of methacrylation. Physical characterization of rheological and mechanical properties revealed that the 3D printed hydrogels of SF-MA (spanning from 10 to 25 wt%) exhibit bone tissue-like viscoelastic behavior and compressive modulus ranging from ≈12 kPa to ≈96 kPa. The gels exhibited favorable degradation (≈48 to 91% in 21 days). This SF-MA bioink afforded the printing of complex structures, with high precision. Pre-osteoblasts were successfully encapsulated in 3D bioprinted SF-MA hydrogels with high viability. 15% SF-MA DLP bioprinted hydrogels efficiently supported cell proliferation with favorable cell morphology and cytoskeletal organization. A progressive increase in cell-mediated calcium deposition up to 14 days confirmed the ability of the gels to drive osteogenesis, which was further augmented by soluble induction factors. This work demonstrates the potential of silk fibroin-derived bioinks for DLP-based 3D bioprinting of scaffolds for tissue engineering.