3D-printed cellulose nanocrystals and gelatin scaffolds with bioactive cues for regenerative medicine: Advancing biomedical applications.

3D printed scaffolds have revolutionized the field of regenerative medicine by overcoming the lacunas such as precision, customization, and reproducibility observed through traditional methods of scaffold preparation such as freeze-drying, electrospinning, etc. Combining the advantages of 3D printed scaffolds along with bioactive cues such as signaling molecules can be an effective treatment approach. In the present study, cellulose nanocrystals (CNCs) along with gelatin, in different ratios, were used for scaffold preparation through the direct ink writing technique and thoroughly characterized. The scaffolds showed porous microstructure, high swelling ratio (∼390 to 590), degradability and porosity (∼65 %). In vitro biocompatibility assays showed high biocompatibility and no toxicity through live-dead, proliferation and hemolysis assay. Further, the optimum formulation was functionalized with nitric oxide (NO)-releasing modified gelatin to enhance the scaffold's biomedical applicability. Functionality assays with this formulation, scratch, and neurite outgrowth showed positive effects of NO on cell migration and neurite length. The study presents the fabrication, modification, and biomedical applicability of the aforementioned inks, which paves new pathways in the field of 3D printing of scaffolds with significant potential for biomedical applications, soft tissue engineering, and wound dressing, for example.

Surface-Modified Diopside-Reinforced PCL Biopolymer Composites with Enhanced Interfacial Strength and Mechanical Properties for Orthopedic Applications.

The phase separation of ceramics in a biopolymer matrix makes it challenging to achieve satisfactory mechanical properties required for orthopedic applications. It has been found that silane coupling agents can modify the surface of the bioceramic phase by forming a molecular bridge between the polymer and the ceramic, resulting in improved interfacial strength and adhesion. Therefore, in the present study, silane-modified diopside (DI) ceramic and ε-polycaprolactone (PCL) biopolymer composites were fabricated by injection molding method. The silane modification of DI resulted in their uniform dispersion in the PCL matrix, whereas agglomeration was found in composites containing unmodified DI. The thermal stability of the silane-modified DI-containing composites also increased. The Young's modulus of the composite containing 50% w/w DI modified by 3% w/w silane increased by 103% compared to composites containing 50% w/w unmodified DI. The biodegradation of the unmodified composites was significantly high, indicating their weak interfacial strength with the PCL matrix (p ≤ 0.001). The osteoconductive behavior of the composites was also validated by in vitro cell-material studies. Overall, our findings supported that the silane-modified composites have improved surface roughness, mechanical, and osteoconductive properties compared to the unmodified composite and have the potential for orthopedic applications.

Strontium-Substituted Nanohydroxyapatite-Incorporated Poly(lactic acid) Composites for Orthopedic Applications: Bioactive, Machinable, and High-Strength Properties.

Traditional metal-alloy bone fixation devices provide structural support for bone repair but have limitations in actively promoting bone healing and often require additional surgeries for implant removal. In this study, we focused on addressing these challenges by fabricating biodegradable composites using poly(lactic acid) (PLA) and strontium-substituted nanohydroxyapatite (SrHAP) via melt compounding and injection molding. Various percentages of SrHAP (5, 10, 20, and 30% w/w) were incorporated into the PLA matrix. We systematically investigated the structural, morphological, thermal, mechanical, rheological, and dynamic mechanical properties of the prepared composites. Notably, the tensile modulus, a critical parameter for orthopedic implants, significantly improved from 2.77 GPa in pristine PLA to 3.73 GPa in the composite containing 10% w/w SrHAP. The incorporation of SrHAP (10% w/w) into the PLA matrix led to an increased storage modulus, indicating a uniform dispersion of SrHAP within the PLA and good compatibility between the polymer and nanoparticles. Moreover, we successfully fabricated screws using PLA composites with 10% (w/w) SrHAP, demonstrating their formability at room temperature and radiopacity when observed under X-ray microtomography (micro-CT). Furthermore, the water contact angle decreased from 93 ± 2° for pristine PLA to 75 ± 3° for the composite containing SrHAP, indicating better surface wettability. To assess the biological behavior of the composites, we conducted in vitro cell-material tests, which confirmed their osteoconductive and osteoinductive properties. These findings highlight the potential of our developed PLA/SrHAP10 (10% w/w) composites as machinable implant materials for orthopedic applications. In conclusion, our study presents the fabrication and comprehensive characterization of biodegradable composites comprising PLA and strontium-substituted nanohydroxyapatite (SrHAP). These composites exhibit improved mechanical properties, formability, and radiopacity while also demonstrating desirable biological behavior. Our results suggest that these PLA/SrHAP10 composites hold promise as machinable implant materials for orthopedic applications.

Synthesis and characterization of sintered beta-tricalcium phosphate: A comparative study on the effect of preparation route.

Beta-tricalcium phosphate (ß-TCP) was prepared by three different routes namely, wet chemical coprecipitation, sol-gel and solution combustion synthesis. The synthesized powders were calcined at different temperatures and characterized for phase evolution study, thermal analysis, Fourier transform infrared (FTIR) spectroscopy, microstructural study for comparative analysis. The optimal thermal treatment required to prepare pure ß-TCP powders was determined and after calcination of the synthesize powders prepared by different routes, pure ß-TCP was obtained. The sintering temperature required to prepare fully dense ß-TCP completely free from α-form was identified. The powders were then used to make dense and compact bodies sintered at 1200 and 1250°C. The sintering behaviour of the dense bodies was analysed using dilatometry, densification and microstructural study. It was found that the pellet prepared from powder synthesized via co-precipitation route attained maximum density compared to the pellets prepared from powders synthesized via sol-gel and solution combustion route.