A nanocomposite hydrogel has potentially applicability in the induction of osteogenesis. The hydrogel was synthesized using 1% gelatin methacrylate (GelMA), a biodegradable and bioactive polymer containing the structure of gelatin, denatured collagen derived from the extracellular bone matrix, and 6% laponite (Lap), a synthetic phyllosilicate of nanosized particles. Initially, 0.6 g of Lap was added to deionized water, and then a solution of GelMA/Igarcure was added under stirring and UV light for crosslinking. The spectra in the Fourier-transform infrared region showed bands that indicate the interaction between gelatin and methacrylate anhydride. X-ray diffraction patterns confirmed the presence of Lap and GelMA in the hydrogel. The thermogravimetric analysis suggested an increase in the thermal stability of the hydrogel with the presence of clay mineral. Rheological analysis showed that the hydrogel had a viscosity that allowed its injectability. The hydrogel did not show acute toxicity at any of the concentrations tested according to the Artemia salina lethality test. It showed cell viability more significant than 80% in the MTT test, which makes it suitable for in vivo osteogenic induction tests. The cell differentiation test showed the differentiation of stem cells into osteogenic cells. It indicates a material with the potential for osteogenic induction and possible application in bone tissue engineering.

In situ 3D printing is attractive for the direct repair of bone defects in underdeveloped countries and in emergency situations. So far, the lack of an interesting method to produce filament using FDA-approved biopolymers and nanoceramics combined with a portable strategy limits the use of in situ 3D printing. Herein, we investigated the osseointegration of new nanocomposite filaments based on polylactic acid (PLA), laponite (Lap), and hydroxyapatite (Hap) printed directly at the site of the bone defect in rats using a portable 3D printer. The filaments were produced using a single-screw extruder (L/D = 26), without the addition of solvents that can promote the toxicity of the materials. In vitro performance was evaluated in the cell differentiation process with mesenchymal stem cells (MSC) by an alkaline phosphatase activity test and visualization of mineralization nodules; a cell viability test and total protein dosage were performed to evaluate cytotoxicity. For the in vivo analysis, the PLA/Lap composite filaments with a diameter of 1.75 mm were printed directly into bone defects of Wistar rats using a commercially available portable 3D printer. Based on the in vitro and in vivo results, the in situ 3D printing technique followed by rapid cooling proved to be promising for bone tissue engineering. The absence of fibrous encapsulation and inflammatory processes became a good indicator of effectiveness in terms of biocompatibility parameters and bone tissue formation, and the use of the portable 3D printer showed a significant advantage in the application of this material by in situ printing.

This study addresses the challenges of osteochondral tissue engineering by developing a hybrid scaffold with intercalated layers of poly(ε-caprolactone) (PCL) in combination with different concentrations of nanosized synthetic smectic clay (Lap) and a hydrogel of chitosan, collagen and demineralized bone powder (DBP). The scaffold design specifically targets the critical junction between subchondral bone and calcified cartilage and utilizes the mechanical strength of PCL/Lap nanocomposites and the bioactivity of the chitosan/collagen/DBP hydrogel to support tissue regeneration. The PCL/Lap nanocomposite, characterized by increased hydrophilicity, improved swelling behavior, and enhanced stiffness, provides a robust scaffold, while the hydrogel layers improve bioactivity and fluid retention. Three-dimensional printing technology was used to fabricate multi-layer scaffold, ensuring interfacial cohesion between the layers. Rheological, morphological, chemical, and mechanical characterizations confirmed the successful integration of the materials and the mechanical suitability for the subchondral environment. Biocompatibility assays demonstrated the non-hemolytic nature of the scaffolds and a favorable trend in cell viability with increasing Lap content. This study presents a novel scaffold design that effectively combines mechanical stability and biological functionality. It fulfills the complex requirements of osteochondral repair and offers a promising platform for future tissue engineering strategies.