Collagen was obtained from porcine skin by mechanical pretreatments with the aim of preserving the triple helix structure of native collagen, which was indirectly corroborated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) results. Moreover, aloe vera (AV), with inherent biological properties, was incorporated into collagen film formulations, and films were prepared by compression and characterized to assess their suitability for biomedical applications. SEM images showed that the fibrillar structure of collagen changed to a rougher structure with the addition of AV, in accordance with the decrease in the lateral packaging of collagen chains observed by XRD analysis. These results suggested interactions between collagen and AV, as observed by FTIR. Considering that AV content higher than 20 wt % did not promote further interactions, this formulation was employed for biological assays and the suitability of AV/collagen films developed for biomedical applications was confirmed.

Native collagen scaffolds were prepared in this work, in which both materials and environmental approaches were considered with the aim of providing a global strategy towards more sustainable biomaterials. From the environmental perspective, it is worth mentioning that acid and enzymatic treatments have been avoided to extract collagen, allowing the reduction in the use of resources, in terms of chemicals, energy, and time, and leading to a low environmental load of this step in all the impact categories under analysis. With the incorporation of chitosan into the scaffold-forming formulations, physical interactions occurred between collagen and chitosan, but the native collagen structure was preserved, as observed by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses. The incorporation of chitosan also led to more homogenous porous microstructures, with higher elastic moduli and compression resistance for both dry and hydrated scaffolds. Furthermore, hydrated scaffolds preserved their size and shape after some compression cycles.

This work reports on the development of collagen films with graphene oxide nanoparticles (GO NPs), aiming toward the development of a new generation of functional sustainable sensors. For this purpose, different GO NP contents up to 3 wt % were incorporated into a collagen matrix, and morphological, thermal, mechanical and electrical properties were evaluated. Independently of the GO NP content, all films display an increase in thermal stability as a result of the increase in the structural order of collagen, as revealed by XRD analysis. Further, the inclusion of GO NPs into collagen promotes an increase in the intensity of oxygen characteristic absorption bands in FTIR spectra, due to the abundant oxygen-containing functional groups, which lead to an increase in the hydrophilic character of the surface. GO NPs also influence the mechanical properties of the composites, increasing the tensile strength from 33.2 ± 2.4 MPa (collagen) to 44.1 ± 1.0 MPa (collagen with 3 wt % GO NPs). Finally, the electrical conductivity also increases slightly with GO NP content, allowing the development of resistive bending sensors.

Native collagen doughs were processed using a syringe-based extrusion 3D printer to obtain collagen scaffolds. Before processing, the rheological properties of the doughs were analyzed to determine the optimal 3D printing conditions. Samples showed a high shear-thinning behavior, reported beneficial in the 3D printing process. In addition, tetrahydrocurcumin (THC) was incorporated into the dough formulation and its effect on collagen structure, as well as the resulting scaffold’s suitability for wound healing applications, were assessed. The denaturation peak observed by differential scanning calorimetry (DSC), along with the images of the scaffolds’ surfaces assessed using scanning electron microscopy (SEM), showed that the fibrillar structure of collagen was maintained. These outcomes were correlated with X-ray diffraction (XRD) results, which showed an increase of the lateral packaging of collagen chains was observed in the samples with a THC content up to 4%, while a higher content of THC considerably decreased the structural order of collagen. Furthermore, physical interactions between collagen and THC molecules were observed using Fourier transform infrared (FTIR) spectroscopy. Additionally, all samples showed swelling and a controlled release of THC. These results along with the mucoadhesive properties of collagen suggested the potential of these THC–collagen scaffolds as sustained THC delivery systems.

The development of inks with suitable rheological, physicochemical, mechanical, and biological properties is crucial for the successful fabrication of functional scaffolds via extrusion-based 3D printing. In this study, collagen/chitosan hydrogels with varying polymer ratios were developed and characterized to evaluate their printability and suitability for cartilage tissue engineering. Rheological analyses revealed that all samples exhibited shear-thinning behavior and solid-like viscoelasticity, with the formulation of an 80:20 COL/CHI ratio (20CHI) demonstrating optimal filament formation and dimensional stability. Physicochemical analyses confirmed the preservation of the collagen triple helix and the formation of hydrogen bonding between chitosan and collagen. 20CHI scaffolds showed swelling capacity and high cohesiveness. In vitro studies confirmed the cytocompatibility of the scaffolds with murine fibroblasts and the ability of the scaffolds to promote adhesion, proliferation, and extracellular matrix production of both chondrocytes and adipogenic mesenchymal stem cells (aMSCs). Quantification of sulfated glycosaminoglycan (sGAG) indicated sustained matrix deposition over 28 days, particularly by chondrocytes. These findings demonstrate that 20CHI hydrogel is a promising candidate for 3D printing of biomimetic scaffolds for cartilage regeneration.