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A novel biodegradable nano/micro hybrid structure was obtained by electrospinning P3HB or PCL nanofibers onto a twisted silk fibroin (SF) structure, with the aim of fabricating a suitable scaffold for tendon and ligament tissue engineering. The electrospinning (ES) processing parameters for P3HB and PCL were optimized on 2D samples, and applied to produce two different nano/micro hybrid constructs (SF/ES-PCL and SF/ES-P3HB).Morphological, chemico-physical and mechanical properties of the novel hybrid scaffolds were evaluated by SEM, ATR FT-IR, DSC, tensile and thermodynamic mechanical tests. The results demonstrated that the nanofibers were tightly wrapped around the silk filaments, and the crystallinity of the SF twisted yarns was not influenced by the presence of the electrospun polymers. The slightly higher mechanical properties of the hybrid constructs confirmed an increase of internal forces due to the interaction between nano and micro components. Cell culture tests with L929 fibroblasts, in the presence of the sample eluates or in direct contact with the hybrid structures, showed no cytotoxic effects and a good level of cytocompatibility of the nano/micro hybrid structures in term of cell viability, particularly at day 1. Cell viability onto the nano/micro hybrid structures decreased from the first to the third day of culture when compared with the control culture plastic, but appeared to be higher when compared with the uncoated SF yarns. Although additional in vitro and in vivo tests are needed, the original fabrication method here described appears promising for scaffolds suitable for tendon and ligament tissue engineering.

Shape memory polymers (SMPs) are an emerging class of active materials whose response can be easily tailored via modifications of the molecular parameters and optimization of the transformation processes. In this work, we originally demonstrated that a correct coupling of polymer transformation processes (co-extrusion with chemical blowing agents, salt co-extrusion/particulate leaching, solvent casting/particulate leaching) and SMPs allows one to obtain porous structures with a broad spectrum of morphological properties resulting in tunable thermo-mechanical and shape recovery properties. Such a wide range of properties could fulfil the specifications of medical applications in which the use of SMP-based foams can be envisaged.

The unique photothermal properties of non-spherical gold nanoparticles under near-infrared (NIR) irradiation find broad application in nanotechnology and nanomedicine. The combination of their plasmonic features with widely used biocompatible poly(vinyl alcohol) (PVA) films can lead to novel hybrid polymeric materials with tunable photothermal properties and a wide range of applications. In this study, thin PVA films containing highly photothermally efficient gold nanostars (GNSs) were fabricated and their properties were studied. The resulting films displayed good mechanical properties and a pronounced photothermal effect under NIR irradiation. The local photothermal effect triggered by NIR irradiation of the PVA-GNS films is highly efficient at killing bacteria, therefore providing an opportunity to develop new types of protective antibacterial films and coatings.

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A complete morphologic characterization of porous scaffolds for tissue engineering application is fundamental, as the architectural parameters, in particular porosity, strongly affect the mechanical and biological performance of the structures. Therefore, appropriate techniques for this purpose need to be selected. Several techniques for the assessment of scaffold porosity have been proposed, including Scanning Electron Microscopy observation, mercury and liquid extrusion porosimetry, gas pycnometry, and capillary flow porometry. Each of these techniques has several drawbacks and, a combination of different techniques is often required so as to achieve an in depth study of the morphologic properties of the scaffold. A single technique is often limited and suitable only for the assessment of a specific parameter. To overcome this limit, the most attractive option would be a single nondestructive technique, yet capable of providing a comprehensive set of data. It appears that micro-computed tomography (micro-CT) can potentially fulfill this role. Initially developed to characterize the 3D trabecular microarchitecture of bone, its use has been recently exploited by researchers for the morphologic characterization of porous biomaterials, as it enables obtaining a full assessment of the porous structures both in terms of pore size and interconnected porosity. This review aims to explore the use of micro-CT in scaffold characterization, comparing it with other previously developed techniques; we also focus on the contribution of this innovative tool to the development of scaffold-based tissue engineering application.