Scaffolds derived from natural polysaccharides are very promising in tissue engineering applications and regenerative medicine, as they resemble glycosaminoglycans in the extracellular matrix (ECM). In this study, we have prepared freeze-dried composite scaffolds of chitosan (CHT) and hyaluronic acid (HA) in different weight ratios containing either no HA (control) or 1%, 5%, or 10% of HA. We hypothesized that HA could enhance structural and biological properties of CHT scaffolds. To test this hypothesis, physicochemical and biological properties of CHT/HA scaffolds were evaluated. Scanning electron microscopy micrographs, mechanical properties, swelling tests, enzymatic degradation, and Fourier transform infrared (FTIR) chemical maps were performed. To test the ability of the CHT/HA scaffolds to support chondrocyte adhesion and proliferation, live–dead and MTT assays were performed. Results showed that CHT/HA composite scaffolds are noncytotoxic and promote cell adhesion. ECM formation was further evaluated with safranin-O and alcian blue staining methods, and glycosaminoglycan and DNA quantifications were performed. The incorporation of HA enhanced cartilage ECM production. CHT/5HA had a better pore network configuration and exhibited enhanced ECM cartilage formation. On the basis of our results, we believe that CHT/HA composite matrixes have potential use in cartilage repair.

We propose a novel hanging spherical drop system for anchoring arrays of droplets of cell suspension based on the use of biomimetic superhydrophobic flat substrates, with controlled positional adhesion and minimum contact with a solid substrate. By facing down the platform, it was possible to generate independent spheroid bodies in a high throughput manner, in order to mimic in vivo tumour models on the lab-on-chip scale. To validate this system for drug screening purposes, the toxicity of the anti-cancer drug doxorubicin in cell spheroids was tested and compared to cells in 2D culture. The advantages presented by this platform, such as feasibility of the system and the ability to control the size uniformity of the spheroid, emphasize its potential to be used as a new low cost toolbox for high-throughput drug screening and in cell or tissue engineering.

Medical adhesives and sealants often require that long-term adhesiveness is achieved. In this work, nanostructured coatings consisting of chitosan and the adhesive bacterial exopolysaccharide levan are fabricated using layer-by-layer (LbL) assembly. Taking advantage of the electrostatic self-assembly mechanism of LbL, the charges of both chitosan and a phosphonate-derivatized levan (Ph-levan) are measured and the feasibility of constructing hybrid films is monitored and confirmed using a quartz crystal microbalance with dissipation monitoring (QCM-D). The adhesive properties between two identical bonded films with a total of 100 layers are compared to control films in which Ph-levan is replaced by alginate, revealing that the detachment force of the former is about 3 times higher than the control. Scanning electron microscopy of the films surface shows that the surface of Ph-levan films is smooth and homogeneous. Cell adhesion tests were conducted using a L929 cell line. Early cell adhesion is significantly higher in chitosan/Ph-levan films when compared to chitosan/alginate controls. These findings establish levan derivatives as bioinspired ingredients for conceiving medical adhesive devices that allow achieving enhanced mechanical and biological performance.