Hyaluronan biofilms reinforced with partially deacetylated chitin nanowhiskers: Extraction, fabrication, in-vitro and antibacterial properties of advanced nanocomposites.

Fabrication of nanocomposite biofilms with enhanced mechanical and antibacterial properties was successfully achieved from hyaluronan (HA) and partially deacetylated chitin nanowhiskers (ChNWs) by a casting-evaporation method. The hydrolysis process of chitin showed an important role in the dimensions, stability, and the crystallinity of extracted ChNWs in a time-dependent manner. The volume fraction of ChNWs nanofiller varying from (0.001 to 0.5) exhibited a great influence on the mechanical properties of the biofilms (young modulus, strength) was enhanced by the high load-bearing capacity of NWs compared with net HA film. The antibacterial activity of the nanocomposite biofilms exhibited significant bactericidal activity against different types of bacteria (-/+ gram). HA/ChNWs Nanocomposite biofilms did not show any toxicity against normal human dermal fibroblasts (NHDF) and human primary osteogenic sarcoma (Saos-2) cell lines. The new biofilms with unique properties like edibleness, environmental friendliness, high mechanical properties, antibacterial performance, and non-cytotoxicity that could be used in skin tissue regenerations, and drug delivery applications.

Electrospinning of hyaluronan/polyvinyl alcohol in presence of in-situ silver nanoparticles: Preparation and characterization.

Novel nanofibers mats were fabricated by electrospinning of polyvinyl alcohol/hyaluronan (PVA/HA) solutions in the presence of silver nanoparticles (AgNPs). The AgNPs were synthesized by in-situ chemical reduction of silver ions (Ag+) using HA as a reducing and stabilizing agent. Narrow size distribution and spherical shape of AgNPs were achieved by optimizing the initial silver nitrate concentration (0.01 to 1 M) and reaction time (10-60 min). HA-AgNPs nanocomposite and PVA/HA-AgNPs nanofibrous mats were fabricated by electrospinning technique from aqueous solution containing a different mass ratio of PVA and HA-AgNPs and characterized by UV/Vis spectroscopy, SEM, TEM, DLS, XRD, TGA, and ATR-FTIR. Mechanical and rheological properties were also investigated and discussed. The novel nanofibrous mats show great potential in skin regeneration and drug carrier applications.

The 3D imaging of mesenchymal stem cells on porous scaffolds using high-contrasted x-ray computed nanotomography.

This study presents an X-ray computed nanotomography (nano-CT) based, high-resolution imaging technique. Thanks to a voxel resolution of 540 nm, this novel technique is suitable for observing the 3D morphology of soft biopolymeric scaffolds seeded with stem cells. A sample of highly porous collagen scaffold seeded with contrasted mesenchymal stem cells (MSC) was investigated by using lab-based nano-CT. The whole volume of the sample was analysed without its destruction. To evaluate the potential of nano-CT, a comparison measurement was done using a standard microscopy technique. Scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX) established an extension and local accumulation of the contrasting agent - heavy metallic osmium tetroxide. The presented imaging technique is novel as it will help to understand better the behaviour of cells while interacting with three-dimensional biomaterials. This is crucial for both experimental and clinical tissue engineering applications in order to limit the risk of uncontrolled cell growth, and potentially tumour formation. LAY DESCRIPTION: Biomaterials play a crucial role in tissue engineering by serving as 3D scaffolds for cellular attachment, proliferation, and in growth ultimately leading to new tissue formation. Cell morphology and proliferation inside the 3D scaffold are necessary to know for assessing cell viability. However, these studies are usually negatively affected by the limitations of imaging techniques. We demonstrate that X-ray computed nanotomography (nano-CT), based on high-resolution imaging technique providing voxel resolution of 540 nm, is a suitable method for observing the 3D morphology of soft biopolymeric scaffolds seeded with stem cells. A sample of highly porous collagen scaffold seeded with contrasted mesenchymal stem cells (MSC) was investigated by using a lab-based nano-CT. The whole volume of the sample was analysed without its destruction. To evaluate the potential of nano-CT, a comparison measurement was done using a standard microscopy technique. Scanning electron microscopy in a combination with energy dispersive X-ray analysis established an extension and local accumulation of the contrasting agent - heavy metallic osmium tetroxide. The presented imaging technique is novel as it will help to understand better the behaviour of cells while interacting with three-dimensional biomaterials. This is crucial for both experimental and clinical tissue engineering applications in order to limit the risk of uncontrolled cell growth, and potentially tumour formation.

Wound dressing based on chitosan/hyaluronan/nonwoven fabrics: Preparation, characterization and medical applications.

Thin layers of chitosan (positively charged)/sodium hyaluronate (negatively charged)/nonwoven fabrics were constructed by polyelectrolyte multilayer pad-dry-cure technique. Pure chitosan (CS) was isolated from shrimp shell and immobilized onto nonwoven fabrics (NWFs) using citric acid (CTA) as cross linker and solvent agents through a pad-dry-cure method. The prepared thin layer of chitosan citrate/nonwoven fabrics (CSCTA/NWFs) were consequently impregnated with hyaluronan (CSCTA/HA/NWFs) in the second path through a pad-dry-cure method. Chitosan/hyaluronan/nonwoven fabrics wound dressing was characterized by different techniques such as FTIR-ATR, TGA and SEM. The antibacterial activity and the cytotoxicity of the dressing sheets were evaluated against Escherichia coli (E. coli) and Streptococcus aureus (S. aureus), mouse fibroblast (NIH-3T3) and keratinocytes (HaCaT) cell lines, respectively. The cell-fabrics interaction was also investigated using fluorescence microscope, based on live/dead staining assay of 3T3 cells. The healing properties of the new wound dressing were evaluated and compared with the control sample.