Fabrication and characterization of a toughened spherical chitosan adsorbent only through physical crosslinking based on mechanism of Chain Rearrangement

Crystallinity Reconstruction of Squid-Pen Chitosan into Mechanically Robust and Multifunctional Bionanocomposite Food Packaging Film

First, we explore the effect of bioacids on the film processing of preprocessed, i.e., deacetylated, chitosan (d-chitosan with molecular weight of 1,000,000 kDa), using monocarboxylic acid (acetic acid), dicarboxylic acid (malic acid), and tricarboxylic acid (citric acid) as model weak acidic solvents to destabilize the hydrogen bonding and transform crystal structures into film. Second, we investigate the chemical and physical toughening effect in the bionanocomposite film composed of cross-linkable multicarboxilic acid, i.e., succinic acid (SA). In doing so, the addition of glycerol as a plasticizer can increase polymer chain mobility, making the biocomposite film more ductile and flexible. The addition of CNC also enhances the tensile strength (41.6%), swelling (43.47%), and oxygen barrier properties (38.81%), as well as significantly improves UV light barrier. The excellent antibacterial properties (99.9% efficiency against S. aureus and K. pneumoniae) of the prepared biocomposite films are found to be independent of the presence of glycerol or CNC. Third, the development of film processability under an industrially relevant process is also demonstrated by doctor blade method. It is found that film processability of the squid-pen's chitosan bionanocomposite can straightforwardly be compatible with and improvable in the presence of poly(vinyl alcohol) employed as a model biodegradable processing aid.

The Emerging Use of ASC/Scaffold Composites for the Regeneration of Osteochondral Defects

Articular cartilage is composed of chondrocytes surrounded by a porous permeable extracellular matrix. It has a limited spontaneous healing capability post-injury which, if left untreated, can result in severe osteochondral disease. Currently, osteochondral (OC) defects are treated by bone marrow stimulation, artificial joint replacement, or transplantation of bone, cartilage, and periosteum, while autologous osteochondral transplantation is also an option; it carries the risk of donor site damage and is limited only to the treatment of small defects. Allografts may be used for larger defects; however, they have the potential to elicit an immune response. A possible alternative solution to treat osteochondral diseases involves the use of stromal/stem cells. Human adipose-derived stromal/stem cells (ASCs) can differentiate into cartilage and bone cells. The ASC can be combined with both natural and synthetic scaffolds to support cell delivery, growth, proliferation, migration, and differentiation. Combinations of both types of scaffolds along with ASCs and/or growth factors have shown promising results for the treatment of OC defects based on in vitro and in vivo experiments. Indeed, these findings have translated to several active clinical trials testing the use of ASC-scaffold composites on human subjects. The current review critically examines the literature describing ASC-scaffold composites as a potential alternative to conventional therapies for OC tissue regeneration.