In situ synthesised TiO2-chitosan-chondroitin 4-sulphate nanocomposites for bone implant applications

Chitosan-TiO2: A Versatile Hybrid Composite

In recent years, a strong interest has emerged in hybrid composites and their potential uses, especially in chitosan–titanium dioxide (CS–TiO₂) composites, which have interesting technological properties and applications. This review describes the reported advantages and limitations of the functionalization of chitosan by adding TiO₂ nanoparticles. Their effects on structural, textural, thermal, optical, mechanical, and vapor barrier properties and their biodegradability are also discussed. Evidence shows that the incorporation of TiO₂ onto the CS matrix improves all the above properties in a dose-dependent manner. Nonetheless, the CS–TiO₂ composite exhibits great potential applications including antimicrobial activity against bacteria and fungi; UV-barrier properties when it is used for packaging and textile purposes; environmental applications for removal of heavy metal ions and degradation of diverse water pollutants; biomedical applications as a wound-healing material, drug delivery system, or by the development of biosensors. Furthermore, no cytotoxic effects of CS–TiO₂ have been reported on different cell lines, which supports their use for food and biomedical applications. Moreover, CS–TiO₂ has also been used as an anti-corrosive material. However, the development of suitable protocols for CS–TiO₂ composite preparation is mandatory for industrial-scale implementation.

The Protective Influence of Chondroitin Sulfate, a Component of Human Milk, on Intestinal Bacterial Invasion and Translocation

BACKGROUND

Human milk is known to be protective against necrotizing enterocolitis, a devastating intestinal inflammatory disease affecting the preterm population. Although the pathogenesis of necrotizing enterocolitis is yet to be solidified, intestinal integrity dysfunction, bacterial invasion and/or translocation, and inflammation may play important roles. Glycosaminoglycans, compounds naturally prevalent in both human milk and the intestine, are thought to be anti-inflammatory and capable of altering bacterial interactions within the gut.

RESEARCH AIM

In this study, we aimed to evaluate the potential of chondroitin sulfate, the most prominent class of glycosaminoglycans in human milk, to protect against bacterial infection in an intestinal in vitro model.

METHODS

T84 cell monolayers were treated with chondroitin sulfate and cell viability was assessed across a number of doses. Monolayers were then pretreated with chondroitin sulfate and subsequently challenged with E. coli invasion and translocation to evaluate any protective role of the compound against infection. Tight junction barrier function was assessed by transepithelial electrical resistance, and cytokine levels were evaluated.

RESULTS

Chondroitin sulfate at any dose up to 750 μg/ml was not associated with any statistically significant decrease in cell viability. Additionally, chondroitin sulfate at 750 μg/ml was associated with a 75% decrease in both bacterial invasion and translocation compared to control.

CONCLUSIONS

These data suggest chondroitin sulfate may protect against bacterial infection through a reduction in both invasion and translocation, importantly without attendant reduction in cell viability.

Naturally derived proteins and glycosaminoglycan scaffolds for tissue engineering applications

Tissue engineering (TE) aims to mimic the complex environment where organogenesis takes place using advanced materials to recapitulate the tissue niche. Cells, three-dimensional scaffolds and signaling factors are the three main and essential components of TE. Over the years, materials and processes have become more and more sophisticated, allowing researchers to precisely tailor the final chemical, mechanical, structural and biological features of the designed scaffolds. In this review, we will pose the attention on two specific classes of naturally derived polymers: fibrous proteins and glycosaminoglycans (GAGs). These materials hold great promise for advances in the field of regenerative medicine as i) they generally undergo a fast remodeling in vivo favoring neovascularization and functional cells organization and ii) they elicit a negligible immune reaction preventing severe inflammatory response, both representing critical requirements for a successful integration of engineered scaffolds with the host tissue. We will discuss the recent achievements attained in the field of regenerative medicine by using proteins and GAGs, their merits and disadvantages and the ongoing challenges to move the current concepts to practical clinical application.