Chitosan Research in 2018

Also in 2018, scientists around the world have been feverishly researching chitosan in a variety of applications. Often involved is chitosan of highest quality, produced by Heppe Medical Chitosan. At the end of the year, we would like to present articles in which HMC Chitosan has been researched for removal of drugs in water and antibacterial action.

In 2018, nearly 3000 articles were published about research with chitosan (source: pubmed, 11.12.18).

Top Terms	Number of articles in 2018
Chitosan composite	364
Chitosan antibacterial	359
Chitosan hydrogel	321
Chitosan nanoparticle	295
Chitosan scaffold	196
Chitosan oligosaccharide	78
Chitosan vaccine	81

Table 1: Most frequent terms used in chitosan-related scientific articles in 2018.

In the following, we present some articles with exciting questions about chitosan applications:

Do chitosan-based sleeves prevent bacterial colonization of implant fixation pins?

Can chitosan nanoparticles enable efficient removal of drugs in water?

Chitosan-based sleeves loaded with silver and chlorhexidine in a percutaneous rabbit tibia model with a repeated bacterial challenge

Shao J., Wang B., Bartels C. J. M., Bronkhorst E. M., Jansen J. A., Walboomers X. F., Yang F. Acta Biomaterialia. 2018 Dec; 82:102-110. doi: 10.1016/j.actbio.2018.10.021.

In orthopedics, external fixations are used to treat open fractures and osteomyelitis, among other things. A major problem is the high risk of infection of the puncture channel, which is up to 50% significantly higher than with permanent implants such as a joint prosthesis. For effective treatment of the infection, a high dose of antibiotics must be applied, which can lead to organ damage as well as antibiotic resistance. To avoid this, researchers develop percutaneous seals and antibacterial coatings of fixation pins.

The authors of this study developed a suitable animal model close to the clinical situation when using fixation pins and tested the efficacy of silver and chlorhexidine-loaded, electrospun chitosan sleeves. Titanium pins with chitosan sleeves were implanted into the tibia of 32 rabbits. Chitosan 90/500 (degree of deacetylation [%] / viscosity (1% chitosan in 1% acetic acid [mPas]) of Heppe Medical Chitosan GmbH was used for preparation of sleeves. The animals received either unloaded chitosan-based sleeves or loaded with silver/cyclohexidine or silver only. Two weeks after implantation, Staphylococcus aureus suspension (1×10⁶ CFU) was injected weekly to the exit site of pins. The infection status of wound was monitored. To study the bacterial colonization animals were euthanized six weeks later. The bacterial density in the percutaneous passage was quantified, attached bacteria were identified by MALDI-TOF and histological analysis was performed.

Results

• 100% bacterial infection of the pin tracts
• Silver loaded sleeves reduced bacterial density and inflammation significantly
• No improvement of antibacterial effects when adding chlorhexidine

Conclusion: The silver loaded chitosan-based sleeves are a promising method to inhibit the antibacterial colonization pins tracts of implants. This could prevent infection of the wound or at least reduce the dose antibiotics necessary for treatment.

Source: https://www.sciencedirect.com/science/article/pii/S1742706118306202?via%3Dihub

A systematic approach of chitosan nanoparticle preparation via emulsion crosslinking as potential adsorbent in wastewater treatment

B. R. Riegger, B. Bäurera, A. Mirzayevaa, G. E. M. Tovarab, M. Bach. Carbohydr Polymers. 2018 Jan 15; 180:46-54. doi: 10.1016/j.carbpol.2017.10.002.

Nowadays, the pollution of the aquatic environment and drinking water with pharmaceuticals, like antibiotics or pain killer, is a major concern. After intake, many drugs are not degraded by the human body and get into the wastewater system. The residues cannot be completely removed by the wastewater treatment plant. For an improvement, the development of a recyclable adsorbent system for active pharmaceutical ingredients is being researched. A promising material is chitosan, as an adsorber for metal ions and organic compounds like dyes or pharmaceutical compounds.

The researchers from Germany produced chitosan nanoparticels with glutaraldehyde as crosslinker and investigated the influence of crosslinker concentration, as well as the molecular weight of chitosan. Chitosans with a degree of deacetylation of 95% and a viscosity of 5, 10, 20, 500, 100 and 200 mPas (1% chitosan in 1% acetic acid) from Heppe Medical Chitosan GmbH were used. The chitosan nanoparticles were tested for adsorption of diclofenac (DCL) and carbamazepine (CBZ), which are among the most commonly detected drug residues in the aquatic environment.

Results:

• Development of an emulsion formulation with cyclohexane as oil phase, Span 80 as surfactant and NaCl as hydrophilic to increase the stability and particle yield
• 1: 1 concentration of crosslinker glutaraldehyde to primary amino groups is sufficient for optimal crosslinking
• All six chitosans of different molecular weight are suitable for synthesis of nanoparticles
• Increasing particle size with increasing molecular weight
• Adsorption of less than 20% CBZ by chitosan nanoparticles
• Adsorption of 60% DCL for low molecular weight or 25% DCL for high molecular weight chitosan
• Adsorption capacity of 351.8 mg / g DLC for low molecular weight chitosan nanoparticles

Conclusion: The authors were able to produce cross-linked chitosan nanoparticles of different molecular weight. The nanoparticles had a good adsorption behavior towards diclofenac, especially with lower molecular weight chitosan.

Source: https://www.sciencedirect.com/science/article/pii/S0144861717311487