Thursday, 28 March, 2024
HomeTechnologyWound dressing to counter antimicrobial resistance

Wound dressing to counter antimicrobial resistance

Polish researchers have harnessed the existing hydrogel dressing manufacturing technique to additional benefit, incorporating an antibacterial and biodegradable substance called chitosan, extracted from the shells of crustaceans, within the dressing itself.

Antimicrobial resistance is becoming a worldwide health threat. A recent report by the Review on Antimicrobial Resistance, commissioned in 2014 by then UK Prime Minister David Cameron and led by economist Jim O'Neill, warns that antimicrobial resistance could kill 10m people each year by 2050, dwarfing even the number of estimated deaths from cancer. Because of this, preventing infection has never been more important.

The protective dressing was developed by Dr Radoslaw Wach and his colleagues from Lodz University of Technology in Poland. Their innovation builds on a type of dressing that has been around for centuries. By providing moisture to a wound, hydrogel dressings can speed up aspects of healing and cool the wound down. The dressings are durable and elastic, meaning they can easily adapt to the shape of the affected body part.

Wach and his colleagues adapted the hydrogel dressing manufacturing technique to make a version of the classic dressing with an added benefit. The team did this by incorporating an antibacterial and biodegradable substance called chitosan, extracted from the shells of crustaceans, within the dressing itself.

The extraction process involves isolating a substance called chitin that is found in the shells and then changing its structure by removing most chemical branches from its acetyl groups. The resulting chitosan then has to be purified before it is used. Chitosan is useful in bandages to stop bleeding and has been known for its antimicrobial properties for decades.

Wach and his colleagues used a technique called irradiation to combine chitosan with hydrogel dressings. The method comprises cross-linking of hydrophilic polymers next to water – just like with basic hydrogel dressings – to form the firm and durable structure of the dressing and sterilise it in a single step. The researchers next shone an electron beam at the polymer containing a solution of chitosan in a substance called lactic acid while making the dressings. This allowed the chitosan to become part of the dressing itself.

"We developed a composition where chitosan is dissolved in lactic acid and, when added to the regular composition of the dressing, it does not adversely change its ability to cross-link during manufacturing or alter its mechanical and functional properties," said Wach. "The new hydrogel wound dressing is biologically active."

Wach hopes the new dressings will one day be used as a replacement for classic hydrogels. "Since wound healing in severe cases may take a long time – up to several weeks – the probability of bacteria-mediated infection is high," he added. "Our novel hydrogel dressing could, therefore, prevent many such infections and avoid serious complications."

The World Health Organisation (WHO) recently published a new list of bacteria for which new antibiotics are needed. The most critical group of all includes bacteria resistant to multiple drugs. These pose a particular threat in hospitals, nursing homes, and among patients whose care requires devices such as ventilators and blood catheters. They include bacteria called Acinetobacter, Pseudomonas and various Enterobacteriaceae, including Klebsiella, E. coli, Serratia, and Proteus. Furthermore, 480,000 people develop multidrug-resistant tuberculosis globally each year, according to the WHO, and drug resistance is starting to complicate the fight against HIV and malaria.

"If our solution is commercialised," concludes Wach, "tens of thousands of infections could be prevented each year."

Abstract
The aim of the study was to develop an antimicrobial hydrogel wound dressing by means of radiation-initiated crosslinking of hydrophilic polymers, i.e. by well-established technology comprising gel manufacturing and its sterilization in one process. The approach included admixture of chitosan of relatively low molecular weight dissolved in lactic acid (LA) into the initial regular components of the conventional hydrogel dressing based on poly(N-vinyl pyrrolidone) (PVP) and agar. Molecular weight of chitosan was regulated by radiation-initiated degradation in the range of 39–132 kg mol−1. Optimum total concentration of LA in the resultant hydrogel dressing was evaluated as 0.05 mol dm−3, that is ca. 0.5%. Presence of LA in the system influenced essential radiation and technological parameters of hydrogel manufacturing. The setting temperature of the pre-hydrogel mixture, resulting from agar ability to congeal, was reduced with LA concentration, yet remained significantly above the room temperature. 0.5% of chitosan was effectively dissolved in aqueous solution of lactic acid due to its pH (lower than 5.5). Radiation parameters of PVP crosslinking in the presence of LA, as determined with generalized Charlesby–Pinner equation, were reflected in slight reduction of the maximum gel fraction and increase in gelation dose and in the factor comparing yields of scission to crosslinking. Nevertheless, essentially physical characteristics of the hydrogel was not affected, except for somewhat increased water uptake capacity, what in turn improves functionality of the dressing as extensive exudate for the wound can be efficiently absorbed. Preliminary microbiological studies showed antimicrobial character of the chitosan-containing hydrogel towards Gram-positive bacterial strain.

Authors
Wiktoria Mozalewska, Renata Czechowska-Biskup, Alicja K Olejnik, Radoslaw A Wach, Piotr Ulański, Janusz M Rosiak

[link url="https://www.sciencedaily.com/releases/2017/05/170501094347.htm"]Elsevier material[/link]
[link url="http://www.sciencedirect.com/science/article/pii/S0969806X16306077"]Radiation Physics and Chemistry abstract[/link]

MedicalBrief — our free weekly e-newsletter

We'd appreciate as much information as possible, however only an email address is required.