An article published in the journal Carbohydrate polymers presented a new approach to using nanogels for antibacterial tissue. Due to the recent upsurge in drug-resistant infections, it has become increasingly important to use strong antimicrobial agents.
To study: Preparation of quaternized chitosan / Ag composite nanogels in reverse miniemulsions for durable and antimicrobial cotton fabricsImage Credit: Jarun Ontakrai / Shutterstock.com
Nanoparticles are at the forefront of scientific research and development, and some exhibit properties that make them an effective tool in the fight against these pathogens. Incorporating these materials into everyday items such as fabric can provide continued protection against these pathogens.
Bacteria on the rise
Pathogenic bacteria are the leading cause of death worldwide, with many human illnesses caused by surfaces infested with microbes. For a long time, antibiotics dominated the techniques for treating bacterial infections and continue to do so. Despite significant improvements, the abuse of antibiotics has led to a dramatic increase in drug-resistant bacteria in recent decades, resulting in disease and death on a large scale.
To solve this problem, one method is to improve the bioavailability of antibiotics while simultaneously reducing the prescribed dose. The development of antimicrobial agents to treat bacterial diseases effectively and reliably is therefore crucial.
How can nanotechnology help?
Recent advances in nanotechnology present an alternative tactic in the fight against bacterial diseases due to the specific chemical and physical characteristics of different nanoparticles.
Due to their larger surface area, variable particle size, and numerous antimicrobial characteristics against drug resistant bacteria, silver nanoparticles (Ag NP) have been widely used in medical tools and pharmaceutical articles.
Although silver ions are generally considered harmless to human cells and tissues, when analyzed at the nanoscale, there is growing concern about the toxicity of silver nanoparticles. The accumulation of these nanoparticles in human organs and tissues can have harmful consequences such as cell death or DNA damage. Additionally, silver NPs can be susceptible to oxidation, making their long-term antibacterial impact insufficient.
These problems can be solved through the encapsulation of silver nanoparticles in a carrier, which is an effective strategy to achieve stability and long lasting antimicrobial potency.
As a soft natural substance, chitosan (CS) exhibits exceptional biocompatibility and biodegradability. However, its low water solubility and poor antibacterial characteristics hamper its antibacterial uses, especially in complex antimicrobial systems. On the other hand, quaternized chitosan (QCS), having constant positive ionic charges on the backbone, is soluble in water at high pH values and shows good antimicrobial capacity.
Many attempts have been made to create QCS / Ag NPs nanocomposites due to the antibacterial superiority offered by the synergistic action of QCS and Ag NPs.
However, previous methods could not produce the desired controllability and flexibility, resulting in low encapsulation efficiency or unmanageable loaded content of silver nanoparticles. Therefore, the importance of an efficient method of producing composite QCS / Ag (CNG) nanogels with the desired controllability and flexibility is critical.
Inverse miniemulsions for the preparation of CNG QCS / Ag
The study found that the reverse mini-emulsion technique efficiently creates composite QCS / Ag nanogels. The silver nanoparticles can be preloaded in the polar dispersion phase containing reactive materials.
In the continuous organic phase, nanometric droplets are formed and stabilized by emulsification. Using the droplet nucleation method, each droplet can be viewed as a nanoreactor, providing excellent encapsulation efficiency and adjustable load of silver nanoparticles. Therefore, the reverse miniemulsion method prevails over other heterogeneous approaches such as reverse emulsion and microemulsion.
The developed QCS / Ag CNGs merged the special characteristics of QCS and silver nanoparticles, exhibiting effective antibacterial properties and minimal cytotoxicity. These composite nanogels can be chemically immobilized on plasma-treated cotton textiles using a pad-drying procedure that helps maintain the antibacterial effects even after washing.
Properties of the tissue integrated into the nanogel
The composite silver nanogels developed in the study demonstrated impressive broad-spectrum antibacterial capacity. By controlling the degree of crosslinking and the dose of QCS / Ag CNG, the antibacterial efficacy can be adjusted as needed.
The growth of C. albicans, E. coli, and S. aureus was significantly suppressed below the optimum degree of crosslinking. The high antibacterial efficacy of composite silver nanogels, in particular against C. albicans (fungi), makes them suitable for a wide range of antimicrobial applications.
The incorporation of antimicrobial properties in pure cotton textiles does not remove their essential qualities of water vapor absorption and permeability, elasticity and tensile strength.
The researchers also found that the thermal stability of pure cotton fabrics was not compromised by the addition of the silver nanogel composites, and that the end product exhibited similar levels of whiteness to pure textiles. The addition of composite silver nanogels added a layer of protection in the cotton fabrics against microbial pathogens without compromising the comfort characteristics of the textile.
Continue reading: NANO-LLPO: Using Nanomaterials to Heal Wounds.
Gao, F., Mi, Y., Wu, X., et al., (2021) Preparation of quaternized chitosan / Ag composite nanogels in reverse miniemulsions for durable and antimicrobial cotton fabrics. Carbohydrate polymers. Available at: https://doi.org/10.1016/j.carbpol.2021.118935