Nanoscale “nesting doll” helps fight antibiotic-resistant bacteria
Japanese scientists have created a “matryoshka” of antibiotic, silver and their stabilizing polymer. The resulting nanoparticles have shown high efficiency in destroying biofilms.
Fighting antibiotic-resistant bacteria is becoming a growing challenge. Bacteria are becoming highly resistant to widely available antibiotics and substances with few side effects, so specialists have to treat patients with increasingly expensive and dangerous compounds.
Some bacteria can form biofilms - dense clusters of millions of cells surrounded by a protective mucus-like substance. The formation of these biofilms is an important strategy for bacteria to resist treatment. The protective mucus allows bacterial colonies to attach to surfaces and be protected from drug exposure over at least half of the colony's surface area.
Dense and multi-layered biofilms protect bacteria from attack by cells of the body's immune system and reduce the effectiveness of antiseptics and antibiotics. The resilience of biofilms has scientists looking for alternatives to antibiotics to kill bacteria.
A team of scientists from Japan has presented a new approach to combat treatment-resistant bacteria. Researchers have developed multilayer nanoparticles that combine several mechanisms for destroying bacteria. The method is based on the long-known silver nanoparticles. They were coated with a polymer shell Soluplus, and placed inside the antibiotic azithromycin. The work was published in the journal Nanoscale.
The team's previous research has shown that encapsulation in a polymer makes nanoparticles stable. In the published work, the scientists took colonies of E. coli and epidermal staphylococcus aureus. Both bacteria often become resistant to antibiotics in hospital settings.
Staphylococcus and E. coli form persistent biofilms on catheters and surgical implants, leading to severe and treatment-resistant infections. In such situations, the proposed nanoparticles can help in delivering antibiotic to the bacteria through the protective mucus.
The proposed matrix attacks bacterial cells with both the antibiotic and silver ions. The polymer shell provides stability and prevents the nanoparticles from sticking together. The more individual nanoparticles hit the biofilm, the more effective the antibacterial action, so the polymer shell is an important element of the proposed method.
The created multilayer nanoparticles were able to penetrate into biofilms and destroy them. The scientists used scanning electron microscopy and optical density measurements to observe how this happens.
The researchers created a miniaturized, highly sensitive LIG electrode system that can monitor bacterial activity in real time. In it, the electrodes have a large surface area, giving bacteria an ideal base for biofilm formation, and are also highly conductive.
Disintegrated bacteria create a different signal than whole cells. The electrodes are able to detect their breakdown by the change in current. This method works without the need to stain the bacteria.
The nanoparticles created can be used to coat medical devices to prevent biofilm formation. The method of detecting the decay of bacterial films with LIG electrodes could help make cancer screening cheaper.