The Centers for Disease Control and Prevention (CDC) calls antibiotic resistance “one of the biggest public health challenges of our time.” But what is antibiotic resistance? How is it affecting our lives? and How can we use nanoparticles to fight it?
Antibiotic Resistance Crisis:
Antibiotics are powerful medications that are widely used for the treatment of infections caused by bacteria. However, taking antibiotics too often or for the wrong purpose caused bacteria to evolve various antibiotic resistance mechanisms.
Some bacteria have developed resistance to nearly all the antibiotic treatments available and can cause serious fatal diseases that were once easily treatable with antibiotics.
Without the invention of new strategies to counteract drug-resistant infections, they are likely to kill more than 10 million people each year by 2050. This is more than the number of people currently dying from cancer.
Ongoing studies are analyzing the ways nanoparticles (small particles ranging between 1 to 100 nanometres in size) can be used to defeat antibiotic-resistant bacteria. The size of nanoparticles and their flexible antibacterial properties make them a favorable solution to this problem since they can be used to not only deliver antibiotics but also to fight bacteria themselves.
The following video explains what nanoparticles are, how they are produced, and how they can enter and kill the bacterial cells:
Source: TCTTPC YouTube
Nanoparticles as Antibiotic Carriers:
According to this study conducted by Zhang and his colleague in late 2020, some nanoparticles can penetrate into the bacterial cells while carrying and protecting the antibiotic agents. These nanoparticles —developed using materials such as metals and chitosan (a type of fiber)— can save the antibiotic from chemicals released by bacteria that can otherwise destroy them.
Chitosan nanoparticle possesses a positive charge making it able to attach to bacterial cells that have a negative charge on their membrane (outer layer of the cell). Source: ResearchGate
Nanoparticles as Antibiotic Drugs:
Nanoparticles can also defeat bacteria directly using mechanisms such as the generation of reactive oxygen species (ROS). ROS are unstable molecules that can easily react with other biomolecules (DNA, protein, etc.) in a cell, disrupt them, and cause cell death.
Silver nanoparticles (SNPs), for instance, can destroy the bacterial membrane and interact with interior components of the bacterium by releasing silver ions that can generate ROS inside the cell. Indeed, severe cellular damages in 5 different types of bacteria were reported when treated with SNPs.
E.coli (a type of bacteria) (left) is severely damaged when treated with a silver nanoparticle (right). Source: pubs.acs.org
Nanoparticles appear to be a promising solution to address the problem
of antibiotic resistance; however, the main factor that limits their application in treatments is that researchers often face side-effects related to nanoparticle toxicity when interacted with biological systems like human cells. For instance, the ROS generated by a high dose of SNPs can damage the human cell components.
New strategies are being investigated to direct the target of nanoparticles to bacterial cells only and reduce their toxicity in order to develop safe and efficient antibacterial nanoparticles.
– Samin Shadravan
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