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Blog In Health

Newly designed nanoparticles deliver antibiotic directly to bacteria

By Paul Bisnar
Posted May 5, 2012 in Health
Conventional antibiotic treatment gives numerous side-effects and body organ damage. For example, Vancomycin is a potent antibiotic used for serious infections like MRSA. However, after intravenous administration it can cause nephrotoxicity, ototoxicity, blood disorders, and skin diseases, to name a few. Also, the constant use of antibiotic causes bacterial resistance to treatment.
The advent of Nanomedicine brings hope to avoid these nasty side-effects and antibiotic resistance. Nanoparticles deliver treatment directly to specific target like cell or bacteria avoiding severe body organ side-effects.
Professor Robert Langer of MIT and Director Omid Farokzhad of Brigham and Women’s Hospital designed new clever nanoparticles that can deliver its antibiotic payload to bacteria undetected by the immune system.
Basically, this is how it works.
The spherical polymer nanoparticles outer layer is covered with polyethylene glycol (PEG), a non-toxic chemical effective for drug-delivery and evasion of immune system when in blood circulation. Underneath the outer layer, researchers put a pH-sensitive layer of long chain amino-acids Histidine. When in the bloodstream, nanoparticles are slightly negatively charged to avoid the detection of the immune system.
During infection, the environment surrounding the bacteria becomes acidic. The bacteria multiply and deplete surrounding oxygen, affecting bacterial metabolism, eventually produce organic acids to surrounding environment. Also, blood cells called neutrophils produce acids as they try to consume the bacteria.
The moment the pH-sensitive layer of nanoparticles sense a change of pH into slightly acidic environment in infection, the previously negatively charged will switch into positively charged nanoparticles. This change to positively charge is important because bacterial cell wall is negatively charge, opposite charge attract each other, making nanoparticles attach to bacterial cell wall. Once nanoparticles attaches to bacteria, it deliver its antibiotic payload like Vancomycin inside the bacteria, eventually killing it.
However, a problem needs to be solved first before this newly designed nanoparticles put into use. Nanoparticles need to avoid other negatively charged tissues or proteins at the infection site, because if not, these “debris” will compete with bacteria for attachment, affecting its antibiotic delivery.