That strength of Penicillin is its molecular core, a cyclic four-membered amide ring termed a beta-lactam. It is a common structural element of the penicillins, their synthetic and semi-synthetic derivatives, and other related molecules that constitute the broad family of drugs called the beta-lactam antibiotics. Just a few examples (of dozens) include amoxicillin, ampicillin and cefazolin.
The beta-lactam structure in a molecule is something that many bacteria don't like at all. It greatly hinders their ability to reproduce by cell division, and so chemists have for years spent time making molecules that all contain the beta-lactam structural motif, but differ in the surrounding molecular "shrubbery."
Carolina's Chuanbing Tang and colleagues paired the drug with a protective polymer developed in Tang's chemistry laboratory.
In lab tests, graduate student Jiuyang Zhang prepared a cobaltocenium metallopolymer that greatly slowed the destructiveness of beta-lactamase on a model beta-lactam molecule (nitrocefin).
The interdisciplinary team, which included Mitzi Nagarkatti and Alan Decho, from the university's School of Medicine and Arnold School of Public Health, respectively, also showed that the antimicrobial effectiveness of the four beta-lactams studied in detail was enhanced by the polymer. The enhancement was modest against two strains, but very pronounced with the hospital-associated strain of MRSA (HA-MRSA).
The metallopolymer by itself even demonstrated antimicrobial properties, lysing bacterial cells while leaving human red blood cells unaffected. By a variety of measures, the polymer was found to be nontoxic to human cells in laboratory tests.
The research paper has been published in the Journal of the American Chemical Society.