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In order to address the dire need for new antibiotics to treat specific strains of drug resistant Gram-negative bacterial infections, a mixed ligand analog of the natural Acinetobacter baumannii selective siderophore, fimsbactin, was coupled to daptomycin, a Gram-positive only antibiotic. The resulting conjugate 11 has potent activity against multidrug resistant strains of A. baumannii both in vitro and in vivo. The study also indicates that conjugation of siderophores to "drugs" that are much larger than the siderophore (iron transport agent) itself facilitates active uptake that circumvents the normal permeability problems in Gram-negative bacteria. The results demonstrate the ability to extend activity of a normally Gram-positive only antibiotic to create a potent and targeted Gram-negative antibiotic using a bacterial iron transport based sideromycin Trojan horse strategy.

Invented by Charles Goodyear, chemical cross-linking of rubbers by sulfur vulcanization is the only method by which modern automobile tires are manufactured. The formation of these cross-linked network structures leads to highly elastic properties, which substantially reduces the viscous properties of these materials. Here, we describe a simple approach to converting commercially available and widely used bromobutyl rubber (BIIR) into a highly elastic material with extraordinary self-healing properties without using conventional cross-linking or vulcanising agents. Transformation of the bromine functionalities of BIIR into ionic imidazolium bromide groups results in the formation of reversible ionic associates that exhibit physical cross-linking ability. The reversibility of the ionic association facilitates the healing processes by temperature- or stress-induced rearrangements, thereby enabling a fully cut sample to retain its original properties after application of the self-healing process. Other mechanical properties, such as the elastic modulus, tensile strength, ductility, and hysteresis loss, were found to be superior to those of conventionally sulfur-cured BIIR. This simple and easy approach to preparing a commercial rubber with self-healing properties offers unique development opportunities in the field of highly engineered materials, such as tires, for which safety, performance, and longer fatigue life are crucial factors.