![]() (A micrometer equals 1/1,000,000 of a meter. Scanning electron micrograph of methicillin-resistant Staphylococcus aureus (MRSA) courtesy of CDCĪn average coccus is about 0.5-1.0 micrometer (µm) in diameter. ![]() scanning electron micrograph of Staphylococcus aureus, a staphylococcus courtesy of Dennis Kunkel's Microscopy negative image of Staphylococcus aureus The wounds completely closed after 10 days when treated with the cis reagent, faster than the usual antibiotic treatment with vancomycin.\)) They demonstrated the efficacy of their nanomaterial by successfully healing MRSA-infected wounds in mice models. In this case, the cell wall was damaged and ruptured by specific interactions.īy simply "flipping" the UV switch from the trans ground state to the cis state, the team was able to control selectivity for either bacterial type. Conversely, the Gram-positive MRSA strain responded to the cis form more effectively. This allowed the MoS 2 nanomaterial to generate intracellular reactive oxygen species and kill the bacteria. aeruginosa, the trans form depolarized the bacterial membrane and pierced it thoroughly. The team used several chemical probes and optical measurements to determine that both the cis and trans forms of the nanomaterial killed bacteria, albeit in very different ways.įor the Gram-negative P. While MoS 2 is a bactericide and the quaternary amino groups allow membrane depolarization, the azobenzene moieties introduce a light-driven switch in the nanostructure from an elongated trans into a curved cis form to create selective surface interactions. ![]() coli, Proteus, Klebsiella, and Enterobacter,19 are often successfully treated with bactericidal beta-lactam antibiotics (aminopenicillins, cephalosporins, carbapenems), trimethoprim/sulfas or fluoroquinolones. To achieve a bactericidal agent that could selectively interact with both chemical surfaces, the team designed a functionalized nanomaterial made of molybdenum disulfide (MoS 2) with azobenzene moieties to which positively charged quaternary amino groups were attached. The aerobic rod-shaped bacteria frequently recovered from urine, such as E. "It is important to achieve strain-selective bactericidal activity," says De. In contrast, Gram-negative bacteria, including Pseudomonas aeruginosa, another health care-associated bacterium with problematic resistance to broadband antibiotics, has both inner and outer membrane mainly composed of phospholipids with a thin peptidoglycan layer. Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), have a bacterial membrane majorly composed of peptidoglycans. Mrinmoy De and colleagues from the Indian Institute of Science in Bengaluru, India, have now succeeded in producing a UV-visible-light-responsive nanomaterial that can be switched to target either Gram-positive or Gram-negative bacteria.īoth bacteria types have very different outer membrane structures and compositions. ![]() Many of the bacterial species in question are widespread in nature, but can cause much more serious, sometimes untreatable, infections in immunocompromised patients.īactericidal materials offer a new approach to combating health care-associated infections that does not rely on antibiotics. As the team reports in their study published in Angewandte Chemie, its effectivity against MRSA can be extended to other selective bacterial infections.Īntibiotic-resistant infections have become an urgent public health concern, particularly in hospital settings. ![]()
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