An activity-based probe targeting the streptococcal virulence factor C5a peptidase.

Development of profiling strategies to provide high resolution understanding of enzymes involved in bacterial infections remains an important need. These strategies help resolve enzyme mechanisms of actions and can guide therapeutic development. We have developed a selective new activity-based probe (ABP) targeting a highly conserved surface bound enzyme, C5a peptidase, present in several pathogenic Streptococci. We demonstrate our probe inhibits C5a peptidase activity and enables detection of C5a peptidase expressing pathogens in microbial mixtures. Our profiling strategy selectively labels the pathogen by phenotype and enables specific isolation of the live bacteria providing a route for further in-depth investigation. This study paves the way towards a rapid detection, isolation, and characterization pipeline for existing and emerging strains of most common pathogenic Streptococci.

Aldehyde-Functionalized Magnetic Particles to Capture Off-Target Chemotherapeutic Agents.

Drug capture is a promising technique to prevent off-target chemotherapeutic agents from reaching systemic circulation and causing severe side effects. The current work examines the viability of using immobilized aldehydes for drug-capture applications via Schiff base formation between doxorubicin (DOX) and aldehydes. Commercially available pyridoxal-5'-phosphate (VB6) was immobilized on iron oxide nanoparticles (IONPs) to capture DOX from human serum. Leaching of VB6 persisted as a primary issue and thus various aldehydes with anchoring groups such as catechol, silatrane, and phosphonate esters have been studied. The phosphonate group-based anchor was the most stable and used for further capture studies. To improve the hydrophilic nature of the aldehydes, sulfonate-containing aldehydes and polyethylene glycols (PEGs) were investigated. Finally, the optimized functionalized iron oxide particles, PEGylated-IONP, were used to demonstrate doxorubicin capture from human serum at biologically relevant temperature (37 °C), time (30 min), and concentrations (µM). The current study sets the stage for the development of potential compact dimension capture device based on surface-anchorable polymers with aldehyde groups.

Hydrothermal Preparation, Crystal Chemistry, and Redox Properties of Iron Muscovite Clay.

The development of functional materials based on Earth-abundant, environmentally benign compositions is critical for ensuring their commercial viability and sustainable production. Here we present an investigation into the crystal chemistry and electrochemical properties of the muscovite clay KFe2.75Si3.25O10(OH)2. We first report a low-temperature hydrothermal reaction that allows for a significant degree of control over sample crystallinity, particle morphology, and cation distribution through the lattice. A complex sequence of stacking faults is identified and characterized using a combination of Mössbauer spectroscopy and total scattering neutron experiments. We then show the existence of a reversible electrochemical process using galvanostatic cycling with complementary cyclic voltammetry suggesting that the redox activity occurs primarily on the surface of the particles. We conclude by determining that the ability to (de)intercalate Li ions from the material is hindered by the strong negative charge on the transition metal silicate layers, which prevents the displacement of the interlayer K ions. This work calls attention to a hugely Earth-abundant family of minerals that possesses useful electrochemical properties that warrant further exploration.

N-Difluoromethylation of imidazoles and benzimidazoles using the Ruppert-Prakash reagent under neutral conditions.

Direct N-difluoromethylation of imidazoles and benzimidazoles has been achieved using TMS-CF3 (the Ruppert-Prakash reagent) under neutral conditions. Difluoromethylated products were obtained in good-to-excellent yields. Inexpensive, commercially available starting materials, neutral conditions, and shorter reaction times are advantages of this methodology. Reactions are accessible through conventional as well as microwave irradiation conditions.