Syntheses and characterization of physically crosslinked hydrogels from dithiocarbamate-derived polyurethane macroiniferter

Dithiocarbamates combined with copper for revitalizing meropenem efficacy against NDM-1-producing Carbapenem-resistant Enterobacteriaceae

The worldwide prevalence of NDM-1-producing Gram-negative pathogens has drastically undermined the clinical efficacy of carbapenems, prompting a need to devise an effective strategy to preserve their clinical value. Here we constructed a focused compound library of dithiocarbamates and systematically evaluated their potential synergistic antibacterial activities combined with copper. SA09-Cu exhibited excellent inhibition against a series of clinical NDM-1-producing carbapenem-resistant Enterobacteriaceae (CRE) in restoring meropenem effect, and slowed down the development of carbapenem resistance. Enzymatic kinetic and isothermal titration calorimetry studies demonstrated that SA09-Cu was a noncompetitive NDM-1 inhibitor. The electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) revealed a novel inhibition mechanism, which is that SA09-Cu could convert NDM-1 into an inactive state by oxidizing the Zn(II)-thiolate site of the enzyme. Importantly, SA09-Cu showed a unique redox tuning ability, and avoided to be reduced by intracellular thiols of bacteria. In vivo experiments indicated that SA09 combined with CuGlu could effectively potentiate MER's effect against NDM-1-producing E. coli (EC23) in the murine infection model. This study provides a highly promising scaffold in developing novel inhibitors to combat NDM-1-producing CREs.

Synthesis and characterization of polyurethane-block-poly(2-hydroxyethyl methacrylate) hydrogels and their surface modification to promote cell affinity

Physically crosslinked hydrogels based on poly(2-hydroxyethyl methacrylate) (PHEMA) and polyurethane macroiniferter (PUMI) were prepared. The synthesis of polyurethane- block-poly(2-hydroxyethyl methacrylate) (PU-b-PHEMA) was verified by spectroscopic analyses. Due to the low fibronectin adsorption from culture media, cell attachment on PU-b-PHEMA surface was poor compared with the PUMI control. To improve the cell affinity of PU-b-PHEMA, fibronectin was conjugated via surface hydroxyl groups. These biomimetic PU-b-PHEMA hydrogel surfaces were tested for tissue engineering applications. A short-term cell culture study revealed that, compared with the unmodified PU-b-PHEMA, fibronectin-conjugated PU-b-PHEMA hydrogel showed more uniform and dense cell attachment and spreading, indicating a potential use for tissue engineering applications.