Enzymatic and microbial biodegradability of poly(ethylene terephthalate) copolymers containing nitrated units

Enzymatic and microbial degradability of poly(ethylene terephthalate) (PET) and PET copolyesters containing 30 mol% of either 5-nitroisophthalic units (PET₇₀NI₃₀) or nitroterephthalic units (PET₇₀NT₃₀) was investigated in laboratory cultures. Two commercial fungal lipases, two bacteria from environmental isolates, and two collection filamentous fungi were tested. The topography of the polymer surface exposed to degradation was characterized by interferometry-confocal microscopy techniques. Biodegradation was estimated by optical and electron microscopy observation, and gel permeation chromatography. Evidence of biodegradation including roughness enhancement, swelling and decrease of the weight-average molecular weight, was only obtained for the case of PET₇₀NT₃₀ cultured with Aspergillus niger. Differences in surface textures were found to be crucial to determine the positive response of this copolyester to biodegradation.     

Ultrasound influence upon calcium carbonate precipitation on bacterial cellulose membranes

The effect of ultrasonic irradiation (40 kHz) on the calcium carbonate deposition on bacterial cellulose membranes was investigated using calcium chloride (CaCl₂) and sodium carbonate (Na₂CO₃) as starting reactants. The composite materials containing bacterial cellulose-calcium carbonate were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and color measurements. The polymorphs of calcium carbonate that were deposited on bacterial cellulose membranes in the presence or in the absence of ultrasonic irradiation were calcite and vaterite. The morphology of the obtained crystals was influenced by the concentration of starting solutions and by the presence of ultrasonic irradiation. In the presence of ultrasonic irradiation the obtained crystals were bigger and in a larger variety of shapes than in the absence of ultrasounds: from cubes of calcite to spherical and flower-like vaterite particles. Bacterial cellulose could be a good matrix for obtaining different types of calcium carbonate crystals.     

Detection of Bacterial Neutral Ceramidase in Diabetic Foot Ulcers with an Optimized Substrate and Chemoenzymatic Probes

Ceramidases (CDases) are important in controlling skin barrier integrity by regulating ceramide composition and affording downstream signal molecules. While the functions of epidermal CDases are known, roles of neutral CDases secreted by skin-residing microbes are undefined. Here, we developed a one-step fluorogenic substrate, S-B , for specific detection of bacterial CDase activity and inhibitor screening. We identified a non-hydrolyzable substrate mimic, C6 , as the best hit. Based on C6 , we designed a photoaffinity probe, JX-1 , which efficiently detects bacterial CDases. Using JX-1 , we identified endogenous low-abundance PaCDase in a P. aeruginosa monoculture and in a mixed skin bacteria culture. Harnessing both S-B and JX-1 , we found that CDase activity positively correlates with the relative abundance of P. aeruginosa and is negatively associated with wound area reduction in clinical diabetic foot ulcer patient samples. Overall, our study demonstrates that bacterial CDases are important regulators of skin ceramides and potentially play a role in wound healing.     

A new track for antibacterial treatment: Progress and challenges of using cytomembrane-based vesicles to combat bacteria

The emergence and re-emergence of antibiotic-resistant bacteria, especially superbugs, are leading to complicated infections that are increasingly difficult to treat. Therefore, novel alternative antimicrobial therapies are urgently needed to reduce the morbidity and mortality caused by antibiotic resistance. The development of biomimetic-based therapy is expected to provide innovative means for addressing this challenging task. As a kind of novel biomaterial, cytomembrane-based vesicles (MVs) continue to receive considerable attention in antimicrobial therapy owing to their inherent biocompatibility, design flexibility, and remarkable ability to interact with biological molecules or the surrounding environment. These remarkable cell-like properties and their inherent interaction with pathogens, toxins, and the immune system underlie MVs-based functional protein therapy and targeted delivery to develop advanced therapeutic strategies against bacterial infection. This review provides a fundamental understanding of the characteristics and physiological functions of cytomembrane-based vesicles, focusing on their potential to combat bacterial infections, including detoxification, immune modulation, antibiotics delivery, and physical therapy. In addition, the future possibilities and remaining challenges for clinically implementing MVs in the field of antibacterial treatment are discussed.     

Nanoarchitectonics in combat against bacterial infection using molecular,interfacial, and material tools

Nanoarchitectonics, as a post-nanotechnology concept, is the methodology for constructing functional materials from nano-units, which bridges the gap between nanotechnology and materials science. The research accomplishes advocating nanoarchitectonics has increased dramatically as overviewed in the initial part of this review. Then, as socially impactful subjects, we exemplify nanoarchitectonics research for bacterial infections according to classifications featured with molecular tools, interfaces, and hierarchically structured materials. In particular, this review article discusses namely three kinds of antibacterial strategies: (i) new antimicrobial agents and therapeutic modalities based on nanoarchitectonics present high bactericidal efficacy against methicillin-resistant Staphylococcus aureus; (ii) antimicrobial nanoarchitectonics structures are integrated into the surface of medical devices to detach or kill approaching bacteria; (iii) the nanoarchitectonics hydrogels act as antimicrobial reservoirs to produce sustained-release antimicrobial agents for long-lasting bacterial killing.