This Communication describes a strategy for designing stimuli-responsive plastics that are capable of responding to chemical signals in the environment by changing shape. The plastics consist of patterned mixtures of poly(phthalaldehyde) polymers in which each polymer contains a different end-capping group, or "trigger". Each polymer within the plastic is capable of responding to a different signal and depolymerizing once the signal reacts with the trigger. This process of depolymerization enables the plastic to alter its physical features quickly and with a magnitude that depends on the length of the responsive polymer.

In contrast to short-lived neutrophils, macrophages display persistent presence in the lung of animals after pulmonary exposure to carbon nanotubes. While effective in the clearance of bacterial pathogens and injured host cells, the ability of macrophages to “digest” carbonaceous nanoparticles has not been documented. Here, we used chemical, biochemical, and cell and animal models and demonstrated oxidative biodegradation of oxidatively functionalized single-walled carbon nanotubes via superoxide/NO* → peroxynitrite-driven oxidative pathways of activated macrophages facilitating clearance of nanoparticles from the lung.

This Article describes the development of conditions for cleaving siliconÀoxygen bonds using catalytic quantities of fluoride at neutral pH in mixed organicÀaqueous solutions that contain buffer. A variety of silicon protecting groups can be removed under these conditions, which show tolerance for acid-and base-sensitive groups. A modified procedure also is presented using catalytic fluoride in anhydrous dimethyl sulfoxideÀmethanol, which generates primarily volatile silicon byproducts.

No abstract

With the advancement of nanocarriers for drug delivery into biomedical practice, assessments of drug susceptibility to oxidative degradation by enzymatic mechanisms of inflammatory cells become important. Here, we investigate oxidative degradation of a carbon nanotube-based drug carrier loaded with Doxorubicin. We employed myeloperoxidase-catalysed and peroxynitrite-mediated oxidative conditions to mimic the respiratory burst of neutrophils and macrophages, respectively. In addition, we revealed that the cytostatic and cytotoxic effects of free Doxorubicin, but not nanotube-carried drug, on melanoma and lung carcinoma cell lines were abolished in the presence of tumor-activated myeloid regulatory cells that create unique myeloperoxidase- and peroxynitrite-induced oxidative conditions. Both ex vivo and in vitro studies demonstrate that the nanocarrier protects the drug against oxidative biodegradation.

We report a facile chemical method for fabricating holey graphene by catalytic oxidation of highly ordered pyrolytic graphite (HOPG) using an Fe porphyrin complex-based covalent organic framework (COF) as a bifunctional surface catalyst-template. We demonstrate regular hole formation after oxidation with H O and NaOCl, COF removal, and HOPG exfoliation.

We report a novel crystalline supramolecular polybenzobisimidazole (SP-PBBI) capable of providing a twodimensional polymer (2DSP-PBBI) by liquid-phase exfoliation. A regular arrangement of rigid rod-like polybenzobisimidazole (PBBI) chains is achieved by interchain hydrogen bonding. Titration of 2DSP-PBBI with cobalt chloride (CoCl 2 ) using UV-Vis spectroscopy demonstrates the presence of bidentate NO ligands on the PBBI backbone and NO-Co(II) complexation. Imaging analysis using atomic force microscopy (AFM) reveals the planar surface morphology of exfoliated 2DSP-PBBI sheets with lateral dimensions of <1 lm and thickness of <30 nm. The size of the polymer crystal growth is tuned by employing condensation/ precipitation polymerization under nonisothermal conditions.

No abstract