Latest ArticlesA novel near-infrared light photothemal-activated H2S-donating nanocomposite hydrogel was developed, through combination of a thermo-labile H2S donor and photothermal nanoparticles in agarose hydrogel. The polyethylenimine dithiocarbamate polymer, a thermo-labile compound, was synthesized as a novel H2S donor. The combination of a thermo-labile hydrogen sulfide donor and photothermal nanoparticles enabled the generation of H2S in agarose hydrogel upon irradiation with near-infrared light. The ability to modulate the photoirradiation for controlled generation and spatiotemporally release of H2S are its specific advantages. This photothermal spatiotemporally controlled H2S-releasing strategy was successfully applied to anti-inflammation treatment in a rat model, demonstrating its utility as a novel H2S-based therapeutic approach.
A promising biomass carbon material, manufactured by the carbonation of Physalis peruviana L. calyx at 700 ℃, is presented in this work. Morphology characterization shows that the carbon material possesses long microtubule bundling and above 30% natural O-atom component on the surface. After KOH chemical etching, the materials maintain the oxygen content but exhibit more micropores and higher specific surface area up to 1732.6 m2/g. Using as an electrode material for supercapacitor, the active carbon material exhibits high specific capacitance up to 339.7 F/g at 0.5 A/g in 3 mol/L KOH aqueous solution through three-electrode system. The active carbon material also exhibits excellent cycling stability (97% retention) by 10, 000 cycles at 10 A/g. The outstanding electrochemical performances are attributing to the unique long microtubule bundling with much more pores and the abundant O element on the surface. This biomass carbon material with excellent electrochemical properties could be a useful material for multiple applications.
Direct, in situ selective detection of intracellular formaldehyde (FA) is of great significance for understanding its function in FA-related diseases. Herein, red carbon dots (RCD) are reported as label-free two-photon fluorescent nanoprobes for detecting and imaging of FA. Upon addition of FA, the -NH2 groups of RCD could quickly and specially react with aldehydes to form Schiff base and then the strong fluorescence of RCD with blue-shift emission is recovery due to the destruction of the hydrogen bond interaction between RCD and water. In addition, the nanoprobes exhibit outstanding photostability, rapid response (< 1 min), high sensitivity (~9.9 μmol/L) and excellent selectivity toward FA over other aldehyde group compounds. Notably, owing to the good cell-membrane permeability and biocompatibility, as well as the large two-photon absorption cross-section, the as-prepared RCD can be used as label-free nanoprobes for selectively detecting and imaging FA in living cells and zebrafishes through one-photon and two-photon excitation. Moreover, RCD could stain the tissue of zebrafishes at depths interval of up to 240 mm under two-photon excitation. This research implied that RCD are promising tools for directly and in situ imaging FA in vivo, thus providing critical insights into FA-related pathophysiological processes.
The series of salen-bridged bis-pillar[1]arenes were conveniently prepared by condensation reaction of 5, 5'-methylenebis(2-hydroxybenzaldehyde) or 5, 5'-(propane-2, 2-diyl)bis(2-hydroxybenzaldehyde) with mono-amido-functionalized pillar[5]arenes containing different terminal aminoalkyl groups in refluxing ethanol. The 1H NMR and 2D-NOESY spectra indicated that the salen-bridged bis-pillar[5]arenes with longer alkylene linker (n=3, 4, 6) formed the fascinating bis-[1]rotaxanes, while the salenbridged bis-pillar[5]arenes with short hydrazine and ethylenediamino linker (n=0, 2) predominately existed in free form. The single crystal structure of the bis-pillar[5]arene ambiguously indicated that two propylenediamino linker inserted in to two cavities of pillar[5]arene to form a novel bis-[1]rotaxanes.
Efficient synthetic routs for the direct and rapid construction of [5-6-6] ABC tricyclic systems of daphmanidin A-type and calyciphylline A-type alkaloids have been successfully developed. For the daphmanidin A-type, the synthesis of [5-6-6] tricyclic framework utilize a HCl-mediated intramolecular Aldol reaction to construct the bicyclo[2.2.2]octane core and a thermal condensation to afford the ABC ring system. In addition, for the calyciphylline A-type, an improved synthesis of ABC [5-6-6] tricyclic system was developed, featuring an introduction of methyl ester group at C2 before the Pd-catalyzed intramolecular oxidative alkylation to construct the desired bowl-shape tricyclic core with stereochemical control.
The deletion of the C-terminal arginine of the anaphylatoxin protein C5a reduces it receptor binding affinity. Understanding how C-terminal arginine affects the structure and bioactivity of C5a is important for the development of C5a C-terminal mimics as drug candidates. Herein, we report the total chemical synthesis of rat C5a and its D-enantiomer with its C-terminal arginine deleted, namely L-rC5a-desArg and D-rC5a-desArg. The structure of rC5a-desArg was then determined by racemic crystallography for the first time. The C-terminal residues of rC5a-Arg were found to expand from the fourth helix in a continuous helical conformation. This C-terminal conformation is significantly different from that of the previously reported full-length of C5a, indicating that the deletion of C-terminal arginine residue could result in the destruction of a positively charged surface formed by two adjacent Arg residues in C5a.
Deposition of platinum (Pt) monolayers (PtML) on Au substrate represents a robust strategy to maximally utilize the Pt atoms and meanwhile achieve high catalytic activity towards methanol oxidation reaction for direct methanol fuel cells owing to a substrate-induced tensile strain effect. However, recent studies showed that PtML on Au substrate are far from perfect smooth monoatomic layer, but actually exhibited three-dimensional nanoclusters. Moreover, the PtML suffered from severe structural instability and thus activity degradation during long-term electrocatalysis. To regulate the growth of PtML on Au surface and also to improve its structural stability, we exploit dealloyed AuCu core-shell nanoparticles as a new substrate for depositing PtML. By using high-resolution scanning transmission electron microscopy and energy dispersive X-ray elemental mapping combined with electrochemical characterizations, we reveal that the dealloyed AuCu core-shell nanoparticles can effectively promote the deposition of PtML closer to a smooth monolayer structure, thus leading to a higher utilization efficiency of Pt and higher intrinsic activity towards methanol oxidation compared to those on pure Au nanoparticles. Moreover, the PtML deposited on the AuCu core-shell NPs showed substantially enhanced stability compared to those on pure Au NPs during long-term electrocatalysis over several hours, during which segregation of Cu to the Au/Pt interface was revealed and suggested to play an important role in stabilizing the PtML catalysts.
A facile and efficient strategy has been developed to fabricate a multifunctional, theranostic anticancer drug delivery platform featuring active targeting, controlled drug release and fluorescence imaging for real-time control of delivery. To this end, thermosensitive poly(N-isopropyl acrylamide) (PNIPAM) nanospheres are decorated with peptide-Au cluster conjugates as a smart nanomedicine platform. A sophisticated trifunctional peptide is designed to release the anticancer drug doxorubicin (DOX), target cells and reduce Au3+ ions to form luminescent Au clusters. Importantly, the peptide-Au cluster moieties are attached to the PNIPAM nanospheres via amide bonds rather than noncovalent interactions, significantly improving their stability in biological medium and drug release efficiency. The in vitro experiments showed that DOX was released in an efficient and controlled manner under physiological conditions.
Reversible boronate-catechol linkage was widely used to construct two-dimensional coatings and threedimensional nanostructures or hydrogels. The construction of these functional materials usually requires the pre-synthesis of macromolecular building blocks, and direct gelation between natural polyphenols and small molecule boronic acids is yet to be investigated. In this study, we fabricated a family of allsmall-molecule dynamic covalent gels consisting of tannic acid and boronic acids. Transparent and thixotropic gels were formed by boronate affinity towards catechol groups abundant on natural polyphenols. The gels showed multi-responsiveness, such as acid-, base-, reduction-and oxidantsensitive depending on the used boronic acid building blocks. The chemistry for gel formation and stimuli-responsiveness was characterized by 11B NMR spectroscopy. The multi-stimuli responsiveness, green processing and facile modular design make the boronic acid-tannic acid gels promising candidates for the development of smart soft materials.
In this paper we report the desgin and synthesis of dihydroxyindoles oligomers based reversible fluorescence sensor. We find dihydroxyindoles-2-carboxylic acid derived oligmer (P-DHICA) has the highest selectivity and sensitivity for Cu2+ detection. This work provide a highly efficient, environmentally friendly biosensor for potential use in medical testing.
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