Ruibing Wang

Cucurbit[7]uril host–guest complexes of the histamine H2-receptor antagonist ranitidine

The macrocyclic host cucurbit[7]uril forms very stable complexes with the diprotonated (K(CB[7])(1) = 1.8 x 10(8) dm(3) mol(-1)), monoprotonated (K(CB[7])(2) = 1.0 x 10(7) dm(3) mol(-1)), and neutral (K(CB[7])(3) = 1.2 x 10(3) dm(3) mol(-1)) forms of the histamine H(2)-receptor antagonist ranitidine in aqueous solution. The complexation behaviour was investigated using (1)H NMR and UV-visible spectroscopy as a function of pH and the pK(a) values of the guest were observed to increase (DeltapK(a1) = 1.5 and DeltapK(a2) = 1.6) upon host-guest complex formation. The energy-minimized structures of the host-guest complexes with the cationic guests were determined and provide agreement with the NMR results indicating the location of the CB[7] over the central portion of the guest. The inclusion of the monoprotonated form of ranitidine slows the normally rapid (E)-(Z) exchange process and generates a preference for the (Z) isomer. The formation of the CB[7] host-guest complex greatly increases the thermal stability of ranitidine in acidic aqueous solution at 50 degrees C, but has no effect on its photochemical reactivity.

Nanomedicine in action: an overview of cancer nanomedicine on the market and in clinical trials

Nanomedicine, defined as the application of nanotechnology in the medical field, has the potential to significantly change the course of diagnostics and treatment of life-threatening diseases, such as cancer. In comparison with traditional cancer diagnostics and therapy, cancer nanomedicine provides sensitive cancer detection and/or enhances treatment efficacy with significantly minimized adverse effects associated with standard therapeutics. Cancer nanomedicine has been increasingly applied in areas including nanodrug delivery systems, nanopharmaceuticals, and nanoanalytical contrast reagents in laboratory and animal model research. In recent years, the successful introduction of several novel nanomedicine products into clinical trials and even onto the commercial market has shown successful outcomes of fundamental research into clinics. This paper is intended to examine several nanomedicines for cancer therapeutics and/or diagnostics-related applications, to analyze the trend of nanomedicine development, future opportunities, and challenges of this fast-growing area.

Highly efficient cross-linked PbS nanocrystal/C60 hybrid heterojunction photovoltaic cells

We present a highly efficient hybrid heterojunction photovoltaic (PV) cell with a colloidal inorganic nanocrystal (NC) electron donor and an organic electron acceptor. The heterojunction is formed by a thin film of cross-linked PbS NCs and a C60 layer. Compared to the PbS-only PV cell, the heterojunction device has improved the power conversion efficient (PCE) from 1.6 % to 2.2 %. The C60 layer effectively prevents the excitons from quenching at the NC/metal interface, which is demonstrated with a significant improvement of the fill-factor (FF) of the heterojunction devices. In addition, a larger open-circuit voltage (VOC) in the heterojunction devices suggests that the electrons in C60 can readily transfer to the PbS NCs through the NC surface linkers. This is supported by the measured optical absorption spectrum of the hybrid system.

A green to blue fluorescence switch of protonated 2-aminoanthracene upon inclusion in cucurbit[7]uril

The inclusion of protonated 2-aminoanthracene in the cavity of cucurbit[7]uril increases its pKa values in the ground and excited states, resulting in the disappearance of the green emission of the neutral excited state and the significant enhancement of the blue emissions from the protonated excited state guest.

Preparation of graphene oxide-manganese dioxide for highly efficient adsorption and separation of Th(IV)/U(VI)

Manganese dioxide decorated graphene oxide (GOM) was prepared via fixation of crystallographic MnO2 (α, γ) on the surface of graphene oxide (GO) and was explored as an adsorbent material for simultaneous removal of thorium/uranium ions from aqueous solutions. In single component systems (Th(IV) or U(VI)), the α-GOM2 (the weight ratio of GO/α-MnO2 of 2) exhibited higher maximum adsorption capacities toward both Th(IV) (497.5mg/g) and U(VI) (185.2 mg/g) than those of GO. In the binary component system (Th(IV)/U(VI)), the saturated adsorption capacity of Th(IV) (408.8 mg/g)/U(VI) (66.8 mg/g) on α-GOM2 was also higher than those on GO. Based on the analysis of various data, it was proposed that the adsorption process may involve four types of molecular interactions including coordination, electrostatic interaction, cation-pi interaction, and Lewis acid-base interaction between Th(IV)/U(VI) and α-GOM2. Finally, the Th(IV)/U(VI) ions on α-GOM2 can be separated by a two-stage desorption process with Na2CO3/EDTA. Those results displayed that the α-GOM2 may be utilized as an potential adsorbent for removing and separating Th(IV)/U(VI) ions from aqueous solutions.

Inclusion complexes of coumarin in cucurbiturils.

Coumarin was found to form stable inclusion complexes with cucurbiturils. In the presence of cucurbit[7]uril (CB[7]), 1 : 1 inclusion complexes were observed in aqueous solution, as monitored by (1)H NMR and UV-visible absorption spectroscopies, and further supported by ab initio calculations, whereas with cucurbit[8]uril (CB[8]) a solid phase 1 : 2 host : guest complex was found in a single crystal X-ray diffraction structure determination.

In vivo reversal of general anesthesia by cucurbit[7]uril with zebrafish models

A general anesthetic is a drug that brings about a reversible loss of consciousness, during a surgical or therapeutic procedure to render the patient free of pain and anxiety. However, the effect of anesthetics may linger far beyond the necessary time required and induce adverse effects. In addition, many surgical patients need to recover to a conscious state that allows them to make important decisions soon after their surgery. Unfortunately, there are currently no clinically-available anti-dotes to reverse the effects of anesthetics. In this study, we demonstrate the in vitro supramolecular host–guest complexations between macrocyclic cucurbit[7]uril (CB[7]) and a commonly used general anesthetic in fish, tricaine mesylate (TM), and we report for the first time the in vivo reversal effect of CB[7] to general anesthesia induced by TM with zebrafish models. These findings might lead to a new approach that may allow patients to regain lucidity much faster than their natural recovery from general anesthesia, and may also be used to reverse potentially life-threatening toxic effects encountered by some patients in response to general anesthesia.

Developmental and organ-specific toxicity of cucurbit(7)uril: in vivo study on zebrafish models†

The macrocyclic molecular container cucurbit[7]uril (CB[7]), the most water-soluble homologue in the cucurbit[n]uril family (n = 5–8, 10, 14), has been evaluated for its in vivo toxicity profile, including its developmental toxicity such as its effect on hatching, growth and survival, as well as its potential organ-specific toxicities such as cardiotoxicity, hepatotoxicity, and locomotion and behavioral toxicity, using zebrafish models. The results revealed that CB[7] has measureable cardiotoxicity and locomotion and behavioral toxicity at concentrations of ∼500 μM or higher, and negligible developmental and hepatotoxicity at concentrations up to 750 μM, although extended exposure to CB[7] in the 500–750 μM concentration range induced the mortality of tested fish. These results demonstrate for the first time with live in vivo animal models that CB[7] has relatively low developmental and organic specific toxicity, and support further exploration of the use of CB[7] in biomedical research at sub-toxic concentrations.

Cucurbit[7]uril: an emerging candidate for pharmaceutical excipients

Cucurbit[7]uril (CB[7]), belonging to the cucurbit[n]uril family (CB[n], n = 5–8, 10, or 13–15), may form host–guest complexes with a variety of small molecules of biomedical interest. The physical and chemical properties of the complexed drugs are often improved as a result of this complexation, suggesting the potential application of CB[7] as a pharmaceutical excipient. This review has summarized the most recent research progress reported between 2011 and early 2017 regarding the biocompatibility of CB[7] and the influence of CB[7] on the stability, solubility, biouptake, and biological activities (including therapeutic efficacies and toxicities) of guest drug molecules. Through this systemic summary and analysis, we intend to stimulate further research efforts in this area and promote the use of CB[7] as an emerging pharmaceutical excipient to improve various properties of drug molecules (or active pharmaceutical ingredients).

A covalently attached film based on poly(methacrylic acid)-capped Fe3O4 nanoparticles

Abstract Poly(methacrylic acid) (PMAA)-capped Fe 3 O 4 nanoparticles were prepared by coprecipitation with PMAA in aqueous solution. Fe 3 O 4 nanoparticles were further assembled with 2-nitro- N -methyl-4-diazonium-formaldehyde resin (NDR) to form a photosensitive precursor film, by virtue of the coulombic attraction between the negatively charged PMAA surface capping agent and the cationic polyelectrolyte of NDR. Covalent bonds were formed under ultraviolet irradiation. As a result of polymer capping of the nanoparticles and covalent linkage, a highly stable multilayer structure was formed. Transmission electron micrographs and selected area electron diffraction pattern revealed the Fe 3 O 4 nanoparticles to be approximately 8 nm in diameter with a cubic phase structure. X-Ray photoelectron spectroscopy provided evidence for the presence of Fe 3 O 4 nanoparticles and NDR within the ultrathin films. The UV-visible spectroscopy and atomic force microscopy measurements supported the improvement of the stability of the film, which became impervious to polar solvents when the linkages between the nanoparticles and polymer changed from ionic bonds to covalent bonds.