Changfu Shan

A novel fluorescent chemosensor based on tetra-peptides for detecting zinc ions in aqueous solutions and live cells

A fluorescent chemosensor is a powerful analytical tool for the visualization and quantitation of analytes in living cells, tissue slices, and whole bodies. Peptides with a reporter ionophore are very valuable as fluorescent chemosensors, because of their higher biological compatibility and solubility compared to organic dyes, and they are more stable than proteins in aqueous solutions. Herein, we report a novel peptide fluorescent chemosensor (HL) based on tetra-peptides conjugated with dansyl groups, which was synthesized by solid phase peptide synthesis. This chemosensor selectively and sensitively detects Zn2+ based on the photo-induced electron transfer (PET) effect by turn-on response in 100% aqueous solutions. As designed, HL can penetrate live HeLa cells and image intracellular Zn2+ by turn-on response. Moreover, HL exhibits low biotoxicity with a limit of detection (LOD) of about 32 nM for Zn2+, implying that HL acts as a highly useful peptide fluorescent chemosensor for biological systems.

Versatile rare-earth oxide nanocomposites: enhanced chemo/photothermal/photodynamic anticancer therapy and multimodal imaging

The development of novel nanocomposites that combine multiple imaging and therapeutic strategies has recently attracted considerable attention because of their cumulative and synergistic therapeutic effects. In this study, doxorubicin (DOX)- and indocyanine green (ICG)-loaded Gd2O3:Eu3+@P(NIPAm-co-MAA)@THA@cRGD nanocomposites {abbreviated as DOX-ICG-TPNPs@cRGD; P(NIPAm-co-MAA): poly[(N-isopropylacrylamide)-co-(methacrylic acid)]; THA: 4,4-trifluoro-1-(9-pentylcarbazole-3-yl)-1,3-butanedione; cRGD: cyclic(Arg-Gly-Asp-d-Phe-Lys)} were designed, assembled, fully characterized, and successfully applied in multimodal imaging diagnosis and therapy. The designed nanocomposites display a versatile, multifunctional platform that includes (a) simultaneous targeting with cRGD, (b) multimodal imaging, including two-photon luminescence (TPL), magnetic resonance imaging (MRI), computed tomography (CT), and photothermal imaging (PTI), and (c) stimuli-responsive coordinated drug delivery; this results in a highly efficient synergistic chemo/photothermal/photodynamic anticancer therapy (chemo/PTT/PDT). An important feature of the obtained nanocomposites is the enhancement of both the PTT and PDT effects of ICG due to the effective light protection of a two-photon sensitized Eu3+ complex. This integrated strategy shows an excellent synergistic inhibition of tumor growth triggered by NIR laser irradiation, as confirmed by both in vitro and in vivo tests. The present study emphasizes the influence and interaction of every component in the nanocomposites and demonstrates that the systematic design of nanocarriers can lead to an assembly of smart nanomaterials with enhanced antitumor efficacy.

An Elaborate Supramolecular Assembly for a Smart Nanodevice for Ratiometric Molecular Recognition and Logic Gates.

Ingenious approaches to supramolecular assembly for fabricating smart nanodevices is one of the more significant topics in nanomaterials research. Herein, by using surface quaternized cationic carbon dots (CDots) as the assembly and fluorescence platform, anionic sulfonatocalix[4]arene with modifiable lower and upper rims as a connector, as well as in situ coordination of Tb(3+) ions, we propose an elaborate supramolecular assembly strategy for the facile fabrication of a multifunctional nanodevice. The dynamic equilibrium characteristics of the supramolecular interaction can eventually endow this nanodevice with functions of fluorescent ratiometric molecular recognition and as a nano-logic gate with two output channels.

Functionalized Eu(III)-Based Nanoscale Metal–Organic Framework To Achieve Near-IR-Triggered and -Targeted Two-Photon Absorption Photodynamic Therapy

The postsynthetic-modified nanoscale metal-organic framework (NMOF) probes selected as potential drug delivery platforms and photodynamic therapy agents to fulfill the effective and safe treatment of neoplastic diseases have attracted increasing attention recently. Herein, a Eu(III)-based NMOF probe elaborately postsynthetically modified with a β-diketonate two-photon-absorbing (TPA) ligand is rationally designed and further functionalized by assembling the photosensitizer molecule (methylene blue, MB) in the pores and a cyclic peptide targeting motif on the surface of the NMOF, which could achieve highly efficient near-infrared (NIR)-triggered and -targeted photodynamic therapy (PDT). On the basis of the luminescence resonance energy transfer process between the NMOF donor and the photosensitizer MB acceptor, the probe can achieve a high tissue-penetrable TPA-PDT effect. Thus, the NMOFs in this study play the role of not only the nanocontainer for the photosensitizer but also the energy-transfer donor. Studies in vitro show enhanced cellular uptake and satisfactory PDT effectiveness toward cancer cells compared to the free photosensitizer MB. It is highly expected that this study contributes to the development of smart luminescent diagnostic and therapeutic probes.

A paper-based lanthanide smart device for acid–base vapour detection, anti-counterfeiting and logic operations

Paper-based devices have attracted extensive attention due to their portability, low-cost, ubiquity, low environmental footprint and ease of operation. In the present study, two lanthanide complexes, namely [Eu(PBA)3(H2O)2] (Eu-PBA) and [Tb(HPBA)2(NO3)3] (Tb-HPBA) were synthesized using an amide-type β-diketone building block, N-(2-pyridinyl)benzoylacetamide (HPBA), which is capable of changing its energy-level to match that of Tb3+ and Eu3+ ions in an acid–base environment. This feature was used for the design and assembly of a simple and cost-effective paper-based lanthanide smart device (abbreviated as Paper-Eu/Tb), which was obtained by impregnating the filter paper with both the Eu-PBA and Tb-HPBA complexes; related homometallic Paper-Eu and Paper-Tb materials were also generated and characterized for comparative purposes. The obtained Paper-Eu/Tb device shows excellent luminescence properties, thus allowing its efficient use as a smart sensor for the naked-eye detection of various acid–base vapours with quick response, good reversibility and selectivity. A similar concept and the resulting paper-based device was also successfully expanded for other applications that include anti-counterfeiting and logic gate systems. Full characterization of the paper-based materials and examples of their use are described. Introduction to the international collaboration The present article is a part of an ongoing collaboration between the College of Chemistry and Chemical Engineering of Lanzhou University (P.R. China) and Instituto Superior Tecnico of University of Lisbon (Portugal). Starting from 2013, this collaboration has been successful in merging the expertise of the Chinese group on novel rare-earth complexes and their smart devices for luminescent probes, tumor marker/treatment, optical anti-counterfeiting, and catalysis with that of the Portuguese group on coordination chemistry, crystal engineering, and catalysis. This Sino-European collaboration has already resulted in the publication of 10 research papers devoted to the design and assembly of various smart nanocomposite materials for applications ranging from cancer therapy and detection of biomarkers to oxidation catalysis and sensing or separation of metal ions.

MOF-Derived Hollow CoS Decorated with CeO x Nanoparticles for Boosting Oxygen Evolution Reaction Electrocatalysis

Transition-metal sulfides (TMSs) have emerged as important candidates for oxygen evolution reaction (OER) electrocatalysts. Now a hybrid nanostructure has been decorated with CeOx nanoparticles on the surface of ZIF-67-derived hollow CoS through in situ generation. Proper control of the amount of CeOx on the surface of CoS can achieve precise tuning of Co2+ /Co3+ ratio, especially for the induced defects, further boosting the OER activity. Meanwhile, the formation of protective CeOx thin layer effectively inhibits the corrosion by losing cobalt ion species from the active surface into the solution. It is thus a rare example of a hybrid hetero-structural electrocatalyst with CeOx NPs to improve the performance of the hollow TMS nanocage.

Ce-Doped NiFe-Layered Double Hydroxide Ultrathin Nanosheets/Nanocarbon Hierarchical Nanocomposite as an Efficient Oxygen Evolution Catalyst

Developing convenient doping to build highly active oxygen evolution reaction (OER) electrocatalysts is a practical process for solving the energy crisis. Herein, a facile and low-cost in situ self-assembly strategy for preparing a Ce-doped NiFe-LDH nanosheets/nanocarbon (denoted as NiFeCe-LDH/CNT, LDH = layered double hydroxide and CNT = carbon nanotube) hierarchical nanocomposite is established for enhanced OER, in which the novel material provides its overall advantageous structural features, including high intrinsic catalytic activity, rich redox properties, high, flexible coordination number of Ce3+, and strongly coupled interface. Further experimental results indicate that doped Ce into NiFe-LDH/CNT nanoarrays brings about the reinforced specific surface area, electrochemical surface area, lattice defects, and the electron transport between the LDH nanolayered structure and the framework of CNTs. The effective synergy prompts the NiFeCe-LDH/CNT nanocomposite to possess superior OER electrocatalytic activity with a low onset potential (227 mV) and Tafel slope (33 mV dec-1), better than the most non-noble metal-based OER electrocatalysts reported. Therefore, the combination of the remarkable catalytic ability and the facile normal temperature synthesis conditions endows the Ce-doped LDH nanocomposite as a promising catalyst to expand the field of lanthanide-doped layered materials for efficient water-splitting electrocatalysis with scale-up potential.

A new multicomponent CDs/Ag@Mg–Al–Ce-LDH nanocatalyst for highly efficient degradation of organic water pollutants

A novel type of multicomponent and recyclable nanocatalyst CDs/Ag@Mg–Al–Ce-LDH was successfully assembled by functionalizing a magnesium–aluminum layered double hydroxide support doped with Ce (denoted as Mg–Al–Ce-LDH) with carbon dots (CDs) and silver nanoparticles (Ag NPs). The selection of CDs was governed by their ability to act as both the stabilizing and the reducing agent, allowing accomplishing an in situ reduction of Ag+ ions to Ag NPs at the surface of the Mg–Al–Ce-LDH matrix. The obtained CDs/Ag@Mg–Al–Ce-LDH nanocatalyst and the related CDs@Mg–Al–Ce-LDH and Ag@Mg–Al–Ce-LDH materials were fully characterized by standard methods. The catalytic activities of all these materials for the reduction of 4-nitrophenol (4-NP) and discoloration of common organic water pollutants were investigated in detail. Among the tested heterogeneous catalysts, the multicomponent CDs/Ag@Mg–Al–Ce-LDH nanocatalyst revealed an excellent catalytic performance. All the reactions are very quick and proceed in aqueous medium under ambient conditions. Such a high activity of CDs/Ag@Mg–Al–Ce-LDH could be explained by a significant synergic effect between CDs and Ag NPs, while the Mg–Al–Ce-LDH carrier itself acts as a co-catalyst wherein cerium ions also increase charge separation efficiency between surface electrons. In addition, the CDs/Ag@Mg–Al–Ce-LDH nanocatalyst can also be easily recovered and successfully reused in several consecutive reaction cycles. This CDs/Ag@Mg–Al–Ce-LDH nanocatalyst thus represents one of the most efficient and recyclable systems so far reported for the reduction of similar kinds of organic water pollutants.