Yonghai Feng

Photothermal lysis of pathogenic bacteria by platinum nanodots decorated gold nanorods under near infrared irradiation

Photothermal lysis is an effective method for fast removal of pathogenic bacteria from bacterial contaminated environments and human body, irrespective of bacterial drug resistance. In the present work, a highly effective photothermal agent, Au@Pt nanorods (NRs), was prepared by modification of Pt nanodots with particle size of 5nm on the surface of Au NRs with a length of ca. 41nm and a width of ca. 13nm. The LSPR absorbance band of Au@Pt NRs could be tuned from 755 to 845nm by changing the Pt loading from 0.05 to 0.2, as compared to Au NRs. The photothermal conversion efficiency of Au@Pt NRs depended on the Pt loading, Au@Pt NRs concentration, and power density. Under NIR irradiation, the Au@Pt0.1 NRs exhibited the highest efficiency in photothermal lysis of both gram-positive and gram-negative bacteria. The introduction of Pt nanodots on the surface of Au@Pt NRs not only enhanced their photothermal conversions but also enhanced their affinity to bacteria and significantly decreased their cytotoxicity. The photothermal lysis of bacteria over Au@Pt NRs caused the damage onto the cell walls of bacteria, implying that the killing of bacteria probably went through the thermal ablation mechanism.

Selective oxidation of 1,2-propanediol to lactic acid catalyzed by hydroxyapatite-supported Pd and Pd–Ag nanoparticles

Selective catalytic oxidation of 1,2-propanediol is an alternative, effective, and environmentally benign method for producing lactic acid. Hydroxyapatite-supported Pd (Pd/HAP) and Pd–Ag (Pd–Ag/HAP) catalysts were prepared by the sol-immobilization method. The as-prepared catalysts were characterized by XRD, TEM, HRTEM, XPS, BET, and CO2-TPD techniques. The average particle sizes of Pd nanocubes in Pd/HAP catalysts were tuned from 6 to 18 nm by changing the amount of KBr and PVP, which significantly affected the 1,2-propanediol conversion and the lactic acid selectivity. Pd/HAP catalyst with cubic Pd nanoparticles was more selective to lactic acid than Pd/HAP catalyst with spherical Pd nanoparticles in the oxidation of 1,2-propanediol. The coalesced Pd and Ag nanoparticles in Pd–Ag/HAP bimetallic catalysts synergistically catalyzed the oxidation of 1,2-propanediol to lactic acid. The support HAP with high basicity promoted the oxidation of 1,2-propanediol to lactic acid. When the catalytic oxidation of 1,2-propanediol with O2 was carried out at 100 °C for 2 h in an alkaline solution, the lactic acid selectivity was 86.2% at the 1,2-propanediol conversion of 96.2% over Pd2/HAP-6 catalyst while the lactic acid selectivity was 88.8% at the 1,2-propanediol conversion of 86.3% over Pd1Ag1/HAP catalyst. The activation energies for the catalytic oxidation of 1,2-propanediol were in the order of Ea (Pd1Ag1/HAP) < Ea (Pd2/HAP-6) < Ea Ag2/HAP.

Differential Modulating Effect of MoS2 on Amyloid Peptide Assemblies

The abnormal fibrillogenesis of amyloid peptides such as amyloid fibril and senior amyloid plaques, is associated with the pathogenesis of many amyloid diseases. Hence, how to modulate amyloid assemblies is considered as an important field related to possible pathogenesis of some diseases. Some two-dimentional nanomaterials, i.e. grapheme oxide, tungsten disulphide, exhibit strong modulation effect on the amyloid fibrillogenesis. Herein, we investigated the modulation effect of Molybdenum Disulfide (MoS2, a kind of 2D nanomaterials) on two amyloid peptide assemblies based on the label-free techniques, including quartz crystal microbalance (QCM), AFM and CD. MoS2 presents different modulating effects on the assembly of Aβ(33-42) and Amylin(20-29), mainly ascribing to the distinct affinity between amyloid peptides and MoS2. So far as we know, it is the first report of MoS2 as a modulator for amyloid aggregation. It enriches the variety of 2D nano-modulators of amyloid fibrillogenesis and the mechanism for self-assembly of amyloid peptides, meanwhile expanding the applications of MoS2 in biology. Amyloid protein misfolding and its irreversible fibrils deposits are considered as the main cause associated with many types of diseases, such as Alzheimer’s diseases (AD) and Type-II diabetes. In the fibrillization process, amyloid peptides aggregate from soluble unstructured monomers into β-sheet rich oligomers and protofibrils, and finally turn into insoluble amyloid fibrils plaques.[1] Since the cytotoxicity of amyloid peptide is mainly related with the aggregates of β-sheet-rich structure, it is a rational envision that a modulator which can reduce, inhibit, or even reverse the fibrillization process, would be of great value in the pathogenesis investigation and potential therapeutic treatment. Many researchers focused on the study of the modulators of amyloid fibrillization.[2] So far, several types of effective modulators have been discovered, such as organic and inorganic nanoparticles, amine modified polystyrene nanoparticles,[3] some designed peptide motifs,[4] and other biomaterials[5]. Recently, carbonaceous materials have been reported to have the inhibitory effect on amyloid aggregation, such as graphene oxide (GO) with surface mediation effect, dimensionality and size effect.[6] The discovery of GO modulation effect motivates the GO applications in the detection of amyloid aggregates and medical research.[7] Those success and excitement in GO study has also opened up a pandora’s box of similar twodimensional (2D) materials. One important part of newlyemerging 2D materials is transition metal dichalcogenides (TMDs). Likewise, WS2 was also reported to have inhibitory effect for amyloidosis and even could be exfoliated by the self-assembly of amyloid.[8] Similar to GO and WS2, MoS2 is a kind of 2D nanomaterial composed of two-dimensional layers stacked in the vertical direction. Because of the weak van der Waals interactions between the sheets of sulfide atoms, MoS2 has excellent lubricating properties. MoS2 could be exfoliated as its single-layer or few-layered forms and used in photoelectrochemical field,[9] switchable transistors,[10] and ultrafast photonics,[11] etc. Recently some studies demonstrated that with appropriate modification MoS2 could be applied in tissue engineering and biomedicine[12] as biosensor, gene delivery and photothermal therapy (PTT) for cancer. It is implied that MoS2 could be a promising material in a variety of bioapplications. In the previous work, although it presented the modulating effect of WS2 and similar 2D nanomaterial on amyloid peptide aggregation, there is still one thing should be clarified that differential modulating effect of MoS2 on the assemblies of amyloid peptides. It will provide the idea and rule of modulating amyloid peptide assemblies by MoS2 and reveal the basic requirement of peptide sequence which could be modulated by MoS2 well. Herein, we want to investigate the modulation effect of MoS2 in the amyloid fibrillization process and further the mechanism of the interaction between MoS2 and different amyloid peptides. Furthermore, traditional techniques utilized to monitor the aggregation process mainly depend on measuring the change of fluorescent spectra upon the dye-binding. However, most of these dyes are insensitive to the early aggregates of amyloid proteins. These dyes have the interaction with amyloid peptide in the aggregation process, which interferes the results of measurement, such as Congo Red and ThT in the in-situ detection.[13] In this work, we combined label-free quartz crystal microbalance (QCM), [a] Dr. J. Wang, H.X. Zhang, Y. H. Feng, Prof. L. Liu Institute for Advanced Materials, Jiangsu University, China E-mail: liul@ujs.edu.cn, [b] Prof. Y. B. Zhang Department of Pharmaceutics, School of Pharmacy, Jiangsu University, China. [c] Prof. M. Dong, Prof. M. Chen Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark Email: dong@inano.au.dk Supporting information for this article is given via a link at the end of the document. [d] School of Mechanical Engineering, Micro/nano Science and Technology Center, Jiangsu University, China. 10.1002/chem.201704593 A cc ep te d M an us cr ip t Chemistry A European Journal This article is protected by copyright. All rights reserved.The abnormal fibrillogenesis of amyloid peptides such as amyloid fibril and senior amyloid plaques, is associated with the pathogenesis of many amyloid diseases. Hence, modulation of amyloid assemblies is related to the possible pathogenesis of some diseases. Some two-dimensional nanomaterials, that is, graphene oxide, tungsten disulfide, exhibit strong modulation effects on the amyloid fibrillogenesis. Herein, the modulation effect of molybdenum disulfide on two amyloid peptide assemblies based on the label-free techniques is presented, including quartz crystal microbalance (QCM), AFM, and CD spectroscopy. MoS2 presents different modulating effects on the assembly of amyloid-β peptide (33-42) [Aβ (33-42)] and amylin (20-29), mainly owing to the distinct affinity between amyloid peptides and MoS2 . This is to our knowledge the first report of MoS2 as a modulator for amyloid aggregation. It enriches the variety of 2D nanomodulators of amyloid fibrillogenesis and explains the mechanism for the self-assembly of amyloid peptides, and expands the applications of MoS2 in biology.

Introduction of an ordered porous polymer network into a ceramic alumina membrane via non-hydrolytic sol–gel methodology for targeted dynamic separation

A highly selective composite imprinted alumina membrane (CIAM) for gentisic acid (GA) was successfully synthesized by the nonhydrolytic sol–gel (NHSG) method with room temperature ionic liquid (RTIL) as the pore template. The carboxylic acid was used as both the functional monomer and the catalyst to form the alumina membrane-based porous imprinted polymer layer. The adsorption capacities, fluxes and permeation selectivities of various CIAMs suggested that cinnamic acid (CA) was the promising functional monomer for preparing a CIAM to separate GA from salicylic acid (SA) and the incorporation of RTIL improved the selectivity of GA over CIAM. The amount of porous imprinted polymer layer on the CIAM significantly affected the separation of GA from SA over CIAM. A three-level Box–Behnken experimental design with three factors combining the response surface modeling was used to optimize the dynamic separation process. The experimental data were well fitted to a second-order polynomial equation using multiple regression analysis. The optimal conditions for the separation of GA from SA were as follows: GA concentration of 0.0325 mmol L−1, temperature of 15.0 °C and flow rate of 1.0 mL min−1. Under these conditions, the experimental separation factor was 13.26 ± 0.87%, which was close to the predicted separation factor.

Evaluation of the Photo-degradation of Alzheimer’s Amyloid Fibrils with a label-free approach

Degradation of amyloid-β (Aβ) aggregates has been considered as an attractive therapeutic and preventive strategy against Alzheimers disease (AD). However, an in situ, real-time, and label-free technique is still lacking to understand the degradation process of Aβ aggregates. In this work, we developed a novel method to quantitatively evaluate the degradation of Aβ fibrils by photoactive meso-tetra(4-sulfonatophenyl)porphyrin under UV irradiation with quartz crystal microbalance (QCM).

Bioinspired Synthesis of Au Nanostructures Templated from Amyloid β Peptide Assembly with Enhanced Catalytic Activity

Peptides have been regarded as useful biomolecule templates to control the synthesis of various inorganic nanomaterials in mild conditions. Inspired by this, the easily self-assembled amyloid β (Aβ) peptide was developed as an alternative template to prepare Au nanostructures for the enhanced catalytic activity, for instance, the reduction of 4-nitrophenol. The presence of Aβ peptide assemblies with different structures could direct the nucleation of Au to form different Au nanostructures. Using the Aβ25-35 monomers, nanoribbons, and nanofibrils prepared by the self-assembly in phosphate buffered (PB) solution at 0, 3, and 12 h, respectively, as templates could controllably prepare Au nanospheres, nanoribbons, and nanofibers, while the Aβ25-35 monomers prepared by the self-assembly in water at 0 h could direct the synthesis of Au nanoflowers. The Aβ25-35-templated Au nanostructures had different catalytic activities due to the size and structure effects, which however are significantly enhanced as compared with the template-free Au nanoparticles.

Fabrication of submicrosized imprinted spheres attached polypropylene membrane using “two-dimensional” molecular imprinting method for targeted separation:

The submicrosized imprinted polypropylene microfiltration membrane (SIPM) for salicylic acid (SA) was prepared by water-in-oil emulsion polymerization method and two-dimensional imprinting method based on polypropylene microfiltration membrane with salicylic acid as template molecule, 4-vinyl pyridine as functional monomer, Span 80 as emulsifier, toluene as the oil phase, ethyleneglycol dimethacrylate as cross-linking agent, and 2,2′-azobis (2-methylpropionitrile) as initiator. The structure, morphology, and surface wettability of SIPM were characterized by Raman spectra, contact angle, and scanning electron microscopy. Flux test shows that the submicrosized imprinted spheres on the membrane is beneficial for increasing the membrane flux. Static adsorption experiment indicates that SIPM has a selective rebinding for salicylic acid. Moreover, the adsorption amount of salicylic acid over SIPM increased with properly increasing the amount of imprinted spheres on the SIPM. Permeation experiment shows that transport mechanism for permeation of the salicylic acid and acetylsalicylic acid toward SIPM is accordance with the facilitated mechanism.