Yang Zhou

Bio: Yang Zhou is an academic researcher from Xi'an Jiaotong University. The author has contributed to research in topics: Materials science & Surface modification. The author has an hindex of 9, co-authored 11 publications receiving 686 citations.

Visual Detection of Copper(II) by Azide- and Alkyne-Functionalized Gold Nanoparticles Using Click Chemistry

Abstract: We report a method for the detection of Cu ions by azideand terminal alkyne-functionalized gold nanoparticles (Au NPs) in aqueous solutions using click chemistry. The catalyst, Cu(I), was conveniently derived from the reduction of Cu(II) in the presence of sodium ascorbate. This method allows the naked eye, without the aid of any advanced instrument, to assay for the presence of Cu ions by the aggregation of Au NPs as a result of the Cu(I)-catalyzed conjugation between the two functional groups. Copper is a transition metal essential for life but also highly toxic to organisms, such as certain algae, fungi and many bacteria and viruses. In recent years, copper has been suspected of causing liver damage in children. The analysis and measurement of copper in environmental and biological samples have become increasingly important. Several methods exist for the detection of Cu ions, for example, those based on organic fluorophores or chromogenic sensors, quantum dots, atomic absorption spectroscopy, inductively coupled plasma mass spectroscopy, absorbance spectro-photometry, peptides and voltammetry. The color changes associated with the aggregation of metal nanoparticles has led to the development of a number of assays for a variety of target species. Colorimetric methods can be convenient and attractive in many applications because they can be easily monitored with the naked eye, without the aid of any advanced instruments. The extinction coefficient of 13 nm-diameter gold nanoparticles is 2.7 4 10m 1 cm , several orders of magnitude more than those of traditional organic chromophores. As a result, colors arising from nanoparticles at nanomolar concentrations can be observed by the naked eye, allowing sensitive detection of small amounts of analytes. Since Cu(I) is used as a catalyst in the cycloaddition reaction between azides and alkynes in click chemistry based on Huisgen6s reaction, the amount of copper needed for its completion is typically small. Therefore, a method that can visualize the progress of the reaction using the aggregation of Au NPs might also be useful for the detection of trace amounts of Cu(II) (by detection of Cu(I)). Because the azide/alkyne functional groups and their conjugation are highly selective and are essentially inert to most biological molecules, oxygen, water, and the majority of common reaction conditions in chemical synthesis, and are tolerant of a wide range of solvents, temperatures, and pH values, we reasoned that an assay based on such chemistry may find myriad uses. Our method for the detection of Cu ions relies on the Cu(I)-catalyzed 1,3-dipolar cycloaddition of alkynes and azides on the surface of functionalized Au NPs, that results in the aggregation of Au NPs (Scheme 1). We synthesized azideand terminal alkyne-functionalized thiols, 1 and 2, and prepared gold NPs coated with these

Preparation and Characterization of Stimuli-Responsive Magnetic Nanoparticles

Abstract: In this work, the main attention was focused on the synthesis of stimuli-responsive magnetic nanoparticles (SR-MNPs) and the influence of glutathione concentration on its cleavage efficiency. Magnetic nanoparticles (MNPs) were first modified with activated pyridyldithio. Then, MNPs modified with activated pyridyldithio (MNPs-PDT) were conjugated with 2, 4-diamino-6-mercaptopyrimidine (DMP) to form SR-MNPs via stimuli-responsive disulfide linkage. Fourier transform infrared spectra (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize MNPs-PDT. The disulfide linkage can be cleaved by reduced glutathione (GHS). The concentration of glutathione plays an important role in controlling the cleaved efficiency. The optimum concentration of GHS to release DMP is in the millimolar range. These results had provided an important insight into the design of new MNPs for biomedicine applications, such as drug delivery and bio-separation.

Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

Abstract: Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed.

Polymer Brushes via Surface-Initiated Controlled Radical Polymerization: Synthesis, Characterization, Properties, and Applications

Abstract: Keywords: Fragmentation Chain-Transfer ; Self-Assembled Monolayers ; Walled Carbon Nanotubes ; Well-Defined Polymer ; Nitroxide-Mediated Polymerization ; Block-Copolymer Brushes ; Poly(Methyl Methacrylate) Brushes ; Transfer Raft Polymerization ; Quartz-Crystal Microbalance ; Poly(Acrylic Acid) Brushes Reference EPFL-REVIEW-148464doi:10.1021/cr900045aView record in Web of Science Record created on 2010-04-23, modified on 2017-05-10

Functionalizing nanoparticles with biological molecules: developing chemistries that facilitate nanotechnology.

Abstract: Chemistries that Facilitate Nanotechnology Kim E. Sapsford,† W. Russ Algar, Lorenzo Berti, Kelly Boeneman Gemmill,‡ Brendan J. Casey,† Eunkeu Oh, Michael H. Stewart, and Igor L. Medintz*,‡ †Division of Biology, Department of Chemistry and Materials Science, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, Maryland 20993, United States ‡Center for Bio/Molecular Science and Engineering Code 6900 and Division of Optical Sciences Code 5611, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States College of Science, George Mason University, 4400 University Drive, Fairfax, Virginia 22030, United States Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Sacramento, California 95817, United States Sotera Defense Solutions, Crofton, Maryland 21114, United States

Plasmon-enhanced optical sensors: a review

Abstract: Surface plasmon resonance (SPR) has found extensive applications in chemi-sensors and biosensors. Plasmons play different roles in different types of optical sensors. SPR transduces a signal in a colorimetric sensor through shifts in the spectral position and intensity in response to external stimuli. SPR can also concentrate the incident electromagnetic field in a nanostructure, modulating fluorescence emission and enabling plasmon-enhanced fluorescence to be used for ultrasensitive detection. Furthermore, plasmons have been extensively used for amplifying a Raman signal in a surface-enhanced Raman scattering sensor. This paper presents a review of recent research progress in plasmon-enhanced optical sensing, giving emphasis on the physical basis of plasmon-enhanced sensors and how these principles guide the design of sensors. In particular, this paper discusses the design strategies for nanomaterials and nanostructures to plasmonically enhance optical sensing signals, also highlighting the applications of plasmon-enhanced optical sensors in healthcare, homeland security, food safety and environmental monitoring.