Chuan-Ling Zhang

Nanoparticles meet electrospinning: recent advances and future prospects

Nanofibres can be fabricated by various methods and perhaps electrospinning is the most facile route. In past years, electrospinning has been used as a synthesis technique and the fibres have been prepared from a variety of starting materials and show various properties. Recently, incorporating functional nanoparticles (NPs) with electrospun fibres has emerged as one of most exciting research topics in the field of electrospinning. When NPs are incorporated, on the one hand the NPs endow the electrospun fibres/mats novel or better performance, on the other hand the electrospun fibres/mats could preserve the NPs from corrosion and/or oxidation, especially for NPs with anisotropic structures. More importantly, electrospinning shows potential applications in self-assembly of nanoscale building blocks for generating new functions, and has some obvious advantages that are not available by other self-assembly methods, i.e., the obtained free-standing hybrid mats are usually flexible and with large area, which is favourable for their commercial applications. In this critical review, we will focus on the fabrication and applications of NPs-electrospun fibre composites and give an overview on this emerging field combining nanoparticles and electrospinning. Firstly, two main strategies for producing NPs-electrospun fibres will be discussed, i.e., one is preparing the NPs-electrospun fibres after electrospinning process that is usually combined with other post-processing methods, and the other is fabricating the composite nanofibres during the electrospinning process. In particular, the NPs in the latter method will be classified and introduced to show the assembling effect of electrospinning on NPs with different anisotropic structures. The subsequent section describes the applications of these NPs-electrospun fibre mats and nanocomposites, and finally a conclusion and perspectives of the future research in this emerging field is given.

Mesostructured Assemblies of Ultrathin Superlong Tellurium Nanowires and Their Photoconductivity

Well-defined periodic mesostructures of hydrophilic ultrathin Te nanowires with aspect ratios of at least 10(4) can be produced by the Langmuir-Blodgett technique without any extra hydrophobic pretreatment or functionalization. Packing the arrayed nanowire monolayers will allow construction of nanomesh-like mesostructures or more complex multilayered structures composed of ultrathin nanowires on a planar substrate. The well-organized monolayer of Te nanowires with periodic mesostructures can be readily used as a stamp to transfer such mesostructured nanopatterns to other substrates or can be embedded within a polymer matrix. The mesostructures of ultrathin Te nanowire films show reversibly switched photoelectric properties between the lower- and higher-conductivity states when the light is off and on, and the photocurrent is influenced by the light intensity and the number of mesostructured nanowire monolayer films. This method can be extended for fabrication of other mesostructured assemblies of ultrathin nanowires or nanotubes.

Controlled Assemblies of Gold Nanorods in PVA Nanofiber Matrix as Flexible Free‐Standing SERS Substrates by Electrospinning

Under control: Controlled assemblies of gold nanorods in a poly(vinyl alcohol) (PVA) nanofiber matrix with tunable optical properties can be achieved by using electrospinning. The resultant assemblies can be used as substrates for surface-enhanced Raman spectroscopy (SERS). This work provides a facile way to control alignment of anisotropic nanostructures in a polymer nanofiber matrix and generates new assemblies with interesting properties.

Facile fabrication of gold nanoparticles-poly(vinyl alcohol) electrospun water-stable nanofibrous mats: efficient substrate materials for biosensors.

Electrospun nanofibrous mats are intensively studied as efficient scaffold materials applied in the fields of tissue engineering, catalysis, and biosensors due to their flexibility and porosity. In this paper, we report a facile route to fabricate gold nanoparticles-poly(vinyl alcohol) (Au NPs-PVA) hybrid water stable nanofibrous mats with tunable densities of Au NPs and further demonstrate the potential application of as-prepared Au NPs-PVA nanofibrous mats as efficient biosensor substrate materials. First, through the designed in situ cross-linkage in coelectrospun PVA-glutaraldehyde nanofibers, water insoluble PVA nanofibrous mats with suitable tensile strength were successfully prepared. Then, 3-mercaptopropyltrimethoxysilane (MPTES) was modified on the surface of obtained PVA nanofibrous films, which triggered successful homogeneous decoration of Au NPs through gold-sulfur bonding interactions. Finally, the Au NPs-PVA nanofibrous mats embedded with horseradish peroxidase (HRP) by electrostatic interactions were used as biosensor substrate materials for H(2)O(2) detection. The fabricated HRP-Au NPs/PVA biosensor showed a highly sensitive detection of H(2)O(2) with a detection limit of 0.5 μM at a signal-to-noise ratio of 3. By modifying other different functional nanaoparticles or enzyme on the PVA nanofibrous film will further expand their potential applications as substrate materials of different biosensors.

Rapid Microwave-Assisted Synthesis of Uniform Ultralong Te Nanowires, Optical Property, and Chemical Stability

Uniform and ultralong single-crystalline tellurium (Te) nanowires with a diameter of 20 nm and length of tens of micrometers can be rapidly synthesized by a microwave-assisted method. The formation process of high-quality Te nanowires is strongly dependent on the reaction conditions such as the amount of polyvinylpyrrolidone (PVP), pH value of initial solution, reaction time, and the choice of surfactant. The hydrophilic Te nanowires display a broadened luminescent emission from shortwave ultraviolet to visible region excited by vacuum-ultraviolet (VUV) under synchrotron radiation at room temperature. Based on the examination of the chemical stability of the as-prepared Te nanowires stored in water, the relationship between the synthetic methodology and chemical stability of Te nanostructures has been discussed.

Macroscopic‐Scale Alignment of Ultralong Ag Nanowires in Polymer Nanofiber Mat and Their Hierarchical Structures by Magnetic‐Field‐Assisted Electrospinning

1D nanomaterials have attracted explosive attention in the context of the physical and chemical fi elds, owing to their potential for novel applications in electronic and optical devices. [ 1 ] With the development of synthetic methodologies, 1D nanomaterials have achieved great success and a wide variety of different materials from organic polymers to inorganic compounds have been prepared. [ 2 , 3 ] Recently, research activities in the fi eld of nanoscience are shifting from the preparation of individual nanoparticles (NPs) to the preparation of NP assemblies and the realization of their applications. [ 4 ] From the viewpoint of application, assembly of these 1D nanomaterials into functional nanomaterials and devices is required, especially for alignment in large scale, which is still one of the most diffi cult problems hindering their applications. Various methods based on self-assembly or directed self-assembly techniques have been used to assemble nanomaterials into functional devices. Several reviews focused on assembly have also appeared. [ 4–6 ] However, most of these methods have been applied to assemble 1D nanostructures with low aspect ratios, such as NPs and nanorods (NRs); few techniques have been successfully applied to assemble nanowires (NWs) with high aspect ratios because the magnitude and range of the repulsive forces of wires, rods, and

A Family of Carbon-Based Nanocomposite Tubular Structures Created by in Situ Electron Beam Irradiation

We report a unique approach for the fabrication of a family of curling tubular nanostructures rapidly created by a rolling up of carbon membranes under in situ TEM electron beam irradiation. Multiwall tubes can also be created if irradiation by electron beam is performed long enough. This general approach can be extended to curve the conductive carbon film loaded with various functional nanomaterials, such as nanocrystals, nanorods, nanowires, and nanosheets, providing a unique strategy to make composite tubular structures and composite materials by a combination of desired optical, electronic, and magnetic properties, which could find potential applications, including fluid transportation, encapsulation, and capillarity on the nanometer scale.