**1. Introduction**

Electrospinning is a convenient and versatile technique to prepare continuous fibers with diameters ranging from tens nanometers to several micrometers [1]. In early works, electro‐ spinning was limited to the fabrication of nanofibers from organic polymers due to the stringent requirement on the viscoelastic behavior of the electrospinning solution [2]. Recent efforts have greatly expanded the application scope of electrospinning technique. Various onedimensional (1D) nanomaterials can be prepared by electrospinning besides the common polymer fibers, such as polymer fibers loaded with nanoparticles and functional molecules, ceramics fibers and metal/metal oxide fibers. Additionally, with the development of electro‐ spinning method and setup, electrospun fibers have not been limited to the morphology of solid interior and smooth surface. Fibers with novel secondary structures, such as core/sheath, hollow and porous, can also be prepared if appropriate processing parameters or new designs of setups are employed.

Due to the small diameter, extremely long length, high surface area and complex pore structures, electrospun fibers have being attracted extensive research interests for their applications in biomedical field [1, 3, 4], such as tissue engineering, drug delivery and wound healing, as well as energy and environmental engineering [5, 6]. The relatively large specific surface area and high porosity make electrospun nanomaterials attract significant attentions in developing ultrasensitive sensors [7-9]. Various electrospun nanomaterial-based sensors have been designed, including resistive sensor, electrochemical sensor, fluorescent sensor, acoustic wave sensor, colorimetric sensor, photoelectric sensor, etc. Among these read-out modes, electrochemical read-out, featured with high sensitivity and selectivity, inexpensive equipment and easy miniaturization, has attracted remarkable attentions in the ultrasensitive detection. In this chapter, we focus on the synthesis of nanofibers with different composition,

© 2013 Huang and You; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

and the design and preparation of electrospun nanofibers with novel secondary structures. Following this, the application of electrospun nanomaterials in constructing electrochemical sensors and their analytical performance is discussed.

empirical knowledge is crucial because the ideal values of these parameters vary considerably

Electrospun Nanofibers: From Rational Design, Fabrication to Electrochemical Sensing Applications

http://dx.doi.org/10.5772/57099

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Electrospinning has been proved to be a versatile method to prepare 1D nanomaterials of polymer, ceramics, metal, and metal oxide. Various functional elements, such as drugs, dyes, DNA, proteins, and nanoparticles, could be incorporated into electrospun nanofibers to form composite nanofibers. Additionally, except for the nanofibers with solid interior and smooth surface, nanofibers with various secondary structures, including core/sheath, hollow, and porous, could be fabricated by electrospinning. In this section, the preparation of electrospun nanofibers with different composition and secondary structures is introduced, and the

In principle, almost all natural and synthetic polymers can be electrospun into their 1D nanostructures through judicious selection of solution and processing parameters [1]. Besides itself nanofibers, polymers can also be used as template or host to load nanoparticles or functional molecules. The produced composite nanofibers exhibit various electronic, optical,

In order to incorporate nanoparticles into electrospun fibers, pre-synthetic Au [12], Fe3O4 [13], SiO2 nanoparticles [14], CdTe quantum dots [15], and Au nanorods (AuNRs) [16] were introduced in polymer solution and then electrospinning was conducted. For example, AuNRs/poly(vinyl alcohol) (PVA) nanofiber was prepared by electrospinning the mixture solution of AuNRs and PVA [16]. The AuNRs were well aligned along the axis direction of the fibers due to the external fields (Fig. 2A). In a one-step method, silver nitrate was dissolved in poly(vinyl pyrrolidone) (PVP)/N, N-dimethylformamide (DMF) [17], or nylon 6/formic acid [18] solution, where DMF and formic acid acted as both a solvent for polymer and a reducing

nanofibers. In addition, the introduction of nanoparticles into polymer nanofibers have also been accomplished by adding appropriate precursors to the electrospinning solution, after that a chemical or physical method was used to reduce the metal precursor. For example, PdCl2 and copolymers of acrylonitrile and acrylic acid (PAN-AA) are dissolved in DMF for electro‐ spinning. And then, the fiber mat was immersed into diluted hydrazine water solution to reduce Pd cations [19]. The as-prepared Pd/PAN-AA composite material showed high catalytic activity toward hydrogenation of dehydrolinalool. Li et al. prepared Ag nanoparticle-loaded PAN nanofibers via electrospinning of PAN/AgNO3-DMF solution followed by UV-irradia‐

Carbon nanotubes (CNTs), an actively studied nano-object, can also be incorporated into electrospun fibers. The goal of most studies in this direction is to improve the electrical conductivity and mechanical strength of the fibers [21-25]. Some exciting properties were also

ion, followed by electrospinning to form Ag nanoparticle-filled composite

with the polymer/solvent system.

magnetic, and biological properties.

agent for the Ag+

tion photoreduction [20].

**3. Fabrication of nanofibers by electrospinning**

**3.1. Electrospun nanofibers with different composition**

parameters that control the composition and morphology are highlighted.
