## 2 History of Electrospinning
### Electrospun Nanoparticles  
Due to its versatility, electrospinning is an extremely essential technique for the treatment of different fillers with disparate textural nature and properties, such as ceramic nanofibers, carbon nanofibers, whiskers and extracted natural polymer materials [27; 28]. The fabrication of fillers by the electrospinning method, results in the altered nano-structural orientation of the resultant fibrous materials, which possess significantly reduced dimensional size in order to produce outstanding mechanical responses as well as the necessary and essential biomedical activities. The diversity of structural identity, emanating from the processing effect, induced by the electric field of the electrospinning process can be distinctly categorized as core-shell, bead, porous and ribbon fibers. These structural orientations are observed by examining the electric response of the individual thread of the fiber. However, when the threads of the fiber reorganize, upon the grounded collector, the mats of different structural orientations are formed and the architectural blueprint leads to the generation of beaded, random, aligned, patterned yarns and 3D structural nanofibers [28; 29]. The electrospinning technique is the most preferred over others; on the account of its: (1) simplicity when utilized to a variety of materials and a very cost-effective method for nanofiber modification, (2) capacity to allow the introduction of bioactive compounds into the nanofibers and (3) utilization of the electrostatic force instead of heat during the processing of nanofibers, since heat can be detrimental to the structure of the highly thermal sensitive materials. Thus, the different nanofillers of disparate behavior and nativity can be, readily fabricated in order to afford nanofibers with desirable and efficient properties for various biomedical applications [30]. In recent years, a plethora of electrospun nanoparticles have been prepared by the electrospinning method in order to alter the dimensional size, for the formation of ultrafine nanofibers and also to attain a uniform porosity, which provides effective use in biomedical applications e.g., tissue engineering, wound dressing. For example, [PERSON] and co-workers [28] prepared the 3D Ni-multiwall carbon nanotubes/carbon fibers by the electrospinning method in order  
Figure 2: Illustration of a typical electrospinning process for the preparation of electrospun nanofibers. to afford a smooth surface hybrid material with diameters ranging between 20-30 nm, leading to a very efficient sensing capacity for detecting sarin nerve agent at 25 \({}^{\circ}\)C. Notwithstanding the impressive task that the electrospinning process possesses in the preparation of various nanomaterials with well-controlled nanofibrous size and refined porosity across the resultant membranes, factors such as the set-up for the electrospinning technique, conditions of an ambient environment and properties of the pristine nanoparticles, altogether, influence the diameters and the morphologies of the envisaged electrospun nanofibers. In general, these electrospinning parameters have an inevitable effect on the properties of the ensuing electrospun scaffolds as well as the morphological features in which the bioactive characteristics can either be augmented or deteriorated, depending on the ultimate purpose in a particular organ of the living organism. By treating raw particles, inter alia, inorganic, organic, natural or synthetic materials; using the electrospinning process is equivalent to the structural modification and control of the surface area-to-volume ratio that will promote the bioactivity of the resultant nanoparticles for use in various in-vivo and/or in-vitro applications.