This paper outlines the story of the inventions and discoveries that directly relate to the genesis and development of electrostatic production and drawing of fibres: electrospinning. Current interest in the process is due to the ease with which nano-scale fibers can be produced in the laboratory. In 1600, the first record of the electrostatic attraction of a liquid was observed by William Gilbert. Christian Friedrich Schönbein produced highly nitrated cellulose in 1846. In 1887 Charles Vernon Boys described the process in a paper on nano-fiber manufacture. John Francis Cooley filed the first electrospinning patent in 1900. In 1914 John Zeleny published work on the behaviour of fluid droplets at the end of metal capillaries. His effort began the attempt to mathematically model the behavior of fluids under electrostatic forces. Between 1931 and 1944 Anton Formhals took out at least 22 patents on electrospinning. In 1938, N.D. Rozenblum and I.V. Petryanov-Sokolov generated electrospun fibers, which they developed into filter materials. Between 1964 and 1969 Sir Geoffrey Ingram Taylor produced the beginnings of a theoretical underpinning of electrospinning by mathematically modelling the shape of the (Taylor) cone formed by the fluid droplet under the effect of an electric field. In the early 1990s several research groups (notably that of Reneker who popularised the name electrospinning) demonstrated electrospun nano-fibers. Since 1995, the number of publications about electrospinning has been increasing exponentially every year.

One of the major challenges with microencapsulation and delivery of low molecular weight bioactive compounds is their diffusional loss during storage and process conditions as well as under gastric conditions. In an attempt to slow down the release rate of core material, electrospray fabricated calcium alginate microhydrogels were coated with low molecular weight and high molecular weight chitosans. Caffeine as a hydrophilic model compound was used due to its several advantages on human behavior especially increasing consciousness. Mathematical modeling of the caffeine release by fitting the data with Korsmeyer-Peppas model showed that Fick's diffusion law could be the prevalent mechanism of the release. Electrostatic interaction between alginate and chitosan (particularly in the presence of 1% low molecular weight chitosan) provided an effective barrier against caffeine release and significantly reduced swelling of particles compared to control samples. The results of this study demonstrated that calcium alginate microhydrogels coated by chitosan could be used for encapsulation of low molecular compounds. However, more complementary research must be done in this field. In addition, electrospray, by producing monodisperse particles, would be as an alternative method for fabrication of microparticles based on natural polymers.

Electrospraying nano- and micro-particle fabrication is a one-step, non-invasive process, which has application in encapsulating of thermosensitive functional, bioactive materials and cells and making microhydrogels. This study investigates the effect of various electrospraying process parameters on the characteristics of calcium alginate microhydrogel particles. The alginate solution concentration, CaCl coagulation bath concentration, voltage, nozzle diameter, distance between nozzle and collecting bath (D), alginate delivery pressure (∼H) were examined. The best droplet formation rate, in non-disperse dripping mode, was obtained at 8 kV using a 500 μm inner diameter nozzle tip, D = 8 cm, H = 20 cm. Morphology, swelling behaviour and texture analysis of the particles which were followed by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) confirmed that 1.5-2% (w/v) CaCl was the desirable concentration for hydrogels formation. Particle size range between 267 and 1500 μm could be obtained by the drip feed mode compared with 2.3-6 μm by the pressure-assisted electrospray through a coaxial head.

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The extract provided a physical barrier that limited the starch exposure to the digestion enzymes and water that led to reduction in starch digestion and the release of glucose.