Nanocapsule formation by electrospinning

In electrospinning, an electrostatic force draws a strand of fiber from a droplet of liquid, and can be used to make multilayered products. High voltage causes the build-up of surplus electrostatic charge in the droplet. The repulsive effect of like charges repel eventually become sufficient to overcome the common forces of surface tension that form the drop in to its onion-like shape, and a liquid stream is emitted in the direction of the nearest surface with a lower electrical charge. If a liquid strand has sufficient molecular cohesion, then as it solidifies by cooling from a melt, or losing solvent from a solution, it will form a continuous fiber. Otherwise the strand breaks up into droplets - electrospraying. Cohesion results from the tendency of long molecules to physically entangle or for smaller biomolecules such as glucose, intramolecular forces such as hydrogen bonding. The strength of influence of the electrostatic force results in fibers and droplets tending towards the nano-scale. Materials produced by this electrohydrodynamic method have are attractive to the food industry as technology for the controlled and extended release of bioactive substances. As an ambient condition process the method can use foodstuffs with damaging them, giving an attractive combination of reliable encapsulation with minimal probability of denaturing that maximizes the stability of the bioactive content. Consequently, there is potential for the development of novel electrospun fibrous or particulate products for the delivery of nutraceutical food complexes by providing a combination of coating to control the point of delivery in the gastrointestinal tract, and a high specific surface area to facilitate absorption. This chapter presents a full examination of electrospinning applications producing food-safe nanofiber products particularly for use as nano-carriers and for encapsulation.