Nanofibers and Electrosprayed Nanoparticles

Nanofibers are generated via the electrospinning technique. In this method, a high-voltage electrical field is applied to the droplets from the polymer solution and as a result the droplets are stretched due to the electrostatic repulsion that dominates the surface tension. Subsequently, the droplets will constitute a conical shape called “Taylor Cone” and as the field strength increases, a fluid jet is formed next to the spinneret tip that is stretched toward the collector. Rapid evaporation occurs under the electrical field and the yield is nonwoven nanoscale fibers (Bhushani & Anandharamakrishnan, 2014; Rieger & Schiffman, 2014). Electrospraying is another method in which nanoparticles are obtained by applying electrical forces. The difference in the content of the solutions justifies the difference between electrospraying and electrospinning. Accordingly, for low-concentrated solutions, the jet is destabilized because of varicose and ultrafine particles are obtained. On the contrary, if the concentration is high, the elongated droplets form nanofibers by whipping instability procedure (Bhushani & Anandharamakrishnan, 2014).

Perez-Masia, et al. (2015) exerted the electrospraying and nanospray drying approaches to encapsulate folic acid by using whey protein concentrate (WPC) and resistant starch as the components of the wall material. The thermal resistance and encapsulation efficiency of enveloped folic acid were evaluated under different conditions during storage. Altogether, the WPC network enhanced the encapsulation efficiency due to its interactions with folic acid and both techniques generated micro, submicron, and nanoscale particles, while electrospraying produced smaller capsules along with controllable size distribution. In another study, Wu, Branford-White, Yu, Chatterton, and Zhu (2011) produced polyacrylonitrile nanofibers to encase vitamin C and E. They used the coaxial electrospinning method to encapsulate the intended vitamins and obtained desirable delivery profiles that are proper for targeted delivery networks.

Stoleru, et al. (2016) employed the electrospinning technique to fabricate a bioactive dual coating composed of chitosan—vitamin E compounds that exhibited both biocidal and antioxidant properties. Also, vitamin E modified the rheological properties of the synthesized layer and caused a fluid-like state as its level was increased. Agarwal, et al. (2016) formulated cellulose acetate (CA) nanofiber mats loaded with vitamins B2 and C, and ZnO nanoparticles. The vitamin-loaded nanofibers revealed slow and controlled release compared to CA films that exhibited burst release, which can be implemented in oral delivery formulations. Li, et al. (2016) produced gelatin nanofibers loaded with vitamin A palmitate and E to be applied as wound-healing dressings. Whey protein isolate, zein, and soy protein isolate were employed in the structure of wall materials. By the addition of vitamins into the nanocarriers, the size of the fibers decreased; furthermore, the nanofibers loaded with vitamin A or E individually revealed a prolonged release for more than 60 h. When both vitamins were incorporated in the system, similar liberation properties were obtained. Finally, the in vivo assays suggested that these engineered dressings are proper candidates for wound-healing purposes in relation to the traditional methods.

Sheng, et al. (2013) fabricated silk fibroin nanofibers loaded with vitamin E. The entrapment of vitamin E in silk nanofibers protected skin fibroblast cells against oxidative stress caused by tert-butyl hydroperoxide. Overall, this vitamin delivery system has a great potential in skin care plus tissue regeneration and related subjects. Madhaiyan, Sridhar, Sundarrajan,

Venugopal, and Ramakrishna (2013) synthesized vitamin B12-bearing poly- caprolactone nanofibers and tested it for transdermal delivery. The morphology of the nanofibers was detected by the SEM apparatus; moreover, the pore size measurements and mechanical properties of the nanofibers were determined by running the related tests. The fibers were exposed to plasma and gradually made hydrophilic in order to heighten the vitamin release. Finally, by considering release rate in PBS buffer performed in the in vitro medium, the vitamin-loaded system was considered as an applicable formulation to be used in transdermal patches.

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