The process parameters include the applied electric field, the distance from the tip of the needle to the collector, the flow rate, etc. The solution parameters include the type of solvent, the molecular weight of the polymer, the concentration of the solution, the viscosity of the solution, the conductivity of the solution, the surface tension, the dipole moment, and the dielectric constant. These factors can be divided into tree category: (i) Solution parameters (ii) process parameters and (iii) ambient parameters. In the electrospinning process, there are several factors that contribute to the fiber morphology. The schematic of the typical electrospinning process is given in Figure 1A. Depending on the spinneret, the electrospinning process can be divided into different types such as needle-less, single, coaxial, side-by-side, and tri-axial electrospinning. In electrospinning, the spinneret is the most important component, by which the multiple configurations can be implemented. During this process, the solvent evaporates and dry polymer fibers are randomly deposited on the collector. Upon further increasing the applied voltage, the charged jet is ejected from the Taylor cone and flows in the direction of the collector. When the intensity of the electric field is increased, the hemispherical surface of the solution elongates at the tip of the capillary and forms a Taylor cone. In the electrospinning process, a high voltage (typically 10 to 30 kV) is applied to a polymer solution in order to induce a charge on the surface of the droplet. A majority of the work has been focused on solution-based electrospinning. The nanofibers can be obtained either from polymer melt or solution. The standard electrospinning setup consists of four main components: a capillary tube containing a polymer solution (or melt), a spinneret or nozzle, a collector, and a high voltage source. Furthermore, this report also highlights the future challenges involved in utilizing core-sheath nanofibers for drug delivery applications. This paper summarizes the physical phenomena, the effects of various parameters in coaxial electrospinning, and the usefulness of core-sheath nanofibers in drug delivery. Numerous studies have reported on the preparation of core-sheath nanofibers by coaxial electrospinning for drug delivery applications. Employing a core-sheath design provides a promising solution for controlling the initial burst release. A drug loaded nanofiber membrane can be prepared via electrospinning using a model drug and polymer solution however, the release of the drug from the nanofiber membrane in a safe and controlled way is challenging as a result of the initial burst release. The use of electrospun nanofibers in drug delivery has increased rapidly over recent years due to their valuable properties, which include a large surface area, high porosity, small pore size, superior mechanical properties, and ease of surface modification. Electrospinning has emerged as one of the potential techniques for producing nanofibers.

Core shell fiber schematic drug loading