A Mini-Review: Needleless Electrospinning of Nanofibers for Pharmaceutical and Biomedical Applications

Abstract

Electrospinning (ES) is a convenient and versatile method for the fabrication of nanofibers and has been utilized in many fields including pharmaceutical and biomedical applications. Conventional ES uses a needle spinneret for the generation of nanofibers and is associated with many limitations and drawbacks (i.e., needle clogging, limited production capacity, and low yield). Needleless electrospinning (NLES) has been proposed to overcome these problems. Within the last two decades (2004–2020), many research articles have been published reporting the use of NLES for the fabrication of polymeric nanofibers intended for drug delivery and biomedical tissue engineering applications. The objective of the present mini-review article is to elucidate the potential of NLES for designing such novel nanofibrous drug delivery systems and tissue engineering constructs. This paper also gives an overview of the key NLES approaches, including the most recently introduced NLES method: ultrasound-enhanced electrospinning (USES). The technologies underlying NLES systems and an evaluation of electrospun nanofibers are presented. Even though NLES is a promising approach for the industrial production of nanofibers, it is a multivariate process, and more research work is needed to elucidate its full potential and limitations.

Scale-up of Electrospinning: Market Overview of Products and Devices for Pharmaceutical and Biomedical Purposes

“…When using multi-needle spinnerets, needles clogging and the interference of close by needles will inversely impact the jet formation and final quality of the fiber mats. The improper configuration of collectors and downwards spinning of the jets result in beads or even interfere with fiber formation [ 56 ]. It is well known that natural polymers have gained increasing interest in pharmacy, but, unfortunately, it is challenging to fabricate NFs from starch and similar natural polymer from pure materials because they have no sufficient mechanical strength beside their relatively low thermostability; this means that without modification it will be impossible, taking into consideration that the modification processes may negatively impact the function of natural polymers [ 57 ].…”

“…Even though the ES technique is relatively simple and easy to handle, it faces many challenges that need to be managed in order to have fibers of a high quality [ 53 ], such as the inconsistent properties between different batches when using natural polymers such as silk fibroin [ 54 ], the toxicity problem resulting from a residual organic solvent, and the stability of active agents with thermal treatment [ 55 ]. Moreover, it is a relatively slow and time-consuming process, the quality of the final NFs is affected by the electrical field interference when using multiple needles to increase the production, the improper optimization of parameters will adversely affect or even interfere with fiber formation [ 56 ], and difficulty in the NF fabrication of native materials of plant origin, such as starch, necessitates some modifications that adversely interfere with the properties of native materials [ 57 ]. Different attempts to use needle-free technologies have been carried out to overcome the limitations, but further studies are needed to formulate NFs with improved quality that fit the pharmaceutical industry [ 56 ].…”

“…Moreover, it is a relatively slow and time-consuming process, the quality of the final NFs is affected by the electrical field interference when using multiple needles to increase the production, the improper optimization of parameters will adversely affect or even interfere with fiber formation [ 56 ], and difficulty in the NF fabrication of native materials of plant origin, such as starch, necessitates some modifications that adversely interfere with the properties of native materials [ 57 ]. Different attempts to use needle-free technologies have been carried out to overcome the limitations, but further studies are needed to formulate NFs with improved quality that fit the pharmaceutical industry [ 56 ]. Although the reviews that demonstrate the scale-up of ES technology have been rapidly growing recently, the majority of studies and reviews available mainly focused on the principle of ES, its applications, parameter optimization, and characterization; therefore, light must be shed on the different approaches that have been proved or exploited for massive NF production, particularly for pharmaceutical drug delivery.…”

Drug Delivery Applications of Three-Dimensional Printed (3DP) Mesoporous Scaffolds

“…Nanodimensional high specific surface area devices can be fabricated with bioactive loaded polymer through the electrospinning technique [ 63 ]. In a conventional electrospinning system, generally comprising of a high-voltage power supply, syringe, pump and a collector, polymeric nanofibers, inorganic nanofibers, and composite nanofibers are ejected into a sequence of droplets forming steady fiber [ 64 , 65 ].…”

A Charge-Based Mechanistic Study into the Effects of Process Parameters on Fiber Accumulating Geometry for a Melt Electrohydrodynamic Process

“…Melt electrowriting processes, as an emergent technology utilizing the principle of electro-hydrodynamics and additive manufacturing [1,2], have aroused wide interest due to its ability to produce polymeric scaffold with tunable microarchitecture [3][4][5][6] and morphology [7][8][9][10][11]. Moreover, the solvent-free characteristic of the process makes it amenable for a broad application scope for engineered tissues [12][13][14][15][16][17][18]. However, the printing fidelity of the engineered scaffold notably deteriorates when the printing toolpath is designed for larger layering dimensions [19] or smaller feature pore sizes [20].…”