Electrospun Environment Remediation Nanofibers Using Unspinnable Liquids as the Sheath Fluids: A Review

Abstract

Electrospinning, as a promising platform in multidisciplinary engineering over the past two decades, has overcome major challenges and has achieved remarkable breakthroughs in a wide variety of fields such as energy, environmental, and pharmaceutics. However, as a facile and cost-effective approach, its capability of creating nanofibers is still strongly limited by the numbers of treatable fluids. Most recently, more and more efforts have been spent on the treatments of liquids without electrospinnability using multifluid working processes. These unspinnable liquids, although have no electrospinnability themselves, can be converted into nanofibers when they are electrospun with an electrospinnable fluid. Among all sorts of multifluid electrospinning methods, coaxial electrospinning is the most fundamental one. In this review, the principle of modified coaxial electrospinning, in which unspinnable liquids are explored as the sheath working fluids, is introduced. Meanwhile, several typical examples are summarized, in which electrospun nanofibers aimed for the environment remediation were prepared using the modified coaxial electrospinning. Based on the exploration of unspinnable liquids, the present review opens a way for generating complex functional nanostructures from other kinds of multifluid electrospinning methods.

Core–Shell Eudragit S100 Nanofibers Prepared via Triaxial Electrospinning to Provide a Colon-Targeted Extended Drug Release

“…When the three-layer working fluids are all electrospinnable, the tri-fluid process is a typical triaxial electrospinning, and the products should be tri-layer core–shell fibers [ 68 ]. However, when the outer layer fluid is a pure solvent for lubricating the working process for a high-quality product, the nano products are double-layer core–shell fibers, and the tri-fluid process is a modified triaxial electrospinning [ 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. The essential meaning is that the outer solvent provides air–solvent and solvent–polymer solution interfaces, instead of a previous air–polymer solution interface, and thus the “dynamic atomization” process is completely modified.…”

“…The commercial pH-sensitive copolymer Eudragit S100 (ES100), which has a pH-dependent solubility [ 42 ], was exploited as the polymeric carrier and also the filament-forming matrix. A modified triaxial electrospinning [ 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ] was developed to create the core–shell ES100 nanofibers, in which a drug-free shell layer of ES100 is intentionally coated on a composite aspirin-ES100 core. The monolithic composite nanofibers (MCFs) with aspirin homogeneously distributed all over the ES100 matrix were prepared using a traditional blended electrospinning and were exploited as control.…”

In Vitro and In Vivo Comparison Study of Electrospun PLA and PLA/PVA/SA Fiber Membranes for Wound Healing

“…The advantage of electrospun fibers is their ability to mimic the extracellular matrix (ECM), thereby preventing scar formation by improving hemostasis and the absorption of wound exudate [3,11]. However, although electrospinning is now rapidly developing the coaxial [14], triaxial [15], side-by-side [16], and multifluid [17] processes for creating core-shell, trilayer core-shell, Janus, and other complex nanostructures, their applications are almost at the stage of concept demonstration [18]. How to deepen the real applications of electrospun fibers, even the commercial products, poses a big challenge to the researchers.…”

Electrosprayed Ultra-Thin Coating of Ethyl Cellulose on Drug Nanoparticles for Improved Sustained Release

“…In a broad meaning, the coating of polymer on a medicated core represents a shell section of a core-shell structure [38][39][40][41][42][43]. Electrospinning, as a brother technique of electrospraying, has broadly demonstrated its great power in creating core-shell nanofibers [44,45].…”