key: cord-0759923-b9gg8545
authors: Kchaou, Mohamed; Alquraish, Mohammed; Abuhasel, Khaled; Abdullah, Ahmad; Ali, Ashraf A.
title: Electrospun Nanofibrous Scaffolds: Review of Current Progress in the Properties and Manufacturing Process, and Possible Applications for COVID-19
date: 2021-03-16
journal: Polymers (Basel)
DOI: 10.3390/polym13060916
sha: 51216aa39ebca29ed6efaf5bda2f71fce1bdca59
doc_id: 759923
cord_uid: b9gg8545

Over the last twenty years, researchers have focused on the potential applications of electrospinning, especially its scalability and versatility. Specifically, electrospun nanofiber scaffolds are considered an emergent technology and a promising approach that can be applied to biosensing, drug delivery, soft and hard tissue repair and regeneration, and wound healing. Several parameters control the functional scaffolds, such as fiber geometrical characteristics and alignment, architecture, etc. As it is based on nanotechnology, the concept of this approach has shown a strong evolution in terms of the forms of the materials used (aerogels, microspheres, etc.), the incorporated microorganisms used to treat diseases (cells, proteins, nuclei acids, etc.), and the manufacturing process in relation to the control of adhesion, proliferation, and differentiation of the mimetic nanofibers. However, several difficulties are still considered as huge challenges for scientists to overcome in relation to scaffolds design and properties (hydrophilicity, biodegradability, and biocompatibility) but also in relation to transferring biological nanofibers products into practical industrial use by way of a highly efficient bio-solution. In this article, the authors review current progress in the materials and processes used by the electrospinning technique to develop novel fibrous scaffolds with suitable design and that more closely mimic structure. A specific interest will be given to the use of this approach as an emergent technology for the treatment of bacteria and viruses such as COVID-19.

Electrospinning is widely attractive to industry and researchers for its scalability, versatility, and potential applications in many fields [1, 2] . It is considered one of the most suitable techniques for fabricating nanofibrous scaffolds, which are known for their high physical porosity and huge potential to mimic defects, such as bone defects [3] [4] [5] . In terms of geometry, the diameter of each electrospun fiber depends on the polymer specificity and electrospinning processing parameters [3] . The electrospinning set-up consists of a high voltage source, an infusion syringe pump, and a collector; the collector might be stationary or portable metal or a coagulating bath [4] [5] [6] . Electrospinning technique produces more thinner, smoother, and folded scaffolds and achieves more uniform drug distribution with less residual liquid than the solvent casting [7] . Therefore, electrospinning induces well-controlled drug release profiles. In the next paragraph, the potential applications of nanofiber scaffolds will be further highlighted.

Nowadays electrospinning is a well-known technology and it has been under a thorough investigations. One of the earliest studies of the electrified jetting phenomenon has been published by Zeleny [8] ; in this paper the role of the surface instability in electrical discharges from charged droplets has been studied. A series of patents from 1934 to 1944 has been published by Formhals [9] [10] [11] [12] . These patents are mainly describing an experimental setup utilizing electrostatic forces to produce fine dried polymer filaments. Another apparatus for the production of patterned, ultrathin, low weight, non-woven fabrics by using electrical spinning has been filled by Simons [13] in 1966. A deformation of a charged liquid meniscus has been studied by Taylor [14] [15] [16] [17] , Taylor described a conical stable geometry at the end of the meniscus which is now known as a Taylor cone. In 1971, Baumgarten [18] used electrospinning apparatus to produce ultra-fine acrylic fibers with diameters below 1.1 µm down to 500 nm. Although the electrospinning process has been extensively studied by many researchers since then for several decades in the literature, many parameters are still under investigation and not yet completely understood [19] .

A research team in Akron University, USA lead by Professor Reneker [20] reintroduced the electrospinning technique to make submicron fibers from different types of synthetic and natural polymers. Yaril's team reported the production of hollow nanotubes by co-electrospining two polymer solutions (PCL and PMMA nanofibers) [21, 22] . Researchers particularly highlighted the desorption limited mechanism of release from polymer nanofibers [23] and discussed electrospinning jets in the form of a polymer fiber with a diameter that can often be conveniently stated in nanometers [24] .

Polyacrylonitrile (PAN) and copolymers of PAN are considered a very important candidate for electrospinning as they have commercial/ technological applications. Among various precursors of carbon nanofibers (CNFs), PAN is considered the best candidate, mainly due to its high carbon yield (up to 56%), flexibility and the ease of its heat treatment stabilization stage to form a stable Zigzag structure during nitrile polymerization [25] [26] [27] [28] [29] [30] [31] [32] [33] . Also, PAN has excellent characteristics, such as spinnability, environmentally friendly nature and varieties of commercial applications.

Inagaki et al. [34] describes the chemistry and applications of CNFs. Barhate and Ramakrishna [35] published a review on nanofibers as a filtering media for tiny materials. Li and Xia [36] discussed about the trends in nanofibers with emphasis on electrospinning techniques to produce nanofibers. PAN nanofibers and carbon nanotube (CNT) reinforced PAN nanofibers were successfully electrospun [37] . In our research team, Ali and et al. [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] published a series of publications studying the characteristics of the electrospun PAN/N, N-dimethylformamide (DMF) polymer solution using different types of collectors. Hot pressing technique has introduced as well to electrospun PAN nanofibers with and without nano reinforcements to produce carbon nano fibers. In their work optimization of the process for PAN nanofibers has been introduced by response surface methodology (RSM).

RSM has been used as a successful tool for optimizing the process in both polymer electrospinning and polymer hydrogels [50] [51] [52] . Process optimization of nanofibers has been investigated by RSM in order to predict the electrospinning parameters affecting the producing nanofiber diameter in order to achieve minimum fiber diameter in nano level. A quantitative relationship between electrospinning parameters and the responses (mean diameter and standard deviation) was established and then the final multi-layers structure of nanofibers and nanoparticles has been achieved for a controlled and robust process [53] [54] [55] .

In the last decade, nanofibers have been generated by electrospinning under pressurized CO 2 . In fact, an evolution of the traditional technique was clarified by several researchers by adding CO 2 in the liquid polymeric solution [56] [57] [58] . The presence of CO 2 in the solution reduced the surface tension of the liquid to be processed and its viscosity. Wahyudiono et al. [59] demonstrated that CO 2 dissolved in the starting liquid polymeric solution introduced greater flexibility in the process with respect to the classical technique by the production of micro-and nanofibers of poly(vinylpyrrolidone (PVP) through the adoption of a more advanced configuration of the process. Baldino et al. [60] reported a more developed technique called supercritical assisted electrospraying (SA-ESPR), in which the addition of supercritical CO 2 (sc-CO 2 ) to a starting polymeric liquid solution produced a controlled size of micro-or nanoparticles. Attempts to produce nano-composite (polymer + drug) using this electrohydrodynamic process have shown encouraging results in the last years [61] .

Electrospinning parameters are essential to understand not only the nature of electrospinning but also the conversion of polymer solutions into nanofibers through Electrospinning. These parameters that affecting electrospinning process and electrospun fiber diameters can be classified under three main categories named as: polymer solution, processing, and environmental.

These parameters can affect morphological characteristic of electrospun fibers as well as its size. A summary discussion of these parameters and their effect on fiber characteristics will be presented:

The concentration or Berry's number of a polymer solution or melt play a crucial role in fiber formation during the electrospinning process. Four critical concentrations from low to high should be noted:

When the concentration is very low, micro to nano beads will be obtained. Here, electrospraying occurs instead of electrospinning, owing to the low viscosity and high surface tensions of the solution [62] .

As the concentration increases, a mixture of fine beads and microfibers will be obtained [63] [64] [65] .

At a specific Berry's number and when the concentration is adequate, smooth nanofibers can be obtained.

At high concentrations, no nanofibers are obtained; helix-shaped, coil structures, and microribbons will be observed [66] .

In general, as the concentration or Berry's number of solution or melt respectively increases the fiber diameter increases within the spin-able range.

Molecular weight of the polymer reflects the degree of polymer chain entanglement in solutions accordingly indicating solution viscosity. In case of keeping the concentration fixed, as molecular weight of the polymer decreases beads formation rather than smooth fiber is the probability. Enhancing molecular weight value results in smooth fiber. Increasing in molecular weight results in micro-ribbon formation [67] .

It is also important to note that by increasing molecular weight even with low concentration micro-ribbon could be formed [68, 69] .

Viscosity of polymer solution is considered one of the most important parameters affecting electrospun fiber diameter and morphology. There is a suitable viscosity for the electrospinning to form fiber [70, 71] . Group of publications on the correlation between polymer solution viscosity and formation of electrospun fiber have been published [67, 72, 73] . Concentration, viscosity and polymer molecular weight all are correlated to each other and one parameter has been used to describe them all named Berry's number it measures the degree of chain entanglement inside the solvent and can be calculated by the product of concentration by intrinsic viscosity. Ali and et al. [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] correlates such parameter with the optimization of electrospun PAN fibers.

Surface tension is important factor in electrospinning. In 2004, Yang and Wang investigated the influence of surface tensions on electrospun PVP fibers with three different types of solvent namely ethanol, DMF, and MC [66] .

As the surface tension of the solution decreases, beaded fibers can be converted into fine fibers [74] [75] [76] [77] [78] [79] [80] . Also, in this study, the surface tension and solution Viscosity can been adjusted by changing the mass ratio of solvents mix and fiber morphologies.

If all other conditions are constant, surface tension identifies the upper and lower boundaries of the electrospinning window [77, 79] .

Solution conductivity is specified by polymer bond type, solvent solubility parameter and any other additives such as salt due to its ionic bond type. Usually, natural polymers are polyelectrolytic in nature, in which the ions increase the charge carrying ability of the polymer jet, subjecting to higher tension under the electric field, resulting in the poor fiber formation on the other hand the synthetic polymers are tending to form good fibers [80] . With the aid of ionic salts, nanofibers with small diameter can be obtained [81] .

Sometimes high solution conductivity can be also achieved by using organic acid instead of regular solvent. Hou et al [81] used formic acid as the solvent to dissolve nylon 6,6 and obtained nano fibers of 3 nm diameter with beads. In their study, small amount of pyridine has been added into the solution to enhance capacity of solution to carry charge aiming to eliminate the beads by increasing the conductivity of the solution. In general, increase in the solution conductivity the more possibility of formation of thinner fibers especially in synthetic polymers.

One of the important parameter in the electrospinning process is the applied voltage value. Only if the applied voltage overcomes the surface tension of the polymer meniscus then an ejected jet comes out from Taylor Cone. However, increasing in the value of applied voltage does not in the favor of the characteristics of the electrospun fiber diameter or/and morphology. Reneker and Chun [82] have proved that there is not much effect of electric field on the diameter of electrospun polyethylene oxide (PEO) nanofibers. Several groups suggested that higher voltages than required to form ejected charged jet implies to form large fiber diameter. Zhang et al [79] theoretically studied the effect of voltage on morphologies and fiber diameters distribution with poly (vinyl alcohol) (PVA)/water solution in a theoretical modeling approach.

Another research groups showed that higher applied voltages may be increase the electrostatic repulsive force on the charged jet and accordingly smaller fiber diameter can be formed. Yuan et al [83] investigated the effect of applied voltage on morphologies and fiber alignment with polysulfone (PSF)/DMAC/acetone as model. In addition to those phenomena, some groups also demonstrated that higher voltage offers the greater probability of beads formation [62, 84, 85] .

Definitely and at the end of the previous discussion voltage does influence fiber diameters. However, the significance level differs according to polymer type, solution concentration and finally the distance between the tip of the spinneret and the nearest point on the collector [86] .

Another important processing parameter is the polymer solution flow rate. Generally, lower flow rate is more recommended as the polymer solution will get enough time for polarization. If the flow rate is very high, bead fibers with thick diameter will form rather than the fine fiber. That can be easily explained due to the short drying time period that the travelling jet has taken until it reaches the collector. Yuan et al [83] studied the effect of the flow rate on the morphologies of the PSF fibers from 20 % PSF/DMAC solution at 10 kV. In their study, bead fibers with thicker diameters obtained as the flow rate is 0.66 mL/h.

Metal collector is acting as the conductive substrate (ground) to collect the charged fibers. Aluminum foil is used as a cover sheet attached to the stationary metal grounded screen but it is difficult to transfer the collected nanofibers to other substrates for various applications. With the need of fibers transferring, diverse collectors have been developed including cone [87] , pin [88] , metal grids [89] , parallel or gridded bar [46] , rotating rods, cylinder or wheel [90] , wet coagulating bath [91] .

Traveling distance between the tip of the charged spinneret and the nearest point of the grounded collector certainly affect the fiber diameter and its morphologies [73] . Conceptually, as the travelling bath increases more time is consumed by the travelling jet and more chance and possibility of getting rid of the solvent and consequently drying of the jet into fine fiber on the collector surface is expected [83] .

Temperature and Humidity are two important environmental parameters that can also affect the fiber diameters and its morphologies. Mituppatham et al. [92] proved that as temperature increases smaller and thinner fiber diameter is collected.

Low humidity tends to dry the solvent totally and increase the velocity of the solvent evaporation. On the contrary, high humidity will lead to thicker fiber diameters. Casper et al. [93] demonstrated that the variety of humidity can also affect the surface morphologies of electrospun polystyrene (PS) fibers.

Tissue engineering integrates science of biology and medicine to design artificial organs for regeneration of tissue function [94, 95] . In order to mimic the extracellular matrix and provide tissue with oxygen and nutrient circulation, functional tissues were fabricated from several materials and specific structures, particularly nanofiber scaffolds [96, 97] . In fact, nanofiber scaffolds are widely used in tissue repair, whether soft or hard regeneration [98] . Faced with therapeutic problems, damaged ligament, fracted bone cartilage, and blood vessels were restored, taking advantage of ENS to repair orthopedic tissues and/or develop organs with high similarity in term of characteristics, properties, and design [99] [100] [101] . Exploring their characteristics, ENS is used for wound healing. In fact, it is considered a solution for the loss of skin integrity caused by injury or illness. It provides additional biological stimuli to support cell and tissue function. As consequence, substantial psychological balance is noticed in the tissue-engineered skin patients [102] [103] [104] .

Exploring the ability to control biomaterial properties (geometry, fiber alignment fiber diameter, composition, etc.), ENS are used to incorporate drugs/proteins into scaffold [104] . In fact, known for its large surface-to-volume ratio, it was demonstrated by several researchers that ENS could be a perfect vehicle for drug delivery, either by dissolving the drug into the electrospinning solution or by mixing the drug with this solution when the drug is not soluble [105] [106] [107] . As consequence, the drug contained inside in the fiber will be released. Several solutions are used to master the adsorption of a drug, particularly when the solubility of the drug is limited. Pillay et al. [108] proposed an immersion step of nanofibers into a drug solution to let the drug molecules chemically and physically bond or attach to the ENS. Yoo et al. [109] demonstrated that nanofiber can biomimetically bind to a drug after electrospinning by controlling physical adsorption (both when we use simple physical adsorption or nanoparticle assembly on the surface or even layer by layer-by-layer multilayer assembly). Chemical adsorption methods can be explored by surface activation (such as plasma or ultraviolet treatments) or bioactive molecule immobilization [110, 111] .

The reliability of the drug delivery application is conditioned by the drug-polymer compatibility, as well as the foreign body's interaction with natural organ or tissue [112, 113] . Varied results were noticed using drugs with different bioactivities, such as antimicrobial [114, 115] , anticancer [116, 117] , anti-inflammatory [118, 119] , cardiovascular [120, 121] , or antihistamine [122, 123] drugs. Another factor that can influence the drug-release kinetic is the type of the polymer used as a matrix for the nanofiber's elaboration and its architecture (sandwiched with microparticle, sandwiched with microfibers, etc.) [124] .

For protein delivery, surface immobilization of bioactive molecules has been used to load proteins into ENS fibers to protect the molecules from the effects of high voltage [125] . The method consists of the fixation of the protein scaffolds surface using suitable chemical conjugation with corresponding functional groups, such as carboxylate [126] . It was reported by Tigli et al. [127] that cell fate powered by peptides is conditioned by the control of the drug feeding ratio.

Cancer has become a leading disease, causing human death worldwide [128] . Cancer is responsible for 15% of human deaths worldwide, with 1.5 million new cases expected annually. Chemotherapy, hormonal therapy, radiation therapy, immunotherapy, and surgery are the current standard methods of treatment. Chemotherapeutic drugs in clinical use such as 5-fluorouracil (5-FU), cisplatin, carboplatin, paclitaxel, gemcitabine (Gemzar), etc. are characterized by either poor bioavailability, poor selectivity and specificity, or by liver accumulation and fast renal clearance [129] . Nanotechnology's evolution offers promise to tackle these problems. For instance, anticancer drug-loaded polymeric nanoparticles (NPs) are advantages to traditional anticancer drug formulations in terms of diminishing the adverse effects of drugs and enhancing their therapeutic efficacy. Generally, through the enhanced permeability and retention effect, some NPs are accumulated preferentially in tumors. Additionally, electrospun nanofibers (NFs) formulation became a promising techniquein the delivery of drug [130] and wound dressing [131] . Due to their high porosity and important surface area to molar ratio that mimics the extracellular matrix, they gained their importance in biomedical engineering [132] . Examples of these formulations include encapsulation of anticancer drugs into biodegradable polymeric nanofibers; 5-FU and salinomycin on poly(lactic-co-glycolic acid) (PLGA) [133] ; Paclitaxel on PCL [134] ; Doxorubicine HCL-block-poly(ethylene glycol)-block-poly(L-lactide) (HCl on PEG-PLLA) [135] , hydroxycamptothecinon (Poly(lactic acid)−Poly(ethylene oxide)) PLA-PEG [136] .

Pawłowska et al. [137] highlighted the development of smart drug delivery systems using the stimuli-responsive electrospun nanofibers. Their developed nanoctruture pillows have the specificity of fast photothermal responsiveness for near-infrared (NIR) light-controlled on-demand drug delivery. The innovative platform consists of electrospun PLLA loaded with a rhodamine B drug model that encapsulates platonic hydrogel P(NIPAAm-co-NIPMAAm)/AuNR [138] . The researchers demonstrated that this emergent nanotechnology is considered an excellent candidate for achieving on-demand drug release in synergy with photothermal treatment.

As reported in many publications, technical reports, and communications, ENS are used in the biosensing [137, 138] , agriculture protection [139, 140] , the fermentation food industry [141, 142] , and biocatalytic remediation of the environment and energy [143, 144] . In fact, to monitor food and agriculture using simpler, faster, and less expensive sensitive detection methods of foodborne illness, researchers and developers have exploited the potential given by the electrospinning technique to innovate 1D micro-and nanobiosensors [145] . Taking into account the surface properties, the high level of porosity, and the capability to interact with green elements, nanofibers have been functionalized with several types of nanomaterials such as graphene and carbone nanotubes to acquire the singularity of multifunctional hybrid electrospun nanofibers. These specificities enhance the reactivity of the materials, improve adsorption, and increase the sites' numbers of catalysts loading and interacting. Zhang et al. [146] proved that the quality of such biochemical sensors is attributed to the strong stretching forces associated with electrospinning that induce polymer orientation along the longer axis of the fiber chains. Therefore, high charge-carrier mobility or polarized photoluminescence can be created [147] . Recent laboratories have incorporated new nanomaterials to create what is called ESN-based chemical and hybrid biosensors, which have been applied in the agri-food sector to address food quality and safety [148] [149] [150] . The conjugated use of polymer, ceramic, and inorganic other materials are reviewed by Mercante et al. [151] . In another branch of this very fertile sector, researchers used biocompatible ESN to entrap bioactive food ingredients, both hydrophilic and hydrophobic types [152] . Besides, they synthesized a food encapsulation method based on ESN to safeguard food from oxidation and damage [153, 154] . Other researchers have produced ultra-fine poly(acrylamide) PAM fibers for use as a water super-absorber and soil erosion resistant agent in irrigation systems [155] . By electrospinning a 290 nm fiber diameter, the optimization of Berry's number, spinning height, and spinning angle on PAM fiber was investigated based on empirical and experimental approaches.

Th application of ESN in environment topics and issues is varied, from energy harvesting/conversion/storage to filtration membranes and catalytic supports [156] [157] [158] . In fact, specific devices made in ENS were developed and incorporated as solar cells, rechargeable batteries, and fuel cells [159] . Exploring the possibility to electrospin metal oxides and/or carbon nanofibers, they can be used as electrode materials thanks to their properties such as high surface-to-volume ratio, short diffusion distance, and large specific surface area [160] . As a consequence, they are able to rapidly transfer electrons and ions, with a large electrode/electrolyte contact area [161] .

As reported by [162] [163] [164] , the mass transport of reactant is feasible using a nonwoven mat of nanofibers. In fact, thanks to their high porosity level and their good interconnection, extensive contact between reactants and active sites on electrocatalysis are provided to fabric fuel cells, particularly from polymer, ceramic, and metal electrospun nanofibers. Their durability and efficiency were confirmed by several researchers and industries [165, 166] .

Nowadays, great efforts are focused on innovation in the design of biomimetic electrospun scaffolds for biotechnological applications. Natural and synthetic polymers as well as ceramic and metallic materials have been tested to improve properties and structure architecture.

Biomimicry is a technologically oriented approach focused on creating innovative solutions that are inspired by nature's wealth [167, 168] . In relation to our topic, researchers have concentrated on a few key sources of inspiration, in terms of shape, function, materials, or ecosystem [169, 170] . They benefit from the easily tunable compositions and structures of electrospun fibers to successfully biomimic via electrospinning.

Wei et al. [171] reported the design of nacre-inspired porous scaffolds for bone repair. Their work was the result of product design strategy that included electrospinning, phase separation, and 3D printing to elaborate layer-by-layer a composite film with nacre-like structure from nano-platelets and polyamide. Nacre has also inspired newly developed coatings and implants (from simple to complex geometries) that functionalize the biomaterials surface in order to induce desirable biological responses [172] [173] [174] .

Wang et al. developed engineered biomimetic superhydrophobic surfaces of electrospun nanomaterials inspired by the lotus leaf [175] . The same property was explored by investigated silver ragwort leaf and hillock bush leaf [101, 176] . Other researchers have focused on the biomimetic of structure and functions of honeycombs, polar bear fur, and spider webs to inspire tissue structure and organ architecture (membrane, bone marrow, etc.) [177, 178] .

To electrospin submicrometric fibers, a panel of materials can be used, from a natural source such as gelatin or collagen to a material from a synthetic category such as polycaprolactone (PCL) and polylactide (PLA), as well as to hybrid types (e.g., PCL blended with collagen) [179] [180] [181] [182] [183] .

Cell adhesion, migration, spreading, and differentiation are the essential characteristics related to the nanofiber surface's stiffness. In fact, after implementation, a successful integrated scaffold should provide good mechanical properties in terms of rigidity and flexibility, with an optimal porosity size and calibration [184] . Pennel et al. [185] made a direct relation between the infiltration and vascularization ability of the new material and its continual stability. Liu et al. [186] demonstrated that polylactide co-trim-ethylene carbonate nanofibers showed enhanced efficiencies as scaffold materials for tissue regeneration. Bao et al. [187] developed multifunctional fibrous scaffolds with shape memory specification. They were especially useful for tissue repair. Many other polymers such as chitosan, alginate, and silk fibroin have been explored for the production of healing mechanisms due to their biodegradability, drug release ability, acceptable hydrophilicity, and non-toxicity [188] [189] [190] [191] [192] [193] . From the animal resource, a polymer solution is developed. Membranes with or without active agents are obtained by electrospining. The cultivation and separation process are operated to create new cells with antibacterial properties.

An appropriate cellular environment is required to assume available scaffold architecture. This architecture is the result of various special arrangements (aligned, random, or cross aligned) [194] . These arrangements should ensure neo-tissue elaboration and proliferation, vascularization, and integration without risk to the original tissue [195] . Lutzweiler et al. [196] considered that the most sensitive property of a scaffold's structure is its ability to diffuse nutrients and metabolites thanks to an optimal pore size and stable architecture. It needs a suitable design for cell migration into scaffold and necessary ligand density on the scaffold surface [197] . According to the principle of regeneration, it should be gradually replaced with extracellular matrix, taking into account the biodegradability of the developed tissue, without any risk of toxication or surrounding organ disturbance [198, 199] .

Other progress related to the architectural point of view consists of the development of gradient structures to tailor cell orientation and their extracellular matrix deposition [200] . The evolution is related to the fabrication of scaffolding with random and aligned fibers on one section. As a consequence, a graded mechanical property throughout the tissue constructs is possible [201] .

The electrospun nanofibers' properties such as morphology and diameter are influenced by intrinsic (solution properties) and extrinsic (process and environment) factors [202] [203] [204] . Dorati et al. [205] reported that solvent concentration, viscosity, electrical conductivity, and elasticity are the most influential parameters on the geometry and morphology of electrospun nanofibers. In fact, to run electrospinning components, a researcher needs a small amount of solution with a suitable concentration to achieve a smooth and uniform nanofiber. Both low or high concentrations could induce a morphological problem or diameter variations according to the interaction of the solvent concentration with the viscosity and the surface tensions effects [206, 207] . As consequence, non-uniform shape and non-mastered diameters of nanofibers have a great probability of being detected. Datta and Dhara [208] combined microfabrication and rolling process to design 3D bone grafts based on 2D ENS of synthetic polymer. This approach needed a graphical design of macro-pore that could be created by a laser-engraving machine on EN sheets to facilitate cellular infiltration into the 3D scaffold. Finally, multi-scalar porosity was rolled up to obtain a 3D scaffold, which was associated to the microfabricated nanofiber sheets for a final bio-engineered organ.

As more sophisticated method, a robocasting 3D printing technique was used to develop an electrospun organ with a complex structure, paving a new way to developing unprecedented scaffold microstructure [209, 210] . A considerable amount of software is needed to control geometry, architectural structure, and manufacturing parameters to result in more closely mimicking material and highly efficient biomedical scaffolds [211] . Table 1 . summarizes the most important applications of the electrospun nanofibrous scaffolds. 

Polymer and Solvent Used Product Characteristics Ref.

A siliceous sponge spicules (SSS) and polylactic acid (PLA).

A nanofiber composite (PLA/SSS) of 50-450-nm with enhanced thermal and mechanical properties; a slight enhancement in human foreskin fibroblast cell proliferation; a decent cytocompatibility; and antibacterial [212] A gelatin solution prepared in ethanol extracted from Crude Carissa Carandas fruits (CCE) and incorporating acetic acid.

A smooth and continuous gelatin fibers mats (GFM) with an average diameter of 235.69 ± 10.45 nm. could be obtained with the optimal conditions of 30% (w/v) gelatin solution, 25% (v/v) ethanol solution, 30% (v/v) acetic acid, a fixed electrostatic field strength of 20 kV and a 15 cm distance between spinneret tip and collector. When 15% (w/w) CCE is used, the CCE-GFM shows high DPPH radical scavenging and tyrosinase inhibitory activity. [213] Anionic surfactants added to a natural biopolymer of galacturonic acid (PGuA) to enable its electrospinning to nanofibers.

Small spindled fibers of 2 to 10 µm length and 287 to 997 nm diameter. Large continuous fibers could be produced when an amount of 10 to 30% of high molecular weight PVA is used.

[214]

Drug Delivery A poly(vinylpyrrolidone)/PVP electrospun to encapsulate β-carotene dissolved in ethanol.

PVP/β-carotene composite nanofibers of 176 to 306 nm average diameter were able to protect the β-carotene properties [215] A blend of poly (ε-caprolactone) and poly (ethylene oxide) (PCL/PEO) incorporating a nanosized hydroxyapatite (n-HA) to carry curcumin.

A nanofiber material with slow release rate of curcumin and with a high cytotoxicity against breast cancer cell line [216] Chitosan/pullulan carried by a shell of polylactic acid (PLA)

A nanofiber with improved thermal properties and rapid dissolving capability in water. [217] Tissue engineering A platelet-derived growth factor (PDGF-BB) contained within a shell of polylactic acid (PLA) and encapsulated within nanofibers A 3D scaffolding nanofibers with microporous structure, acceptable mechanical properties and high cell compatibility.

[218]

Crystalline cellulose (NCC) in a matrix of cellulose acetate (CA) polymer.

a bio-tissues of nanofibers with uniform diameter, moderate thermal properties and improved mechanical properties of 30 MPa tensile strength and 1.597 MPa module of elasticity.

[219]

A blend of poly(ε-caprolactone), poly(ethylene glycol), poly(ε-caprolactone) (PCEC) along with polylactide (PLA).

A biodegradable polylactide (PLA)/PCEC fibrous membranes compatible with bone tissues.

[220] Cancer therapy A poly(ε-caprolactone) (PCL) A scaffolding system of long nanofibers to carry breast cancer therapy [221, 222] Wound dressing A zein/Graphene oxide (GO) blend. The GO is loaded by Tetracycline hydrochloride (TCH).

A nanofiber composite with enhanced mechanical properties and improved release profile.

[223]

Gene delivery A biopolymer incorporating nano-hydroxyapatite (nHAp) modified with linear polyethylenimine (LPEI), and poly(ε-caprolactone) (PCL).

A homogeneous and cohesive composite with structural characteristics, swelling and degradation behavior dependent on the size and amount of the included inorganic particles.

[224]

Filter media. A poly(ε-caprolactone) (PCL) Nanofibers (NF) of average diameters of 180 and 234 nm with improved bioprotective activity and filtration efficiency [225, 226] 

COVID-19 is a disease caused by a new kind of coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) manifested in Wuhan, Hubei, China at the end of 2019 [227] . This novel coronavirus can cause fever, respiratory failure, septic shock, and even death. Researchers believe that SARS-cov2 has zoonotic origin as bat coronaviruses, pangolin coronaviruses, and previously discovered SARS-CoV [228] . To date, COVID-19 is expected to greatly impact society and the economy and to widely change our daily lifestyle [229] . Despite the number of research studies, the high kinetics of publication, and global strategies in relation to this pandemic [230] [231] [232] , development of protection methods and solutions and the search for an efficient, well-controlled, and accurate means of drug dose delivery, especially with regard to the respiratory system of newly infected COVID-19 patients by using biodegradable electrospun polymer, are still considered potential issues until an effective vaccine is developed and made widely available [233] .

As soon as the pandemic appeared, Tebyetekerwa et al. [234] innovated unique electrospun nanofibers for filtration membranes in face masks. They proposed the use of durable and yet reliable electrospun nonwoven filters with 10 nm fiber diameter, as the filtration efficiency of polymeric nanofibers mats is excellent and can adsorb submicronic and nanosized organisms [235] .

In this context, Zussman's research group developed a sticker to upgrade surgical masks called "Maya" [236] . This innovative product showed successful results in the protection of respirators, trapping nanometric particles and, thanks to new functionalities given by the electropunk nanofibers, efficiently neutralizing the virus from droplets that might reach the mask surface. Bin Ding's team developed other types of masks using nanofibrous membrane-based desiccants for energy efficient humidity control and atmospheric water harvesting [237] . The new technology of a wood-inspired moisture pump was adapted based on electrospun nanofibrous membrane for solar-driven continuous indoor dehumidification.

Other smart masks were developed by DooKim's group, which was exploring electrospun nanostructure performance [238] . The researchers designed a membrane to use as an additional filter for tissue-based face masks. Thanks to its nanostructured arrangement with 100-500 nm dimeter fibers, this electrospun membrane showed an excellent filtering efficiency even after being hand washed more than 20 times.

Another new generation of masks using electrospun nanostructure was proposed by Sio et al. [236] . They developed smart self-disinfecting face masks based on a multilayer electrospun membrane. They introduced nanoclusters and plasmonic nanoparticles with a hierarchical arrangement to realize chemically driven and on-demand anti-pathogen activities.

Suitable disinfection methods and protocols should be produced so filters can be reused without compromising filtration efficiency. Khanzada et al. [239] developed aloe vera and polyvinyl alcohol electrospun nanofibers for protective clothes. The efficiency of the innovative product was confirmed by using antimicrobial activity tests to check against Gram-positive and Gram-negative bacteria. An optimum composition for highantimicrobial activity against S. aureus, compared with E. coli bacteria was patented. For possible use as a fast absorbent carrier of anti-COVID-19 drug delivery, some researchers are trying to prepare scaffolding that would be able to carry such drugs while controlling the degree of a drug's absorption by the human body-something that would be indispensable [240, 241] . However, this new applied nanotechnology is not yet mastered for use with newly discovered drugs.

Based on our review study, it is clear that electrospun nanofiber scaffolds are still facing many challenges with relation to the choice of materials (properties, performance, etc.), production policy (complexity, process, rate, etc.), and manipulation (scaffold storage, cost, etc.). In some applications, such as drug delivery, the improvement of drug-polymer compatibility is a primary focus for biologists, with the need to ameliorate the rate of matrix hydration and drug diffusion of the fiber-comprising polymer. Besides, ENS encounter some other practical limitations, such as scare cell infiltration and inadequate mechanical strength for load-bearing application, for example. Therefore, researchers are still focused on innovation in design, material, and architecture, as well as innovation in the manufacturing process. 

Review for Application of Electrospinning and Electrospun Nanofibers Technology in Textile Industry

Electrospinning: A fascinating fiber fabrication technique

An Introduction to Electrospinning and Nanofibers

Electrospinning Over Solvent Casting: Tuning of Mechanical Properties of

Electrospun Flexible Self-Standing γ-Alumina Fibrous Membranes and Their Potential as High-Efficiency Fine Particulate Filtration Media

Industrial Upscaling of Electrospinning and Applications of Polymer Nanofibers: A Review

Comparison of Electrospun and Solvent Cast Polylactic Acid (PLA)/Poly (vinyl alcohol) (PVA) Inserts as Potential Ocular Drug Delivery Vehicles

Instability of Electrified Liquid Surfaces

Processing and Apparatus for Preparing Artificial Threads

Method of Producing Artificial Fiber

Production of Artificial Fibers Forming Liquids

Method and Apparatus for Spinning. U.S. Patent 2349950

Process and apparatus for producing patterned non-woven fabrics

Disintegration of Water Drops in an Electric Field

Stability of a Horizontal Fluid Interface in a Vertical Electric Field

Electrohydrodynamics: A Review of the Role of Interfacial Shear Stresses

Electrically Driven Jets

Electrostatic spinning of acrylic microfibers

Electrospinning Process and Applications of Electrospun Fibers

Electrospun Polyaniline/Poly(Methyl Methacrylate)-Derived Turbostratic Carbon Micro. Nanotubes

Electrospinning Jets and Polymer Nanofibers

Desorption-Limited Mechanism of Release from Polymer Nanofibers

Electrospinning and the formation of nanofibers

Preparation and Electrochemical Characterization of Ionicconducting Lithium Lanthanum Titanate Oxide/Polyacrylonitrile Submicron Composite Fiber-Based Lithium-Ion Battery Separators

Vinyl and Related Polymers

Experimental Evaluation of Man-Made Fibre Brittleness

A Review of Heat Treatment on Polyacrylonitrile Fiber

Alkaline Hydrolysis of Polyacrylonitrile; on the Reaction Mechanism

Polyacrylonitrile-Based Nanofibers-A Atate-of-the-Art Review

Structure and Properties of Carbon Nanotube Reinforced Nano-Composites

Ultra-Fine Carbon Fibers and Fibrous Structures From Electro-Spun PAN Polymer Solution

Electrospinning of Continuous Carbon Nanotube-Filled Nanofiber Yarns

Review Nanofibrous Filtering Media: Filtration Problems and Solutions from Tiny Materials

Electrospinning of Nanofibers: Reinventing the Wheel?

Preparation of Carbon Nanotube Embedded in PAN Nanofiber Composites by Electrospinning Process

Wet Electrospun Nanofibers

Electrospinning Optimization for Precursor Carbon Nanofiber

Self-Assembled Ultra-Fine Carbon Coils by with Electrospinning

Presented at Synthesis, Characterization and Industrial Applications of Nanoparticles and Nanostructure Materials Work Shop hosted by MuCSAT and NSF

Hot-Pressed Electrospun PAN Nanofibers: An Idea for Flexible Carbon Mat

Wet-Electrospun CuNP/Carbon Nano Fiber Composites: Potential Application for Surface Mounted Component

Electrospun EGNPs/PS Ultra-Thin Fibril Composites: An Idea for Luminescence and Thermal Controllable Strong Fabrics

A Novel 3-D Graphite Structure from Thermally Stabilized Electrospun MWCNTs/PAN Nanofibril Composite Fabrics

Hot-Pressed Electrospun MWCNTs/Carbon Nano Fibril Composites: Potential Applications for Breaking Pads and Journal Bearings

Mechanical and Tribological Properties of Hot-Pressed Electrospun MWCNTs/Carbon Nanofibril Composite Fabrics

Electrospun Precursor Carbon Nanofiber Optimization by Using Response Surface Methodology, I WIN EG 29-30

A Novel Polystyrene/Epoxy Ultra-Fine Fabric by Electrospinning

Regeneration of Bombyx Mori Silk by Electrospinning, Part 2. Process Optimization and Empirical Modeling Using Response Surface Methodology

Response Surface Methodology Modeling of Diamond like Carbon Film Deposition

Response Surface Methodology Applied to Silicon Trench Etching in Cl2/HBr/O2 Using Transformer Coupled Plasma Technique

Application of Empirical Modeling in Multi-layers Membrane Manufacturing

Design and Analysis of Experiments

A Mathematical Modeling for Electrochemical Turning

Controlling the Composition, Morphology, Porosity and Surface Chemistry of Lignin-Based Electrospun Carbon Materials

Electrospun Melamine-Blended Activated Carbon Nanofibers for Enhanced Control of Indoor CO 2

Recent Advances in Carbon Nanofibers and Their Applications A Review

Formation of PVP Hollow Fibers by Electrospinning in One-Step Process at sub and Supercritical CO 2

Supercritical Assisted Electrospray: An Improved Micronization Process Lucia Baldino, Stefano Cardea and Ernesto Reverchon

A Supercritical CO 2 Assisted Electrohydrodynamic Process Used to Produce Microparticles and Microfibers of a Model Polymer

The effect of Processing Variables on the Morphology of Electrospun Nanofibers and Textiles

Bead-to-fiber Transition in Electrospun Polystyrene

Beaded Nanofibers Formed During Electrospinning

The Change of Bead Morphology Formed on Electrospun Polystyrene Fibers

Influence of Solvents on the Formation of Ultrathin Uniform poly (Vinyl Pyrrolidone) Nanofibers with Electrospinning

Effect of Molecular Weight on Fibrous PVA Produced by Electrospinning

Study on Correlation of Morphology of Electrospun Products of Polyacrylamide with Ultrahigh Molecular Weight

Electrostatic Fiber Spinning from Polymer Melts, Experimental Observations on Fiber Formation and Properties

Regeneration of Bombyx Mori Silk by Electrospinning-part 1: Processing Parameters and Geometric Properties

Preparation and Characterization of a Nanoscale Poly (Vinyl Alcohol) Fiber Aggregate Produced by an Electrospinning Method

Biological Efficacy of Silk Fibroin Nanofiber Membranes for Guided Bone Regeneration

Role of Molecular Weight of Atactic Poly (Vinyl Alcohol) (PVA) in the Structure and Properties of PVA Nanofabric Prepared by Electrospinning

Electrospinning of Gelatin Fibers and Gelatin/PCL Composite Fibrous Scaffolds

Trends in electrospinning of natural nanofibers. Phys. Status solidi

Electrospun Poly(e-caprolactone) Microfiber and Multilayer Nanofiber/Microfiber Scaffolds: Characterization of Scaffolds and Measurement of Cellular Infiltration

Study on Morphology of Electrospun Poly(Vinyl Alcohol) mats

Structure and Process Relationship of Electrospun Bioabsorbable Nanofiber Membranes

Electrospun Polymer Nanofibres with Small Diameters

Nanometre Diameter Fibres of Polymer, Produced by Electrospinning

Morphology of Ultrafine Polysulfone Fibers Prepared by Electrospinning

Processing and Microstructural Characterization of Porous Biocompatible Protein Polymer thin Films

Electrospinning of polyurethane fibers

Effects of Electrospinning Parameters on Polyacrylonitrile Nanofiber Diameter: An Investigation by Response Surface Methodology

Formation of Water-Resistant Hyaluronic Acid Nanofibers by Blowing-Assisted Electro-Spinning and Non-Toxic Post Treatments

Electrospinning of Continuous Aligned Polymer Fibers

Electrospinning Nanofibers as Uniaxially Aligned Arrays and Layer-by-Layer Stacked Films

Aligned Biodegradable Nanofibrous Structure: A Potential Scaffold for Blood Vessel Engineering

Electrospun three-dimensional silk fibroin nanofibrous scaffold

Ultrafine Electrospun Polyamide-6 Fibers: Effect of Solution Conditions on Morphology and Average Fiber Diameter

Controlling Surface Morphology of Electrospun Polystyrene Fibers: Effect of Humidity and Molecular Weight in the Electrospinning Process

Mechanical and Thermal Characteristics of Optimized Electrospun Nylon 6,6 Nanofibers by Using Taguchi Method

Handbook of Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine

Advances in regenerative medicine and tissue engineering: Innovation and transformation of medicine

Hydrophilic Surface Functionalization of Electrospun Nanofibrous Scaffolds in Tissue Engineering

Fabrication of Multilayered Nanofiber Scaffolds with a Highly Aligned Nanofiber Yarn for Anisotropic Tissue Regeneration

Current Approaches to Electrospun Nanofibers for Tissue Engineering

Rational Design of Nanofiber Scaffolds for Orthopedic Tissue Repair and Regeneration

Engineering biomimetic superhydrophobic surfaces of electrospun nanomaterials

Bioinspired Scaffold Designs for Regenerating Musculoskeletal Tissue Interfaces

Advances in Skin Regeneration Using Tissue Engineering

Nanofibrous Scaffolds for Skin Tissue Engineering and Wound Healing Based on Nature-Derived Polymers

Electrospinning: Applications in Drug Delivery and Tissue Engineering

Recent Development of Electrospinning for Drug Delivery

Recent Advances in Electrospun for Drug Delivery Purpose

A Review of the Effect of Processing Variables on the Fabrication of Electrospun Nanofibers for Drug Delivery Applications

Surface-Functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery

Drug Delivery Applications of Core-Sheath Nanofibers Prepared by Coaxial Electrospinning: A Review

Additive Electrospraying: A route to process Electrospun Scaffolds for Controlled Molecular Release

Transdermal Drug Delivery System: A Review

Oliveira Solid-State Characterization and Compatibility Studies of Penciclovir, Lysine Hydrochloride, and Pharmaceutical Excipients

Electrospun Zein/Eudragit Nanofibers Based Dual Drug Delivery System for the Simultaneous Delivery of Aceclofenac and Aantoprazole

Permeability Study of Ciprofloxacin from Ultra-thin Nanofibrous Film through Various Mucosal Membranes

Prevention of Local Liver Cancer Recurrence After Surgery Using Multilayered Cisplatin-Loaded Polylactide Electrospun Nanofibers

Development, Optimization, and Characterization of Polymeric Electrospun Nanofiber: A New Attempt in Sublingual Delivery of Nicorandil for the Management of Angina Pectoris

Drug Delivery System Based on Cyclodextrin-Naproxen Inclusion Complex Incorporated in Electrospun Polycaprolactone Nanofibers

Oral Fast-Dissolving Drug Delivery Mem-branes Prepared from Electrospun Polyvinylpyrrolidone Ultrafine Fibers

Drug and Cell Delivery for Cardiac Regeneration

Delivery of Antioxidant and Anti-inflammatory Agents for Tissue Engineered Vascular Grafts

Electrospinning Nanofibers for Therapeutics Delivery

Advances in Oligonucleotide Drug Delivery

Polycaprolactone Scaffold as Targeted Drug Delivery System and Cell Attachment Scaffold for Postsurgical Care of Limb Salvage

Bioactive Electrospun Scaffolds Delivering Growth Factors and Genes for Tissue Engineering Applications

Electrospun Nanofibers Surface-modified with Fluorescent Proteins

Cellular Behavior on Epidermal Growth Factor (EGF)-Immobilized PCL/Gelatin Nanofibrous Scaffolds

Black Phosphorus Nanosheets as a Robust Delivery Platform for Cancer Theragnostic

Progress and Perspectives on Targeting Nanoparticles for Brain Drug Delivery

Biodegradable electrospun fibers for drug delivery

A Review on Wound Dressings with an Emphasis on Electrospun Nanofibrous Polymeric Bandages

Drug Loading and Delivery Using Nanofibers Scaffolds

Preparation and Characterization of Electrospun PLGA/Gelatin Nanofibers as a Drug Delivery System by Emulsion Electrospinning

Salinomycin-Loaded Nanofibers for Glioblastoma Therapy

Encapsulation of Anticancer Drugs (5-Fluorouracil and Paclitaxel) into Polycaprolactone (PCL) Nanofibers and in Vitro Testing for Sustained and Targeted Therapy

Ultrafine Medicated Fibers Electrospun from W/O Emulsions

III. 6-Methylpurine Derived Sugar Modified Nucleosides: Synthesis and Evaluation of Their Substrate Activity with Purine Nucleoside Phosphorylases

Ultraviolet Light-Assisted Electrospinning of Core-Shell Fully Cross-Linked P(NIPAAm-co-NIPMAAm) Hydrogel-Based Nanofibers for Hermally Induced Drug Delivery Self-Regulation

Multifunctional Platform Based on Electrospun Nanofibers and Plasmonic Hydrogel: A Smart Nanostructured Pillow for Near-Infrared Light-Driven Biomedical Applications

Electrospun Nanofibers: New Generation Materials for Advanced Applications

Electrospun Doping of Carbon Nanotubes and Platinum Nanoparticles into the β-Phase Polyvinylidene Difluoride Nanofibrous Membrane for Biosensor and Catalysis Applications

Electrospun Nanofibres in Agriculture and the Food Industry: A Review

Smart Fabric Sensors and e-Textile Technologies: A Review

Application of Electrospinning Technique in Development of Intelligent Food Packaging: A short Review of Recent Trends

Avocado Oil Incorporated in Ultrafine Zein Fibers by Electrospinning

Electrospun Carbon Fiber Mat with Layered Architecture for Anode in Microbial Fuel Cells

Photocatalytic Hydrogen Generation by Splitting of Water from Electrospun Hybrid Nanostructures

Electrospinning Design of Functional Nanostructures for Biosensor Applications

Electrospinning Graphene Quantum Dots into a Nanofibrous Membrane for Dual-Purpose Fluorescent and Electrochemical Biosensors

Nanofiber Electrodes for Biosensors

Vinyl Alcohol)/Permutite Fibrous Film Loaded with Cinnamaldehyde for Active Food Packaging

Electrospun Fibro-Porou Spolyurethan Ecoating Sforimplantableglucosebiosensors

Electrospinning-Based (bio)Sensors for Food and Agricultural Applications: A review

The Development of Collagen Based Composite Scaffolds for Bone Regeneration

Role of the Encapsulation in Bioavailability of Phenolic Compounds

Encapsulation of Bioactive Compound in Electrospun Fibers and its Potential Application

New Generation of Super Absorber Nano-Fibroses Hybrid Fabric by Electro-Spinning

Novel Nanofiber-Based Triple-Layer Proton Exchange Membranes for Fuel Cell Applications

Electrospinning of Multilevel Structured Functional Micro-/Nanofibers and Their Applications

Nematic Shaped Cadmium Sulfide Doped Electrospun Nanofiber Mat: Highly Efficient

Scaffolds with a High Surface Area-to-Volume Ratio and Cultured Under Fast Flow Perfusion Result in Optimal O2 Delivery to the Cells in Artificial Bone Tissues

Anodic Electrochemical Performances of MgCo 2 O 4 Synthesized by Oxalate Decomposition Method and Electrospinning Technique for Li-ion Battery Application

Characterization and Modification of Electrospun Fiber Mats for Use in Composite Proton Exchange Membranes

Surface Enriched Nanofiber Mats for Efficient Adsorption of Cr(VI) Inspired by Mature

Applications of Electrospun Nanofibers

Electrospinning Based all-Nano Composite Materials: Recent Achievements and Perspectives

An Effective and Low Cost Pd-Ce Bimetallic Decorated Carbon Nanofibers as Electro-Catalyst for Direct Methanol Fuel Cells Applications

Product and Technology Innovation: What Can Biomimicry Inspire?

Streamlining the Front End of Innovation for Environmentally Sustainable Products

Realistic Imitation of Mosquito's Proboscis: Electrochemically Etched Sharp and Jagged Needles and Their Cooperative Inserting Motion

Biomimetic Electrospun Nanofibrous Structures for Tissue Engineering

Silk Fibroin/Poly(L-lactic Acid-co-ε-Caprolactone) Electrospun NanoFibrous Scaffolds Exert a Protective Effect Following Myocardial Infarction

A Review on Properties of Natural and Synthetic Based Electrospun Fibrous Materials for

Asymmetric Membranes: A Potential Scaffold for Wound Healing Applications

Progess in Superhydrophobic Surface Development

Self-Assembly of Electrospun Polymer Nanofibers: A General Phenomenon Generating Honeycomb-Patterned Nanofibrous Structures

Polyamide 6 Composite Nano-Fiber/net Functionalized by Polyethyleneimine on Quartz Crystal Microbalance for Highly Sensitive Formaldehyde Sensors

Electrospun Polycaprolactone Nanofiber Scaffolds for Tissue Engineering

Multi-Functional Electrospun Nanofibers from Polymer Blends for Scaffold Tissue Engineering

Current Progress in Application of Polymeric Nanofibers to Tissue Engineering

Biophysical Regulation of Cell Behavior-Cross Talk between Substrate Stiffness and Nanotopography

The Performance of Cross-linked Acellular Arterial Scaffolds as Vascular Grafts; Pre-Clinical Testing in Direct and Isolation Loop Circulatory Models

Current Applications of Poly(Lactic Acid) Composites in Tissue Engineering and Drug Delivery

Electrospun Biomimetic Fibrous Scaffold from Shape Memory Polymer of PDLLA-co-TMC for Bone Tissue Engineering

Electrospun asymmetric membranes for wound dressing applications

A Porous Hydrogel-Electrospun Composite Scaffold Made of Oxidized Alginate/Gelatin/Silk Fibroin for Tissue Engineering Application

Situ Crosslinking of Electrospun Gelatin-Carbodiimide Nanofibers: Fabrication, Characterization, and Modeling of Solution Parameter

Biomimetic Hybrid Systems for Tissue Engineering

Advances in Hybrid Fabrication toward Hierarchical Tissue Constructs

Biomimicry of Microbial Polysaccharide Hydrogels for Tissue Engineering and Regenerative Medicine: A Review

Design and 3D Printing of Scaffolds and Tissues

Advancing Biomaterials of Human Origin for Tissue Engineering

The Overview of Porous, Bioactive Scaffolds as Instructive Biomaterials for Tissue Regeneration and Their Clinical Translation

Chapter 1 in vitro biofabrication of Tissues and Organs, Biofabrication Micro-and Nano-Fabrication

Recent Advances in Biomaterials for 3D Scaffolds: A review

Design and Fabrication of Scaffold-Based Tissue Engineering

Strategies to Tune Electrospun Scaffold Porosity for Effective Cell Response in Tissue Engineering

Role of Offset and Gradient Architectures of 3-D Melt Electrowritten Scaffold on Differentiation and Mineralization of Osteoblasts

Structural Design and Environmental Applications of Electrospun Nanofibers

Recent Advances in Electrospun Sustainable Composites for Biomedical, Environmental, Energy, and Packaging Applications

Recent Progress in the Design and Synthesis of Nanofibers with Diverse Synthetic Methodologies: Characterization and Potential Applications

The Effect of Process Parameters on Alignment of Tubular Electrospun Nanofibers for Tissue Regeneration Purposes

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

Comprehensive Review Summarizing Effect of Electrospinning Parameters and Potential Applications of Nanofibers in Biomedical and Biotechnology

Engineering Porosity in Electrospun Nanofiber Sheets by Laser Engraving: A Strategy to Fabricate 3D Scaffolds for Bone Graft Applications

Direct Ink Writing Technology (3D Printing) of Graphene-Based Ceramic Nanocomposites: A Review

Hybrid Additive Microfabrication Scaffold Incorporated with Highly Aligned Nanofibers for Musculoskeletal Tissues

Design of a Scaffold Parameter Selection System with Additive Manufacturing for a

Bio-Based Polymer Nanofiber with Siliceous Sponge Spicules Prepared by Electrospinning: Preparation, Characterisation, and Functionalisation

Electrospun Gelatin Fiber Mats Mixed With C.carandas Extract and its Enhanced Stability and Bioactivity

Solution Properties and Electrospinning of Poly(Galacturonic Acid) Nanofibers

Encapsulation of β-Carotene in Poly(Vinylpyrrolidone) (PVP) by Electrospinning Technique

Combination of Nano-Hydroxyapatite and Curcumin in a Biopolymer Blend Matrix: Characteristics and Drug Release Performance of Fibrous Composite Material Systems

Fast Dissolving Oral Films for Drug Delivery Prepared from Chitosan/Pullulan Electrospinning Nanofibers

Bioactive Proteins Delivery through Core-Shell Nanofibers for Meniscal Tissue Regeneration

Manufacture of a Bio-Tissue Based on Nanocrystalline Cellulose from Chilean Bamboo Chusquea Quila and a Polymer Matrix Using Electrospinning

Preparation and Characterization of Poly (E-CAPROLACTONE) Nano Fibers by Electrospinning Technique for Tissue Enginerring Applications

Manufacture of PCL Scaffolds through Electrospinning Technology to Accommodate Triple Negative Breast Cancer Cells Culture

Biocompatible Electrospinning Chitosan Nanofibers: A Novel Delivery System with Superior Local Cancer Therapy

Electrospun Zein/Graphene Oxide Nanosheet Composite Nanofibers with Controlled Drug Release as Antibacterial Wound Dressing

Biopolymers/poly(εcaprolactone)/Polyethylenimine Functionalized Nano-Hydroxyapatite Hybrid Cryogel: Synthesis, Characterization and Application in gene Delivery

Spider-Web-Inspired PM0.3 Filters Based on Self-Sustained Electrostatic Nanostructured Networks

Performance of Nanofiber/Microfiber Hybrid Air Filter Prepared by Wet Paper Processing

Evolutionary Study of COVID-19, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) as an Emerging Coronavirus: Phylogenetic Analysis and Literature Review

Severe Acute Respiratory Syndrome Coronavirus 2-Specific Antibodies in Pets in Wuhan

Positive and Negative Impacts of COVID-19, an Analysis with Special Reference to Challenges on the Supply Chain in South Asian countries

Current Strategies and Approaches in Combating SARS-CoV-2 Virus that Causes COVID-19

Surface Disinfection to Protect against Microorganisms: Overview of Traditional Methods and Issues of Emergent Nanotechnologies

Global Research on Coronavirus Disease (COVID-19). Available online

Outlook on the Worldwide Market for Nanofibers to 2030-Initiatives Using Nanofibers to Aid the Response to COVID-19

Electrospun Nanofibers-Based Face Masks

Electrospinning and Emerging Healthcare and Medicine Possibilities

Personalized Reusable Face Masks with Smart Nano-Assisted Destruction of Pathogens for COVID-19: A Visionary Road

Super Hygroscopic Nanofibrous Membrane-Based Moisture Pump for Solar-Driven Indoor Dehumidification

Recyclable Nano-Fiber Filtered Face Masks a Boon for Supply Fiasco

Fabrication of Promising Antimicrobial Aloe Vera/PVA Electrospun Nanofibers for Protective Clothing

Biosensors for the Detection of Bacterial and Viral Clinical Pathogens

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

The authors declare no conflict of interest.