Recent progress in electrospun nanofibers and their applications in heavy metal wastewater treatment

Polymeric Nanofibers via Green Electrospinning for Safe Food Engineering

Electrospun functional nanofibers enable controlled release of the loaded active ingredient and an adjustable dissolution rate. However, the widespread use of toxic organic solvents in electrospinning poses risks to human health and the environment whereas increasing production costs and complexity. This article examines the application of eco-friendly electrospinning technologies in food engineering, with a focus on water-based and melt electrospinning methods. It provides a detailed analysis of water-soluble biopolymers and synthetic polymers, highlighting their current applications and challenges in food engineering. Water-based electrospinning is proposed as a sustainable alternative, offering scalability and reduced environmental impact. This transition is essential for advancing food engineering toward more sustainable and environmentally responsible practices.

Antiviral Activity of Electrospun Polyamide Ultrathin Fibers Against SARS-CoV-2 Variant

The development of new strategies to produce nanomaterials that can be used as personal protective equipment with antiviral activity and low toxicity is crucial. Electrospun ultrathin fibers have attracted considerable attention due to their potential for biomedical applications, including antiviral activity. Herein, we electrospun different grades of commercially available polyamide to produce ultrathin fibers and investigate their antiviral activity against SARS-CoV-2 Gamma lineage (P.1). We evaluated the morphology, chemical composition, and mechanical properties of the ultrathin fibers. We also investigated the in vitro cytotoxicity, hemolytic activity, and antiviral activity against SARS-CoV-2 Gamma lineage (P.1) of the developed ultrathin fibers. The ultrathin fibers had the following diameters and elastic moduli: (i) unmodified crude ultrathin polyamide (PAP) 0.59 μm and 3 MPa, (ii) polyamide Biotech (PAAM) 0.74 μm and 2.2 MPa, and (iii) Amni Virus-Bac OFF polyamide (PAVB) 0.69 μm and 1.06 MPa. The ultrathin PAP fibers showed increased antiviral activity compared to the other ultrathin fibers (PAAM and PAVB). None of the electrospun fibers showed cytotoxicity at the lowest concentration (12.5%). Additionally, hemolysis tests demonstrated a nonhemolytic profile for all fiber groups, reinforcing their biocompatibility and suitability for biomedical applications. The antiviral properties of the electrospun ultrathin PAP fibers, combined with their noncytotoxic and nonhemolytic characteristics, highlight their potential to be used as personal protection against SARS-CoV-2.

Generalized and Scalable Synthesis of Manganese Dioxide-Based Tubular Micromotors for Heavy Metal Ion Removal

Synthetic nano- and micromachines hold immense promise in biomedicine and environmental science. Currently, bubble-driven tubular micro/nanomotors have garnered increasing attention owing to their exceptional high-speed self-propulsions. However, complex and low-yield preparation methods have hindered their widespread applications. Herein, we present a generalized, scalable, and low-cost electrospinning-based strategy to fabricate MnO2-based composite tubular micromotors (MnO2-TMs) for efficient heavy metal ion removal. The inherent flexibility of precursor nanofibers derived from diverse matrix materials enables the creation of MnO2-TMs with a wide range of morphologies. In response to morphology changes, the MnO2-TMs, based on a bubble-propelled mechanism, exhibit multimodal motion patterns, including linear, circular, and spiral to stochastic swinging. To elucidate the underlying morphology-to-motion relationship, we conducted systematic simulations of fluid dynamics around the MnO2-TMs. Furthermore, by incorporation of Fe3O4 nanoparticles, the capabilities of MnO2-TMs can be expanded to include magnetic manipulation for directional navigation and efficient retrieval. Benefiting from these attributes, MnO2-TMs excel in removing heavy metal ions from water. The developed MnO2-MnWO4@Fe3O4 TMs exhibit prominent adsorption capacities of 586.5 mg g-1 for Cu2+ and 156.4 mg g-1 for Pb2+. Notably, the magnetic property facilitates rapid separation and retrieval of the micromotors, and the absorbed ions can be simply recovered by pH adjustment. This work establishes a general framework for developing MnO2-based tubular micro/nanomotors to address environmental challenges.

Design and Production of Functionalized Electrospun Fibers for Palladium Recovery

Adsorption stands out as a leading wastewater treatment method for ion removal or recovery. Polymeric fibers, notably electrospun ones, are gaining prominence due to their high capacity and easy recovery. Electrospinning offers a cost-effective means to produce fibers with a large surface area and high adsorption capacity. These fibers can be further functionalized with chemical substances acting as specific ligands for metal ions, bolstering their adsorption capabilities. In this study, dithioester-functionalized electrospun fibers were synthesized as an alternative to conventional sorbents for palladium recovery from acidic chloride solutions, similar to those used in hydrometallurgical processes for platinum group metal recovery (Pd, Pt, Rh···) from spent catalysts. Fibers with identical chemical composition but varying morphology were examined to assess their impact on palladium adsorption efficiency (i.e., beads-free and beads-on-string morphologies). Experimental investigations involved model solutions with varying palladium concentration, temperature, acidity (adjusted with HCl content), and salinity (adjusted with NaCl), utilizing both pure and dithioester-functionalized fibers. Experimental results demonstrate enhanced adsorption efficiency at lower temperatures and in 0.1 M HCl, with a negligible influence from solution salinity. Moreover, both pure polymeric and dithioester-functionalized electrospun fibers exhibit highly efficient palladium recovery. Furthermore, under optimal conditions, starting from an 80 mg/L palladium solution, a 95% recovery of palladium can be achieved with a sorbent dosage below 4 g/L of functionalized electrospun fibers. The adsorption data are well described by the Langmuir isotherm model for the pure polymeric fibers. At the same time, the contribution of dithioesters has been separately accounted for to describe the behavior of functionalized electrospun fibers. Thermal recovery of palladium from the spent sorbents has also been investigated.

Recent advancement of nano-biochar for the remediation of heavy metals and emerging contaminants: Mechanism, adsorption kinetic model, plant growth and development

Even though researches have shown that biochar can improve soil-health and plant-growth even in harsh environments and get rid of harmful heavy metals and new contaminants, it is still not sustainable, affordable, or effective enough. Therefore, scientists are required to develop nanomaterials in order to preserve numerous aquatic and terrestrial species. The carbonaceous chemical known as nano-biochar (N-BC) can be used to get rid of metal contamination and emerging contaminants. However, techniques to reduce hetero-aggregation and agglomeration of nano-biochar are needed that lead to the emergence of emerging nano-biochar (EN-BC) in order to maximise its capacity for adsorption of nano-biochar. To address concerns in regards to the expanding human population and sustain a healthy community, it is imperative to address the problems associated with toxic heavy metals, emerging contaminants, and other abiotic stressors that are threatening agricultural development. Nano-biochar can provide an effective solution for removal of emerging contaminants, toxic heavy metals, and non-degradable substance. This review provides the detailed functional mechanistic and kinetics of nano-biochar, its effectiveness in promoting plant growth, and soil health under abiotic stress. Nonetheless, this review paper has comprehensively illustrated various adsorption study models that will be employed in future research.

Impact Evaluations of Articles in Current Drug Delivery based on Web of Science

A total of 1534 and 308 articles were published in the journal Current Drug Delivery (CDD), from 2004 and 2019 to 2021, respectively. In this commentary, their impacts were analyzed based on search data about citation times in the Web of Science. These publications were categorized from different standpoints and evaluated in terms of their citations, particularly in the year 2021. The thematic, contemporary, and local features of these articles, as well as the article types and publication formats, were interpreted. Results demonstrated that CDD should be loyal to the contents about drug delivery, particularly nano-drug delivery systems and nano-pharmaceutical technologies. Publications from the developing and developed countries and regions showed no remarkable differences; therefore, submissions are similarly welcomed. Research articles and review articles are the main stream of CDD. The ratio of review papers is about 30%, which is reasonable but should not be further extended. Moreover, open publications with an article processing charge always have a high impact than those with subscription.

Electrospinning of pullulan-based orodispersible films containing sildenafil

Feasibility of electrospinning in the manufacturing of sildenafil-containing orodispersible films (ODFs) intended to enhance oxygenation and to reduce pulmonary arterial pressure in pediatric patients was evaluated. Given the targeted subjects, the simplest and safest formulation was chosen, using water as the only solvent and pullulan, a natural polymer, as the sole fiber-forming agent. A systematic characterization in terms of shear and extensional viscosity as well as surface tension of solutions containing different amounts of pullulan and sildenafil was carried out. Accordingly, electrospinning parameters enabling the continuous production, at the highest possible rate, of defect-free fibers with uniform diameter in the nanometer range were assessed. Morphology, microstructure, drug content and relevant solid state as well as ability of the resulting non-woven films to interact with aqueous fluids were evaluated. To better define the role of the fibrous nanostructure on the performance of ODFs, analogous films were produced by spin- and blade-coating and tested. Interestingly, the disintegration process of electrospun products turned out to be the fastest (i.e. occurring within few s) and compliant with Ph. Eur. and USP limits, making relevant ODFs particularly promising for increasing sildenafil bioavailability, thus lowering its dosages.

Fabrication of Polyamide6/Polyaniline as an Effective Nano-web Membrane for Removal of Cr (VI) from Water and a Black Box Approach in Modeling of Adsorption Process

Chromium (Cr), as a highly toxic heavy metal ion, is still a severe environmental issue, although many research efforts have been put into its removal from water. Polyaniline (PANI), as a conductive polymer, demonstrated great capability in heavy metal adsorption due to its low cost, ease of synthesis, reversible redox behavior, and chemical stability. However, using PANI powder alone in heavy metal removal causes secondary pollution and aggregation in water. The PANI coating on a substrate could tackle this problem. In this study, polyaniline-coated polyamide6 (PA6/PANI) nano-web membrane was used for the removal of Cr(VI) in both adsorption and filtration-adsorption modes. The PA6/PANI nano-web membrane was fabricated via PA6 electrospinning followed by in-situ polymerization of the aniline monomer. The electrospinning condition of PA6 was optimized by the Taguchi method. The PA6/PANI nano-web membrane was characterized by FESEM, N2-adsorption/desorption, FT-IR, contact angle measurement, and tensile test. FT-IR and FESEM results demonstrated the successful synthesis of PA6/PANI nano-web and PANI homogeneous coating on PA6 nanofibers, respectively. The N2 adsorption/desorption results indicated that the pore volume of the PA6/PANI nano-web decreased by 39% compared to PA6 nanofibers. The tensile test and water contact angle studies showed that the coating of PANI on PA6 nanofibers improves the mechanical properties and hydrophilicity of PA6 by 10% and 25%, respectively. The application of PA6/PANI nano-web in the removal of Cr(VI) in batch and filtration modes exhibits excellent removal of 98.4 and 86.7%, respectively. A pseudo first order model well described the adsorption kinetics, and the adsorption isotherm was best fitted by the Langmuir model. A black box modeling approach based on artificial neural networks (ANN) was developed to predict the removal efficiency of the membrane. The superior performance of PA6/PANI in both adsorption and filtration-adsorption systems makes it a potential candidate for the removal of heavy metals from water on an industrial scale.

The influence of the ultrasonic treatment of working fluids on electrospun amorphous solid dispersions

Based on a working fluid consisting of a poorly water-soluble drug and a pharmaceutical polymer in an organic solvent, electrospinning has been widely exploited to create a variety of amorphous solid dispersions However, there have been very few reports about how to prepare the working fluid in a reasonable manner. In this study, an investigation was conducted to determine the influences of ultrasonic fluid pretreatment on the quality of resultant ASDs fabricated from the working fluids. SEM results demonstrated that nanofiber-based amorphous solid dispersions from the treated fluids treated amorphous solid dispersions exhibited better quality than the traditional nanofibers from untreated fluids in the following aspects: 1) a straighter linear morphology; 2) a smooth surface; and 3) a more evener diameter distribution. The fabrication mechanism associated with the influences of ultrasonic treatments of working fluids on the resultant nanofibers' quality is suggested. Although XRD and ATR-FTIR experiments clearly verified that the drug ketoprofen was homogeneously distributed all over the TASDs and the traditional nanofibers in an amorphous state regardless of the ultrasonic treatments, the in vitro dissolution tests clearly demonstrated that the TASDs had a better sustained drug release performance than the traditional nanofibers in terms of the initial release rate and the sustained release time periods.

Biphasic drug release from electrospun structures

INTRODUCTION

Biphasic release, as a special drug-modified release profile that combines immediate and sustained release, allows fast therapeutic action and retains blood drug concentration for long periods. Electrospun nanofibers, particularly those with complex nanostructures produced by multi-fluid electrospinning processes, are potential novel biphasic drug delivery systems (DDSs).

AREAS COVERED

This review summarizes the most recent developments in electrospinning and related structures. In this review, the role of electrospun nanostructures in biphasic drug release was comprehensively explored. These electrospun nanostructures include monolithic nanofibers obtained through single-fluid blending electrospinning, core-shell and Janus nanostructures prepared via bifluid electrospinning, three-compartment nanostructures obtained via trifluid electrospinning, nanofibrous assemblies obtained through the layer-by-layer deposition of nanofibers, and the combined structure of electrospun nanofiber mats with casting films. The strategies and mechanisms through which complex structures facilitate biphasic release were analyzed.

EXPERT OPINION

Electrospun structures can provide many strategies for the development of biphasic drug release DDSs. However, many issues such as the scale-up productions of complex nanostructures, the in vivo verification of the biphasic release effects, keeping pace with the developments of multi-fluid electrospinning, drawing support from the state-of-the-art pharmaceutical excipients, and the combination with traditional pharmaceutical methods need to be addressed for real applications.

Fast and convenient delivery of fluidextracts liquorice through electrospun core-shell nanohybrids

Introduction: As an interdisciplinary field, drug delivery relies on the developments of modern science and technology. Correspondingly, how to upgrade the traditional dosage forms for a more efficacious, safer, and convenient drug delivery poses a continuous challenge to researchers. Methods, results and discussion: In this study, a proof-of-concept demonstration was conducted to convert a popular traditional liquid dosage form (a commercial oral compound solution prepared from an intermediate licorice fluidextract) into a solid dosage form. The oral commercial solution was successfully encapsulated into the core-shell nanohybrids, and the ethanol in the oral solution was removed. The SEM and TEM evaluations showed that the prepared nanofibers had linear morphologies without any discerned spindles or beads and an obvious core-shell nanostructure. The FTIR and XRD results verified that the active ingredients in the commercial solution were compatible with the polymeric matrices and were presented in the core section in an amorphous state. Three different types of methods were developed, and the fast dissolution of the electrospun core-shell nanofibers was verified. Conclusion: Coaxial electrospinning can act as a nano pharmaceutical technique to upgrade the traditional oral solution into fast-dissolving solid drug delivery films to retain the advantages of the liquid dosage forms and the solid dosage forms.

A Sequential Electrospinning of a Coaxial and Blending Process for Creating Double-Layer Hybrid Films to Sense Glucose

This study presents a glucose biosensor based on electrospun core-sheath nanofibers. Two types of film were fabricated using different electrospinning procedures. Film F1 was composed solely of core-sheath nanofibers fabricated using a modified coaxial electrospinning process. Film F2 was a double-layer hybrid film fabricated through a sequential electrospinning and blending process. The bottom layer of F2 comprised core-sheath nanofibers fabricated using a modified process, in which pure polymethacrylate type A (Eudragit L100) was used as the core section and water-soluble lignin (WSL) and phenol were loaded as the sheath section. The top layer of F2 contained glucose oxidase (GOx) and gold nanoparticles, which were distributed throughout the polyvinylpyrrolidone K90 (PVP K90) nanofibers through a single-fluid blending electrospinning process. The study investigated the sequential electrospinning process in detail. The experimental results demonstrated that the F2 hybrid film had a higher degradation efficiency of β-D-glucose than F1, reaching a maximum of over 70% after 12 h within the concentration range of 10-40 mmol/L. The hybrid film F2 is used for colorimetric sensing of β-D-glucose in the range of 1-15 mmol/L. The solution exhibited a color that deepened gradually with an increase in β-D-glucose concentration. Electrospinning is flexible in creating structures for bio-cascade reactions, and the double-layer hybrid film can provide a simple template for developing other sensing nanomaterials.

Recent Progress of the Preparation and Application of Electrospun Porous Nanofibers

Electrospun porous nanofibers have gained a lot of interest recently in various fields because of their adjustable porous structure, high specific surface area, and large number of active sites, which can further enhance the performance of materials. This paper provides an overview of the common polymers, preparation, and applications of electrospun porous nanofibers. Firstly, the polymers commonly used to construct porous structures and the main pore-forming methods in porous nanofibers by electrospinning, namely the template method and phase separation method, are introduced. Secondly, recent applications of electrospun porous nanofibers in air purification, water treatment, energy storage, biomedicine, food packaging, sensor, sound and wave absorption, flame retardant, and heat insulation are reviewed. Finally, the challenges and possible research directions for the future study of electrospun porous nanofibers are discussed.

A Correlation Analysis between Undergraduate Students' Safety Behaviors in the Laboratory and Their Learning Efficiencies

Students' behaviors have a close relationship with their learning efficiencies, particularly about professional knowledge. Different types of behaviors should have different influences. Disclosing the special relationship between undergraduate students' conscious safety behaviors in their laboratory experiments with their learning efficiencies is important for fostering them into professional talents. In this study, a course entitled "Advanced Methods of Materials Characterization" was arranged to contain three sections: theoretical learning in the classroom, eight characterization experiments in the laboratory in sequence, and self-training to apply the knowledge. In the final examination, eighteen percent was allocated to the examination questions about safety issues. The students' scores for this section were associated with their total roll scores. Two quantitative relationships are disclosed. One is between the students' final examination score (y) and their subjective consciousness of safety behaviors (x) in their laboratory experiments, as y = 5.56 + 4.83 x (R = 0.9192). The other is between their grade point average (y) and safety behavior evaluation (x) as y = 0.51 + 0.15 x (R = 0.7296). Undergraduate students' behaviors in scientific laboratories need to be verified to have a close and positive relationship with their professional knowledge learning efficiencies. This offers a hint that improving students' safety behaviors and enhancing their subjective safety awareness are conducive to improving their learning efficiency for professional knowledge.

Electrospun self-emulsifying core-shell nanofibers for effective delivery of paclitaxel

The poor solubility of numerous drugs pose a long-existing challenge to the researchers in the fields of pharmaceutics, bioengineering and biotechnology. Many "top-down" and "bottom-up" nano fabrication methods have been exploited to provide solutions for this issue. In this study, a combination strategy of top-down process (electrospinning) and bottom-up (self-emulsifying) was demonstrated to be useful for enhancing the dissolution of a typical poorly water-soluble anticancer model drug (paclitaxel, PTX). With polyvinylpyrrolidone (PVP K90) as the filament-forming matrix and drug carrier, polyoxyethylene castor oil (PCO) as emulsifier, and triglyceride (TG) as oil phase, Both a single-fluid blending process and a coaxial process were utilized to prepare medicated nanofibers. Scanning electron microscope and transmission electron microscope (TEM) results clearly demonstrated the morphology and inner structures of the nanofibers. The lipid nanoparticles of emulsions after self-emulsification were also assessed through TEM. The encapsulation efficiency (EE) and in vitro dissolution tests demonstrated that the cores-shell nanofibers could provide a better self-emulsifying process int terms of a higher EE and a better drug sustained release profile. Meanwhile, an increase of sheath fluid rate could benefit an even better results, suggesting a clear process-property-performance relationship. The protocols reported here pave anew way for effective oral delivery of poorly water-soluble drug.

Recent Progress of Electrospun Herbal Medicine Nanofibers

Herbal medicine has a long history of medical efficacy with low toxicity, side effects and good biocompatibility. However, the bioavailability of the extract of raw herbs and bioactive compounds is poor because of their low water solubility. In order to overcome the solubility issues, electrospinning technology can offer a delivery alternative to resolve them. The electrospun fibers have the advantages of high specific surface area, high porosity, excellent mechanical strength and flexible structures. At the same time, various natural and synthetic polymer-bound fibers can mimic extracellular matrix applications in different medical fields. In this paper, the development of electrospinning technology and polymers used for incorporating herbal medicine into electrospun nanofibers are reviewed. Finally, the recent progress of the applications of these herbal medicine nanofibers in biomedical (drug delivery, wound dressing, tissue engineering) and food fields along with their future prospects is discussed.

The Applications of Ferulic-Acid-Loaded Fibrous Films for Fruit Preservation

The aim of this study was to develop a novel ultrathin fibrous membrane with a core-sheath structure as an antioxidant food packaging membrane. The core-sheath structure was prepared by coaxial electrospinning, and the release of active substances was regulated by its special structure. Ferulic acid (FA) was incorporated into the electrospun zein/polyethylene oxide ultrathin fibers to ensure their synergistic antioxidant properties. We found that the prepared ultrathin fibers had a good morphology and smooth surface. The internal structure of the fibers was stable, and the three materials that we used were compatible. For the different loading positions, it was observed that the core layer ferulic-acid-loaded fibers had a sustained action, while the sheath layer ferulic-acid-loaded fibers had a pre-burst action. Finally, apples were selected for packaging using fibrous membranes to simulate practical applications. The fibrous membrane was effective in reducing water loss and apple quality loss, as well as extending the shelf life. According to these experiments, the FA-loaded zein/PEO coaxial electrospinning fiber can be used as antioxidant food packaging and will also undergo more improvements in the future.