Functional Nanofibers and Their Applications

Self-replicating nanomaterials as a new generation of smart nanostructures

Self-replication is the process by which a system or entity autonomously reproduces or generates copies of itself, transmitting hereditary information through its molecular structure. Self-replication can be attractive for various researchers, ranging from biologists focused on uncovering the origin of life, to synthetic chemists and nanotechnologists studying synthetic machines and nanorobots. The capability of a single structure to act as a template to produce multiple copies of itself could allow the bottom-up engineering of progressively complex reaction networks and nanoarchitectures from simple building blocks. Herein, we review nucleic acid-based and amino acid-based self-replicating systems and completely synthetic artificial systems and specially focused on specific aspects of self-replicating nanomaterials. We describe their mechanisms of action and provide a full discussion of the principal requirements for achieving nanostructures capable of self-replication.

Conductive and flexible gold-coated polylactic acid nanofiber-based electrochemical aptasensor for monitoring cortisol level in sweat and saliva

Conductive nanofibers can exhibit excellent mechanical properties such as flexibility, elasticity, porosity, large surface area-to-volume ratio, etc making them suitable for a wide range of applications including biosensor development. Their large surface area provides more active sites for immobilization of large amount of bioreceptors enabling more interaction sites with the target analytes, enhancing sensitivity and detection capabilities. However, engineering conductive nanofibers with such excellent properties is challenging limiting their effective deployment for intended applications. In this research, we propose a novel approach for easy fabrication of highly conductive and flexible nanofiber leveraging the electrospinning, electroless deposition and have applied it to cortisol monitoring; a common biomarker for stress which is often quantified through enzyme-linked immunoassays using blood or saliva samples. By adopting the nanofiber sheet as a transducer for aptamer immobilization and cortisol sensing our developed biosensor was able to detect cortisol in buffer, artificial saliva, and artificial sweat within five minutes, from 10 pg/mL to 10 µg/mL (27.59 pM to 27.59 µM) with a low detection limit of 1 pg/ml (2.76 pM). The Au-coated PLA nanofiber-based electrochemical biosensor's flexibility allows for compact manufacturing, rendering it an optimal choice for integration into point-of-care testing and wearable systems.

Ceria-based electrospun nanofibers and their widespread applications: A review

Electrospinning is a highly efficient technique for producing nanofibers, and it is noted for its cost-effectiveness, versatility, and user-friendly nature. The article evaluates the production of Ceria-based nanofibers primarily utilizing electrospinning technology and electrospinning parameters and explores their various potential applications. Ceria infused with lanthanoids and transition metals demonstrates significant potential as catalysts, optical sensors, and supercapacitors in various energy-related industrial applications. Their role as catalysts in water-gas and reverse water-gas shift reactions greatly enhances the water-splitting reaction in the Deacon process. Composite ceria nanofibers for wound therapy were developed by integrating polyurethane, cellulose acetate, and zein for biological applications. Soot-induced blockages in automobile filters pose challenges for the regeneration process of diesel particle filters, and the effectiveness of ceria-based nanofibers in soot and CO oxidation has been explored. Ce-based nanofibers produced via the electrospinning technique, with different operating parameters, exhibit notable variations in their morphology. Research indicates that, compared to traditional ceria, Ce-based nanofibers demonstrate greater surface area and porosity, a higher density of oxygen vacancies, and improved oxygen transfer efficiency, all essential for numerous redox and catalytic processes. The nanofibrous structure enhances electrical conductivity by expanding the surface area accessible for interaction with active components. The nanofibrous composite structure exhibits enhanced thermal and mechanical durability, making it appealing for numerous applications.

Exploration of low-sulfonate lignin electrospinning conditions for the development of new renewable lubricant formulations

This study explores the preparation of lubricating oleo-dispersions using electrospun nanofibrous mats made from low-sulfonate lignin (LSL) and polycaprolactone (PCL). The rheological and tribological properties of the oleo-dispersions were significantly modulated for the first time through the exploration of LSL/PCL ratio and electrospinning conditions such as applied voltage, distance between the tip and collector, flow rate, ambient humidity, and collector configuration. Adequate uniform ultrathin fibers and Small-amplitude oscillatory shear (SAOS) functions of the oleo-dispersions, with storage modulus values ranging from 102 to 105 Pa at 25 °C, were obtained with a flow rate of 0.5 ml h-1, an applied voltage of 15 kV, relative humidity 45% and a static collector. The LSL/PCL ratio directly affected the mechanical properties of the membranes, influencing stiffness and wear resistance. Higher PCL content enhanced membrane stiffness, reflected in increased SAOS values, but also led to higher friction coefficients (from 0.11 to 0.18) and more pronounced wear traces (measured by wear diameter: 440 to 860 μm). These interactions underscore the complex relationship between micro- and/or nano-structures and tribological performance. This study establishes a clear link between electrospinning conditions and the performance of oleo-dispersions, offering a versatile platform for the development of customizable, renewable lubricants. These findings contribute to the advancement of sustainable lubrication technologies, demonstrating the potential of tailor-made oleo-dispersions as alternatives to traditional lubricants.

Review on need for designing sustainable and biodegradable face masks: Opportunities for nanofibrous cellulosic filters

The surge in microbial illnesses, notably seen during the COVID-19 pandemic, has led to the global use of face masks-cloth, surgical, medical, and respirator types-to curb respiratory pathogen spread. Widely used by the public, patients, and healthcare workers, masks play a key role in reducing airborne transmission. However, synthetic, non-biodegradable materials in these masks have sparked environmental concerns due to disposal issues. Moreover, challenges like limited microbial filtration, poor fit, breathing resistance, and low reusability raise further issues, as does the failure to neutralize trapped microbes. Addressing these issues calls for high-performance, biodegradable masks crafted from renewable nanofibrous materials using advanced technology. Antimicrobial nanomaterial coatings can further reduce contamination risks for users and the environment. Nanofibrous materials, with their high surface area, enhance filtration, allow customization, and improve capture efficiency. Research is progressing on sustainable, biodegradable filters, particularly with cellulose materials. This review outlines mask types and limitations, spotlighting nanofibrous filters for their filtration efficiency, breathability, and sustainability. It also delves into nanofiber manufacturing and assesses bacterial cellulose-a promising renewable nanofibrous material suited for air filtration.

Processing and Properties of Polyhydroxyalkanoate/ZnO Nanocomposites: A Review of Their Potential as Sustainable Packaging Materials

The escalating environmental concerns associated with conventional plastic packaging have accelerated the development of sustainable alternatives, making food packaging a focus area for innovation. Bioplastics, particularly polyhydroxyalkanoates (PHAs), have emerged as potential candidates due to their biobased origin, biodegradability, and biocompatibility. PHAs stand out for their good mechanical and medium gas permeability properties, making them promising materials for food packaging applications. In parallel, zinc oxide (ZnO) nanoparticles (NPs) have gained attention for their antimicrobial properties and ability to enhance the mechanical and barrier properties of (bio)polymers. This review aims to provide a comprehensive introduction to the research on PHA/ZnO nanocomposites. It starts with the importance and current challenges of food packaging, followed by a discussion on the opportunities of bioplastics and PHAs. Next, the synthesis, properties, and application areas of ZnO NPs are discussed to introduce their potential use in (bio)plastic food packaging. Early research on PHA/ZnO nanocomposites has focused on solvent-assisted production methods, whereas novel technologies can offer additional possibilities with regard to industrial upscaling, safer or cheaper processing, or more specific incorporation of ZnO NPs in the matrix or on the surface of PHA films or fibers. Here, the use of solvent casting, melt processing, electrospinning, centrifugal fiber spinning, miniemulsion encapsulation, and ultrasonic spray coating to produce PHA/ZnO nanocomposites is explained. Finally, an overview is given of the reported effects of ZnO NP incorporation on thermal, mechanical, gas barrier, UV barrier, and antimicrobial properties in ZnO nanocomposites based on poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). We conclude that the functionality of PHA materials can be improved by optimizing the ZnO incorporation process and the complex interplay between intrinsic ZnO NP properties, dispersion quality, matrix-filler interactions, and crystallinity. Further research regarding the antimicrobial efficiency and potential migration of ZnO NPs in food (simulants) and the End-of-Life will determine the market potential of PHA/ZnO nanocomposites as active packaging material.

Flaxseed (Linum usitatissimum) mucilage: A versatile stimuli-responsive functional biomaterial for pharmaceuticals and healthcare

The present review is novel as it discusses the main findings of researchers on the topic and their implications, as well as highlights the emerging research in this particular area and its future prospective. The seeds of Flax (Linum usitatissimum) extrude mucilage (FSM) that has a diverse and wide range of applications, especially in the food industry and as a pharmaceutical ingredient. FSM has been blended with several food and dairy products to improve gelling ability, optical properties, taste, and user compliance. The FSM is recognized as a foaming, encapsulating, emulsifying, suspending, film-forming, and gelling agent for several pharmaceutical preparations and healthcare materials. Owing to stimuli (pH) -responsive swelling-deswelling characteristics, high swelling indices at different physiological pHs of the human body, and biocompatibility, FSM is considered a smart material for intelligent, targeted, and controlled drug delivery applications through conventional and advanced drug delivery systems. FSM has been modified through carboxymethylation, acetylation, copolymerization, and electrostatic complexation to get the desired properties for pharma, food, and healthcare products. The present review is therefore devoted to the isolation techniques, structural characterization, highly valuable properties for food and pharmaceutical industries, preclinical and clinical trials, pharmacological aspects, biomedical attributes, and patents of FSM.

Quantum Dots on a String: In Situ Observation of Branching and Reinforcement Mechanism of Electrospun Fibers

Immobilization of quantum dots (QDs) on fiber surfaces has emerged as a robust approach for preserving their functional characteristics while mitigating aggregation and instability issues. Despite the advancement, understanding the impacts of QDs on jet-fiber evolution during electrospinning, QDs-fiber interface, and composites functional behavior remains a knowledge gap. The study adopts a high-speed imaging methodology to capture the immobilization effects on the QDs-fiber matrix. In situ observations reveal irregular triangular branches within the QDs-fiber matrix, exhibiting distinctive rotations within a rapid timeframe of 0.00667 ms. The influence of FeQDs on Taylor cone dynamics and subsequent fiber branching velocities is elucidated. Synthesis phenomena are correlated with QD-fiber's morphology, crystallinity, and functional properties. PAN-FeQDs composite fibers substantially reduced (50-70%) nano-fibrillar length and width while their diameter expanded by 17%. A 30% enhancement in elastic modulus and reduction in adhesion force for PAN-FeQDs fibers is observed. These changes are attributed to chemical and physical intertwining between the FeQDs and the polymer matrix, bolstered by the shifts in the position of C≡N and C═C bonds. This study provides valuable insights into the quantum dot-fiber composites by comprehensively integrating and bridging jet-fiber transformation, fiber structure, nanomechanics, and surface chemistry.

Multifactorial evaluation of an ultra-fast process for electrospinning of recycled expanded polystyrene to manufacture high-efficiency membranes for nanoparticle air filtration

The increased production of polystyrene waste has led to the need to find efficient ways to dispose of it. One possibility is the use of solid waste to produce filter media by the electrospinning technique. The aim of this work was to develop an ultra-fast electrospinning process applied to recycled polystyrene, with statistical evaluation of the influence of polymeric solution parameters (polymer concentration and percentage of DL-limonene) and process variables (flow rate, voltage, and type of support) on nanoparticle collection efficiency, air permeability, and fiber diameter. An extensive characterization of the materials and evaluation of the morphology of the fibers was also carried out. It was found that recycled expanded polystyrene could be used in electrospinning to produce polymeric membranes. The optimized condition that resulted in the highest nanoparticle collection efficiency was a polymer concentration of 13.5%, percentage of DL-limonene of 50%, voltage of 25 kV, and flow rate of 1.2 mL/h, resulting in values of 99.97 ± 0.01%, 2.6 ± 0.5 × 10-13 m2, 0.19 Pa-1, and 708 ± 176 nm for the collection efficiency of nanoparticles in the range from 6.38 to 232.9 nm, permeability, quality factor, and mean fiber diameter, respectively. All the parameters were found to influence collection efficiency and fiber diameter. The use of DL-limonene, a natural solvent, provided benefits including increased collection efficiency and decreased fiber size. In addition, the electrostatic filtration mechanism was evaluated using the presence of a copper grid as a support for the nanofibers. The findings demonstrated that an electrospinning time of only 5 min was sufficient to obtain filters with high collection efficiencies and low pressure drops, opening perspectives for the application of polystyrene waste in the development of materials with excellent characteristics for application in the area of atmospheric pollution mitigation.

Innovative Electrospun Nanofiber Mats Based on Polylactic Acid Composited with Silver Nanoparticles for Medical Applications

Nanofibers are some of the most attractive materials that can modify functionalities for developing new kinds of specific applications and are mainly used as a biomedical material. Herein, we designed and prepared antibacterial nonwoven fiber mats of PLA and PLA composited with Ag nanoparticles by electrospinning. The effects of varying filler contents on their chemical, surface morphology, thermal, water absorbency, and antibacterial properties were investigated using FTIR, SEM/EDS, DSC, swelling ratio, and qualitative and quantitative antibacterial tests. FTIR and EDS spectra indicated that Ag nanoparticles were incorporated in the PLA without chemical bonding. SEM revealed that the average diameter of the PLA nanofibers containing the Ag nanoparticles was more significant than those without those particles. In addition, fiber diameters are proportional to the amount of Ag nanoparticle contents. DSC indicated that the Ag nanoparticles can be incorporated within the PLA matrix without strongly affecting their thermal properties. Moreover, the crystallinity of the composite nonwoven fiber mats was higher than those of fiber mats in the neat PLA. However, TGA revealed that the loaded Ag can improve the thermal stability of the PLA electrospun fiber mats. Accordingly, the antibacterial activities revealed that all the composite nanofiber mats exhibited excellent resistance against S. aureus and E. coli bacterial strains. In addition, in the cell toxicity study, all produced hybrids of nonwoven fiber mats induced a reduction in cell viability for the L929 fibroblast cells. Our results suggest that the designed and prepared nonwoven fiber mats may have good potential for use in the biomedical field, particularly in wound dressing applications.

A Review on the Progress in Core-Spun Yarns (CSYs) Based Textile TENGs for Real-Time Energy Generation, Capture and Sensing

This review is a critical analysis of the current state-of-the-art in core spun yarn textile triboelectric nanogenerators (CSY-T-TENGs) for self-powered smart sensing applications. The rapid expansion of wireless communication, flexible conductive materials, and wearable electronics over the last ten years is now demanding autonomous energy, which has created a new research space in the field of wearable T-TENGs. Current research is exploring T-TENGs made from CSYs as stable and reliable energy harvesters and sensing devices for modern wearable IoT platforms. CSY-TENGs are emerging as an important technology due to its simple structure, low cost, and excellent performance in converting mechanical energy into electrical energy and due to its sensing ability. This paper provides a critical review on current progress, it analyzes the unique advantages of CSYs T-TENGs over conventional T-TENGs, it describes fabrication techniques and discusses the materials used along with their properties and electrical performance characteristics, and it highlights the recent advancements in their integration with self-excitation circuits, charge storage devices and IoT-enabled smart sensing applications, such as environmental and health monitoring. In the conclusion, it discusses the challenges and future directions of CSYs T-TENGs and it provides a future road map for optimization, upscaling, and commercialization of the technology.

CO2-Activation Nanofiber Carbon Paper as a High-Performance Interlayer for Trapping Polysulfides in Li-S Batteries

Lithium-sulfur (Li-S) batteries have high theoretical energy density but low sulfur utilization due to the inherent insulating nature of sulfur and the shuttle effect of polysulfides. Herein, the CO₂-activation carbon paper was prepared by poly(p-phenylenebenzobisoxazole) (PBO) nanofiber and was first applied as an interlayer for efficiently alleviating the shuttle effect of polysulfides in Li-S batteries. This interlayer exhibits good flexibility and strength with rich -C═O and -COOH functional groups on the three-dimensional porous structure, which improves chemical adsorption on Li₂S_x species and ion rapid diffusion via interconnected diffusion channels and thus enhances the electrochemical kinetics. The initial specific capacity is 1367.4 mAh g^-1 and remains 999.8 mAh g^-1 after 200 cycles at 0.2C and 780.1 mAh g^-1 at 5C, and the Coulombic efficiency is high, up to 99.8%, which is much better than that for the carbon paper without CO₂ activation. The highly conductive flexible PBO carbon paper may bring breakthroughs in performance and thus lead to more practical applications of Li-S batteries.

Phytochemical-Based Nanomaterials against Antibiotic-Resistant Bacteria: An Updated Review

Antibiotic-resistant bacteria (ARB) is a growing global health threat, leading to the search for alternative strategies to combat bacterial infections. Phytochemicals, which are naturally occurring compounds found in plants, have shown potential as antimicrobial agents; however, therapy with these agents has certain limitations. The use of nanotechnology combined with antibacterial phytochemicals could help achieve greater antibacterial capacity against ARB by providing improved mechanical, physicochemical, biopharmaceutical, bioavailability, morphological or release properties. This review aims to provide an updated overview of the current state of research on the use of phytochemical-based nanomaterials for the treatment against ARB, with a special focus on polymeric nanofibers and nanoparticles. The review discusses the various types of phytochemicals that have been incorporated into different nanomaterials, the methods used to synthesize these materials, and the results of studies evaluating their antimicrobial activity. The challenges and limitations of using phytochemical-based nanomaterials, as well as future directions for research in this field, are also considered here. Overall, this review highlights the potential of phytochemical-based nanomaterials as a promising strategy for the treatment against ARB, but also stresses the need for further studies to fully understand their mechanisms of action and optimize their use in clinical settings.

A proof of concept to define the parameters affecting poly-L-lactide-co-poly-ε-caprolactone shape memory electrospun nanofibers for biomedical applications

This study is a proof of concept performed to evaluate process parameters affecting shape memory effect of copolymer poly-L-lactide-co-poly-ε-caprolactone (PLA:PCL) 70:30 ratio based nanofibrous scaffolds. A design of experiment (DOE) statistical approach was used to define the interaction between independent material and process variables related to electrospun scaffold manufacturing, such as polymer solution concentration (w/v%), spinning time (min), and needle size (Gauge), and their influence on Rf% (ability of the scaffold to maintain the induced temporary shape) and Rr% (ability of the scaffold to recover its original shape) outputs. A mathematical model was obtained from DOE useful to predict scaffold Rf% and Rr% values. PLA-PCL 15% w/v, 22G needle, and 20-min spinning time were selected to confirm the data obtained from theoretical model. Subsequent morphological (SEM), chemical-physical (GPC and DSC), mechanical (uniaxial tensile tests), and biological (cell viability and adhesion) characterizations were performed.

Anchoring silver nanoparticles on nanofibers by thermal bonding to construct functional surface

Generally, the anchoring of inorganic nanoparticles onto the surface of fibers faces the problem of poor stability, which limits the wide application of nanoparticle functionalized fibers. Herein, nanofibers with shell-core structures were constructed by coaxial electrospinning of two polymers with different melting points (T_m). Polyglycolic acid (PGA, T_m = 225 °C) was employed as the core layer, while polycaprolactone (PCL, T_m = 60 °C) was used as the shell layer. Silver nanoparticles (AgNPs) were electrosprayed on the nanofibers and the shell layer (PCL) was heated and melted to bond the AgNPs, thus realizing a stable AgNP-composited nanofiber for the construction of antibacterial functional surface. By regulating the shell-core flow ratio and the condition for heat treatment, the appropriate thickness of the shell layer was obtained with a flow ratio of 3:1 (PCL:PGA). The optimal composite structure was constructed when the thermal bonding was taken under 80 °C for 5 min. Furthermore, it was found that the composite nanofibers prepared by thermal bonding had better hydrophilicity, mechanical property, and AgNPs bonding stability, and their antibacterial rate against Staphylococcus aureus (S. aureus) reached over 97%. Overall, a facile and universal method for the preparation of nanoparticle-anchored nanofibers was established in this study. The robust nanoparticle-composited nanofibers are promising for applications in optoelectronic devices, electrode materials, and so on.

Modification and Functionalization of Fibers Formed by Electrospinning: A Review

The development of new materials with specific functionalities for certain applications has been increasing with the advent of nanotechnology. A technique widely used for this purpose is electrospinning, because control of several parameters involved in the process can yield nanoscale fibers. In addition to the production of innovative and small-scale materials, through structural, chemical, physical, and biological modifications in the fibers produced in electrospinning, it is possible to obtain specific properties for a given application. Thus, the produced fibers can serve different purposes, such as in the areas of sensors, catalysis, and environmental and medical fields. Given this context, this article presents a review of the electrospinning technique, addressing the parameters that influence the properties of the fibers formed and some techniques used to modify them as specific treatments that can be conducted during or after electrospinning. In situ addition of nanoparticles, changes in the configuration of the metallic collector, use of alternating current, electret fibers, core/shell method, coating, electrospray-coating, plasma, reinforcing composite materials, and thermal treatments are some of the examples addressed in this work. Therefore, this work contributes to a better comprehension of some of the techniques mentioned in the literature so far.

Shape-Memory Polymers Hallmarks and Their Biomedical Applications in the Form of Nanofibers

Shape-Memory Polymers (SMPs) are considered a kind of smart material able to modify size, shape, stiffness and strain in response to different external (heat, electric and magnetic field, water or light) stimuli including the physiologic ones such as pH, body temperature and ions concentration. The ability of SMPs is to memorize their original shape before triggered exposure and after deformation, in the absence of the stimulus, and to recover their original shape without any help. SMPs nanofibers (SMPNs) have been increasingly investigated for biomedical applications due to nanofiber's favorable properties such as high surface area per volume unit, high porosity, small diameter, low density, desirable fiber orientation and nanoarchitecture mimicking native Extra Cellular Matrix (ECM). This review focuses on the main properties of SMPs, their classification and shape-memory effects. Moreover, advantages in the use of SMPNs and different biomedical application fields are reported and discussed.

Enhanced antibacterial efficacy and mechanism of octyl gallate/beta-cyclodextrins against Pseudomonas fluorescens and Vibrio parahaemolyticus and incorporated electrospun nanofibers for Chinese giant salamander fillets preservation

A series of alkyl gallates were evaluated for the antibacterial activity against two common Gram-negative foodborne bacteria (Pseudomonas fluorescens and Vibrio parahaemolyticus) associated with seafood. The length of the alkyl chain plays a pivotal role in eliciting their antibacterial activities and octyl gallate (OG) exerted an excellent inhibitory efficacy. To extend the aqueous solubility, stability, and bactericidal properties of octyl gallate (OG), an inclusion complex between OG and β-cyclodextrin (βCD), OG/βCD, was prepared and identified with various methods including X-ray diffraction (XRD), differential scanning calorimeter (DSC) and Fourier transform infrared spectroscopy (FTIR). Furthermore, the enhanced inhibitory effect and potential antibacterial mechanism of OG/βCD against two Gram-negative and Gram-positive foodborne bacteria were comprehensively investigated. The results show that OG/βCD could function against bacteria through effectively damaging the membrane, permeating into cells, and then disturbing the activity of the respiratory electron transport chain to cause the production of high-level intracellular hydroxyl radicals. Moreover, the reinforced OG/βCD-incorporated polylactic acid (PLA) nanofibers were fabricated using the electrospinning technique as food packaging to extend the Chinese giant salamander fillet's shelf life at 4 °C. This research highlights the antibacterial effectiveness of OG/βCD in aqueous media, which can be used as a safe multi-functionalized food additive combined with the benefits of electrospun nanofibers to extend the Chinese giant salamander fillets shelf life by 15 d at 4 °C.

Field-flow fractionation for nanoparticle characterization

This review presents field-flow fractionation: The elements of theory enable the link between the retention and the characteristics of the nanometer-sized analytes to be highlighted. In particular, the nature of force and its way of being applied are discussed. Four types of forces which determine four types of techniques were considered: hydrodynamic, sedimentation, thermal, and electrical; this is to show the importance of the choice of technique in relation to the characterization objectives. Then the separation performance is presented and compared with other separation techniques: field-flow fractionation has the greatest intrinsic separation capability. The characterization strategies are presented and discussed; on the one hand with respect to the characteristics needed for the description of nanoparticles; on the other hand in connection with the choice of the nature of the force, and also of the detectors used, online or offline. The discussion is based on a selection of published study examples. Finally, current needs and challenges are addressed, and as response, trends and possible characterization solutions.

Antimicrobial mechanism of alkyl gallates against Escherichia coli and Staphylococcus aureus and its combined effect with electrospun nanofibers on Chinese Taihu icefish preservation

The objective of this study was to investigate the antibacterial activity and potential mechanism of alkyl gallates against Escherichia coli and Staphylococcus aureus. Results show that the length of the alkyl chain plays a pivotal role in eliciting the activity and octyl gallate (OG) exerted excellent bactericidal activity through a multiple bactericidal mechanism. OG functions against both bacteria through damaging bacterial cell wall integrity, permeating into cells and then interacting with DNA, as well as disturbing the activity of the respiratory electron transport chain to induce a high-level toxic ROS (hydroxyl radicals) generation and up-regulation of the ROS genes. Also, electrospun nanofibers with OG have unique superiorities for maintaining the freshness of the icefish (4 °C). This research not only provides a more in-depth understanding of the interaction between OG and microorganisms but also highlights the great promise of using OG as a safe multi-functionalized food additive for food preservations.

Experimental and Computational Investigation of Intra- and Interlayer Space for Enhanced Depth Filtration and Reduced Pressure Drop

The buildup of pressure drop with mass loading of particles aggravates the breathing resistance and energy consumption of filters. This study investigated the role of intra- and interlayer space of filter media on the pressure drop development with continued particle loading. Five basic morphologies, including microfibers, nanofibers, microbeads-on-strings, and a mix of those morphologies were fabricated via electrospinning. Then the variations of layered constructions were made, to include a total 14 different filter structures. For a single layer filter media, the pore size rather than the percent porosity had a major impact on the pressure drop. For dual layers, the space between the layers and the placement order of webs were important factors affecting the pressure drop and depth loading of particles. Computational modeling was used to interpret the role of the interlayer space on the pressure drop, by monitoring the air flow and particle movement within the filter constructions, where the computational prediction corresponded to the tendency of the experimental findings. The novelty of this study lies in the combined approach of the experimental and computational work to understand the particle capture phenomenon during the mass loading.

Advances in Functional Polymer Nanofibers: From Spinning Fabrication Techniques to Recent Biomedical Applications

Functional polymeric micro-/nanofibers have emerged as promising materials for the construction of structures potentially useful in biomedical fields. Among all kinds of technologies to produce polymer fibers, spinning methods have gained considerable attention. Herein, we provide a recent review on advances in the design of micro- and nanofibrous platforms via spinning techniques for biomedical applications. Specifically, we emphasize electrospinning, solution blow spinning, centrifugal spinning, and microfluidic spinning approaches. We first introduce the fundamentals of these spinning methods and then highlight the potential biomedical applications of such micro- and nanostructured fibers for drug delivery, tissue engineering, regenerative medicine, disease modeling, and sensing/biosensing. Finally, we outline the current challenges and future perspectives of spinning techniques for the practical applications of polymer fibers in the biomedical field.