Electro-spinning/netting: A strategy for the fabrication of three-dimensional polymer nano-fiber/nets

Polydopamine-coated polycaprolactone/carbon nanotube fibrous scaffolds loaded with basic fibroblast growth factor for wound healing

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PBAT/PLA-Based Electrospun Nanofibrous Protective Clothes with Superhydrophobicity, Permeability, and Thermal Insulation Characteristics for Individuals with Disabilities

This study presents the development of multifunctional protective clothing for disabled individuals using PBAT/PLA biopolymeric-based electrospun nanofibrous membranes. The fabric consists of a superhydrophobic electrospun nanofibrous cloth reinforced with silica nanoparticles. The resulting nanofiber membranes were characterized using FE-SEM, a CA goniometer, breathability and hydrostatic pressure resistance tests, UV-vis spectroscopy, thermal infrared photography, tensile tests, and nanoindentation. The results demonstrated the integration of superhydrophobicity, breathability, and mechanical improvements in the protective clothing. The nanofibrous porous structure of the fabric allowed breathability, while the silica nanoparticles acted as an effective infrared reflector to keep the wearer cool on hot days. The fabric's multifunctional properties make it suitable for various products, such as outdoor clothing and accessories for individuals with disabilities. This study highlights the importance of selecting appropriate textiles for protective clothing and the challenges faced by disabled individuals in terms of mobility, eating, and dressing. The innovative and purposeful design of this multifunctional protective clothing aimed to enrich the lives of individuals with disabilities.

Developing novel multifunctional protective clothes for disabled individuals using bio-based electrospun nanofibrous membranes

A novel kind of protective apparel for handicapped persons has been created with bio-based electrospun nanofibrous (NFs) membranes. Hydrophobic membranes with fine polylactic acid (PLA) NFs had a smooth, bead-less structure with an average diameter of 950 nm. The hydrophilic layer has a similar pattern but a smaller fiber diameter dispersion and an average diameter of 750 nm. The silica nanoparticle-modified super-hydrophobic top layer (contact angle, ~153°) repels water and keeps the user dry. Super-hydrophilic silver nanoparticles in the fabric's bottom layer react with perspiration to kill microorganisms. The fabric's porosity (avg. 1.2-1.5 μm) allows for breathability, while silica nanoparticles boost infrared radiation reflection, keeping users cool on hot days. The dual-layer textile has 4.9 MPa ultimate tensile strength and 68 % elongation compared to the membrane's super-hydrophobic and super-hydrophilic layers. Wearing protective clothes reduced hand temperature by 25 % in direct sunlight and 13 % in a sun simulator with 1 Sun. This fabric will work well for adult diapers, outdoor clothing, and disability accessories. Overall, the protective textiles may improve the quality of life for disabled and elderly people by providing usable textile items adapted to their needs.

Construction of semiconductor nanocomposites for room-temperature gas sensors

Gas sensors are essential for ensuring public safety and improving quality of life. Room-temperature gas sensors are notable for their potential economic benefits and low energy consumption, and their expected integration with wearable electronics, making them a focal point of contemporary research. Advances in nanomaterials and low-dimensional semiconductors have significantly contributed to the enhancement of room-temperature gas sensors. These advancements have focused on improving sensitivity, selectivity, and response/recovery times, with nanocomposites offering distinct advantages. The discussion here focuses on the use of semiconductor nanocomposites for gas sensing at room temperature, and provides a review of the latest synthesis techniques for these materials. This involves the precise adjustment of chemical compositions, microstructures, and morphologies. In addition, the design principles and potential functional mechanisms are examined. This is crucial for deepening the understanding and enhancing the operational capabilities of sensors. We also highlight the challenges faced in scaling up the production of nanocomposite materials. Looking ahead, semiconductor nanocomposites are expected to drive innovation in gas sensor technology due to their carefully crafted design and construction, paving the way for their extensive use in various sectors.

Harnessing the Coil Electrospinning Method for Fabricating Superflexible and Multiscale-Patterned Fibrous Tubular Scaffolds with Topographical Features

The fibrous tubular scaffold (FTS) has potential as a vascular graft; however, its clinical application is hindered by insufficient mechanical properties. Inadequate mechanical properties of vascular grafts can lead to some serious side effects such as intimal hyperplasia, luminal expansion, and blood thrombogenicity. In this study, we developed a novel fibrous tubular scaffold comprising multiscale fibers to ensure superior mechanical properties. Our novel approach involves a one-step manufacturing method that can fabricate the superflexible fibrous tubular scaffold (SF-FTS) with topographical features via a modified electrospinning setup. We investigated the effect of humidity and temperature during the fabrication process on the formation of multiscale fibers. It was demonstrated that the incorporation of multiscale fibers and topographical features significantly enhances the mechanical properties of FTS. The mechanical advantages of SF-FTS were confirmed through the kinking resistance test, compressive test, and in vivo experiments. Additionally, we explored the interaction between the multiscale fibers and human umbilical vein endothelial cells (HUVECs) behavior. Our results suggest a novel strategy for fabricating FTS with advanced mechanical properties, and the designed SF-FTS holds promise as a potential candidate for clinical applications.

Polymer-Based Wound Dressings Loaded with Essential Oil for the Treatment of Wounds: A Review

Wound healing can result in complex problems, and discovering an effective method to improve the healing process is essential. Polymeric biomaterials have structures similar to those identified in the extracellular matrix of the tissue to be regenerated and also avoid chronic inflammation, and immunological reactions. To obtain smart and effective dressings, bioactive agents, such as essential oils, are also used to promote a wide range of biological properties, which can accelerate the healing process. Therefore, we intend to explore advances in the potential for applying hybrid materials in wound healing. For this, fifty scientific articles dated from 2010 to 2023 were investigated using the Web of Science, Scopus, Science Direct, and PubMed databases. The principles of the healing process, use of polymers, type and properties of essential oils and processing techniques, and characteristics of dressings were identified. Thus, the plants Syzygium romanticum or Eugenia caryophyllata, Origanum vulgare, and Cinnamomum zeylanicum present prospects for application in clinical trials due to their proven effects on wound healing and reducing the incidence of inflammatory cells in the site of injury. The antimicrobial effect of essential oils is mainly due to polyphenols and terpenes such as eugenol, cinnamaldehyde, carvacrol, and thymol.

Emerging Trends of Nanofibrous Piezoelectric and Triboelectric Applications: Mechanisms, Electroactive Materials, and Designed Architectures

Over the past few decades, significant progress in piezo-/triboelectric nanogenerators (PTEGs) has led to the development of cutting-edge wearable technologies. Nanofibers with good designability, controllable morphologies, large specific areas, and unique physicochemical properties provide a promising platform for PTEGs for various advanced applications. However, the further development of nanofiber-based PTEGs is limited by technical difficulties, ranging from materials design to device integration. Herein, the current developments in PTEGs based on electrospun nanofibers are systematically reviewed. This review begins with the mechanisms of PTEGs and the advantages of nanofibers and nanodevices, including high breathability, waterproofness, scalability, and thermal-moisture comfort. In terms of materials and structural design, novel electroactive nanofibers and structure assemblies based on 1D micro/nanostructures, 2D bionic structures, and 3D multilayered structures are discussed. Subsequently, nanofibrous PTEGs in applications such as energy harvesters, personalized medicine, personal protective equipment, and human-machine interactions are summarized. Nanofiber-based PTEGs still face many challenges such as energy efficiency, material durability, device stability, and device integration. Finally, the research gap between research and practical applications of PTEGs is discussed, and emerging trends are proposed, providing some ideas for the development of intelligent wearables.

Recent Advances in the Fabrication and Performance Optimization of Polyvinyl Alcohol Based Vascular Grafts

Cardiovascular disease is one of the diseases with the highest morbidity and mortality rates worldwide, and coronary artery bypass grafting (CABG) is a fast and effective treatment. More researchers are investigating in artificial blood vessels due to the limitations of autologous blood vessels. Despite the availability of large-diameter vascular grafts (Ø > 6 mm) for clinical use, small-diameter vascular grafts (Ø < 6 mm) have been a challenge for researchers to overcome in recent years. Vascular grafts made of polyvinyl alcohol (PVA) and PVA-based composites have excellent biocompatibility and mechanical characteristics. In order to gain a clearer and more specific understanding of the progress in PVA vascular graft research, particularly regarding the preparation methods, principles, and functionality of PVA vascular graft, this article discusses the mechanical properties, biocompatibility, blood compatibility, and other properties of PVA vascular graft prepared or enhanced with different blends using various techniques that mimic natural blood vessels. The findings reveal the feasibility and promising potential of PVA or PVA-based composite materials as vascular grafts.

Dendritic boron and nitrogen doped high-entropy alloy porous carbon fibers for high-efficiency hydrogen evolution reaction

Among various electrocatalysts, high-entropy alloys (HEAs) have gained significant attention for their unique properties and excellent catalytic activity in the hydrogen evolution reaction (HER). However, the precise synthesis of HEA catalysts in small sizes remains challenging, which limits further improvement in their catalytic performance. In this study, boron- and nitrogen-doped HEA porous carbon nanofibers (HE-BN/PCNF) with an in situ-grown dendritic structure were successfully prepared, inspired by the germination and growth of tree branches. Furthermore, the dendritic fibers constrained the growth of HEA particles, leading to the synthesis of quantum dot-sized (1.67 nm) HEA particles, which also provide a pathway for designing HEA quantum dots in the future. This work provides design ideas and guiding suggestions for the preparation of borated HEA fibers with different elemental combinations and for the application of dendritic nanofibers in various fields.

Recycling and high-value utilization of polyethylene terephthalate wastes: A review

Polyethelene terephthalate (PET) is a well-known thermoplastic, and recycling PET waste is important for the natural environment and human health. This study provides a comprehensive overview of the recycling and reuse of PET waste through energy recovery and physical, chemical, and biological recycling. This article summarizes the recycling methods and the high-value products derived from PET waste, specifically detailing the research progress on regenerated PET prepared by the mechanical recycling of fiber/yarn, fabric, and composite materials, and introduces the application of PET nanofibers recycled by physical dissolution and electrospinning in fields such as filtration, adsorption, electronics, and antibacterial materials. This article explains the energy recovery of PET through thermal decomposition and comprehensively discusses various chemical recycling methods, including the reaction mechanisms, catalysts, conversion efficiencies, and reaction products, with a brief introduction to PET biodegradation using hydrolytic enzymes provided. The analysis and comparison of various recycling methods indicated that the mechanical recycling method yielded PET products with a wide range of applications in composite materials. Electrospinning is a highly promising recycling strategy for fabricating recycled PET nanofibers. Compared to other methods, physical recycling has advantages such as low cost, low energy consumption, high value, simple processing, and environmental friendliness, making it the preferred choice for the recycling and high-value utilization of waste PET.

Gas Sensors Based on Semiconductor Metal Oxides Fabricated by Electrospinning: A Review

Electrospinning has revolutionized the field of semiconductor metal oxide (SMO) gas sensors, which are pivotal for gas detection. SMOs are known for their high sensitivity, rapid responsiveness, and exceptional selectivity towards various types of gases. When synthesized via electrospinning, they gain unmatched advantages. These include high porosity, large specific surface areas, adjustable morphologies and compositions, and diverse structural designs, improving gas-sensing performance. This review explores the application of variously structured and composed SMOs prepared by electrospinning in gas sensors. It highlights strategies to augment gas-sensing performance, such as noble metal modification and doping with transition metals, rare earth elements, and metal cations, all contributing to heightened sensitivity and selectivity. We also look at the fabrication of composite SMOs with polymers or carbon nanofibers, which addresses the challenge of high operating temperatures. Furthermore, this review discusses the advantages of hierarchical and core-shell structures. The use of spinel and perovskite structures is also explored for their unique chemical compositions and crystal structure. These structures are useful for high sensitivity and selectivity towards specific gases. These methodologies emphasize the critical role of innovative material integration and structural design in achieving high-performance gas sensors, pointing toward future research directions in this rapidly evolving field.

Electrospinning-netting of spider-inspired polycaprolactone/collagen nanofiber-nets incorporated with Propolis extract for enhanced wound healing applications

Nanofibers hold significant promise for wound healing applications, but their potential is limited by their large diameter. To overcome this limitation, the development of nanofibrous systems with refined nanonets (approximately 20 nm in diameter) represents a notable improvement. In this study, a composite of polycaprolactone/collagen (PCLC) nano-fiber/nets (NFNs) was fabricated using benign solvents (acetic acid and formic acid) via the electro-spinning/netting (ESN) technique, harnessing the regenerative potential of collagen as a biological macromolecule. Additionally, to enhance the natural attributes of the NFNs structure, Propolis extract, renowned for its wound healing properties, was incorporated. Five ESN solutions were prepared: PCL, PCLC, PCLC/Pro 5 %, PCLC/Pro 10 %, and PCLC/Pro 15 %. NaCl salt was introduced into all ESN solutions to improve nanonets formation. FE-SEM imaging demonstrated successful nano-net formation in all ESN solutions except for the PCL formulation. The fabricated scaffolds exhibited spider-like nanonets with the addition of collagen and further enhanced nano-net formation with Propolis incorporation. Trunk nanofibers showed filamentous structures without any beads, with an average diameter of 164-728 nm, while the diameter of branched fibers (nanonets) was approximately 20 nm. WVTR values of the NFNs were comparable to commercial dressings such as Tegaderm. The results also demonstrated the potent cytoprotective effects of Propolis-loaded NFNs in a dose-dependent manner. Furthermore, the viability of HFF-2 cells after 72 h of culture on PCLC NFNs significantly increased compared to PCL nanofibers. The highest cell viability was observed in PCLC/Pro 15 % nanofibers after 24, 48, and 72 h of cell culture, indicating the proliferative effect of Propolis extract in nanoformulated form. Additionally, the scaffolds exhibited a hemocompatibility of <3 %, further highlighting their potential in wound healing therapeutics.

Recycling Waste Agricultural Nets as Cement Composites

The advancement of agricultural mesh technology has contributed to its improved properties. As a result, agricultural nets are widely adopted in large-scale farming applications, for example, in cereal crop farming. However, a consequence of this increased use of agricultural nets is the accumulation of large amounts of waste. The current paper focuses on the recycling of agricultural nets used in wrapping straw bales to develop additives and fillers in cement composites. The research details an analysis of the use of waste agricultural meshes as an ingredient in cement composites. Six test series of different mixtures were conducted. In the first four series, agricultural waste was utilised as an additive in a composite comprising aggregate and cement slurry (the amounts of wasted nets were 20, 40, 60, and 80 kg/m3). In the last test series, the recyclate utilised comprised a mixture of cement slurry and waste only. The composites were subjected to standard tests and thermal resistance tests. The results showcased that that the addition of a net worsened the workability of the concrete mixture, and with increasing amounts of addition, the consistency of the mixture could change from liquid to dense plastic. The flexural strength of the composite decreased with increasing amounts of recyclate. In subsequent test series, the flexural strength value was lower than that of the control (3.93 MPa), from 7.38% (3.64 MPa) for the composite with 20 kg/m3 of recyclate to 37.66% (2.45 MPa) for the composite with of 80 kg/m3 recyclate. The flexural strength value of the net-filled composite without aggregate was very high (10.44 MPa), where the value obtained for the control composite was 62.36% lower. The results of the compressive strength test showed a decrease in this parameter with increasing amounts of additive. The value assessed for the control composite was 27.99 MPa. As expected, the composite that had no aggregate and consisted of only recycled filler had the lowest compressive strength. The value of this parameter was 13.07 MPa, and it was 53.31% lower than that of the control composite. The results of the tests of resistance to temperatures were similar to those recorded for the composites with polypropylene fibres. All composites demonstrated a significant decrease in their compressive and flexural strength after annealing. SEM imaging showed that the net fibres were closely bonded to the cement stone. Finally, it was concluded that recyclates performed best as fillers in lightweight composites with a low density, low absorption, high flexural strength, and satisfactory compressive strength.

Nanostructured Medical Devices: Regulatory Perspective and Current Applications

Nanomaterials (NMs) are having a huge impact in several domains, including the fabrication of medical devices (MDs). Hence, nanostructured MDs are becoming quite common; nevertheless, the associated risks must be carefully considered in order to demonstrate safety prior to their immission on the market. The biological effect of NMs requires the consideration of methodological issues since already established methods for, e.g., cytotoxicity can be subject to a loss of accuracy in the presence of certain NMs. The need for oversight of MDs containing NMs is reflected by the European Regulation 2017/745 on MDs, which states that MDs incorporating or consisting of NMs are in class III, at highest risk, unless the NM is encapsulated or bound in such a manner that the potential for its internal exposure is low or negligible (Rule 19). This study addresses the role of NMs in medical devices, highlighting the current applications and considering the regulatory requirements of such products.

Electrospinning technologies for the delivery of Biopharmaceuticals: Current status and future trends

This review provides an in-depth exploration of electrospinning techniques employed to produce micro- or nanofibres of biopharmaceuticals using polymeric solutions or melts with high-voltage electricity. Distinct from prior reviews, the current work narrows its focus on the recent developments and advanced applications in biopharmaceutical formulations. It begins with an overview of electrospinning principles, covering both solution and melt modes. Various methods for incorporating biopharmaceuticals into electrospun fibres, such as surface adsorption, blending, emulsion, co-axial, and high-throughput electrospinning, are elaborated. The review also surveys a wide array of biopharmaceuticals formulated through electrospinning, thereby identifying both opportunities and challenges in this emerging field. Moreover, it outlines the analytical techniques for characterizing electrospun fibres and discusses the legal and regulatory requirements for their production. This work aims to offer valuable insights into the evolving realm of electrospun biopharmaceutical delivery systems.

Therapeutic effects of electrospun chitosan nanofibers on animal skin wounds: A systematic review and meta-analysis

Electrospun chitosan nanofibers (QSNFs) enhance the healing process by mimicking skin structure and function. The aim of this study was to analyze the therapeutic effects of QSNFs application on animal skin wounds to identify a potential direction for translational research in dermatology. The PRISMA methodology and the PICO scheme were used. A random effects model and mean difference analysis were applied for the meta-analysis. A meta-regression model was constructed, risk of bias was determined, and methodological quality assessment was performed. Of the 2370 articles collected, 54 studies were selected based on the inclusion and exclusion criteria. The wound healing area was used for building models on the 3rd, 7th, and 14th days of follow-up; the results were - 10.4% (95% CI, -18.2% to -2.6%, p = 0.001), -21.0% (95% CI, -27.3% to -14.7%, p = 0.001), and - 14.0% (95% CI, -19.1 to -8.8%, p = 0.001), respectively. Antioxidants and synthetic polymers combined with QSNFs further reduced skin wound areas (p < 0.05). The results show a more efficient reduction in wound area percentages in experimental groups than in control groups, so QSNFs could potentially be applied in translational human medicine research.

Xylan derived carbon dots composite with PCL/PLA for construction biomass nanofiber membrane used as fluorescence sensor for detection Cu2+ in real samples

Water and soil pollution caused by Cu2+ is not conducive to sustainable development of environment and could cause damage to environment and even human body. Currently, fluorescent sensor solutions analysis method has been used for Cu2+ detection, but they also suffer from drawbacks including easy leakage, difficult storage, and inaccurate. Herein, a green solid-state biomass fluorescence platform (NBU-CDs) consisting of xylan-derived carbon dots (U-CDs) and polylactic acid/polycaprolactone (PLA/PCL) was designed by using in situ electrospinning technology. The prepared NBU-CDs fluorescence platform showed good fluorescence effect and can be served as fluorescence sensor for detecting Cu2+ with high sensitively, selectively and low detection limit (LOD = 0.83 μM). The practical applications of NBU-CDs exhibited high specificity for Cu2+ detection in zebrafish, water samples (school lake, Xuanwu Lake and Yangtze River) with high recovery rates of 97 %-104 % and soil (pond soil, grassland soil and bamboo soil) samples, respectively. The developed fluorescence platform was utilized to predict water and soil safety by monitoring Cu2+ concentration and provides a new strategy for Cu2+ detection.

Silica NPs in PLA-Based Electrospun Nanofibrous Non-Woven Protective Fabrics with Dual Hydrophilicity/Hydrophobicity, Breathability, and Thermal Insulation Characteristics for Individuals with Disabilities

A perfect protective fabric for handicapped individuals must be lightweight, waterproof, breathable, and able to absorb water. We present a multifunctional protective fabric in which one side is hydrophobic based on the intrinsic hydrophobic biopolymer polylactic acid (PLA) to keep the disabled person from getting wet, while the other side is super-hydrophilic due to embedded silica nanoparticles (NPs) to keep the disabled person safe from a sudden spill of water or other beverage on their skin or clothes. The porosity of the electrospun nanofibrous structure allows the fabric to be breathable, and the silica NPs play an important role as a perfect infrared reflector to keep the person's clothing cool on warm days. Adding white NPs, such as silicon dioxide, onto or into the textile fibers is an effective method for producing thermally insulated materials. Due to their ability to efficiently block UV light, NPs in a network keep the body cool. Such a multifunctional fabric might be ideal for adult bibs and aprons, outdoor clothing, and other amenities for individuals with disabilities.

Development of Support Layers and Their Impact on the Performance of Thin Film Composite Membranes (TFC) for Water Treatment

Thin-film composite (TFC) membranes have gained significant attention as an appealing membrane technology due to their reversible fouling and potential cost-effectiveness. Previous studies have predominantly focused on improving the selective layers to enhance membrane performance. However, the importance of improving the support layers has been increasingly recognized. Therefore, in this review, preparation methods for the support layer, including the traditional phase inversion method and the electrospinning (ES) method, as well as the construction methods for the support layer with a polyamide (PA) layer, are analyzed. Furthermore, the effect of the support layers on the performance of the TFC membrane is presented. This review aims to encourage the exploration of suitable support membranes to enhance the performance of TFC membranes and extend their future applications.

Nanofibers in Respiratory Masks: An Alternative to Prevent Pathogen Transmission

Recent global outbreak of COVID-19 has raised serious awareness about our abilities to protect ourselves from hazardous pathogens and volatile organic compounds. Evidence suggests that personal protection equipment such as respiratory masks can radically decrease rates of transmission and infections due to contagious pathogens. To increase filtration efficiency without compromising breathability, application of nanofibers in production of respiratory masks have been proposed. The emergence of nanofibers in the industry has since introduced a next generation of respiratory masks that promises improved filtration efficiency and breathability via nanometric pores and thin fiber thickness. In addition, the surface of nanofibers can be functionalized and enhanced to capture specific particles. In addition to conventional techniques such as melt-blown, respiratory masks by nanofibers have provided an opportunity to prevent pathogen transmission. As the surge in global demand for respiratory masks increases, herein, we reviewed recent advancement of nanofibers as an alternative technique to be used in respiratory mask production.

Development of Light-Polymerized Dental Composite Resin Reinforced with Electrospun Polyamide Layers

As the mechanical properties of resin-based dental composite materials are highly relevant in clinical practice, diverse strategies for their potential enhancement have been proposed in the extant literature, aiming to facilitate their reliable use in dental medicine. In this context, the focus is primarily given to the mechanical properties with the greatest influence on clinical success, i.e., the longevity of the filling in the patient's mouth and its ability to withstand very strong masticatory forces. Guided by these objectives, the goal of the present study was to ascertain whether the reinforcement of dental composite resins with electrospun polyamide (PA) nanofibers would improve the mechanical strength of dental restoration materials. For this purpose, light-cure dental composite resins were interspersed with one and two layers comprising PA nanofibers in order to investigate the influence of such reinforcement on the mechanical properties of the resulting hybrid resins. One set of the obtained samples was investigated as prepared, while another set was immersed in artificial saliva for 14 days and was subsequently subjected to the same set of analyses, namely Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Findings yielded by the FTIR analysis confirmed the structure of the produced dental composite resin material. They also provided evidence that, while the presence of PA nanofibers did not influence the curing process, it strengthened the dental composite resin. Moreover, flexural strength measurements revealed that the inclusion of a 16 μm-thick PA nanolayer enabled the dental composite resin to withstand a load of 3.2 MPa. These findings were supported by the SEM results, which further indicated that immersing the resin in saline solution resulted in a more compact composite material structure. Finally, DSC results indicated that as-prepared as well as saline-treated reinforced samples had a lower glass transition temperature (Tg) compared to pure resin. Specifically, while pure resin had a Tg of 61.6 °C, each additional PA nanolayer decreased the Tg by about 2 °C, while the further reduction was obtained when samples were immersed in saline for 14 days. These results show that electrospinning is a facile method for producing different nanofibers that can be incorporated into resin-based dental composite materials to modify their mechanical properties. Moreover, while their inclusion strengthens the resin-based dental composite materials, it does not affect the course and outcome of the polymerization reaction, which is an important factor for their use in clinical practice.

A novel slip-velocity model to simulate the filtration performance of nanofiber media

Aerosols such as PM_2.5 and PM₁₀ can have an immense impact on human health. With the outbreak of SARS-CoV-2, it is urgent to filter aerosols by media filtration technology. Electrospun nanofibers are a promising material for achieving high efficiency, low resistance, light weight, and environmentally friendly air filtration. But research on filtration theory and computer simulation of nanofiber media is still lacking. The traditional method involving computational fluid dynamics (CFD) and Maxwell's first-order slip boundary overestimates the slip velocity on the fiber surface. In this study, a new modified slip boundary was proposed, which introduced a slip velocity coefficient on the basis of the no-slip boundary to address the slip wall. Our simulation results were compared with the experimental pressure drop and particle capture efficiency of real polyacrylonitrile (PAN) nanofiber media. The computational accuracy on pressure drop of the modified slip boundary improved 24.6% and 11.2% compared with that of the no-slip boundary and Maxwell's first-order slip boundary, respectively. It was found that the particle capture efficiency near the most-penetrating particle size (MPPS) was significantly increased when slip effect occurred. This may be explained by the slip velocity on the fiber surface, which would make particles more accessible to the fiber surface and captured by interception.

Electrospun Nanofibers for Dura Mater Regeneration: A Mini Review on Current Progress

Dural defects are a common problem in neurosurgical procedures and should be repaired to avoid complications such as cerebrospinal fluid leakage, brain swelling, epilepsy, intracranial infection, and so on. Various types of dural substitutes have been prepared and used for the treatment of dural defects. In recent years, electrospun nanofibers have been applied for various biomedical applications, including dural regeneration, due to their interesting properties such as a large surface area to volume ratio, porosity, superior mechanical properties, ease of surface modification, and, most importantly, similarity with the extracellular matrix (ECM). Despite continuous efforts, the development of suitable dura mater substrates has had limited success. This review summarizes the investigation and development of electrospun nanofibers with particular emphasis on dura mater regeneration. The objective of this mini-review article is to give readers a quick overview of the recent advances in electrospinning for dura mater repair.

Selective separation of dye/salt mixture using diatomite-based sandwich-like membrane

A novel nanofiltration membrane was developed by entrapping a layer of modified diatomaceous earth between two layers of electrospun polysulfone (E-PSf) nanofibers. The diatomaceous earth particles and the fabricated membrane were characterized using FTIR, SEM, EDS, zeta potential, and water contact angle techniques. The static adsorption and dynamic separation of pristine E-PSF and sandwich-like membranes for methylene blue (MB) with/without salt were investigated under different operating conditions. The Langmuir model suited the MB adsorption isotherm data with a linear regression correlation coefficient (R²) >0.9955. As pH increased, both flux and MB rejection of the sandwich-like membrane improved by up to 183.8 LMH and 99.7%, respectively, when operated under gravity. The water flux of the sandwich-like membrane was sharply increased by increasing the pressure up to 19,518.2 LMH at 4.0 bar. However, this came at the expense of MB rejection (10.93%) and reduced its practical impact. At a high salt concentration, the sandwich-like membrane also indicated remarkable dye/salt separation with a higher permeation of salt (<0.2% NaCl rejection) and MB rejection (>99%). The performance of the regenerated diatomaceous material and membrane was maintained during five cycles of operation compared to that of the original ones.

An Intelligent Wearable Filtration System for Health Management

To develop intelligent wearable protection systems is of great significance to human health engineering. An ideal intelligent air filtration system should possess reliable filtration efficiency, low pressure drop, healthcare monitoring function, and man-machine interactive capability. However, no existing intelligent protection system covers all these essential aspects. Herein, we developed an intelligent wearable filtration system (IWFS) via advanced nanotechnology and machine learning. Based on the triboelectric mechanism, the fabricated IWFS exhibits a long-lasting high particle filtration efficiency and bacteria protection efficiency of 99% and 100%, respectively, with a low-pressure drop of 5.8 mmH₂O. Correspondingly, the charge accumulation of the optimized IWFS (87 nC) increased to 3.5 times that of the pristine nanomesh, providing a significant enhancement of the particle filtration efficiency. Theoretical principles, including the enhancement of the β-phase and the lower surface potential of the modified nanomesh, were quantitatively investigated by molecular dynamics simulation, band theory, and Kelvin probe force microscopy. Furthermore, we endowed the IWFS with a healthcare monitoring function and man-machine interactive capability through machine learning and wireless transmission technology. Crucial physiological signals of people, including breath, cough, and speaking signals, were detected and classified, with a high recognition rate of 92%; the fabricated IWFS can collect healthcare data and transmit voice commands in real time without hindrance by portable electronic devices. The achieved IWFS not only has practical significance for human health management but also has great theoretical value for advanced wearable systems.

Core-Shell Polyvinyl Alcohol (PVA) Base Electrospinning Microfibers for Drug Delivery

In this study, electrospun membranes were developed for controlled drug release applications. Both uniaxial Polyvinyl alcohol (PVA) and coaxial fibers with a PVA core and a poly (L-lactic acid) (PLLA) and polycaprolactone (PCL) coating were produced with different coating structures. The best conditions for the manufacture of the fibers were also studied and their morphology was analyzed as a function of the electrospinning parameters. Special attention was paid to the fiber surface morphology of the coaxial fibers, obtaining both porous and non-porous coatings. Bovine serum albumin (BSA) was used as the model protein for the drug release studies and, as expected, the uncoated fibers were determined to have the fastest release kinetics. Different release rates were obtained for the coated fibers, which makes this drug release system suitable for different applications according to the release time required.

Electrospun Core-Sheath Fibers with a Uniformly Aligned Polymer Network Liquid Crystal (PNLC)

Electrospun polymer-liquid crystal (PLC) fibers have potential applications such as wearable sensors and adaptive textiles because of their rapid response and high flexibility. However, existing PLC fibers only have a narrow responsive range and poor resistance to heat and chemicals. Herein, a new type of PLC fiber is prepared by using a coaxial electrospinning process. The core solution is 4'-pentyl-4-biphenylcarbonitrile (5CB), and the sheath solution is a mixture containing 13 wt % PVP and 10 wt % reactive mesogen (RM). After UV exposure of the fibers, 5CB in the core and RM diffusing from the core are cross-linked into an LC polymer. The fibers have a highly uniform morphology with an average diameter of 3.2 ± 0.5 μm, and mesogens inside the fibers align unidirectionally with the long axis of the fibers. The fibers show a broad phase-transition temperature range between 13.5 and 155.5 °C and have a response time of less than 10 s. The temperature range can also be controlled by adjusting components in the electrospun fibers and UV exposure time. The core-sheath fibers prepared in such a manner exhibit excellent heat and chemical resistance with reversible optical responses. Moreover, when the fibers are exposed to volatile organic compounds (VOCs) such as toluene, the fibers show a rapid optical response to toluene vapor within 25 s. This study demonstrates that the fibers are potentially useful for preparing flexible temperature and chemical sensors.

Biological Scaffolds Assembled with Magnetic Nanoparticles for Bone Tissue Engineering: A Review

Superparamagnetic iron oxide nanoparticles (SPION) are widely used in bone tissue engineering because of their unique physical and chemical properties and their excellent biocompatibility. Under the action of a magnetic field, SPIONs loaded in a biological scaffold can effectively promote osteoblast proliferation, differentiation, angiogenesis, and so on. SPIONs have very broad application prospects in bone repair, bone reconstruction, bone regeneration, and other fields. In this paper, several methods for forming biological scaffolds via the biological assembly of SPIONs are reviewed, and the specific applications of these biological scaffolds in bone tissue engineering are discussed.

Periodontal Ligament-Mimetic Fibrous Scaffolds Regulate YAP-Associated Fibroblast Behaviors and Promote Regeneration of Periodontal Defect in Relation to the Scaffold Topography

Although multiple regenerative strategies are being developed for periodontal reconstruction, guided periodontal ligament (PDL) regeneration is difficult because of its cellular and fibrous complexities. Here, we manufactured four different types of PDL-mimic fibrous scaffolds on a desired single mat. These scaffolds exhibited a structure of PDL matrix and human PDL fibroblasts (PDLFs) cultured on the scaffolds resembling morphological phenotypes present in native PDLF. The scaffold-seeded PDLF exerted proliferative, osteoblastic, and osteoclastogenic potentials depending on the fiber topographical cues. Fiber surface-regulated behaviors of PDLF were correlated with the expression patterns of yes-associated protein (YAP), CD105, periostin, osteopontin, and vinculin. Transfection with si-RNA confirmed that YAP acted as the master mechanosensing regulator. Of the as-spun scaffolds, aligned or grid-patterned microscale scaffold regulated the YAP-associated behavior of PDLF more effectively than nanomicroscale or random-oriented microscale scaffold. Implantation with hydrogel complex conjugated with microscale-patterned or grid-patterned scaffold, but not other types of scaffolds, recovered the defected PDL with native PDL-mimic cellularization and fiber structure in the reformed PDL. Our results demonstrate that PDL-biomimetic scaffolds regulate topography-related and YAP-mediated behaviors of PDLF in relation to their topographies. Overall, this study may support a clinical approach of the fiber-hydrogel complex in guided PDL regenerative engineering.

Light Scattering of Electrospinning Jet with Internal Structures by Flow-Induced Phase Separation

Herein, the direct morphological evidence of the extension-induced phase-separated structures in the electrospinning jet observed by high-speed video imaging and by light scattering technique is reported. Model solutions of poly(vinyl alcohol) (PVA)/water are electrospun. Two types of internal structures, that is, long strings and short ellipsoids, are found. A light scattering model is derived for the V_v scattering configuration to account for the scattered intensities contributed from the liquid jet itself and those from the internal structures. For the severely stretching jet of PVA/water, the Vv intensity profile is dominant by the internal structures to mask the scattering contribution from the jet itself. Moreover, the H_v intensity profile reflects the anisotropy of the oriented chains parallel to the jet axis. For the 7 wt% solution, the derived extension rate in the vicinity of the Taylor cone apex is about 3420 s^-1 , which is higher than the Rouse relaxation rate measured by rheometer. It is concluded that extension-induced phase separation of the single-phase PVA solution is likely to occur in Taylor-cone apex to trigger the self-assembly process for producing strings (and/or bulges) in the flowing jet, which eventually transform to become the nanofibers, after solvent removal, to be collected on the grounded collector.

High-performance multifunctional electrospun fibrous air filter for personal protection: A review

With the increasingly serious air pollution and the rampant coronavirus disease 2019 (COVID–19), preparing high–performance air filter to achieve the effective personal protection has become a research hotspot. Electrospun nanofibrous membrane has become the first choice of air filter because of its small diameter, high specific surface area and porosity. However, improving the filtration performance of the filter only cannot meet the personal needs: it should be given more functions based on high filtration performance to maximize the personal benefits, called, multifunctional, which can also be easily realized by electrospinning technology, and has attracted much attention. In this review, the filtration mechanism of high–performance electrospun air filter is innovatively summarized from the perspective of membrane. On this basis, the specific preparation process, advantages and disadvantages are analyzed in detail. Furthermore, other functions required for achieving maximum personal protection benefits are introduced specifically, and the existing high–performance electrospun air filter with multiple functions are summarized. Finally, the challenges, limitations, and development trends of manufacturing high–performance air filter with multiple functions for personal protection are presented.

Biodegradation of environmental pollutants using catalase-based biocatalytic systems

The synergistic combination of biocatalysts and nanomaterials provides a new interface of a robust biocatalytic system that can effectively remediate environmental pollutants. Enzymes, such as catalase-based constructs, impart the desired candidature for catalytic transformation processes and are potential alternatives to replace conventional remediation strategies that have become laborious and somewhat inefficient. Furthermore, the controlled or uncontrolled discharge of various emerging pollutants (EPs) into water bodies is equally proportional to the fast-growing population and extensive urbanization. EPs affect the entire living being and continuously deteriorate the environmental system, directly or indirectly. The occurrence of EPs (even released after partial treatments, but still in bioactive forms) disturbs ecological integrity. Due to the ineffectiveness of in-practice traditional remediation processes, new and robust treatment measures as effective and sustainable remediation have become a meaningful goal. In this context, special attention has been shifted to engineering an enzyme (catalase)-based biodegradation system with immense prospects in environmental cleanup. The unique synergistic combination of nanomaterials (having multifunctional attributes) with enzymes of interest makes them a state-of-the-art interface that can further ameliorate bio-catalysis and biodegradation performance. This review covers current research and scientific advancement in developing and deploying catalase-based biocatalytic systems to mitigate several EPs from the environment matrices. The biocatalytic features of catalase, along with the mechanistic insight into H₂O₂ neutralization, several nano-based materials loaded with catalase, including nanoparticles (NPs), carbon nanotubes (CNTs), metal-organic frameworks (MOFs), polymeric-based composites, oxime-functionalized cryo-gel disks, electro-spun nanofibrous membranes, and other hybrid materials have also been discussed with suitable examples.

HEPA filters for airliner cabins: State of the art and future development

The airliner cabin environment is very important to the health of passengers and crew members, and the use of high-efficiency particulate air (HEPA) filters for recirculated air in the environmental control systems (ECS) is essential for the removal of airborne particles such as SARS CoV-2 aerosols. A HEPA filter should be high efficiency, low-pressure drop, high dust-holding capacity (DHC), lightweight, and strong for use in aircraft. We conducted an experimental study on 23 HEPA filters with glass fiber media that are used in different commercial airliner models. The tested filters had a median filtration efficiency of >99.97% for particles with a diameter of 0.3-0.5 μm, a pressure drop of 134-412 Pa at rated airflow rate, and a DHC of 32.2-37.0 g/m² . The use of nanofiber media instead of glass fiber media can reduce the pressure drop by 66.4%-94.3% and significantly increase the quality factor by analysis of literature data. The disadvantages of poor fire resistance and small DHC can be overcome by the use of flame-retardant polymers and fiber structural design. As a new lightweight and environmentally friendly filter material, nanofiber media could be used as air filters in ECS in the future.

Mass Production of Hierarchically Designed Engine-Intake Air Filters by Multinozzle Electroblow Spinning

Particulate matter damages engines of vehicles when blown into the ventilation system. Conventional engine-intake filter is cellulose microfiber board with an average diameter larger than ten microns, which has low removal efficiency of ultrafine particular matter. In this work, we apply ultrafine polyurethane nanofibers (∼122.8 nm) onto pleated cellulose board using scalable multinozzle electroblow spinning technology, which improves filtration efficiency of particulate matter with a diameter of less than 0.3 μm PM_0.3 greatly. The thermoplastic polyurethane 85A nanofiber membranes are transparent, and display superior filtration performance which meets up with the 95% filtration efficiency standard in GB 19083-2010 technical requirements for protective face mask for medical use. The lightweight pleated thermoplastic polyurethane/cellulose composites intercept ∼90% ultrafine PM_0.3 under airflow velocity of 32 L min^-1 and possess great resistance to shock. These hierarchically designed filters follow a mechanical mechanism and can be used in on-road and off-road cars in the long run.

Sub-Nanoporous Engineered Fibrous Aerogel Molecular Sieves with Nanogating Channels for Reversible Molecular Separation

Gating molecular separation using artificial sub-nanoporous molecular sieves is highly desirable in large-scale chemical and energy processing, such as gas separation, hydrogen recovery, carbon dioxide capture, seawater desalination, etc. However, it has remained an insurmountable challenge to create such materials. Herein, a binary meso-reconstruction strategy to develop biomimetic sub-nanoporous engineered aerogel molecular sieves (NAMSs) with reversible nanogating channels is demonstrated, in which sub-1 nm pores (≈7 Å) provide coupling size-thermodynamic gated functions that enable molecule discrimination and trapping in a reversible manner. The NAMSs show polarity-reversible adsorption in which adsorbate molecules are discriminated by each gate-admission sponge-fiber molecular sieve, facilitating size/interface synergistically induced selective separation of 1,3,5-trimethyl benzene/ethylene glycol with high separation factor and fast adsorption rate. The nanogating aerogel molecular sieves with molecularly defined sub-1 nm nanoporous architecture (≈7 Å), Murray's law hierarchical channels, ultrahigh surface area (686 m² g^-1 ), and robust self-supporting characteristics define a new benchmark for both aerogels and molecular sieves, exhibiting great potential in diversified on-demand molecular separations that are prevalent in chemical, energy, and environmental processes.

2D Polymer Nanonets: Controllable Constructions and Functional Applications

Two-dimensional (2D) polymer nanonets have demonstrated great potential in various application fields due to their integrated advantages of ultrafine diameter, small pore size, high porosity, excellent interconnectivity, and large specific surface area. Here, a comprehensive overview of the controlled constructions of the polymer nanonets derived from electrospinning/netting, direct electronetting, self-assembly of cellulose nanofibers, and nonsolvent-induced phase separation is provided. Then, the widely researched multifunctional applications of polymer nanonets in filtration, sensor, tissue engineering, and electricity are also given. Finally, the challenges and possible directions for further developing the polymer nanonets are also intensively highlighted. This article is protected by copyright. All rights reserved.

Multistage-Split Ultrafine Fluffy Nanofibrous Membrane for High-Efficiency Antibacterial Air Filtration

Antibacterial air filtration membranes are essential for personal protection during the pandemic of coronavirus disease 2019 (COVID-19). However, high-efficiency filtration with low pressure drop and effective antibiosis is difficult to achieve. To solve this problem, an innovative electrospinning system with low binding energy and high conductivity was built to enhance the jet splitting, and a fluffy nanofibrous membrane containing numerous ultrafine nanofibers and large quantities of antibacterial agents was achieved, which was fabricated by electrospinning polyamide 6 (PA6), poly(vinyl pyrrolidone) (PVP), chitosan (CS), and curcumin (Cur). The filtration efficiency for 0.3 μm NaCl particles was 99.83%, the pressure drop was 54 Pa, and the quality factor (QF) was up to 0.118 Pa^-1. CS and Cur synergistically enhanced the antibacterial performance; the bacteriostatic rates against Escherichia coli and Staphylococcus aureus were 99.5 and 98.9%, respectively. This work will largely promote the application of natural antibacterial agents in the development of high-efficiency, low-resistance air filters for personal protection by manufacturing ultrafine nanofibers with enhanced antibiosis.

Facile Preparation of Hydrophobic PLA/PBE Micro-Nanofiber Fabrics via the Melt-Blown Process for High-Efficacy Oil/Water Separation

Polylactic acid (PLA) micro-nanofiber fabrics with a large specific surface area and excellent biodegradability are commonly used in oil/water separation; however, challenges remain due to their poor mechanical properties. Herein, a thermoplastic polylactic acid/propylene-based elastomer (PLA/PBE) polymer was prepared by blending PLA with PBE. Then, PLA/PBE micro-nanofiber fabrics were successfully prepared using a melt-blown process. The results show that the PLA/PBE micro-nanofiber fabric has a three-dimensional porous structure, improving the thermal stability and fluidity of the PLA/PBE blended polymers. The PLA/PBE micro-nanofiber fabric demonstrated a significantly reduced average fiber diameter and an enhanced breaking strength. Moreover, the water contact angle of the prepared samples is 134°, which suggests a hydrophobic capacity. The oil absorption rate of the fabric can reach 10.34, demonstrating excellent oil/water separation performance. The successful preparation of PLA/PBE micro-nanofiber fabrics using our new method paves the way for the large-scale production of promising candidates for high-efficacy oil/water separation applications.

Recent Progress in Protective Membranes Fabricated via Electrospinning: Advanced Materials, Biomimetic Structures, and Functional Applications

Electrospinning is a significant micro/nanofiber processing technology and has been rapidly developing in the past 2 decades. It has several applications, including advanced sensing, intelligent manufacturing, and high-efficiency catalysis. Here, multifunctional protective membranes fabricated via electrospinning in terms of novel material design, construction of novel structures, and various protection requirements in different environments are reviewed. To achieve excellent comprehensive properties, such as, high water vapor transmission, high hydrostatic pressure, optimal mechanical property, and air permeability, combinations of novel materials containing nondegradable/degradable materials and functional structures inspired by nature have been investigated for decades. Currently, research is mainly focused on conventional protective membranes with multifunctional properties, such as, anti-UV, antibacterial, and electromagnetic-shielding functions. However, important aspects, such as, the properties of electrospun monofilaments, development of "green electrospinning solutions" with high solid content, and approaches for enhancing adhesion between hydrophilic and hydrophobic layers are not considered. Based on this systematic review, the development of electrospinning for protective membranes is discussed, the existing gaps in research are discussed, and solutions for the development of technology are proposed. This review will assist in promoting the diversified development of protective membranes and is of great significance for fabricating advanced materials for intelligent protection.

Electrospun Nanofiber Membranes for Air Filtration: A Review

Nanomaterials for air filtration have been studied by researchers for decades. Owing to the advantages of high porosity, small pore size, and good connectivity, nanofiber membranes prepared by electrospinning technology have been considered as an outstanding air-filter candidate. To satisfy the requirements of material functionalization, electrospinning can provide a simple and efficient one-step process to fabricate the complex structures of functional nanofibers such as core-sheath structures, Janus structures, and other multilayered structures. Additionally, as a nanoparticle carrier, electrospun nanofibers can easily achieve antibacterial properties, flame-retardant properties, and the adsorption properties of volatile gases, etc. These simple and effective approaches have benefited from the significate development of electrospun nanofibers for air-filtration applications. In this review, the research progress on electrospun nanofibers as air filters in recent years is summarized. The fabrication methods, filtration performances, advantages, and disadvantages of single-polymer nanofibers, multipolymer composite nanofibers, and nanoparticle-doped hybrid nanofibers are investigated. Finally, the basic principles of air filtration are concluded upon and prospects for the application of complex-structured nanofibers in the field of air filtration are proposed.

Application of Electrospun Nonwoven Fibers in Air Filters

Air filtration has seen a sizable increase in the global market this past year due to the COVID-19 pandemic. Nanofiber nonwoven mats are able to reach certain efficiencies with a low-pressure drop, have a very high surface area to volume ratio, filter out submicron particulates, and can customize the fiber material to better suit its purpose. Although electrospinning nonwoven mats have been very well studied and documented there are not many papers that combine them. This review touches on the various ways to manufacture nonwoven mats for use as an air filter, with an emphasis on electrospinning, the mechanisms by which the fibrous nonwoven air filter stops particles passing through, and ways that the nonwoven mats can be altered by morphology, structure, and material parameters. Metallic, ceramic, and organic nanoparticle coatings, as well as electrospinning solutions with these same materials and their properties and effects of air filtration, are explored.

An Electrospun Sandwich-Type Lipase-Membrane Bioreactor for Hydrolysis at Macroscopic Oil-Water Interfaces

The core task for lipase catalytic system design is to construct a suitable oil-water interface for lipase distribution. In comparison to the micro-oil-water interface, the macro-oil-water interface (top oil-bottom water) served as a simplified lipase catalytic system that is more in line with industrial applications but limited in catalytic efficiency. Based on the assumption that one potential carrier can help lipase reach to the macro-oil-water interface, in the current work, sandwich-type lipase-membrane bioreactors (SLMBs) fabricated by a facile layer-by-layer electrospinning process were reported. These SLMBs were composed of a hydrophilic polyamide 6 nanofibrous membrane (NFM) as the bottom layer, a blended electrospun lipase/PVA NFM as the middle layer, and a hydrophobic EC/PU NFM as the top layer. The lipase loading can be controlled by altering the electrospinning time of the middle layer. Under the optimized conditions, the catalytic efficiency of the SLMBs was 2.05 times higher than that of free lipase. In addition, the SLMBs exhibit much better pH (high activity over a broad pH range of 5-10), temperature (retained 62% at 80 °C), storage stability (no loss of activity after being stored at 4 °C for 11 days), and reusability (retained 23% after five cycles) than free lipase.

Biodegradable and high-performance multiscale structured nanofiber membrane as mask filter media via poly(lactic acid) electrospinning

The usage of single-use face masks (SFMs) has increased since the outbreak of the coronavirus pandemic. However, non-degradability and mismanagement of SFMs have raised serious environmental concerns. Moreover, both melt-blown and nanofiber-based mask filters inevitably suffer from poor filtration performance, like a continuous decrease in the removal efficiency for particulate matter (PM) and weak breathability. Herein, we report a new method to create biodegradable and reusable fibrous mask filters. The filter consists of a true nanoscale bio-based poly(lactic acid) (PLA) fiber (an average size of 37 ± 4 nm) that is fabricated via electrospinning of an extremely dilute solution. Furthermore, we designed a multiscale structure with integrated features, such as low basis weight (0.91 g m-2), small pore size (0.73 μm), and high porosity (91.72%), formed by electrospinning deposition of true nanoscale fibers on large pore of 3D scaffold nanofiber membranes. The resultant mask filter exhibited a high filtration efficiency (PM0.3-99.996%) and low pressure drop (104 Pa) superior to the commercial N95 filter. Importantly, this filter has a durable filtering efficiency for PM and natural biodegradability based on PLA. Therefore, this study offers an innovative strategy for the preparation of PLA nanofibers and provides a new design for high-performance nanofiber filters.

Smart/stimuli-responsive hydrogels: Cutting-edge platforms for tissue engineering and other biomedical applications

Recently, biomedicine and tissue regeneration have emerged as great advances that impacted the spectrum of healthcare. This left the door open for further improvement of their applications to revitalize the impaired tissues. Hence, restoring their functions. The implementation of therapeutic protocols that merge biomimetic scaffolds, bioactive molecules, and cells plays a pivotal role in this track. Smart/stimuli-responsive hydrogels are remarkable three-dimensional (3D) bioscaffolds intended for tissue engineering and other biomedical purposes. They can simulate the physicochemical, mechanical, and biological characters of the innate tissues. Also, they provide the aqueous conditions for cell growth, support 3D conformation, provide mechanical stability for the cells, and serve as potent delivery matrices for bioactive molecules. Many natural and artificial polymers were broadly utilized to design these intelligent platforms with novel advanced characteristics and tailored functionalities that fit such applications. In the present review, we highlighted the different types of smart/stimuli-responsive hydrogels with emphasis on their synthesis scheme. Besides, the mechanisms of their responsiveness to different stimuli were elaborated. Their potential for tissue engineering applications was discussed. Furthermore, their exploitation in other biomedical applications as targeted drug delivery, smart biosensors, actuators, 3D and 4D printing, and 3D cell culture were outlined. In addition, we threw light on smart self-healing hydrogels and their applications in biomedicine. Eventually, we presented their future perceptions in biomedical and tissue regeneration applications. Conclusively, current progress in the design of smart/stimuli-responsive hydrogels enhances their prospective to function as intelligent, and sophisticated systems in different biomedical applications.

Recent trends in therapeutic strategies for repairing endometrial tissue in intrauterine adhesion

Intrauterine adhesion (IUA) is a common gynaecological disease that develops from infection or trauma. IUA disease may seriously affect the physical and mental health of women of childbearing age, which may lead to symptoms such as hypomenorrhea or infertility. Presently, hysteroscopic transcervical resection of adhesion (TCRA) is the principal therapy for IUAs, although its function in preventing the recurrence of adhesion and preserving fertility is limited. Pharmaceuticals such as hormones and vasoactive agents and the placement of nondegradable stents are the most common postoperative adjuvant therapy methods. However, the repair of injured endometrium is relatively restricted due to the different anatomical structures of the endometrium. Recently, the treatment outcome of IUAs has improved with the advancement of hysteroscopic techniques. In particular, the application of bioactive scaffolds combined with tissue engineering technology has proven to have high therapeutic potential or endometrial repair in IUA treatment. Herein, this review has summarized past therapeutic strategies, including postoperative adjuvant therapy, cell or therapeutic molecular delivery therapy methods and bioactive scaffold-based tissue engineering methods. Therefore, this review presented the recent therapeutic strategies for repairing endometrium treatment and pointed out the issues of clinical concern to provide alternative methods for the management of IUAs.