Photothermal Welding, Melting, and Patterned Expansion of Nonwoven Mats of Polymer Nanofibers for Biomedical and Printing Applications

Breathable Dual-Mode Leather-Like Nanotextile for Efficient Daytime Radiative Cooling and Heating

Incorporating passive radiative cooling and heating into personal thermal management has attracted tremendous attention. However, most current thermal management materials are usually monofunctional with a narrow temperature regulation range, and lack breathability, softness, and stretchability, resulting in a poor wearer experience and limited application scenarios. Herein, a breathable dual-mode leather-like nanotextile (LNT) with asymmetrical wrinkle photonic microstructures and Janus wettability for highly efficient personal thermal management is developed via a one-step electrospinning technique. The LNT is synthesized by self-bonding a hydrophilic cooling layer with welding fiber networks onto a hydrophobic photothermal layer, constructing bilayer wrinkle structures that offer remarkable optical properties, a wetting gradient, and unique textures. The resultant LNT exhibits efficient cooling capacity (22.0 °C) and heating capacity (22.1 °C) under sunlight, expanding the thermal management zone (28.3 °C wider than typical textiles). Additionally, it possesses favorable breathability, softness, stretchability, and sweat-wicking capability. Actual wearing tests demonstrate that the LNT can provide a comfortable microenvironment for the human body (1.6-8.0 °C cooler and 1.0-7.1 °C warmer than typical textiles) in changing weather conditions. Such a wearable dual-mode LNT presents great potential for personal thermal comfort and opens up new possibilities for all-weather smart clothing.

Enhancing tendon-bone integration and healing with advanced multi-layer nanofiber-reinforced 3D scaffolds for acellular tendon complexes

Advancements in tissue engineering are crucial for successfully healing tendon-bone connections, especially in situations like anterior cruciate ligament (ACL) restoration. This study presents a new and innovative three-dimensional scaffold, reinforced with nanofibers, that is specifically intended for acellular tendon complexes. The scaffold consists of a distinct layered arrangement comprising an acellular tendon core, a middle layer of polyurethane/type I collagen (PU/Col I) yarn, and an outside layer of poly (L-lactic acid)/bioactive glass (PLLA/BG) nanofiber membrane. Every layer is designed to fulfill specific yet harmonious purposes. The acellular tendon core is a solid structural base and a favorable environment for tendon cell functions, resulting in considerable tensile strength. The central PU/Col I yarn layer is vital in promoting the tendinogenic differentiation of stem cells derived from tendons and increasing the expression of critical tendinogenic factors. The external PLLA/BG nanofiber membrane fosters the process of bone marrow mesenchymal stem cells differentiating into bone cells and enhances the expression of markers associated with bone formation. Our scaffold's biocompatibility and multi-functional design were confirmed through extensive in vivo evaluations, such as histological staining and biomechanical analyses. These assessments combined showed notable enhancements in ACL repair and healing. This study emphasizes the promise of multi-layered nanofiber scaffolds in orthopedic tissue engineering and also introduces new possibilities for the creation of improved materials for regenerating the tendon-bone interface.

Stretchable photothermal membrane of NIR-II charge-transfer cocrystal for wearable solar thermoelectric power generation

Harvesting sunlight into cost-effective electricity presents an enticing prospect for self-powered wearable applications. The photothermal materials with an extensive absorption are fundamental to achieve optical and thermal concentration of the sunlight for efficiency output electricity of wearable solar thermoelectric generators (STEGs). Here, we synthesize an organic charge-transfer (CT) cocrystal with a flat absorption from ultraviolet to second near-infrared region (200 to 1950 nanometers) and a high photothermal conversion efficiency (PCE) of 80.5%, which is introduced into polyurethane toward large-area nanofiber membrane by electrospinning technology. These corresponding membranes demonstrate a high PCE of 73.7% under the strain more than 80%. Sandwiched with carbon nanotube-based thermoelectric fibers, the membranes as stretchable solar absorbers of STEGs could supply a notably increase temperature gradient, processing a maximum output voltage density of 23.4 volts per square meter at 1:00 p.m. under sunlight. This strategy presents an important insight in heat management for wearable STEGs with a desired electricity output.

Nanofibrous scaffolds for the healing of the fibrocartilaginous enthesis: advances and prospects

With the current developmental advancements in nanotechnology, nanofibrous scaffolds are being widely used. The healing of fibrocartilaginous enthesis is a slow and complex process, and while existing treatments have a certain effect on promoting their healing, these are associated with some limitations. The nanofibrous scaffold has the advantages of easy preparation, wide source of raw materials, easy adjustment, easy modification, can mimic the natural structure and morphology of the fibrocartilaginous enthesis, and has good biocompatibility, which can compensate for existing treatments and be combined with them to promote the repair of fibrocartilaginous enthesis. The nanofibrous scaffold can promote the healing of fibrocartilaginous enthesis by controlling the morphology and ensuring controlled drug release. Hence, the use of nanofibrous scaffold with stimulative response features in the musculoskeletal system has led us to imagine its potential application in fibrocartilaginous enthesis. Therefore, the healing of fibrocartilaginous enthesis based on a nanofibrous scaffold may be a novel therapeutic approach.

Microfluidic-Assisted Self-Assembly of 2D Nanosheets toward in situ Generation of Robust Nanofiber Film

Methods allow the enhancement of nanofibers via self-assembly are potentially important for new disciplines with many advantages, including multi-anchor interaction, intrinsic mechanical properties and versatility. Herein, a microfluidic-assisted self-assembly process to construct hydroxyl functionalized boron nitride nanosheets (OH-BNNS)/graphene oxide (GO)/thermoplastic polyurethane (TPU) composite nanofiber film, in which stable and precisely controlled self-assembly is fulfilled by the confined ultra-small-volume chip is demonstrated. Multiple fine structural analyses alongside with the density-functional theory (DFT) calculations are implemented to confirm the synergistic effect of noncovalent interactions (hydrogen bonding interaction, π - π stacking interaction, and van der Waals attraction) plays a critical role in the robust micro-structure and a massive 700% enhancement of mechanical strength via adding only 0.3 wt% OH-BNNS and GO. Importantly, profiled from broadband optical absorption ability, robust mechanical properties and outstanding flexibility, the self-assembled 3D OH-BNNS/GO/TPU nanofiber film reveals an adorable evaporation rate of 4.04 kg m-2  h-1 under one sun illumination with stable energy transfer efficiency (93.2%) by accompanying hydrogen bonding interaction. This microfluidic-assisted self-assembly strategy will provide a constructive entry point for the rational design of nanofibers and beyond.

High-Strength Magnetic Hydrogels with Photoweldability Made by Stepwise Assembly of Magnetic-Nanoparticle-Integrated Aramid Nanofiber Composites

Hydrogels capable of transforming in response to a magnetic field hold great promise for applications in soft actuators and biomedical robots. However, achieving high mechanical strength and good manufacturability in magnetic hydrogels remains challenging. Here, inspired by natural load-bearing soft tissues, a class of composite magnetic hydrogels is developed with tissue-mimetic mechanical properties and photothermal welding/healing capability. In these hydrogels, a hybrid network involving aramid nanofibers, Fe₃O₄ nanoparticles, and poly(vinyl alcohol) is accomplished by a stepwise assembly of the functional components. The engineered interactions between nanoscale constituents enable facile materials processing and confer a combination of excellent mechanical properties, magnetism, water content, and porosity. Furthermore, the photothermal property of Fe₃O₄ nanoparticles organized around the nanofiber network allows near-infrared welding of the hydrogels, providing a versatile means to fabricate heterogeneous structures with custom designs. Complex modes of magnetic actuation are made possible with the manufactured heterogeneous hydrogel structures, suggesting opportunities for further applications in implantable soft robots, drug delivery systems, human-machine interactions, and other technologies.

In-situ forming dynamic covalently crosslinked nanofibers with one-pot closed-loop recyclability

Polymeric nanofibers are attractive nanomaterials owing to their high surface-area-to-volume ratio and superior flexibility. However, a difficult choice between durability and recyclability continues to hamper efforts to design new polymeric nanofibers. Herein, we integrate the concept of covalent adaptable networks (CANs) to produce a class of nanofibers ⎯ referred to dynamic covalently crosslinked nanofibers (DCCNFs) via electrospinning systems with viscosity modulation and in-situ crosslinking. The developed DCCNFs possess homogeneous morphology, flexibility, mechanical robustness, and creep resistance, as well as good thermal and solvent stability. Moreover, to solve the inevitable issues of performance degradation and crack of nanofibrous membranes, DCCNF membranes can be one-pot closed-loop recycled or welded through thermal-reversible Diels-Alder reaction. This study may unlock strategies to fabricate the next generation nanofibers with recyclable features and consistently high performance via dynamic covalent chemistry for intelligent and sustainable applications.

Organic Charge-Transfer Cocrystals toward Large-Area Nanofiber Membrane for Photothermal Conversion and Imaging

Organic photothermal materials integrating a high-efficiency light-heat conversion effect and high flexibility have generated immense interest in fundamental research and practical applications. Nevertheless, their practical applications still remain a challenge, owing to the complicated design, tedious synthesis, and limited programmable substrates. Herein, an organic charge-transfer cocrystal with a narrow energy gap of 0.33 eV and a high photothermal conversion efficiency (PCE) of 69.3% was rationally designed and synthesized via a facile self-assembly process, which was introduced into polyurethane for forming a large-area photothermal nanofiber membrane via electrospinning technology. Femtosecond transient absorption spectroscopy elucidates that the excellent PCE is attributed to the nonradiation transition process, including internal conversion and charge dissociation processes. Furthermore, the temperature of the as-prepared photothermal nanofiber membrane could quickly rise to 52 °C under laser irradiation with a power density of 0.183 W/cm², suggesting a high PCE of 53.7%. This work successfully achieves the fabrication of a large-area photothermal membrane and the development of photothermal imaging.

Crimped nanofiber scaffold mimicking tendon-to-bone interface for fatty-infiltrated massive rotator cuff repair

Electrospun fibers, with proven ability to promote tissue regeneration, are widely being explored for rotator cuff repairing. However, without post treatment, the microstructure of the electrospun scaffold is vastly different from that of natural extracellular matrix (ECM). Moreover, during mechanical loading, the nanofibers slip that hampers the proliferation and differentiation of migrating stem cells. Here, electrospun nanofiber scaffolds, with crimped nanofibers and welded joints to biomimic the intricate natural microstructure of tendon-to-bone insertion, were prepared using poly(ester-urethane)urea and gelatin via electrospinning and double crosslinking by a multi-bonding network densification strategy. The crimped nanofiber scaffold (CNS) features bionic tensile stress and induces chondrogenic differentiation, laying credible basis for in vivo experimentation. After repairing a rabbit massive rotator cuff tear using a CNS for 3 months, the continuous translational tendon-to-bone interface was fully regenerated, and fatty infiltration was simultaneously inhibited. Instead of micro-CT, μCT was employed to visualize the integrity and intricateness of the three-dimensional microstructure of the CNS-induced-healed tendon-to-bone interface at an ultra-high resolution of less than 1 μm. This study sheds light on the correlation between nanofiber post treatment and massive rotator cuff repair and provides a general strategy for crimped nanofiber preparation and tendon-to-bone interface imaging characterization.

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Electrospun scaffold mimicking the microstructure of ECM was fabricated.

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The translational microstructure of tendon-to-bone interface was regenerated.

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Tendon-to-bone interface was 3D visualized with resolution less than 1 μm.

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Muscle fatty infiltration was inhibited for massive rotator cuff tear.

Metal-Organic Framework-Based Nanoheater with Photo-Triggered Cascade Effects for On-Demand Suppression of Cellular Thermoresistance and Synergistic Cancer Therapy

Nanomedicine with stable light-heat conversion and spatiotemporally controllable drug activation is crucial for the success of photothermal therapy (PTT). Herein, a metal-organic framework (MOF)-based nanoheater with light-triggered multi-responsiveness is engineered to in-situ and on-demand sensitize cancer cells to local hyperthermia. Well-dispersed platinum nanoparticles synthesized inside nanospaces of the MOF are employed as the near-infrared (NIR)-harvesting unit with stable and high light-heat conversion performance. A conformation switchable polymer shell is constructed as a secondary light-responding unit to gate the targeted activation of a molecular inhibitor against thermoresistance. By cascade transformation of light stimuli to downstream signals, the nanoheater enables inhibitor release to go with local heating at the same time restricted in lesion sites to maximize efficacy and minimize systemic toxicity. The efficient photothermal conversion and the blockage of cellular heat-protective pathways provide a dual-mode of action which selectively sensitizes cancer cells to hyperthermia in a spatiotemporally controlled manner. With NIR as the remote switch, the MOF-based nanosystem demonstrates localized and boosted PTT efficacy against cancer both in vitro and in vivo. These results present nanosized MOFs as tailorable and versatile platforms for synergistic and precise cancer therapy.

Facemask Global Challenges: The Case of Effective Synthesis, Utilization, and Environmental Sustainability

Coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a rapidly spreading pandemic and is severely threatening public health globally. The human-to-human transmission route of SARS-CoV-2 is now well established. The reported clinical observations and symptoms of this infection in humans appear in the range between being asymptomatic and severe pneumonia. The virus can be transmitted through aerosols and droplets that are released into the air by a carrier, especially when the person coughs, sneezes, or talks forcefully in a closed environment. As the disease progresses, the use and handling of contaminated personal protective equipment and facemasks have become major issues with significant environmental risks. Therefore, providing an effective method for treating used/contaminated facemasks is crucial. In this paper, we review the environmental challenges and risks associated with the surge in facemask production. We also discuss facemasks and their materials as sources of microplastics and how disposal procedures can potentially lead to the contamination of water resources. We herein review the potential of developing nanomaterial-based antiviral and self-cleaning facemasks. This review discusses these challenges and concludes that the use of sustainable and alternative facemask materials is a promising and viable solution. In this context, it has become essential to address the emerging challenges by developing a new class of facemasks that are effective against the virus, while being biodegradable and sustainable. This paper represents the potentials of natural and/or biodegradable polymers for manufacturing facemasks, such as wood-based polymers, chitosan, and other biodegradable synthetic polymers for achieving sustainability goals during and after pandemics.

Nanofiber/hydrogel core-shell scaffolds with three-dimensional multilayer patterned structure for accelerating diabetic wound healing

Impaired angiogenesis is one of the predominant reasons for non-healing diabetic wounds. Herein, a nanofiber/hydrogel core–shell scaffold with three-dimensional (3D) multilayer patterned structure (3D-PT-P/GM) was introduced for promoting diabetic wound healing with improved angiogenesis. The results showed that the 3D-PT-P/GM scaffolds possessed multilayered structure with interlayer spacing of about 15–80 μm, and the hexagonal micropatterned structures were uniformly distributed on the surface of each layer. The nanofibers in the scaffold exhibited distinct core–shell structures with Gelatin methacryloyl (GelMA) hydrogel as the shell and Poly (d, l-lactic acid) (PDLLA) as the core. The results showed that the porosity, water retention time and water vapor permeability of the 3D-PT-P/GM scaffolds increased to 1.6 times, 21 times, and 1.9 times than that of the two-dimensional (2D) PDLLA nanofibrous scaffolds, respectively. The in vitro studies showed that the 3D-PT-P/GM scaffolds could significantly promote cell adhesion, proliferation, infiltration and migration throughout the scaffolds, and the expression of cellular communication protein-related genes, as well as angiogenesis-related genes in the same group, was remarkably upregulated. The in vivo results further demonstrated that the 3D-PT-P/GM scaffolds could not only effectively absorb exudate and provide a moist environment for the wound sites, but also significantly promote the formation of a 3D network of capillaries. As a result, the healing of diabetic wounds was accelerated with enhanced angiogenesis, granulation tissue formation, and collagen deposition. These results indicate that nanofiber/hydrogel core–shell scaffolds with 3D multilayer patterned structures could provide a new strategy for facilitating chronic wound healing.

Phytic Acid Doped Polypyrrole as a Mediating Layer Promoting Growth of Prussian Blue on Cotton Fibers for Solar-Driven Interfacial Water Evaporation

Phytic acid doped polypyrrole (PPy) as a mediating layer was in-situ coated on cotton fibers (CFs) to promote the growth of Prussian blue (PB) and construct the PB/PPy@CFs composite. The results showed that the proper amounts of PA doped PPy in-situ generated significantly promoted the growth of PB on CFs, the PB deposition ratio increased from 12.29% (PB@CFs) to 32.4% (PB/PPy@CFs), and the growth of PB on PPy@CFs could be completed in 4 h. Scanning electron microscopy (SEM) showed that the PB particles with perfect nano cubic structure were formed in the composite. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) showed that both PB and PPy were successfully deposited on CFs. The PB/PPy@CFs composite had excellent light absorption, hydrophilicity, wettability, and photothermal property, and the surface could be heated up to 81.5 °C under one sun illumination. The PB/PPy@CFs composite as a photothermal conversion material was used for solar-driven interfacial water evaporation, the water evaporation rate was 1.36 kg·m-2·h-1 at the optical concentration of 1 kW·m2, and the corresponding photothermal conversion efficiency increased from 81.69% (PB@CFs) to 90.96% (PB/PPy@CFs).

On-Demand Drug Delivery Systems Using Nanofibers

On-demand drug-delivery systems using nanofibers are extensively applicable for customized drug release based on target location and timing to achieve the desired therapeutic effects. A nanofiber formulation is typically created for a certain medication and changing the drug may have a significant impact on the release kinetics from the same delivery system. Nanofibers have several distinguishing features and properties, including the ease with which they may be manufactured, the variety of materials appropriate for processing into fibers, a large surface area, and a complex pore structure. Nanofibers with effective drug-loading capabilities, controllable release, and high stability have gained the interest of researchers owing to their potential applications in on-demand drug delivery systems. Based on their composition and drug-release characteristics, we review the numerous types of nanofibers from the most recent accessible studies. Nanofibers are classified based on their mechanism of drug release, as well as their structure and content. To achieve controlled drug release, a suitable polymer, large surface-to-volume ratio, and high porosity of the nanofiber mesh are necessary. The properties of nanofibers for modified drug release are categorized here as protracted, stimulus-activated, and biphasic. Swellable or degradable polymers are commonly utilized to alter drug release. In addition to the polymer used, the process and ambient conditions can have considerable impacts on the release characteristics of the nanofibers. The formulation of nanofibers is highly complicated and depends on many variables; nevertheless, numerous options are available to accomplish the desired nanofiber drug-release characteristics.

Micro-and-nanometer topological gradient of block copolymer fibrous scaffolds towards region-specific cell regulation

Regulating cell behavior and function by surface topography has drawn significant attention in tissue engineering. Herein, a gradient fibrous scaffold comprising anisotropic aligned fibers and isotropic annealed fibers was developed to provide a controllable direction of cell migration, adhesion, and spreading. The electrospun aligned fibers were engraved to create surface gradients with micro-and-nanometer roughness through block copolymer (BCP) self-assembly induced by selective solvent vapor annealing (SVA). The distinct manipulation of cell behavior by annealed fibrous scaffolds with tailored self-assembled nanostructure and welded fibrous microstructure has been illustrated by in situ/ex situ small angle X-ray scattering (SAXS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and in vitro cell culture. Further insights into the effect of integrated gradient fibrous scaffold were gained at the level of protein expression. From the perspective of gradient topology, this region-specific scaffold based on BCP fibers shows the prospect of guiding cell migration, adhesion and spreading and provides a generic method for designing biomaterials for tissue-engineering.

Advanced Strategies of Biomimetic Tissue-Engineered Grafts for Bone Regeneration

The failure to repair critical-sized bone defects often leads to incomplete regeneration or fracture non-union. Tissue-engineered grafts have been recognized as an alternative strategy for bone regeneration due to their potential to repair defects. To design a successful tissue-engineered graft requires the understanding of physicochemical optimization to mimic the composition and structure of native bone, as well as the biological strategies of mimicking the key biological elements during bone regeneration process. This review provides an overview of engineered graft-based strategies focusing on physicochemical properties of materials and graft structure optimization from macroscale to nanoscale to further boost bone regeneration, and it summarizes biological strategies which mainly focus on growth factors following bone regeneration pattern and stem cell-based strategies for more efficient repair. Finally, it discusses the current limitations of existing strategies upon bone repair and highlights a promising strategy for rapid bone regeneration.

Intelligent non-colorimetric indicators for the perishable supply chain by non-wovens with photo-programmed thermal response

Spoiled perishable products, such as food and drugs exposed to inappropriate temperature, cause million illnesses every year. Risks range from intoxication due to pathogen-contaminated edibles, to suboptimal potency of temperature-sensitive vaccines. High-performance and low-cost indicators are needed, based on conformable materials whose properties change continuously and irreversibly depending on the experienced time-temperature profile. However, these systems can be limited by unclear reading, especially for colour-blind people, and are often difficult to be encoded with a tailored response to detect excess temperature over varying temporal profiles. Here we report on optically-programmed, non-colorimetric indicators based on nano-textured non-wovens encoded by their cross-linking degree. This combination allows a desired time-temperature response to be achieved, to address different perishable products. The devices operate by visual contrast with ambient light, which is explained by backscattering calculations for the complex fibrous material. Optical nanomaterials with photo-encoded thermal properties might establish new design rules for intelligent labels.