Dynamic Pluronic F127 Crosslinking Enhancement of Biopolymeric Nanocomposites for Piezo-Triboelectric Single-Hybrid Nanogenerators and Self-Powered Sensors.

Biomechanical and nanomechanical energy harvesting systems have gained a wealth of interest, resulting in a plethora of research into the development of biopolymeric-based devices as sustainable alternatives. Piezoelectric, triboelectric, and hybrid nanogenerator devices for electrical applications are engineered and fabricated using innovative, sustainable, facile-approach flexible composite films with high performance based on bacterial cellulose and BaTiO3 , intrinsically and structurally enhanced by Pluronic F127, a micellar cross-linker. The voltage and current outputs of the modified versions with multiwalled carbon nanotube as a conductivity enhancer and post-poling effect are 38 V and 2.8 µA cm-2 , respectively. The multiconnective devices' power density can approach 10 µW cm-2 . The rectified output power is capable of charging capacitors, driving light-emitting diode lights, powering a digital watch and interfacing with a commercial microcontroller board to operate as a piezoresistive force sensor switch as a proof of concept. Magnetoelectric studies show that the composites have the potential to be incorporated into magnetoelectric systems. The biopolymeric composites prove to be desirable candidates for multifunctional energy harvesters and electronic devices.

MoNP-doped Defective Carbon Fibers with Bark-like Nanosurface as Effective Bifunctional Electrocatalysts for Zn-air Batteries.

The flexible air electrode with high oxygen electrocatalytic performance and outstanding stability under various deformations plays a vital role in high-performance flexible Zn-air batteries (ZABs). Herein, a self-supported Mo, N, and P co-doped carbon cloth (CC) denoted as MoNP@CC with bark-like surface structure is fabricated by a facile two-step approach via a one-pot method and pyrolysis. The surface of the electrode shows a nanoscale "rift valley" and uniformly distributed active sites. Taking advantage of the nano-surface as well as transition metal and heteroatom doping, the self-supported electrocatalysis air electrode exhibits considerable oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) performance in terms of low overpotential (388 mV at 10 mA cm-2) for OER and a much positive potential (0.74 V) at 1.0 mA cm-2 for ORR. Furthermore, MoNP@CC is further used for the flexible ZAB to demonstrate its practical application. The MoNP@CC-based ZAB displays a good cycling performance for 2800 min and an open-circuit voltage of 1.44 V. This work provides a new approach to the construction of a high-performance, self-supported electrocatalysis electrode used for a flexible energy storage device.

A Self-Healing and Sweat-Chargeable Hydrogel Electrolyte for All-in-One Flexible Supercapacitors.

Flexible solid-state supercapacitors (SCs) with hydrogel as an electrolyte and separator combine the advantages of wearability and energy storage and exhibit a broad application prospect in wearable energy textiles. However, irreversible electrolyte damage and unstable electrode-electrolyte interfaces during mechanical deformations remain bottlenecks in realizing truly wearable applications. Herein, poly(acrylic acid) (PAA)-Fe hydrogels were prepared through a simple thermal polymerization strategy. The dynamic reversible metal coordination bonds between Fe3+ and carboxylic acids confers the hydrogels with excellent self-healing properties. As expected, the prepared hydrogels exhibited superior mechanical strength (tensile stress of 45.80 kPa), ionic conductivity (0.076 S cm-1), and self-healing properties. Subsequently, the SCs were constructed using composite hydrogel electrodes (MnO2@CC embedded in the PAA-Fe hydrogels) as symmetrical electrodes (marked as MSCs). The reversible metal coordination bonds between composite hydrogel electrodes formed an ultrastable electrode/electrolyte interface in the all-in-one MSCs, thus revealing excellent mechanical durability. The all-in-one MSCs delivered a remarkable specific capacitance (30.98 F g-1 at 0.2 A g-1), excellent cyclic stability (87.24% after 5000 cycles), outstanding mechanical deformation stability, and impressive electrochemical output stability after self-healing (capacitance retention of 85.34% after five cycles of cutting/self-healing). It is noteworthy that the all-in-one MSCs employed NaCl as an electrolyte, which can be obtained from human sweat. As a proof of the self-charged concept, the all-in-one MSCs can be reused in sweat, whose capacitance was maintained at 90.05% of the initial state after three repetitions. This work is expected to shine light into the design of all-in-one and fabric-based SCs and the development of wearable energy textiles.

Highly Stretchable and Fluorescent Visualizable Thermoplastic Polyurethane/Tetraphenylethylene Plied Yarn Strain Sensor with Heterogeneous and Cracked Structure for Human Health Monitoring.

Smart wearable technology has been more and more widely used in monitoring and prewarning of human health and safety, while flexible yarn-based strain sensors have attracted extensive research interest due to their ability to withstand greater external strain and their significant application potential in real-time monitoring of human motion and health signals. Although several strain sensors based on yarn structures have been reported, it remains challenging to strike a balance between high sensitivity and wide strain ranges. At the same time, visual signal sensing is expected to be used in strain sensors thanks to its intuitiveness. In this work, thermoplastic polyurethane (TPU) and tetraphenylethylene (TPE) were wet-spun to fabricate flexible fluorescent fibers used as the substrate of the sensor, followed by the drop addition of polydimethylsiloxane (PDMS) beads and curing to produce a heterogeneous structure, which were further twisted into a plied yarn. Finally, a visualizable flexible yarn strain sensor based on solidified liquid beads and crack structure was obtained by loading polydopamine (PDA) and polypyrrole (PPy) in situ. The sensor exhibited high sensitivity (the GF value was 58.9 at the strain range of 143-184%), a wide working strain range (0-184%), a low monitoring limit (<0.1%), a fast response (58.82 ms), reliable responses at different frequencies, and excellent cycle durability (over 2000 cycles). At the same time, the yarn strain sensor also had excellent photothermal characteristics and a fluorescence crack visualization effect. These attractive advantages enabled yarn strain sensors to accurately monitor various human activities, showing great application potential in health monitoring, personalized medical diagnosis, and other aspects.

Synergetic effects of tetracycline hydrochloride incorporated regenerated cellulose acetate - Bacterial cellulose hybrid nanocomposite: Potential in biomedical application.

Litter from cigarette waste is a significant threat to organisms and ecosystems. However, this waste contains cellulose acetate (CA) that can be recycled into raw materials. In this study, recycled CA from cigarettes (CFCA) electrospun through electro-spinning technique and developed hybrid nanocomposite by incorporating CFCA in the fermentation media, followed by self-assembly of bacterial cellulose (BC). CFCA exhibit excessive hydrophobicity due to their high crystallinity and reorientation of hydrophobic groups. We aimed to improve the hydrophilic, thermal and mechanical properties of CFCA. We examined fiber morphology using a scanning electron microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction Analysis (XRD), thermogravimetric analysis (TGA), swelling capacity and mechanical properties. BC/CFCA showed higher swelling capacity, improved thermal properties, and good tensile strength compared to CFCA. Additionally, tetracycline hydrochloride (TC) was loaded into developed BC/CFCA matrix and evaluated in-vitro drug release, antibacterial activity and cytotoxicity. In-vitro drug release results showed that developed BC/CFCA can able to control TC release. In addition, prepared BC/CFCA-TC composites demonstrated excellent antibacterial activity against gram-positive and gram-negative bacteria. More importantly, BC/CFCA-TC composites exhibit good cytotoxicity on mouse fibroblast cells (L929). These characteristics of BC/CFCA-TC membranes indicate they may successfully serve as wound dressings and other medical biomaterials.

High Electrochemical Capacity MnO2/Graphene Hybrid Fibers Based on Crystalline Regulatable MnO2 for Wearable Supercapacitors.

Fiber-based supercapacitors (FSCs) exhibit desirable application potential and development prospects in wearable energy storage devices because of their flexibility and wearability. However, the low capacity in the unit volume and insufficient fiber strength hinder their further development in practical application. Herein, the MnO2 nanomaterials with regulatable crystalline structure were synthesized by one-step hydrothermal strategy. The formation of the MnO2 crystalline structure involved the "crimp-phase transition" process. Among them, the 2 × 2 tunnel type α-MnO2 nanowires exhibited excellent electrochemical capacitance (43.8 F g-1), high rate performance (61%, 0.25 to 6 A g-1), and remarkable cyclic stability (99%), which can be attributed to their good symmetry in space and high shared vertices proportion. On this basis, the α-MnO2 nanowires were coblended with GO to construct MnO2/rGO hybrid fibers by scalable continuous wet spinning and in situ acid reduction. Noteworthily, in MnO2/rGO hybrid fibers, the doping amount of MnO2 nanowires as high as 50 wt % could be achieved, while the strength reached 11.73 MPa, which can be ascribed to the superior surface morphology of MnO2 nanowires and the unique cement wall structure of hybrid fibers. Finally, the obtained hybrid fiber electrodes were assembled into symmetrical FSCs. Notably, the FSCs delivered remarkable volume specific capacitance (129.5 F cm-3) and impressive energy density (18 mWh cm-3) at 1.75 A cm-3. In addition, the assembled all-solid-state FSCs indicated excellent deformability and application potential. This work offers some insight for promoting the continuous preparation of fiber electrodes, the development of FSCs, and practical application in wearable energy textile.

FeCo/N-co-doped 3D carbon nanofibers as efficient bifunctional oxygen electrocatalyst for Zn-air batteries.

Flexible zinc-air batteries (ZABs) are expected to become a promising candidate in energy storage equipment for wearable electronic devices. However, the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have impeded the development of ZABs. Herein, an FeCo- and N-codoped bifunctional electrocatalyst (FeCoNCF) is fabricated by simple one-pot and pyrolysis strategies. Concretely, the bacterial cellulose (BC) and Prussian blue analogue (PBA) derived transition metal and nitrogen doped carbon (M-N-C) composites provide ORR and OER active sites. FeCoNCF exhibits outstanding ORR and OER activities. It displays a favorable high half-wave potential (0.81 V) and a low overpotential at 10 mA cm-2 (341 mV), which are on a par with commercial Pt/C and RuO2, and shows outstanding stability. The sandwich-type flexible zinc-air battery containing FeCoNCF shows a favorable power density (49.29 mW cm-2) and superior cycling stability.

Acceptance and associated factors of HIV testing among college students in China: A systematic review and meta-analysis.

BACKGROUND: Although HIV testing is helpful for early detection and treatment of HIV, its utilization rate is low among college students in China. Understanding the acceptance and associated factors of HIV testing is the key to improve the detection rate. The purpose of the systematic review was to examine the acceptance and associated factors of HIV testing (including HIV self-testing and HIV counseling and testing services) among college students in China. METHODS: This systematic review was reported following PRISMA guidelines 2020. Electronic sources such as PubMed, Embase, Web of Science, CNKI, CBM, Wanfang Database and VIP Database were searched for relevant studies published before September 2022. The tool by Agency for Healthcare Research and Quality (AHRQ) was used to assess quality for cross-sectional studies. The random-effects and fixed-effect model were employed to estimate the pooled proportions and associated factor of HIV testing acceptance. The Cochrane's Q statistic and I2 test were used to examine heterogeneity. All the quantitative meta analyses were conducted using STATA version 12 software. RESULTS: A total of 21 eligible studies with 100, 821 participants were included in the systematic review. The pooled acceptance rate of HIV testing was 68% (95% CI = 60, 76), and varies between regions in China. Male, heterosexual and urban college students had higher HIV testing acceptance. Gender, medical specialty, sexual education, sexual behavior, HIV/AIDS knowledge, perception HIV risk, and previous HIV testing were the factors associated with HIV testing acceptance. CONCLUSION: The review revealed that most of the college students intend to accept HIV detection, and the proportion of acceptance influenced by different factors. Therefore, the government and universities should implement targeted measures, improve HIV testing services, and promote HIV testing behavior. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022367976.

Hydrogel transformed from sandcastle-worm-inspired powder for adhering wet adipose surfaces.

Normally, hydrogel adhesives do not perform well on adipose matters that are covered with bodily fluids. Besides, the maintenance of high extensibility and self-healing ability in fully swollen state still remains challenging. Based on these concerns, we reported a sandcastle-worm-inspired powder, which was made of tannic acid-functionalized cellulose nanofiber (TA-CNF), polyacrylic acid (PAA) and polyethyleneimine (PEI). The obtained powder can rapidly absorb diverse bodily fluids and transform into a hydrogel, displaying fast (＜3 s), self-strengthening and repeatable wet adhesion to adipose tissues. Due to the dense physically cross-linked network, the formed hydrogel still showed excellent extensibility (∼14 times) and self-healing ability after being immersed in water. Moreover, excellent hemostasis, antibacterial ability and biocompatibility make it suitable for numerous biomedical applications. With combined advantages of powders and hydrogels, such as good adaptability to irregular sites, efficient drug loading capacity and tissue affinity, the sandcastle-worm-inspired powder offers significant promise as tissue adhesive and repair materials. This work may open new avenues for designing high-performance bioadhesives with efficient and robust wet adhesiveness to adipose tissues.

Regeneration and modification of cellulose acetate from cigarette waste: Biomedical potential by encapsulation of tetracycline hydrochloride.

Cigarette waste are pervasive litter on Earth, posing a major threat to organisms and ecosystems. However, these waste contain cellulose acetate (CA) and can be recycled, transforming into raw materials for new products. Polymers like CA can be used in biomedical applications as drug carriers and scaffolds for drug release. In this study, cigarette filters waste was collected, recycled and used for fabricating the nanofibrous membrane of cellulose acetate nanofibers (CFCA) through electrospinning technique. Tetracycline hydrochloride (TC) was encapsulated in the nanofibers to prevent bacterial infections. Various analyses were conducted: Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction Analysis (XRD) and Thermogravimetric analysis (TGA). CA and CFCA exhibited high water uptake properties and exhibited similar breaking stress and strain values. Both CA and CFCA effectively acted as stable drug carriers, with sustained in vitro drug release. Antibacterial activity was demonstrated by the drug-loaded CA and CFCA nanofibers against, Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli. Based on their cytotoxicity evaluations on mouse fibroblast cells (L929), CA and CFCA fibrous mats demonstrated no cytotoxicity and similar cell viability results. Consequently, the TC-loaded nanofibers made from CA and CFCA exhibited suitable properties for wound healing applications.

Amphiphilic sodium alginate-polylysine hydrogel with high antibacterial efficiency in a wide pH range.

Bacterial infection is a major pathological factor leading to persistent wounds. With the aging of population, wound infection has gradually become a global health-issue. The wound site environment is complicated, and the pH changes dynamically during healing. Therefore, there is an urgent need for new antibacterial materials that can adapt to a wide pH range. To achieve this goal, we developed a thymol-oligomeric tannic acid/amphiphilic sodium alginate-polylysine hydrogel film, which exhibited excellent antibacterial efficacy in the pH range from 4 to 9, achieving the highest achievable 99.993 % (4.2 log units) and 99.62 % (2.4 log units) against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, respectively. The hydrogel films exhibited excellent cytocompatibility, suggesting that the materials are promising as a novel wound healing material without the concern of biosafety.

In situ grown bacterial cellulose/MoS2 composites for multi-contaminant wastewater treatment and bacteria inactivation.

For the purpose of developing multifunctional water purification materials capable of degrading organic pollutants while simultaneously inactivating microorganisms from contaminated wastewater streams, we report here a facile and eco-friendly method to immobilize molybdenum disulfide into bacterial cellulose via a one-step in-situ biosynthetic method. The resultant nanocomposite, termed BC/MoS2, was shown to possess a photocatalytic activity capable of generating •OH from H2O2, while also exhibiting photodynamic/photothermal mechanisms, the combination of which exhibits synergistic activity for the degradation of pollutants as well as for bacterial inactivation. In the presence of H2O2, the BC/MoS2 nanocomposite exhibited excellent antibacterial efficacy upwards of 99.9999% (6 log units) for the photoinactivation of both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus upon infrared (IR) lamp illumination (100 W, 760 nm ≤ λ ≤ 5000 nm, 15 cm vertical distance; 5 min). Mechanistic studies revealed synergistic pathogen inactivation resulting from the combination of photocatalytically generated •OH and hyperthermia induced by the photothermal conversion of the near-IR light. In addition, the BC/MoS2 nanocomposite also showed excellent photodegradation activity for common aqueous contaminants in the presence of H2O2, including malachite green (a textile dye), catechol violet (a phenol) and formaldehyde. Taken together, our findings demonstrate that sustainable materials such as BC/MoS2 have potential applications in wastewater treatment and microorganism disinfection.

Manufacturing Technics for Fabric/Fiber-Based Triboelectric Nanogenerators: From Yarns to Micro-Nanofibers.

Triboelectric nanogenerator (TENG), as a green energy harvesting technology, has aroused tremendous interest across many fields, such as wearable electronics, implanted electronic devices, and human-machine interfaces. Fabric and fiber-structured materials are excellent candidates for TENG materials due to their inherent flexibility, low cost, and high wearing comfort. Consequently, it is crucial to combine TENG with fabric/fiber materials to simultaneously leverage their mechanical energy harvesting and wearability advantages. In this review, the structure and fundamentals of TENG are briefly explained, followed by the introduction of three distinct methods for preparing fabric/fiber structures: spinning and weaving, wet spinning, and electrospinning. In the meantime, their applications have been discussed, focusing primarily on energy harvesting and wearable self-powered sensors. Finally, we discussed the future and challenges of fabric and fiber-based TENGs.

Astragalus Polysaccharides/PVA Nanofiber Membranes Containing Astragaloside IV-Loaded Liposomes and Their Potential Use for Wound Healing.

Delayed wound healing is a common and serious complication in diabetic patients, especially the slow healing of foot ulcers, which seriously affects the quality of life of patients and is also the most important risk factor for lower limb amputation. The multifunctional novel dressing prepared by loading the polymer nanofibers with anti-inflammatory and prohealing plant extracts can promote the wound repair of these ulcers by electrospinning technology. Liposomes are nanoparticles prepared from phospholipids and have been widely used as drug delivery systems. Liposomes can be combined with electrospun nanofibrous webs to facilitate local and sustained delivery of loaded bioactive substances. In this study, liposomes were prepared with astragaloside IV (AS) by employing a modified ethanol injection method and conducting the physical and chemical characterization (e.g., the particle size, polydispersity index, zeta potential, and entrapment efficiency). Astragalus polysaccharides were extracted from Astragalus membranaceus. Subsequently, we prepared the electrospun polyvinyl alcohol (PVA)/astragalus polysaccharide (APS)/astragaloside IV (AS) nanofibers. The morphology of the produced ASL/APS/PVA, APS/PVA, and PVA nanofibers were analyzed by scanning electron microscopy (SEM), and it turns out that the addition of astragalus extract made the fiber diameter smaller and the fibers arranged neatly with no dripping. An induced diabetic rat model was built, and a diabetic ulcer model was built by total cortical resection to assess the prorepair ability of the prepared nanofibers. According to in vivo animal experiments, the nanofibrous membrane loaded with APS and ASL was reported to inhibit the occurrence of wound inflammation, enhance the deposition of collagen fibers (P < 0.05) and the repair of regenerated epithelium (P < 0.05), and effectively strengthen the wound healing of diabetic rats (P < 0.05). In brief, PVA-loaded APS/ASL nanofibrous membranes refer to a prominent wound healing dressing material, which can effectively facilitate the healing of diabetic wounds, and they are demonstrated to be highly promising for application in diabetic wound dressings and tissue engineering.

Light-driven self-disinfecting textiles functionalized by PCN-224 and Ag nanoparticles.

Toward the goal of preventing microbial infections in hospitals or other healthcare institutions, here we developed a self-disinfecting textile with synergistic photodynamic/photothermal antibacterial property. Porphyrinic Metal-organic frameworks (PCN-224) and Ag nanoparticles (NPs) were in situ grown on knitted cotton textile (KCT) successively to achieve rapid photodynamic antibacterial and durable bacteriostatic effect. Light-driven singlet oxygen (1O2) generated from PCN-224 and heat generated from Ag could function synergistically to realize rapid bacterial inactivation. Interestingly, 1O2 could promote Ag NPs to be degraded to release more Ag+ ions, achieving durable bacteriostatic effect. Antibacterial assay demonstrated 6 and 4.49 log unit inactivation toward two typical bacterial strains (E. coli and S. aureus) under Xe arc lamp in 30 min, respectively. Even after ten washes, the textile still maintained 6 log unit bacterial inactivation. Mechanism study proved light-driven 1O2 and heat are main factors causing bacterial inactivation, they could work synergistically to enhance bacterial inactivation efficiency. Photothermal study revealed that the textile could reach to 69 â„ƒ under visible light and 79.1 â„ƒ under 780-nm light-laser, which showed much potential in photothermal material applications. Taken together, our findings demonstrated a synergistic self-disinfecting cotton textile that exhibited constructive significance for preventing microbial infections and transmissions.

Preparation of Amidoxime Polyacrylonitrile Chelating Nanofibers and Their Application for Adsorption of Metal Ions.

Polyacrylonitrile (PAN) nanofibers were prepared by electrospinning and they were modified with hydroxylamine to synthesize amidoxime polyacrylonitrile (AOPAN) chelating nanofibers, which were applied to adsorb copper and iron ions. The conversion of the nitrile group in PAN was calculated by the gravimetric method. The structure and surface morphology of the AOPAN nanofiber were characterized by a Fourier transform infrared spectrometer (FT-IR) and a scanning electron microscope (SEM), respectively. The adsorption abilities of Cu2+ and Fe3+ ions onto the AOPAN nanofiber mats were evaluated. FT-IR spectra showed nitrile groups in the PAN were partly converted into amidoxime groups. SEM examination demonstrated that there were no serious cracks or sign of degradation on the surface of the PAN nanofibers after chemical modification. The adsorption capacities of both copper and iron ions onto the AOPAN nanofiber mats were higher than those into the raw PAN nanofiber mats. The adsorption data of Cu2+ and Fe3+ ions fitted particularly well with the Langmuir isotherm. The maximal adsorption capacities of Cu2+ and Fe3+ ions were 215.18 and 221.37 mg/g, respectively.