Self-powered portable melt electrospinning for in situ wound dressing.

BACKGROUND: Electrospun (e-spun) nanofibers for wound dressing have attracted wide attention due to its large specific surface area, large porosity and breathability. Compared with solution electrospinning (e-spinning), melt e-spinning is more bio-friendly without toxic solvent participation, which provides the possibility of in situ e-spinning on wounds directly. However, previously reported melt e-spinning devices were usually bulky and cumbersome due to their necessary heating unit, and different components were separated to avoid electrostatic interference. RESULTS: In this article, we report on a self-powered hand-held melt e-spinning gun which can work without any external power supply (outdoors). The problem of electrostatic interference for this integrated device was solved by using a special high heat transfer insulation unit. The apparatus is easy and safe to operate by a single hand due to its small volume (24 × 6 × 13 cm3) and light weight (about 450 g). Some biodegradable polymers, for example, polycaprolactone (PCL) fibers were successful e-spun onto wounds directly by using this dressing gun. CONCLUSIONS: PCL fibrous membrane has good biocompatibility and can be in situ electrospun to wound surface as a wound dressing by the portable melt e-spinning gun. Besides wound dressing, this hand-held melt e-spinning gun may be used in 3D printing and experimental teaching demonstration aids.

Ultrasensitive Fluorescence Lifetime Tuning in Patterned Polymer Composite Nanofibers with Plasmonic Nanostructures for Multiplexing.

Regulating fluorescence lifetime of lanthanide nanocomposites is highly desired for optical multiplexing applications, for instance, security printing, anticounterfeiting, and data storage. Herein, sensitive fluorescence lifetime tuning in nanocomposite fibers is reported which are composed of silica-coated gold nanorods assembled in Eu-polystyrene nanofibers. The prepared nanofibers possess unique properties of tunable fluorescence lifetime and distinct textured patterns together with superior flexibility and superhydrophobicity. In a single 612 nm emission channel, over ten different populations of fluorescence lifetime from the range of 322-551 µs are harvested. Thanks to the tunable fluorescence lifetime and different textured patterns, a security pattern to demonstrate optical multiplexing applications is designed. The security pattern hides the real information of "69" in a noticeable scene that shows fake information "8" under UV radiation or "13" by only watching their pattern structures.

Stretchable, flexible and breathable polylactic acid/polyvinyl pyrrolidone bandage based on Kirigami for wounds monitoring and treatment.

Chronic wounds are slow to recover. During treatment, the dressing needs to be removed to check the recovery status, a process that often results in wound tears. Traditional dressings lack stretching and flexing properties and are not suitable using on wounds in joints, which require movement from time to time. In this study, we present a stretchable, flexible and breathable bandage consisting of three layers, including Mxene coating on the top, the polylactic acid/polyvinyl pyrrolidone (PLA/PVP) layer designed as Kirigami in the middle, and the f-sensor at the bottom. By the way, the f-sensor is in contact with the wound sensing real-time microenvironmental changes due to infection. When the infection intensifies, the Mxene coating at the top is utilized to enable anti-infection treatment. And Kirigami structure of PLA/PVP ensures that this bandage has stretchability, bendability, and breathability. The stretch of the smart bandage increases to 831 % compared to the original structure, and the modulus reduces to 0.04 %, which adapts extremely well to the movement of the joints and relieves the pressure on the wound. This monitoring-treatment closed-loop working mode, eliminating the need to remove dressings and avoid tissue tearing, shows a promising capability in the field of surgical wound care.

Icy core-shell composite nanofibers with cooling, antibacterial and healing properties for outdoor burns.

Burns are usually difficult to treat because their susceptibe to bacterial infections. When burns is accompanied by hyperthermia, the heat accumulated on the skin will causes extensive tissue damage. Most dressings focus on the treatment process, while ignoring the first-aid treatment to remove hyperthermia. To make matters worse, when outdoors, it is hard to find clean water to wash and cool the burned area. A dressing which can simultaneously realize first-time cooling and repairing treatment of the burned area can shorten treatment time, and is especially beneficial for outdoor use. In this study, a handheld coaxial electrospinning device is developed for preparing platelet-rich plasma @Polycaprolactone-epsilon polylysine (PRP@PCL/ε-PL) core-shell nanofibers. The nanofibers can be synchronously transformed into ice fibers during the spinning process, and directly deposited on the skin. The whole process is convenient to use outdoor. Via dual cooling mechanisms, first aid can take away the excessive heat in the burn area by nanofibers. These core-shell nanofibers also show its excellent antimicrobial and tissue regeneration-promoting properties. Therefore, it achieves first-time cooling and repair treatment of the burned area at the same time. Moreover, due to direct in-situ deposition of this handheld coaxial electrospinning, better antimicrobial properties, and faster healing performance are achieved. By using this integrated strategy that combines cooling, antibacterial and healing promotion, the burn recovery time is shortened from 21 days to 14 days.

One-Step Preparation of a Core-Spun Cu/P(VDF-TrFE) Nanofibrous Yarn for Wearable Smart Textile to Monitor Human Movement.

At present, wearable electronic sensors are widely investigated and applied for human life usage especially for the flexible piezoelectric sensor based on piezoelectric fibers. However, most of these fiber-based piezoelectric sensors are thin films, which might had poor air permeability, or do not adapt to complex body movements. In this study, a piezoelectric sensing fabric was proposed based on core-spun Cu/P(VDF-TrFE) nanofibrous yarns. These yarns were fabricated by P(VDF-TrFE) as a piezoelectric material and Cu wire as an inner electrode layer through a one-step conjugate electrospinning process. The Cu/P(VDF-TrFE) fabrics showed good flexibility, breathability, mechanical stability, and sensing capability after continuous running for 60 min or after washing. A 4 cm × 4 cm fabric could generate a current of 38 nA and voltage of 2.7 V under 15 N pressure. Once the fabric was fixed onto the clothes, human motion could be monitored by collecting its generated current, and the signal could be wirelessly transmitted onto a smartphone. Therefore, this study may provide a simple and promising approach to design a smart textile for human motion monitoring.

Synergistic antibacterial polyacrylonitrile/gelatin nanofibers coated with metal-organic frameworks for accelerating wound repair.

Bacterial infections prolong the wound healing time and increase the suffering of patients, thus it is important to develop wound dressing that can inhibit bacterial infection. Herein, we use two methods including "doping method" and "secondary growth method" to prepare ZIF-8@gentamicin embedded in and coated on polyacrylonitrile/gelatin (PG) nanofibers, separately. Composite nanofibers prepared by the secondary growth method achieve higher drug loading than that of the doping method, and the release rate can be adjusted by pH. Simultaneously increasing drug loading and regulating its release rate are achieved in the secondary growth method, which cannot be achieved by the doping method. Furthermore, synergistic antibacterial property occurs in the composite nanofibers prepared by the secondary growth method, and gentamicin loaded on ZIF-8 promotes the antibacterial effect, which shows better antibacterial effect than the doping method. As a result, during the wound infection of mouse, composite nanofibers prepared by the secondary growth method exhibit a faster recovery effect than the doping method, which effectively shortened the wound healing time from 21 days to 16 days.

Three-dimensional porous composite scaffolds for in vitro marrow microenvironment simulation to screen leukemia drug.

The traditional 2D culture medium used for simulating the in vitro microenvironment for leukemia cells usually leads to 95% of the drug test results being different to the subsequent clinical results. Unlike this 2D culture, 3D scaffolds are more similar to the bone marrow microenvironment so can better simulate the drug effect on leukemia cells, which can benefit the preliminary screening of drugs for clinical use. For this purpose, the freeze-drying method was proposed for the fabrication of 3D scaffolds of graphene oxide/silk fibroin/carboxymethyl chitosan (GO/SF/CMCS). Experimental results show that these 3D scaffolds exhibit a better swelling ratio because of the embedding of GO. The improved hydrophilicity of the scaffolds brings about promoted adhesion and proliferation of leukemia cells. In contrast to the traditional 2D culture, leukemia cells in this 3D culture show stronger drug resistance, which is consistent with the previously reported clinical results. It implies that these 3D GO/SF/CMCS scaffolds can simulate well the in vivo bone marrow microenvironment, making it a promising platform for preliminary drug screening for clinical use.

In situ melt electrospun polycaprolactone/Fe3O4 nanofibers for magnetic hyperthermia.

Magnetic fibrous membrane used to generate heat under the alternating magnetic field (AMF) has attracted wide attention due to their application in magnetic hyperthermia. However, there is not magnetic fibrous membrane prepared by melt electrospinning (e-spinning) which is a solvent-free, bio-friendly technology. In this work, polycaprolactone (PCL)/Fe3O4 fiber membrane was prepared by melt e-spinning and using homemade self-powered portable melt e-spinning apparatus. The hand-held melt e-spinning apparatus has a weight of about 450 g and a precise size of 24 cm in length, 6 cm in thickness and 13 cm in height, which is more portable for widely using in the medical field. The PCL/Fe3O4 composite fibers with diameters of 4-17 µm, are very uniform. In addition, the magnetic composite fiber membrane has excellent heating efficiency and thermal cycling characteristics. The results indicated that self-powered portable melt e-spinning apparatus and PCL/Fe3O4 fiber membrane may provide an attractive way for hyperthermia therapy.

Performance of polyvinyl pyrrolidone-isatis root antibacterial wound dressings produced in situ by handheld electrospinner.

Antibacterial dressings are an increasingly important tool for the prevention and management of wound infections, particularly in light of concerns surrounding conventional drug-resistant antibiotics. Handheld electrospinning devices provide opportunities for the rapid application of antibacterial dressing materials to wounds, but spinning formulations need to be compatible with live biological surfaces. We report the development of a new antibacterial formulation compatible with handheld electrospinning, and its manufacture directly on a wound site. Nanofibrous dressing mats were produced from polyvinyl pyrrolidone (PVP) containing isatis root (Indigowoad root or Ban-Lan-Gen), a traditional Chinese medicine, commonly used for the treatment of infectious disease. The resulting wound dressing mats of PVP/isatis root exhibited well-defined fibrous structures and excellent surface wetting, and permeability characteristics. The presence of isatis root conferred antibacterial activity against gram negative and gram positive strains. Moreover, in a Kunming mouse skin injury model, direct electrospinning of PVP/isatis root formulations on to wound sites produced near complete wound closure after 11 days and epidermal repair in histological studies.

A high performance wearable strain sensor with advanced thermal management for motion monitoring.

Resistance change under mechanical stimuli arouses mass operational heat, damaging the performance, lifetime, and reliability of stretchable electronic devices, therefore rapid thermal heat dissipating is necessary. Here we report a stretchable strain sensor with outstanding thermal management. Besides a high stretchability and sensitivity testified by human motion monitoring, as well as long-term durability, an enhanced thermal conductivity from the casted thermoplastic polyurethane-boron nitride nanosheets layer helps rapid heat transmission to the environments, while the porous electrospun fibrous thermoplastic polyurethane membrane leads to thermal insulation. A 32% drop of the real time saturated temperature is achieved. For the first time we in-situ investigated the dynamic operational temperature fluctuation of stretchable electronics under repeating stretching-releasing processes. Finally, cytotoxicity test confirms that the nanofillers are tightly restricted in the nanocomposites, making it harmless to human health. All the results prove it an excellent candidate for the next-generation of wearable devices.

[Effect of Polyvinyl Alcohol/Graphene Oxide Aerogel on the Biological Characteristics of Acute Leukemia Cell Lines].

OBJECTIVE: To investigate the effects of polyvinyl alcohol (PVA) + graphene oxide (GO, weight content 1 wt%) aerogel three-dimensional (3D) scaffolds culture system on the proliferation, phenotype and drug resistance of ALL cell line Jurkat and AML cell line HL-60. METHODS: Jurkat cells and HL-60 cells were seeded in PVA+GO aerogel scaffolds for culture, and the structure of cells were observed by the scanning electron microscopy. Cell proliferation activity was measured by Cell Counting Kit-8 (CCK-8), cell phenotypes were analyzed by flow cytometry after fluorescent staining, then were compared with 2D cultured cells. Ara-C was used in drug resistance experiment, and CCK8 was used to detected cell proliferation activity. RESULTS: The proliferation activity of Jurkat cells grown in aerogel scaffolds was higher than that by 2D cultured in long-term culture. However, in HL-60 cells, the proliferation activity on 3D scaffold only at the 8th to 20th day was higher than that on the traditional 2D culture. Expression of CD4 in Jurkat cells increased after culture for 30 days, but the cell phenotypes in the 3D aerogel scaffolds were similar to 2D cultured cells. Phenotype of HL-60 cells was certainly changed after culture for 30 days, the cells can be divided into CD13+CD14-CD45+HLA-DR+,CD13-CD14--CD45+HLA-DR+ and CD13-CD14-CD45+HLA-DR- groups, and a new CD13+CD14-CD45-HLA-DR+ group of cells appeared in the cells cultured in 3D scaffolds, but not in 2D cultured cells. Drug resistance experiments showed that Jurkat cells in aerogel scaffolds have stronger drug resistance than those in 2D culture. CONCLUSION: PVA+GO (1 wt%) aerogel scaffolds can improve the proliferation and drug resistance of leukemia cells, and the phenotypes were the same as those in 2D culture, which can be used for cell amplification and biology characteristics studies and drug experiments. However, cell phenotypes should be analyzed before culture, and the effects of phenotypes changes on drug resistance should be eliminated.

Poly(propylene fumarate)-based materials: Synthesis, functionalization, properties, device fabrication and biomedical applications.

Poly(propylene fumarate) (PPF) is a biodegradable polymer that has been investigated extensively over the last three decades. It has led many scientists to synthesize and fabricate a variety of PPF-based materials for biomedical applications due to its controllable mechanical properties, tunable degradation and biocompatibility. This review provides a comprehensive overview of the progress made in improving PPF synthesis, resin formulation, crosslinking, device fabrication and post polymerization modification. Further, we highlight the influence of these parameters on biodegradation, biocompatibility, and their use in a number of regenerative medicine applications, especially bone tissue engineering. In particular, the use of 3D printing techniques for the fabrication of PPF-based scaffolds is extensively reviewed. The recent invention of a ring-opening polymerization method affords precise control of PPF molecular mass, molecular mass distribution (ƉM) and viscosity. Low ƉM facilitates time-certain resorption of 3D printed structures. Novel post-polymerization and post-printing functionalization methods have accelerated the expansion of biomedical applications that utilize PPF-based materials. Finally, we shed light on evolving uses of PPF-based materials for orthopedics/bone tissue engineering and other biomedical applications, including its use as a hydrogel for bioprinting.

Fabrication of pure chitosan nanofibrous membranes as effective absorbent for dye removal.

The pure chitosan nanofibrous membranes with average fiber diameter of 86±18, 114±17,164±28nm were successfully prepared by electrospinning. Batch adsorption experiments of using chitosan nanofibrous membranes as adsorbent to remove acid blue-113 were conducted. The adsorption capacity of 1377mg/g was achieved by the chitosan nanofibrous membrane with average fiber diameter of 86nm, which was superior to the chitosan microscale sample with the adsorption capacity of 412mg/g. The average fiber diameter and the corresponding equilibrium adsorption capacity of pure chitosan nanofibrous membranes fitted well with linear relationship in our test range. The results also showed that the adsorption followed with pseudo second-order kinetics model, and the adsorption behavior was accordance with the Langmuir isotherm model. The pure chitosan nanofibrous membrane showed promise and feasibility as an effective adsorbent for dye removal.

Wireless piezoelectric devices based on electrospun PVDF/BaTiO3 NW nanocomposite fibers for human motion monitoring.

Real-time personalized motion monitoring and analysis are important for human health. Thus, to satisfy the needs in this area and the ever-increasing demand for wearable electronics, we design and develop a wireless piezoelectric device consisting of a piezoelectric pressure sensor based on electrospun PVDF/BaTiO3 nanowire (NW) nanocomposite fibers and a wireless circuit system integrated with a data conversion control module, a signal acquisition and amplification module, and a Bluetooth module. Finally, real-time piezoelectric signals of human motion can be displayed by an App on an Android mobile phone for wireless monitoring and analysis. This wireless piezoelectric device is proven to be sensitive to human motion such as squatting up and down, walking, and running. The results indicate that our wireless piezoelectric device has potential applications in wearable medical electronics, particularly in the fields of rehabilitation and sports medicine.

Electrospun nanofibers for wound healing.

Electrospinning has been widely used as a nanofiber fabrication technique. Its simple process, cost effectiveness and versatility have appealed to materials scientists globally. Pristine polymeric nanofibers or composite nanofibers with dissimilar morphologies and multidimensional assemblies ranging from one dimension (1D) to three dimensions (3D) can be obtained from electrospinning. Critically, these as-prepared nanofibers possessing high surface area to volume ratio, tunable porosity and facile surface functionalization present numerous possibilities for applications, particularly in biomedical field. This review gives us an overview of some recent advances of electrospinning-based nanomaterials in biomedical applications such as antibacterial mats, patches for rapid hemostasis, wound dressings, drug delivery systems, as well as tissue engineering. We further highlight the current challenges and future perspectives of electrospinning-based nanomaterials in the field of biomedicine.

In situ precise electrospinning of medical glue fibers as nonsuture dural repair with high sealing capability and flexibility.

PURPOSE: In this work, we propose an in situ precise electrospinning of medical glue fibers onto dural wound for improving sealing capability, avoiding tissue adhesion, and saving time in dural repair. METHODS: N-octyl-2-cyanoacrylate, a commercial tissue adhesive (medical glue), can be electrospun into ultrathin fibrous film with precise and homogeneous deposition by a gas-assisted electrospinning device. RESULTS: The self-assembled N-octyl-2-cyanoacrylate film shows high compactness and flexibility owing to its fibrous structure. Simulation experiments on egg membranes and goat meninges demonstrated that this technology can repair small membrane defects quickly and efficiently. CONCLUSION: This method may have potential application in dural repair, for example, working as an effective supplementary technique for conventional dura suture.

Fabrication and biocompatibility of poly(l-lactic acid) and chitosan composite scaffolds with hierarchical microstructures.

The scaffold microstructure is crucial to reconstruct tissue normal functions. In this article, poly(l-lactic acid) and chitosan fiber (PLLA/CTSF) composite scaffolds with hierarchical microstructures both in fiber and pore sizes were successfully fabricated by combining thermal induced phase separation and salt leaching techniques. The composite scaffolds consisted of a nanofibrous PLLA matrix with diameter of 50-500nm, and chitosan fibers with diameter of about 20µm were homogenously distributed in the PLLA matrix as a microsized reinforcer. The composite scaffolds also had high porosity (>94%) and hierarchical pore size, which were consisted of both micropores (50nm-10µm) and macropores (50-300µm). By tailoring the microstructure and chemical composition, the mechanical property, pH buffer and protein adsorption capacity of the composite scaffold were improved significantly compared with those of PLLA scaffold. Cell culture results also revealed that the PLLA/CTSF composite scaffolds supported MG-63 osteoblast proliferation and penetration.

In situ deposition of a personalized nanofibrous dressing via a handy electrospinning device for skin wound care.

Current strategies for wound care provide limited relief to millions of patients who suffer from burns, chronic skin ulcers or surgical-related wounds. The goal of this work is to develop an in situ deposition of a personalized nanofibrous dressing via a handy electrospinning (e-spinning) device and evaluate its properties related to skin wound care. MCM-41 type mesoporous silica nanoparticles decorated with silver nanoparticles (Ag-MSNs) were prepared by a facile and environmentally friendly approach, which possessed long-term antibacterial activity and low cytotoxicity. Poly-ε-caprolactone (PCL) incorporated with Ag-MSNs was successfully electrospun (e-spun) into nanofibrous membranes. These in situ e-spun nanofibrous membranes allowed the continuous release of Ag ions and showed broad-spectrum antimicrobial activity against two common types of pathogens, Staphylococcus aureus and Escherichia coli. In addition, the in vivo studies revealed that these antibacterial nanofibrous membranes could reduce the inflammatory response and accelerate wound healing in Wistar rats. The above results strongly demonstrate that such patient-specific dressings could be broadly applied in emergency medical transport, hospitals, clinics and at the patients' home in the near future.

Melt electrospinning of poly(lactic acid) and polycaprolactone microfibers by using a hand-operated Wimshurst generator.

A conventional melt electrospinning setup usually needs a large, heavy high-voltage power supply and cannot work without a plug (electricity supply). In this article, we report a new melt electrospinning setup based on a small hand-operated Wimshurst generator, which can avoid electrical interference between the high-voltage spinning system and the heating system, and make the setup very portable and safe. Poly(lactic acid) (PLA) and polycaprolactone (PCL) fibers with diameters of 15-45 µm were fabricated successfully by using this apparatus. Experimental parameters such as the rotational speed of the generator handle (a half turn to two turns per second) and the spinning distance (2-14 cm) were investigated. In addition, PLA and PCL fibers were directly melt-electrospun onto a pork liver, and the temperature and adhesiveness of the deposited fibers were studied. The results indicate that the apparatus and melt-electrospun polymer microfibers may be used in dressing for wound healing.

Surface modification of nano-silica on the ligament advanced reinforcement system for accelerated bone formation: primary human osteoblasts testing in vitro and animal testing in vivo.

The Ligament Advanced Reinforcement System (LARS) has been considered as a promising graft for ligament reconstruction. To improve its biocompatibility and effectiveness on new bone formation, we modified the surface of a polyethylene terephthalate (PET) ligament with nanoscale silica using atom transfer radical polymerization (ATRP) and silica polymerization. The modified ligament is tested by both in vitro and in vivo experiments. Human osteoblast testing in vitro exhibits an ∼21% higher value in cell viability for silica-modified grafts compared with original grafts. Animal testing in vivo shows that there is new formed bone in the case of a nanoscale silica-coated ligament. These results demonstrate that our approach for nanoscale silica surface modification on LARS could be potentially applied for ligament reconstruction.