Nanofiber Device Research Articles

A neural tract-inspired conduit for facile, on-demand biopsy of glioblastoma.

A major hurdle to effectively treating glioblastoma (GBM) patients is the lack of longitudinal information about tumor progression, evolution, and treatment response. In this study, we report the use of a neural tract-inspired conduit containing aligned polymeric nanofibers (i.e., an aligned nanofiber device) to enable on-demand access to GBM tumors in 2 rodent models. Depending on the experiment, a humanized U87MG xenograft and/or F98-GFP+ syngeneic rat tumor model was chosen to test the safety and functionality of the device in providing continuous sampling access to the tumor and its microenvironment. The aligned nanofiber device was safe and provided a high quantity of quality genomic materials suitable for omics analyses and yielded a sufficient number of live cells for in vitro expansion and screening. Transcriptomic and genomic analyses demonstrated continuity between material extracted from the device and that of the primary, intracortical tumor (in the in vivo model). The results establish the potential of this neural tract-inspired, aligned nanofiber device as an on-demand, safe, and minimally invasive access point,thus enabling rapid, high-throughput, longitudinal assessment of tumor and its microenvironment, ultimatelyleading to more informed clinical treatment strategies.

Economic optimization of antibody capture through Protein A affinity nanofiber chromatography

In this study we compare a nanofiber device and a resin column, both with the same Protein A ligand, for the capture of four different monoclonal antibodies and a trivalent crystallizable fragments (Fc) of antibody. We show that the dynamic binding capacity of the nanofiber device varies slightly with residence time, with the transfer kinetics slower for the IgG1, than for the IgG4 antibody. Surface plasmon resonance shows that the trivalent Fc binds to multiple Protein A ligand sites due to its three repeating Fc units, whereas multiple IgG antibodies bind to a single Protein A ligand. The nanofiber device gives comparable eluate purity to the resin column but at lower antibody concentrations due to its larger housing volume and lower binding capacity. It can be used for up to 200 cycles without performance loss and gives consistent eluate quality when scaled from 0.4 mL to 3.75 mL. We show that the use of a single nanofiber device to process one 2000 L clarified harvest through multiple cycles can reduce the Cost of Goods fivefold compared with a resin column. Costs are potentially lower for up to thirteen 2000 L harvests if device reuse can be validated. Nanofiber devices are thus an attractive option for manufacture of pre-clinical or clinical trial material where the number of batches is limited.

A sandwich-like flexible nanofiber device boosts moisture induced electricity generation for power supply and multiple sensing applications

Moisture-electricity generators (MEGs) are emerging as an attractive sustainable power supply due to their clean energy harvesting and conversion. However, there still remain some challenges in the development of high-performance and practical MEGs. Herein, we develop a novel sulfonate-polyaniline-bifunctionalized lignin (SAlignin), which can be incorporated into additive polyacrylonitrile for engineering electrospun nanofiber membrane (BioMem) to improve moisture power generation. To achieve maximal electric conversion efficiency, a flexible sandwich-like MEG (fMEG) consisting of an outer bilayer electrode of carbonized BioMem and an inner hygroscopic layer of as-spun BioMem is constructed. The unique structures and compositions endow fMEG with optimal ion diffusion, streaming tendency and surface potential for moisture electric generation. Importantly, phase-field simulation reveals that the interpenetrating network of SAlignin and polyacrylonitrile has good moisture absorption capacity and electricity generation, thereby boosting electric outputs. We identify that fMEG exhibits SAlignin-dose dependent increase in power conversion efficiency, and can generate a stable voltage of 0.28 V and current of 125 nA/cm2. In addition, electric output can be further improved by assembling multiple fMEG units in series or parallel, which is sufficient to power up electronic devices. More excitingly, fMEG can sensitively detect humid wind, and especially harvest the energy from human breath for respiration monitoring. Particularly, fMEG exhibits the potential of real-time monitoring of different human motions, including finger movements, sound waves and neck pulses. Therefore, our study provides new insights for advancing MEGs and related applications.

High‐Performance Voice Recognition Based on Piezoelectric Polyacrylonitrile Nanofibers

AbstractAcoustic sensors show a wide application in diverse fields. However, it is still a challenge to develop highly sensitive transducing materials for the detection of low‐to‐middle decibel sounds. Herein, for the first time the remarkable property of an acoustic sensor based on electrospun polyacrylonitrile (PAN) nanofibers in the recognition of human voices is reported. The nanofiber device shows a sensitivity as high as 23 401 mV P−1 to 70 dB sound, which is much higher than most of the acoustic sensors reported in the literature. First the sounds from different musical instruments are used as a standard sound source to show the high accuracy of the nanofiber device to distinguish different sounds, e.g., from both the same and different instruments, and then people's voices are tested. Experimental results show that the device can distinguish people's voices with high resolution and the influence of background noise on speech recognition is very small. The acoustic sensor is stable and can be used in sound detection for a long time. Electrospun PAN membranes may be useful for the development of voice recognition systems for security, environmental protection, scientific research, and other high‐tech applications.

Efficient conversion of sound noise into electric energy using electrospun polyacrylonitrile membranes

Abstract Herein, we report the novel ability of electrospun polyacrylonitrile (PAN) nanofibrous membranes to convert low-mid frequency noise into electricity with high voltage outputs. The acoustoelectric device is prepared by sandwiching a thin PAN fibrous membrane between two metal-coated plastic film electrodes. Under 117 dB sound (frequency 100–500 Hz), the nanofiber device can generate peak electric outputs as high as 58 V and 12 μA, with a maximum output power of 210.3 μW (areal power density 17.53 μW/cm2), which is much larger than that of other acoustoelectric devices reported. The electrical energy generated after rectification can be used to run commercial electronic devices (e.g., LEDs) directly. It can also be stored in a power bank and accumulated into larger power for further uses. Electrospun PAN may serve as a potential candidate to recycle sound noise, white pollution, into usable electric energy.

Short duration cancer treatment: inspired by a fast bio-resorbable smart nano-fiber device containing NIR lethal polydopamine nanospheres for effective chemo-photothermal cancer therapy.

BackgroundThe objective of this study was to evaluate the efficacy of a combination of Photothermal therapy (PTT) and chemotherapy in a single nano-fiber platform containing lethal polydopamine nanopheres (PD NPs) for annihilation of CT 26 cancer cells.MethodPolydioxanone (PDO) nanofiber containing PD and bortezomib (BTZ) was fabricated via electrospinning method. The content of BTZ and PD after optimization was 7% and 2.5% respectively with respect to PDO weight. PD NPs have absorption band in near-infrared (NIR) with resultant rapid heating capable of inducing cancer cell death. The samples was divided into three groups – PDO, PDO+PD, and PDO+PD-BTZ for analysis.ResultsIn combined treatment, PDO nanofiber alone could not inhibit cancer cell growth as it neither contain PD or BTZ. However, PDO+PD fiber showed a cell viability of approximately 20% after 72 hr of treatment indicating minimal killing via hyperthermia. In the case of PDO composite fiber containing BTZ, the effect of NIR irradiation reduced the viability of cancer cells down to around 5% after 72 h showing the efficiency of combination therapy on cancer cells elimination. However, due to higher photothermal conversion that may negatively affect normal cells above 46°C, we have employed 1 s “OFF” and 2 s “ON” after initial 9 s continuous irradiation to maintain the temperature between 42 and 46°C over 3 mins of treatment using 2 W/cm2; 808 nm laser which resulted to similar cell death.ConclusionIn this study, combination of PTT and chemotherapy treatment on CT 26 colon cancer cells within 3 min resulted in effective cell death in contrast to single treatment of either PTT and chemotherapy alone. Our results suggest that this nanofiber device with efficient heating and remote control drug delivery system can be useful and convenient in the future clinical application for localized cancer therapy.

High-output acoustoelectric power generators from poly(vinylidenefluoride-co-trifluoroethylene) electrospun nano-nonwovens

Conversion of mechanical forces, vibrations and sound which have energy in the range of milli- to tens of watts (also referred to as “small kinetic energies” in this paper) into electricity has received global attention owing to the potential in powering electronic devices. However, most of the small kinetic energy generators can only generate electric power below 1µW/cm3. As a result, an energy storage device is required to accumulate the energy generated until it reaches a sufficient level. Herein, we report the exceptionally-high acoustoelectric conversion ability of randomly-orientated electrospun poly(vinylidenefluoride-co-trifluoroethylene) nanofiber nonwoven webs. The optimized device under sound is able to generate peak voltage and current of 14.5V and 28.5μA with a volume power density output of 306.5μW/cm3 (5.9mW/cm3 based on nanofiber web thickness). Without accumulation in any energy storage unit, the electricity generated by the nanofiber device is sufficient to light up tens of commercial LEDs, run electrochemical reactions and protect metals from corrosion. Such a novel acoustoelectric generator may offer an effective solution to recycling noise pollution into usable electricity.

Mechanical Energy‐to‐Electricity Conversion of Electron/Hole‐Transfer Agent‐Doped Poly(Vinylidene Fluoride) Nanofiber Webs

Electrospun poly(vinylidene fluoride) (PVDF) nanofibers have shown novel property to convert kinetic energy into electricity. However, most of the PVDF nanofiber energy devices are based on pure PVDF. In this paper, the effect of small molecule doping on PVDF nanofiber diameter, β phase content, and mechanical‐to‐electrical energy conversion property is reported. Two chemicals, tri‐p‐tolylamine (TTA) and 2‐(4‐tert‐butylphenyl)‐5‐(4‐biphenylyl)‐1,3,4‐oxadiazole (Butyl‐PBD) which have electron‐ and hole‐transfer features, respectively, are chosen as dopants. When the nanofibers contain 0.5% TTA or 1% Butyl‐PBD, they show high β phase content and electric outputs. By combining a layer of nanofiber web which contained TTA with a layer of nanofiber web containing Butyl‐PBD, the voltage output is changed to 3.1 V, increasing by ≈100% when compared with the single layer nanofiber device of the same thickness. In addition, asymmetric electric outputs are observed in the two layer energy device. These novel features are probably attributed to the high internal polarity across the nanofiber web. image

A Luteolin-Loaded Electrospun Fibrous Implantable Device for Potential Therapy of Gout Attacks

The recurrence of acute gout attacks remains an unsolved problem in clinical therapy. In order to tackle this problem, poly(ε-caprolactone) (PCL)/gelatin composite fibrous devices loaded with luteolin are presented via electrospinning for the therapy of gout and its recurrence. The luteolin-loaded fibrous device has the capability of inhibiting metabolic activities and reducing inflammation-associated cytokine productions (TNF-a, IL-1β, IL-6) that are secreted by lipopolysaccharide stimulated RAW 264.7 macrophages. The device can also suppress the reaction activities of xanthine oxidase for 7 d in vitro. In vivo, acute gout model is established by injecting monosodium urate (MSU) crystals into New Zealand rabbits' knees, then the luteolin-loaded PCL/gelatin (5:5) nanofiber device is implanted near the gout sites. The results show that the device can alleviate the acute gouty arthritis. In the mean time, the luteolin-loaded PCL fiber device with a longer drug release profile is implanted in a recurrent gout model, which is constructed by injecting MSU crystals into rabbits' knees three times. The results on day 21 reveal that this device has the potential to overcome the recurrence of gout. Therefore, the drug-loaded polymer fiber device can be an inspiration for potential gout therapy to overcome recurrent attacks.

An implantable smart magnetic nanofiber device for endoscopic hyperthermia treatment and tumor-triggered controlled drug release

The study describes the design and synthesis of an implantable smart magnetic nanofiber device for endoscopic hyperthermia treatment and tumor-triggered controlled drug release. This device is achieved using a two-component smart nanofiber matrix from monodisperse iron oxide nanoparticles (IONPs) as well as bortezomib (BTZ), a chemotherapeutic drug. The IONP-incorporated nanofiber matrix was developed by electrospinning a biocompatible and bioresorbable polymer, poly (d,l-lactide-co-glycolide) (PLGA), and tumor-triggered anticancer drug delivery is realized by exploiting mussel-inspired surface functionalization using 2-(3,4-dihydroxyphenyl)ethylamine (dopamine) to conjugate the borate-containing BTZ anticancer drug through a catechol metal binding in a pH-sensitive manner. Thus, an implantable smart magnetic nanofiber device can be exploited to both apply hyperthermia with an alternating magnetic field (AMF) and to achieve cancer cell-specific drug release to enable synergistic cancer therapy. These results confirm that the BTZ-loaded mussel-inspired magnetic nanofiber matrix (BTZ-MMNF) is highly beneficial not only due to the higher therapeutic efficacy and low toxicity towards normal cells but also, as a result of the availability of magnetic nanoparticles for repeated hyperthermia application and tumor-triggered controlled drug release. Statement of SignificanceThe current work report on the design and development of a smart nanoplatform responsive to a magnetic field to administer both hyperthermia and pH-dependent anticancer drug release for the synergistic anticancer treatment. The iron oxide nanoparticles (IONPs) incorporated nanofiber matrix was developed by electrospinning a biocompatible polymer, poly (d,l-lactide-co-glycolide) (PLGA), and tumor-triggered anticancer drug delivery is realized by surface functionalization using 2-(3,4-dihydroxyphenyl)ethylamine (dopamine) to conjugate the boratecontaining anticancer drug bortezomib through a catechol metal binding in a pH-sensitive manner. This implantable magnetic nanofiber device can be exploited to apply hyperthermia with an alternating magnetic field and to achieve cancer cell-specific drug release to enable synergistic cancer therapy, which results in an improvement in both quality of life and patient compliance.

An implantable active-targeting micelle-in-nanofiber device for efficient and safe cancer therapy.

Nanocarriers have attracted broad attention in cancer therapy because of their ability to carry drugs preferentially into cancer tissue, but their application is still limited due to the systemic toxicity and low delivery efficacy of intravenously delivered chemotherapeutics. In this study, we develop a localized drug delivery device with combination of an active-targeting micellar system and implantable polymeric nanofibers. This device is achieved first by the formation of hydrophobic doxorubicin (Dox)-encapsulated active-targeting micelles assembled from a folate-conjugated PCL-PEG copolymer. Then, fabrication of the core-shell polymeric nanofibers is achieved with coaxial electrospinning in which the core region consists of a mixture of poly(vinyl alcohol) and the micelles and the outer shell layer consists of cross-linked gelatin. In contrast to the systematic administration of therapeutics via repeatedly intravenous injections of micelles, this implantable device has these capacities of greatly reducing the drug dose, the frequency of administration and side effect of chemotherapeutic agents while maintaining highly therapeutic efficacy against artificial solid tumors. This micelle-based nanofiber device can be developed toward the next generation of nanomedicine for efficient and safe cancer therapy.

One-step in situ synthesis of single aligned graphene–ZnO nanofiber for UV sensing

Schematic of the microfabrication of gold electrodes, electrospinning with collector as pre patterned electrode, UV sensing with single aligned Gr–ZnO nanofiber device.

Photonic crystal nanofiber using an external grating

We implemented a photonic crystal nanofiber device by reversibly combining an optical nanofiber and a nanofabricated grating. Using the finite-difference time-domain method, we designed the system for minimal optical loss while tailoring the resonant wavelength and bandwidth of the device. Experimentally, we demonstrated that the combined system shows a strong photonic stop band in good agreement with numerical predictions. The resulting device may be used to realize strong light-matter coupling near the nanofiber surface.

Nano Approach Investigation of the Conduction Mechanism in Polyaniline Nanofibers

A nanotechnological approach is applied to measurements of the electric field dependence of resistance under a high electric field while in low voltage. With this technique, the conduction mechanism on a mesoscopic scale is explored in a single, nonagglomerated nanofiber. Polyaniline nanofibers are prepared by vigorous mixing of aniline and oxidation agent ammonium persulfate in acid solution. They exhibit a uniform nanoscale morphology rather than agglomeration as that produced via conventional chemical oxidation. The as-synthesized polyaniline nanofibers are doped (dedoped) with a HCl acid (NH(3) base), and their temperature behaviors of resistances follow an exponential function with an exponent of T(-1/2). To measure the conduction mechanism in a single nanofiber, the dielectrophoresis technique is implemented to position nanofibers on top of two electrodes with a nanogap of 100-600 nm, patterned by electron-beam lithography. After the devices are irradiated by electron beam to reduce contact resistances, their temperature behaviors and electric field dependences are unveiled. The experimental results agree well with the theoretical model of charging energy limited tunneling. Other theoretical models such as Efros-Shklovskii and Mott's one-dimensional hopping conduction are excluded after comparisons and arguments. Through fitting, the size of the conductive grain, separation distance between two grains, and charging energy per grain in a single polyaniline nanofiber are estimated to be about 4.9 nm, 2.8 nm, and 78 meV, respectively. The nanotechnological approach, where the nanogap and the dielectrophoresis technique are used for single nanofiber device fabrication, is applied for determination of mesoscopic charge transport in a polyaniline conducting polymer.

Wave propagation in prestretched polymer nanofibers

Wave propagation in prestretched ultrathin polymer fibers (e.g., those as-electrospun polymer nanofibers) are under the influence of prestretch, surface energy, and nonlinear elasticity. A one-dimensional nonlinear elastic model is proposed to take into account such combined influence in the wave propagation phenomenon. In the model, the polymer nanofibers are considered to behave as hyperelastic Mooney–Rivlin solid. For small dynamic disturbance, linearized wave equation is established by superimposing the dynamic displacement as linear disturbance on the prestretched equilibrium state. Explicit wave dispersion relations are obtained and relevant numerical examples are demonstrated in examining the dependency of wave phase speed upon the wave number at varying surface properties, fiber radius, and prestretch. In the limiting case of neglecting the dynamic effect, the present wave equation can yield the governing equation of surface rippling in compliant nanofibers. This governing equation is capable of predicting the initiation condition of surface rippling and the critical fiber radius, below which compliant nanofibers cannot be produced due to surface instability. Results obtained in this study are applicable as the theoretical basis of dynamic characterization of compliant nanowires/nanofibers, nanofiber device design, and nanostructural analysis.

Electrochemical fabrication and electronic behavior of polypyrrole nano-fiber array devices

Electrochemically active Polypyrrole (PPy) nano-fiber array device was fabricated via electrochemical deposition method using aluminum anodic oxide (AAO) membrane as template. After alkaline treatment electrochemically active PPy nano-fiber lost electrochemical activity, and became electrochemically inactive PPy. The electronic properties of PPy nano-fiber array devices were measured by means of a simple method. It was found that for an indium–tin oxide/electrochemically inactive PPy nano-fiber device, the conductivity of nano-fiber increased with the increase of voltage applied on the two terminals of nano-fiber. The electrochemical inactive PPy nano-fiber might be used as a nano-fiber switching diode. Both Au/electrochemically active PPy and Au/electrochemically inactive PPy nano-fiber devices demonstrate rectifying behavior, and might have been used for further application as nano-rectifiers.