skip to main content

Title: A Review on Electrospun Luminescent Nanofibers: Photoluminescence Characteristics and Potential Applications

Background: Photoluminescent materials have been used for diverse applications in thefields of science and engineering, such as optical storage, biological labeling, noninvasive imaging,solid-state lasers, light-emitting diodes, theranostics/theragnostics, up-conversion lasers, solar cells,spectrum modifiers, photodynamic therapy remote controllers, optical waveguide amplifiers andtemperature sensors. Nanosized luminescent materials could be ideal candidates in these applications.

Objective: This review is to present a brief overview of photoluminescent nanofibers obtainedthrough electrospinning and their emission characteristics.

Methods: To prepare bulk-scale nanosized materials efficiently and cost-effectively, electrospinningis a widely used technique. By the electrospinning method, a sufficiently high direct-current voltageis applied to a polymer solution or melt; and at a certain critical point when the electrostatic forceovercomes the surface tension, the droplet is stretched to form nanofibers. Polymer solutions or meltswith a high degree of molecular cohesion due to intermolecular interactions are the feedstock. Subsequentcalcination in air or specific gas may be required to remove the organic elements to obtainthe desired composition.

Results: The luminescent nanofibers are classified based on the composition, structure, and synthesismaterial. The photoluminescent emission characteristics of the nanofibers reveal intriguing featuressuch as polarized emission, energy transfer, fluorescent quenching, and sensing. An overview of theprocess, controlling parameters and techniques associated with electrospinning of organic, inorganicand composite nanofibers are discussed in detail. The scope and potential applications of these luminescentfibers also conversed.

Conclusion: The electrospinning process is a matured technique to produce nanofibers on a largescale. Organic nanofibers have exhibited superior fluorescent emissions for waveguides, LEDs andlasing devices, and inorganic nanofibers for high-end sensors, scintillators, and catalysts. Multifunctionalitiescan be achieved for photovoltaics, sensing, drug delivery, magnetism, catalysis, andso on. The potential of these nanofibers can be extended but not limited to smart clothing, tissueengineering, energy harvesting, energy storage, communication, safe data storage, etc. and it isanticipated that in the near future, luminescent nanofibers will find many more applications in diversescientific disciplines.

more » « less
Award ID(s):
1436120 1626376
Author(s) / Creator(s):
Date Published:
Journal Name:
Current Nanoscience
Page Range / eLocation ID:
321 to 362
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Fabrication of highly stable, reversible, and efficient portable sensors for the detection of explosives for safety and security is challenging due to the robustness of the currently available detection tools, limiting their mass deployment to the explosion prone areas. This paper reports a new direction towards the sensing of nitro- and peroxide-based explosives using highly stable rare-earth-doped BaWO 4 nanofibers with remarkable sensitivity and reversibility. BaWO 4 nanofibers doped with Tb 3+ and Eu 3+ ions are fabricated through a sol–gel electrospinning process, and their emission characteristics and application as a fluorescent probe for the sensing of 2-nitrotoluene and H 2 O 2 , explosive taggants representing a broad class of explosives, are studied in detail. Scheelite structured BaWO 4 nanofibers exhibit excellent luminescence characteristics, and the rare-earth ion doping in the polycrystalline BaWO 4 nanofibers is tailored to achieve blue, green, red, and white light emissions. These nanofibers are extremely sensitive to 2-nitrotoluene and H 2 O 2 with rapid response time, and sensitivity is observed within the range of 1–400 ppb and 1–10 ppm, towards 2-nitrotoluene and H 2 O 2 , respectively. The fluorescence quenching of BaWO 4 nanofibers in the presence of 2-nitrotoluene and H 2 O 2 is exponential with the quenching constants up to 1.73 × 10 6 and 2.73 × 10 4 L mol −1 , respectively, which are significantly higher than those of most of the fluorescent probes based on metal–organic frameworks and conjugated organic materials. After exposing to 2-nitrotoluene, the luminescence of the nanofibers is retained completely upon heating at 120 °C for 10 min and the sensory response is retained as fresh nanofibers, and currently available fluorescent explosive sensors could not achieve such a recovery. The high sensitivity and selectivity of scalable rare-earth-doped BaWO 4 nanofibers provide a new platform for the simultaneous detection of two classes of explosives. 
    more » « less
  2. Inherently conductive polymers (CPs) can generally be switched between two or more stable oxidation states, giving rise to changes in properties including conductivity, color, and volume. The ability to prepare CP nanofibers could lead to applications including water purification, sensors, separations, nerve regeneration, wound healing, wearable electronic devices, and flexible energy storage. Electrospinning is a relatively inexpensive, simple process that is used to produce polymer nanofibers from solution. The nanofibers have many desirable qualities including high surface area per unit mass, high porosity, and low weight. Unfortunately, the low molecular weight and rigid rod nature of most CPs cannot yield enough chain entanglement for electrospinning, instead yielding polymer nanoparticles via an electrospraying process. Common workarounds include co-extruding with an insulating carrier polymer, coaxial electrospinning, and coating insulating electrospun polymer nanofibers with CPs. This review explores the benefits and drawbacks of these methods, as well as the use of these materials in sensing, biomedical, electronic, separation, purification, and energy conversion and storage applications. 
    more » « less
  3. Abstract

    The field of nanotechnology has been gaining great success due to its potential in developing new generations of nanoscale materials with unprecedented properties and enhanced biological responses. This is particularly exciting using nanofibers, as their mechanical and topographic characteristics can approach those found in naturally occurring biological materials. Electrospinning is a key technique to manufacture ultrafine fibers and fiber meshes with multifunctional features, such as piezoelectricity, to be available on a smaller length scale, thus comparable to subcellular scale, which makes their use increasingly appealing for biomedical applications. These include biocompatible fiber‐based devices as smart scaffolds, biosensors, energy harvesters, and nanogenerators for the human body. This paper provides a comprehensive review of current studies focused on the fabrication of ultrafine polymeric and ceramic piezoelectric fibers specifically designed for, or with the potential to be translated toward, biomedical applications. It provides an applicative and technical overview of the biocompatible piezoelectric fibers, with actual and potential applications, an understanding of the electrospinning process, and the properties of nanostructured fibrous materials, including the available modeling approaches. Ultimately, this review aims at enabling a future vision on the impact of these nanomaterials as stimuli‐responsive devices in the human body.

    more » « less
  4. Fluorides are promising host materials for optical applications. This paper reports the photoluminescent (PL) and cathodoluminescent (CL) characteristics of barium hexafluorogermanate BaGeF 6 nanowires codoped with Ce 3+ , Tb 3+ and Sm 3+ rare earth ions, produced by a solvothermal route. The synthesized BaGeF 6 nanowires exhibit uniform morphology and size distribution. X-ray diffraction divulges the one-dimensional growth of crystalline BaGeF 6 structure, with the absence of any impurity phases. Visible luminescence is recorded from the nanowires in green and red regions, when the nanowires are codoped with Ce 3+ /Tb 3+ , and Ce 3+ /Tb 3+ /Sm 3+ , respectively, under a UV excitation source. The PL emission from the codoped BaGeF 6 nanowires, when excited by a 254 nm source, originates from the efficient energy transfer bridges between Ce 3+ , Tb 3+ and Sm 3+ ions. The decay time of the visible luminescent emission from the nanowires is in the order of subnanoseconds, being one of the shortest decay time records from inorganic scintillators. The CL emission from the BaGeF 6 nanowires in the tunable visible range reveals their potential use for the detection of high-energy radiation. The PL emissions are sensitive to H 2 O 2 at low concentrations, enabling their high-sensitivity detection of H 2 O 2 using BaGeF 6 nanowires. A comparison with BaSiF 6 nanowires is made in terms of decay time and its sensitivity towards H 2 O 2 . 
    more » « less
  5. Abstract

    Upconversion nanoparticles (UCNPs) convert low‐energy infrared (IR) or near‐infrared (NIR) photons into high‐energy emission radiation ranging from ultraviolet to visible through a photon upconversion process. In comparison to conventional fluorophores, such as organic dyes or semiconductor quantum dots, lanthanide‐ion‐doped UCNPs exhibit high photostability, no photoblinking, no photobleaching, low cytotoxicity, sharp emission lines, and long luminescent lifetimes. Additionally, the use of IR or NIR for excitation in such UCNPs reduces the autofluorescence background and enables deeper penetration into biological samples due to reduced light scattering with negligible damage to the samples. Because of these attributes, UCNPs have found numerous potential applications in biological and medicinal fields as novel fluorescent materials. Different upconversion mechanisms commonly observed in UCNPs, various methods that are used in their synthesis, and surface modification processes are discussed. Recent applications of Ln‐UCNPs in the biological and medicinal fields, including in vivo and in vitro biological imaging, multimodal imaging, photodynamic therapy, drug delivery, and antibacterial activity, are also presented.

    more » « less