Novel Multifunctional Luminescent Electrospun Fluorescent Nanofiber Chemosensor-Filters and Their Versatile Sensing of pH, Temperature, and Metal Ions

Abstract

Novel multifunctional fluorescent chemosensors composed of electrospun (ES) nanofibers with high sensitivity toward pH, mercury ions (Hg2+), and temperature were prepared from poly(N-Isopropylacrylamide-co-N-methylolacrylamide-co-rhodamine derivative) (poly(NIPAAm-co-NMA-co-RhBN2AM)) by employing an electrospinning process. NIPAAm and NMA moieties provide hydrophilic and thermo-responsive properties (absorption of Hg2+ in aqueous solutions), and chemical cross-linking sites (stabilization of the fibrous structure in aqueous solutions), respectively. The fluorescent probe, RhBN2AM is highly sensitive toward pH and Hg2+. The synthesis of poly(NIPAAm-co-NMA-co-RhBN2AM) with different compositions was carried on via free-radical polymerization. ES nanofibers prepared from sensory copolymers with a 71.1:28.4:0.5 NIPAAm:NMA:RhBN2AM ratio (P3 ES nanofibers) exhibited significant color change from non-fluorescent to red fluorescence while sensing pH (the λPL, max exhibited a 4.8-fold enhancement) or Hg2+ (at a constant Hg2+ concentration (10−3 M), the λPL, max of P3-fibers exhibited 4.7-fold enhancement), and high reversibility of on/off switchable fluorescence emission at least five times when Hg2+ and ethylenediaminetetraacetic acid (EDTA) were sequentially added. The P3 ES nanofibrous membranes had a higher surface-to-volume ratio to enhance their performance than did the corresponding thin films. In addition, the fluorescence emission of P3 ES nanofibrous membranes exhibited second enhancement above the lower critical solution temperature. Thus, the ES nanofibrous membranes prepared from P3 with on/off switchable capacity and thermo-responsive characteristics can be used as a multifunctional sensory device for specific heavy transition metal (HTM) in aqueous solutions.

The Relationships between the Working Fluids, Process Characteristics and Products from the Modified Coaxial Electrospinning of Zein

“…This is particularly challenging when the final products are nanoparticles or nanofibers [4,5,6,7,8,9]. Both of them can be generated by electrohydrodynamic atomization (EHDA) using electrostatic energy [10,11,12,13,14,15,16], and while there are numerous reports of such fabrication processes, it remains the case that it is extremely difficult to predict the outcome of a given experiment.…”

Electrospun Polycaprolactone Nanofibers as a Reaction Membrane for Lateral Flow Assay

“…The method has been advancing towards large-scale manufacture, production of organized structures through different strategies such as multiple-jet nozzle electrospinning [8] and needleless electrospinning [9], which have been employed to generate complex structure for biomedical functionalities, drug delivery systems and advanced composite nanofibers with fillers for biomimetic scaffolds [10,11,12,13,14,15]. Electrospun nanofibrous materials feature high surface-area-to-volume ratio, high porosity, interconnected porous network, and flexible functionality; characteristics that have been widely utilized in biomedical applications [16,17,18,19]. Despite having these favorable features, only a few studies have applied electrospun nanofibers in LFA.…”

Electrospun Environment Remediation Nanofibers Using Unspinnable Liquids as the Sheath Fluids: A Review

“…What is more, when solvents are explored as the sheath working fluids, modified coaxial electrospinning can be utilized to stabilize the working process [32], keep the working processes from clogging, manipulate the nanofibers' diameter without the additions of salt or other additives, and systematically improve the nanofibers' quality. In the traditional blending electrospinning, the working process is regulated by a series of variables, including the properties of the solution, experimental parameters and surrounding conditions [33][34][35][36][37][38][39]. The properties of solution further include the viscosity, conductivity, surface tension, molecular weight of polymer and dielectric constant; the operational variables include flow rate, electric field force, distance between needle and receiving screen, diameter and shape of needle, material composition and surface morphology of receiving screen, and so on; the surrounding parameters include temperature, humidity, wind speed, and maybe the vacuum state.…”