The first use of electrospun nanofibrous membranes as highly responsive fluorescence quenching-based optical sensors for metal ions (Fe3+ and Hg2+) and 2,4-dinitrotoluene (DNT) is reported. A fluorescent polymer, poly(acrylic acid)−poly(pyrene methanol) (PAA−PM), was used as a sensing material. Optical chemical sensors were fabricated by electrospinning PAA−PM and thermally cross-linkable polyurethane latex mixture solutions. These sensors showed high sensitivities due to the high surface area-to-volume ratio of the nanofibrous membrane structures.

We report a new fabrication approach to highly sensitive optical sensors by combining the techniques of electrospinning and electrostatic layer-by-layer adsorption. A fluorescent probe, hydrolyzed poly[2-(3-thienyl) ethanol butoxy carbonyl-methyl urethane] (H-PURET), was electrostatically assembled onto the surface of cellulose acetate (CA) electrospun nanofibrous membranes. The fluorescence of these membranes can be quenched by extremely low concentrations (ppb) of methyl viologen (MV 2+) and cytochrome c (cyt c) in aqueous solutions. This high sensitivity is attributed to the high surface-area-to-volume ratio of the electrospun membranes and efficient interaction between the fluorescent conjugated polymer and the analytes.

We report the fabrication of novel metal oxide-coated polymeric nanofibers using the electrospinning technique. Polyacrylonitrile fibers were electrospun into a nonwoven fiber membrane. The membranes were subsequently immersed in an aqueous solution of metal halide salts and halogen scavengers at room temperature to apply the metal oxide coating. Tin dioxide and titanium dioxide were both successfully coated by this method. Coated fibers were characterized by scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Glass slides were coated with metal oxides by the same technique and were analyzed by X-ray photoelectron spectroscopy to determine the metal oxide surface composition. Fiber diameters were on the order of 100 nm, and the observed coating thickness ranged from about 20 to 80 nm.

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