Browsing by Keyword "Nanofibers"
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Item Enhanced photostability and sensing performance of graphene quantum dots encapsulated in electrospun polyacrylonitrile nanofibrous filtering membranes(2018-06-01) Ruiz, Virginia; Pérez-Marquez, Ana; Maudes, Jon; Grande, Hans-Jürgen; Murillo, Nieves; Tecnalia Research & Innovation; PRINTEXWe report a method to encapsulate graphene quantum dots (GQD) in polyacrylonitrile (PAN) nanofibrous membranes to manufacture robust filtering membranes by electrospinning. GQD-PAN membranes with different nanofiber diameter were prepared tuning the electrospinning parameters, all exhibiting the characteristic fluorescence fingerprint of the GQD probes. The photoluminescence (PL) stability of GQD embedded in the PAN fibers was significantly enhanced with respect to that of water dispersed GQD luminescent probes. The PL of GQD-PAN filtering membranes showed remarkable time stability, both stored dry and immersed in phosphate buffer solutions (PBS), as well as exposed to continuous light irradiation. However, the PL intensity of GQD-PAN membranes was irreversibly quenched by highly oxidant free chlorine solutions. Thus, electrospun GQD-PAN membranes exhibited excellent performance as turn-off fluorescence sensing platforms for free chlorine detection in PBS 0.1 M pH 7. The analytical performance of GQD-PAN membranes was comparable to that of GQD solutions with optimal concentrations, displaying a fast (no need of incubation time) and linear response to chlorine concentration in the 10–600 μM range, a low detection limit of 2 μM, high sensitivity, reproducibility and selectivity. Moreover, the sensing performance of the membranes was very stable after being immersed in PBS for months, outperforming the stability of GQD solutions.Item Label-free optical biosensing using low-cost electrospun polymeric nanofibers(2020-11-26) Martínez-Pérez, Paula; Ponce-Alcántara, Salvador; Murillo, Nieves; Pérez-Márquez, Ana; Maudes, Jon; Peraile, Inés; González-López, Laura; Gil-García, Matilde; Lorenzo-Lozano, Paloma; García-Rupérez, Jaime; Tecnalia Research & Innovation; PRINTEXPolymeric nanofiber matrices are promising structures to develop biosensing devices due to their easy and affordable large-scale fabrication and their high surface-to-volume ratio. In this work, the suitability of a polyamide 6 nanofiber matrix for the development of a label-free and real-time Fabry–Pérot cavity-based optical biosensor was studied. For such aim, in-flow biofunctionalization of nanofibers with antibodies, bound through a protein A/G layer, and specific biodetection of 10 µg/mL bovine serum albumin (BSA) were carried out. Both processes were successfully monitored via reflectivity measurements in real-time without labels and their reproducibility was demonstrated when different polymeric nanofiber matrices from the same electrospinning batch were employed as transducers. These results demonstrate not only the suitability of correctly biofunctionalized polyamide 6 nanofiber matrices to be employed for real-time and label-free specific biodetection purposes, but also the potential of electrospinning technique to create affordable and easy-to-fabricate at large scale optical transducers with a reproducible performance.Item Optical sensors based on polymeric nanofibers layers created by electrospinning(2018) Ponce-Alcántara, S.; Martín-Sánchez, D.; Pérez-Márquez, A.; Maudes, J.; Murillo, N.; García-Rupérez, J.; PRINTEX; Tecnalia Research & InnovationPorous materials have become ideal candidates for the creation of optical sensors that are able to reach extremely high sensitivities, due to both the possibility to infiltrate the target substances on them and to their large surface-to-volume ratio. In this work, we present a new alternative for the creation of porous optical sensors based on the use of polymeric nanofibers (NFs) layers fabricated by electrospinning. Polyamide 6 (PA6) NFs layers with average diameters lower than 30 nm and high porosities have been used for the creation of Fabry-Pérot optical sensing structures, which have shown an experimental sensitivity up to 1060 nm/RIU (refractive index unit). This high sensitivity, together with the low production cost and the possibility to be manufactured over large areas, make NFs-based structures a very promising candidate for the development of low-cost and high performance optical sensors.Item PS/PMMA-CdSe/ZnS Quantum Dots Hybrid Nanofibers for VOCs Sensors(2018-12) De San Luis, Alicia; Aguirreurreta, Ziortza; Pardo, Leticia M.; Perez-Marquez, Ana; Maudes, Jon; Murillo, Nieves; Paulis, María; Leiza, Jose Ramon; Tecnalia Research & Innovation; PRINTEXHybrid nanofibers containing CdSe/ZnS quantum dots have been produced by electrospinning of hybrid latexes to characterize the electro‐optical behavior of this novel luminescent sensing material. The latexes are synthesized by seeded semi‐batch emulsion polymerization yielding cross‐linked core‐shell PS/QDs/PMMA particles with efficiently encapsulated quantum dots guaranteeing a good optical stability. Addition of polyvinyl alcohol (PVA) or polyethylene oxide (PEO) to the latexes is necessary to produce polymeric dispersions suitable for electrospinning manufacture of the nanometric fibers. The optimized polymeric dispersions are successfully electrospun obtaining fluorescent nanofibers in both cases. The hybrid nanofibers are sensitive to selected solvents (acetone, methanol and THF) and present positive response making them good candidates for the production of VOC sensors.