Core-shell nanoparticles optical sensors - Rational design of zinc ions fluorescent nanoprobes of improved analytical performance

• Published in: Optical materials 2017-10, Vol.72, p.214-219
• Main Authors: Woźnica, Emilia, Gasik, Joanna, Kłucińska, Katarzyna, Kisiel, Anna, Maksymiuk, Krzysztof, Michalska, Agata
• Format: Article
• Language: English
• Subjects: Core-shell fluorescent nanospheres; Surface limited reaction zone; Zinc ions emission sensors
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2017.05.059

In this work the effect of affinity of an analyte to a receptor on the response of nanostructural fluorimetric probes is discussed. Core-shell nanoparticles sensors are prepared that benefit from the properties of the phases involved leading to improved analytical performance. The optical transduction system chosen is independent of pH, thus the change of sample pH can be used to control the analyte - receptor affinity through the “conditional” binding constant prevailing within the lipophilic phase. It is shown that by affecting the “conditional” binding constant the performance of the sensor can be fine-tuned. As expected, increase in “conditional” affinity of the ligand embedded in the lipophilic phase to the analyte results in higher sensitivity over narrow concentration range – bulk reaction and sigmoidal shape response of emission intensity vs. logarithm of concentration changes. To induce a linear dependence of emission intensity vs. logarithm of analyte concentration covering a broad concentration range, a spatial confinement of the reaction zone is proposed, and application of core-shell nanostructures. The core material, polypyrrole nanospheres, is effectively not permeable for the analyte - ligand complex, thus the reaction is limited to the outer shell layer of the polymer prepared from poly(maleic anhydride-alt-1-octadecene). For herein introduced system a linear dependence of emission intensity vs. logarithm of Zn2+ concentration was obtained within the range from 10−7 to 10−1 M. Schematic representation of a) polymeric nanosphere and b) core-shell nanospheres with polypyrrole nanoparticles core and PMAO shell - the confined reaction zone nanoprobes. [Display omitted] •Tailoring of sensitivity and linear response range of optical nanoprobes due to confinement of the reaction zone.•Core-shell nanostructures prepared with conducting polymer core and a lipophilic polymeric shell.•The reaction leading to optical signal formation is limited to the outer layer.•This results in linear dependence of emission intensity vs. logarithm of analyte concentration.