Development of Fluorescent Film Sensors for the Detection of Divalent Copper

Abstract

Monolayers of several peptide lipids at air-water and air-solid interfaces were prepared using Langmuir and Langmuir-Blodgett (LB) film techniques, and tested as fluorescent sensors for copper ions in aqueous phase. In one method, both the ionophore and the fluorophore were in the same molecule (lipid A), so intramolecular interaction was responsible for the fluorescence quenching of monolayers of this lipid. In the other method, ionophore and fluorophore were located on two different molecules (lipids B and C) so the intramolecular coupling does not exist; instead the fluorescence quenching was realized by a through-space interaction mechanism. Several experimental techniques, including pi-A isotherm, epifluorescence microscopy, and absorption and emission spectroscopies were used to study the different characteristics of copper ion effect on the properties of the lipid monolayers. Additionally, the fluorescence quenching properties of the Langmuir monolayers were found to be transferred to the one-layer LB films. On LB films, the fluorescence response presented a clear selectivity for copper ions in comparison with several other transition metal ions. Further, an excellent reversibility was observed: the fluorescence was switched OFF by immersing the solid substrate in copper ion solution and ON by washing with HCl solution. The intermolecular approach used here seems to be a very flexible and general method to design surface-oriented fluorescent sensors to meet different analytic purposes.

Assembly of π‐Conjugated Nanosystems for Electronic Sensing Devices

“…[24] Such assembly strategy has very extensive application value and great exploitation foreground in sensing field. [33,34] Another interesting approach to assemble π-conjugated compounds is organic gel method. Generally, gel materials are kinds www.advelectronicmat.de of solid-like structure on the rheological mechanics but liquid on the microscopic, which have quite interesting properties.…”

BODIPY-Based Ratiometric Fluoroionophores with Bidirectional Spectral Shifts for the Selective Recognition of Heavy Metal Ions

“…Cu 2+ showed a fluorescence quenching effect on BDP-DPA, which has often been found for other metal-ion fluoroionophores due to energy/ electron transfer (e.g., paramagnetic Cu 2+ ). 10,11,17,22,25,26,31,36 The response of BDP-DPA to variations in pH was investigated ( Figure S2). The fluorescence bands around 591 nm originating from BDP-DPA were stable at pH 5.0, 7.0, and 9.0.…”

Design of Fluorescent Materials for Chemical Sensing

“…they are covalently immobilized at a surface or form surfactant aggregates. A number of materials such as silica particles, 43 glass and gold surfaces, 44 quantum dots, 45 Langmuir-Blodgett films, 46 vesicles, 47 liposomes, 48 and others 49 are used combined with many chemical receptors to create sensitive fluorescent materials.…”

“…46 This system was based on lipophilic peptides as selective receptors for the metal ion and lipophilic dansyl derivatives. They compared the systems that have receptor and fluorophore covalently bound to the same lipid (5, Fig.…”