There is great need for stand-alone luminescence-based chemosensors that exemplify selectivity, sensitivity, and applicability and that overcome the challenges that arise from complex, real-world media. Discussed herein are recent developments toward these goals in the field of supramolecular luminescent chemosensors, including macrocycles, polymers, and nanomaterials. Specific focus is placed on the development of new macrocycle hosts since 2010, coupled with considerations of the underlying principles of supramolecular chemistry as well as analytes of interest and common luminophores. State-of-the-art developments in the fields of polymer and nanomaterial sensors are also examined, and some remaining unsolved challenges in the area of chemosensors are discussed. CONTENTS 4.4. Explosives 4.5. Pharmaceutical Agents 4.6. Biologically Relevant 4.6.1. Adenosine Triphosphate (ATP)
High concentrations of certain nutrients, including phosphate, are known to lead to undesired algal growth and low dissolved oxygen levels, creating deadly conditions for organisms in marine ecosystems. The rapid and robust detection of these nutrients using a colorimetric, paper-based system that can be applied on-site is of high interest to individuals monitoring marine environments and others affected by marine ecosystem health. Several techniques for detecting phosphate have been reported previously, yet these techniques often suffer from high detection limits, reagent instability, and the need of the user to handle toxic reagents. In order to develop improved phosphate detection methods, the commonly used molybdenum blue reagents were incorporated into a paper-based, colorimetric detection system. This system benefited from improved stabilization of the molybdenum blue reagent as well as minimal user contact with toxic reagents. The colorimetric readout from the paper-based devices was analyzed and quantified using RGB analyses (via ImageJ), and resulted in the detection of phosphate at detection limits between 1.3 and 2.8 ppm in various aqueous media, including real seawater.
Reported herein is the immobilization of N-(1naphthyl)ethylenediamine (NED) on cellulose via an epichlorohydrin (ECH)-based covalent attachment and the implementation of the functionalized cellulose into an ultrasensitive, paper-based device for nitrite detection. The reported functionalization procedure resulted in a 12.9-fold higher functionalization density than the density that results from the previously reported procedures, and the subsequent device allows for nitrite detection limits in synthetic freshwater and real seawater of 0.26 and 0.22 μM, respectively. The sensor is efficient in a wide range of temperature, humidity, turbidity, and salinity conditions and has been successfully applied for nitrite detection in real water samples.
Herein we report a robust and easy method for detecting cesium metal ion (Cs + ) in partially aqueous solutions using the fluorescence quenching of 2,4-bis[4-(N,N-dihydroxyethylamino)phenyl]squaraine. This squaraine dye was found to be both highly sensitive (low limits of detection) and selective (limited response to other metals) for cesium ion detection. The detection is likely based on the metal complexing to the dihydroxyethanolamine moieties, which disrupts the donor-acceptor-donor architecture and leads to efficient quenching.
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