Fabrication of a Paper‐Based Turn‐Off Fluorescence Sensor for Cu²⁺Ion from a Pyridinium Porphyrin

Abstract

A cationic porphyrin, 5,10,15,20‐tetrakis(1‐methyl‐4‐pyridinio)porphyrin tetraiodide (TMPyP) was reported herein to exert selective, turn‐off fluorescence when complexed with Cu2+ ion. Although discernible spectroscopic changes of charged porphyrins with various metal ions were previously utilized as colorimetric sensors, the application of fluorescence quenching of charged porphyrins with Cu2+ ion has never been investigated in much detail before. Coupled with the ease of synthesis, the finding led to a construction of a simple paper‐based sensor for Cu2+ with good selectivity and sensitivity, with a limit of detection at 0.16 ppm, which is below the recommended amount in drinking water. Notably, this performance could be achieved with the need of only a handheld UV lamp and a smartphone or a compact camera, both of which are now considered to be highly accessible. Thanks to the simplicity of all involved processes, this study highlights a unique way in creating a new practical and economical sensor for Cu2+ ion.

Recent Advances in Porphyrin-Based Materials for Metal Ions Detection

“…Therefore, suitable materials can be tailored for each specific application on the basis of their diversity and mechanistic knowledge. Moreover, with an increase in the demand for fast and convenient detection methods in modern society, and under the inspiration of Prabphal et al [ 71 ], people can design more real-time, fast, and convenient porphyrin sensors by combining with electronic technology and mobile devices.…”

“…With the help of imaging systems of micro-devices, such as mobile phones, color changes can be identified more finely. Since porphyrin is a colored compound, the colorimetric detection of metal ions can be achieved through cooperation with metal ions [ 71 , 72 , 73 ].…”

Using Recycled Bacterial Culture Media to Demonstrate Anti-Counterfeiting Measures and Ninhydrin Tests with “Turn Off Fluorescence” to High School Students

“…The instructor can explain to students that ninhydrin is selective and sensitive to α-amino acids; in the same way, turn “off” fluorescence based sensors are sensitive and selective to specific reagents. Many researchers have developed turn “off” fluorescence based paper sensors for the detection of a heavy metal such as copper, mercury, etc. − This will help students to learn and understand how turn “off” fluorescence based sensor works.…”

“…Due to this reaction between ninhydrin and media, the UV fluorescence of media gets shielded. When any material shields the fluorescence of another material because of physical, chemical, or biological interactions between them, this is known as turn “off” fluorescence. − When it is selective to a specific material only and sensitive even at a very low concentration, it is used as a sensor for various applications. When such compounds are immobilized on a paper substrate, this is called a paper sensor. − …”

N-Confused Porphyrin Immobilized on Solid Supports: Synthesis and Metal Ions Sensing Efficacy

“…Porphyrins and analogues, well known by their impressive applications in several areas such as catalysis [ 25 , 26 , 27 , 28 ], photocatalysis [ 29 , 30 ] electronic materials [ 31 , 32 , 33 ], supramolecular chemistry [ 34 , 35 ], biomimetic models [ 36 , 37 ] , and medicine [ 25 , 38 , 39 , 40 , 41 , 42 , 43 ], are also often used as sensor probes due to their unique photophysical and photochemical properties [ 25 , 35 , 44 , 45 , 46 ]. In fact, porphyrins as free-bases or as metallo complexes have been used to create the so-called artificial noses and tongues for gas, cations, anions, and neutral species detection [ 47 ].…”