Environmentally Friendly Ag+ Detection of “Turn-on” Fluorescent Sensor with a Mega-Stokes Shift and Its Application in Biological Systems

Abstract

A "turn on" fluorescent sensor based on 2- [4-(2-aminoethylthio)butylthio]ethanamine ionophore and [5]helicene fluorophores, MC4 was developed for detection of Ag + . An aqueous ethanol solution, an environmental friendly condition, was chosen as a working condition. MC4 exhibited Ag + -induced fluorescent enhancement with a low detection limit of 32 ppb for Ag + . The detection limit of the sensor was below the permissible concentrations of Ag + for drinking water as regulated by the United States Environmental Protection Agency (U.S. EPA) and World Health Organization (WHO). Moreover, MC4 exhibited a strong fluorescent signal and expansive stokes shift of 213 nm. This very expansive stokes shift could reduce interferences from self-absorption and auto-fluorescence. The sensor also provided highly selective recognition of Ag + , distinguishing it from other competing ions through the photoinduced electron transfer (PET). Importantly, this sensor is able to track Ag + in HepG2 cells, indicating that it shows good potential for practical applications.

Synthesis and Spectrophotometric Studies of 9‐Substituted‐4,5‐dimethoxyacridine Multifunctionalizable Fluorescent Dyes and Their Macrocyclic Derivatives

“…A study on 4,5‐dimethoxyacridone ( 12 ) indicated that methoxy groups reduced quantum yield compared to the unsubstituted acridone ( 2 ) (0.410→0.100). All of the fluorescent compounds showed extremely large Stokes ‐shifts compared to the reported dyes [46–54] . This advantageous photophysical property can reduce interferences from self‐absorption and auto‐fluorescence, thus provides outstanding sensitivity and resolution for optochemical devices.…”

“…All of the fluorescent compounds showed extremely large Stokes-shifts compared to the reported dyes. [46][47][48][49][50][51][52][53][54] This advantageous photophysical property can reduce interferences from self-absorption and autofluorescence, thus provides outstanding sensitivity and resolution for optochemical devices. Compounds with large Stokesshifts, especially functionalizable-group-containing derivatives, which are reported herein, can have great importance for practical applications and are in the focus of very recent research activities.…”

“…Compounds with large Stokesshifts, especially functionalizable-group-containing derivatives, which are reported herein, can have great importance for practical applications and are in the focus of very recent research activities. [46][47][48][49][50][51][52][53][54] Although studies on photophysical behavior of the new fluorescent precursors were carried out primarily from the aspect of the nature of the substituent at position 9 of acridine, it should be noted that fluorescence properties of acridine dyes strongly depend on the polarity of the medium as well as on the hydrogen-bonding ability of the solvent (they generally have weak fluorescence in apolar solvents and strong fluorescence in protic solvents). [45,55,56] Moreover, the protonated forms of these weak bases usually have spectral features quite different than those of the corresponding neutral forms.…”

Beyond “Mega”: Origin of the “Giga” Stokes Shift for Triazolopyridiniums

“…Compared to “mega” Stokes shift fluorophores, , a much smaller set of molecules have Stokes shifts greater than 10,000 cm –1 , − for whom we suggest the designation “giga” Stokes shift. In the past, “mega” Stokes shift fluorophores have been utilized for imaging, ,− thermometry, , sensing, − and organic light-emitting diode (OLED) applications. Several of these applications rely upon the minimal self-absorption of “mega” Stokes shift fluorophores, which is expected to be further minimized for “giga” Stokes shift fluorophores.…”