A cap-type Schiff base acting as a fluorescence sensor for zinc(ii) and a colorimetric sensor for iron(ii), copper(ii), and zinc(ii) in aqueous media

Abstract

A simple and low cost chemosensor is described. This sensor could simultaneously detect three biologically important metal ions through fluorogenic (Zn(2+)) and chromogenic (Fe(2+), Cu(2+), and Zn(2+)) methods in aqueous solution. The sensor could function as a "turn-on" fluorescence receptor only to Zn(2+) ions. In addition, the sensor could be successfully applied to the detection of intracellular Zn(2+). Meanwhile, the sensor displayed an obvious red color upon selective binding with Fe(2+). Therefore, the sensor could serve as a useful tool for the discrimination of Fe(2+) from Fe(3+) in aqueous media. Moreover, the sensor also showed color changes from yellow to colorless upon selective binding with Zn(2+) and Cu(2+), respectively. The detection limit of the sensor for Cu(2+) (1.5 μM) is far below the guidelines of the World Health Organization (30 μM) as the maximum allowable copper concentration in drinking water, and therefore it is capable of being a practical system for the monitoring of Cu(2+) concentrations in aqueous samples. These results provide a new approach for selectively recognizing the most important three trace elements in the human body simultaneously, for Zn(2+) by emission spectra and Fe(2+), Cu(2+), and Zn(2+) by the naked eye.

Addressing of multiple-metal ions on a single platform

“…Kim et al [71] investigated the excellent sensing capabilities of a Schiff base capped with a tripodal structure for better chelation of metal ions. The cap-type Schiff base 41 worked as a fluorogenic as well as chromogenic sensor for simultaneous detection of Zn 2+ , Fe 2+ and Cu 2+ ions in aqueous medium.…”

Mesoporous silica thin film mechanized with a DNAzyme-based molecular switch for electrochemical biosensing

“…After 10 min incubation under gently stirring, the electrode was washed with buffer and further dipped into a 100 μM AA solution. After 10 min incubation, the electrode was washed with double distilled and square wave voltammograms were recorded in 0.1 M KCl solution containing 5 mM K 3 [Fe(CN) 6 ]/K 4 [Fe(CN) 6 ] (1:1). The square wave voltammograms were recorded by applying a positive-going SWV potential scan (0.09-0.358 V) under the following conditions: step potential 5 mV, frequency 10 Hz, amplitude 20 mV, and scan rate 50 mV/s.…”

“…In this context, a special interest has been devoted to the development of sensor systems for copper. Several electrochemical, fluorescent, colorimetric and electrochemiluminescent sensors for copper have been designed [4][5][6][7][8][9]. Among these, excellent results have been reported for fluorescent biosensors based on specific Cu(II)-specific DNAzyme [10][11][12], but electroanalytical methods based on similar DNAzymes have not been described despite the high sensitivity, low cost, flexibility and miniaturization facility of electrochemical biosensors [13][14][15][16][17].…”

A colorimetric chemosensor for the sequential detection of copper(II) and cysteine

“…It is a functional compound of many proteins and enzymes [19,20]. However, abnormal levels of biological Cys can lead to several health problems.…”