“Novel Dextrin‐Cysteine Schiff Base: A Highly Efficient Sensor for Mercury Ions in Aqueous Environment”

Abstract

We report a highly sensitive electrochemical and fluorescence sensor for the detection of toxic environmental pollutant Hg2+ ions by using a novel dextrin‐cysteine‐Schiff base (DCS). The sensor is developed by the periodate oxidation of dextrin followed by Schiff base formation with an amino acid, cysteine. The new characterized DCS is used as an efficient and selective sensor for the detection of Hg2+ ions in aqueous solution both by electrochemical and fluorescence quenching process. The detection limit (LOD) by the electrochemical method is 0.74 nM which is much lower than that by the fluorometric detection, where LOD value is found to be 40.93 μM. The Schiff base/glassy carbon electrode (DCS/GCE) shows an excellent selectivity towards Hg2+ ions compare to other environmentally relevant ions where almost nil current response is observed. The DCS/GCE also exhibits remarkable sensing of Hg2+ in real water samples such as river and tap water. The electrochemical sensing of Hg2+ by DCS is found to be superior to that of fluorescence sensing.

Highly selective and sensitive electrochemical sensing of trace Zn2+ ions, by grafted Tricholoma mushroom polysaccharide/Ag composite nanoparticles in aqueous medium

“…[ 32 ] Also, the peak appear at the position 0.5 and 0.4 (Figure 5) show the presence of oxygen and nitrogen with weight % 27.65 and 12.65, respectively, suggesting the composite Ag NPs contain Ag, C, N and O element. [ 33 ] The existence of C, N, O in the EDAX spectrum indicates that the Ag NPs formed inside the polymer matrix.…”

Materials Approaches for Improving Electrochemical Sensor Performance

“…The resulting sensor benefitted from the selectivity of the Schiff base, coordinating with mercury­(II) ions over interfering metal ions and demonstrated an impressive detection range from 93.30 nM to 3.98 mM . Another study marked the first use of a dextrin-cysteine Schiff base (DCS) for electrochemical and fluorescent detection of mercury­(II), exhibiting an electrochemical limit of detection of less than 1 nM . Capable of detecting more than just ions, sometimes Schiff bases are used to fabricate metal complexes on electrodes, such as nickel or cobalt Schiff base complexes, in order to sense molecular analytes.…”

A novel selective “turn-on’’ fluorescent sensor for Hg2+ and its utility for spectrofluorimetric analysis of real samples

“…Besides, -C=C-, -OH and -C=O stretching of the aldehyde functional groups of salicylaldehyde were observed at 1555 cm -1 , 3142 cm -1, and 1662 cm -1 , respectively. As can be seen from FT-IR spectra of FS, stretching vibrations of -C=C-, -CH=N, -C-H, -ArH and -OH were observed at 1575 cm -1 , 1634 cm -1 , 2917-2867 cm -1 , 3061-3050 cm -1 and 3271 cm -1 , respectively (13,29). Importantly, -C=O stretching of salicylaldehyde (1662 cm -1 ) and -NH2 stretching of 9,10bis(aminomethyl)anthracene (3256-3167 cm -1 ) were disappeared after the formation of FS which were important evidence for the proposed structure of FS.…”

“…As seen in this figure, the effect of different competitive ions on relative fluorescent signal change of 10 µM FS in DMSO:water (pH 8.0, 1:1 v/v) were insignificant when compared with response of Hg 2+ ion that clearly showed selectivity of FS against to Hg 2+ . The pH of analysis medium for fluorescent sensors which were designed for detection or determination of metal ions was important parameter, therefore, the effect of pH on relative fluorescent signal change of 10 µM FS in DMSO: water (1:1 v/v) with the addition of Hg 2+ was investigated between pH 4 and 11 (29,33) when other conditions kept steady. For that purpose, pH of 10 µM FS in DMSO: water (1:1 v/v) was adjusted by Britton-Robinson buffer (Figure 5a).…”

“…In Figure2b, the fluorescent sensor FS showed a very weak fluorescent signal at ~420 nm when excited at 360 nm. It is a well-known phenomenon for Schiff base due to photoinduced electron transfer (PET) process from Schiff base to fluorophore group of sensor (7,23,27,29).…”