A Novel Fluorescent Probe for the Detection of Cyanide Ions in Solutions and Studies on Its Biophysical Interactions with ctDNA and Proteases

Abstract

A new cationic indolium based styryl dye as a fluorescent probe, (E)-2-(4-(dibutylamino)styryl)-1,3,3trimethyl-3H-indol-1-ium iodide (Ci), was synthesized and its anions selectivity/sensitivity properties /molecular interactions with protease enzymes (pepsin/trypsin) and ctDNA has been studied by spectroscopic and computational methods. The fluorescence measurements at different temperatures indicated that quenching mechanism of enzymes by Ci was static. H and S data pointed out electrostatic/hydrophobic interactions with pepsin, and also hydrogen bonds/van der Waals forces with trypsin of Ci. According to Förster's non-radiative energy transfer, binding distances (r) were calculated as 3.53/3.27 nm for pepsin/trypsin. It was also investigated that groove binding is effective in interaction with ctDNA. The results were supported with molecular docking analyzes which have same tendency. Ci has been demonstrated hypsochromic effect with a decrease in solvent polarity and it showed highly selective colorimetric and fluorometric sensing behavior for cyanide ions in organic solvent and aqueous solution. 1 H NMR titration was performed to examine the interaction mechanism between Ci and cyanide ions. The LOD values of cyanide ion were reported as 4.87x10 -9 M and 9.70x10 -7 M in DMSO and DMSO/H2O binary mixture, respectively. In addition, sensitivity of Ci as a chemosensor to cyanide ions was investigated in bitter almond samples.

A ferrocene-based chemo-dosimeter for colorimetric and electrochemical detection of cyanide and its estimation in cassava flour

“…The probe VDP2 has been synthesized easily by a single-step condensation reaction, as shown in Scheme 2. The probe was structurally characterized using 1 H & 13 C NMR and mass spectral techniques. The ion sensing behaviour of the probe was screened using electronic spectra and electrochemical methods in H 2 O-DMSO (9 : 1, v/v) medium.…”

“…In the free VDP2, the signal appeared at 8. The proposed nucleophilic addition mechanism was further explained by the 13 C NMR titration experiment (Fig. 9).…”

“…The reaction mechanism between VDP2 and CN − was delineated using 1 H and 13 C NMR titration experiments in DMSO-d 6 .…”

“…[6][7][8] Among the probes reported so far, reaction-based ones (chemodosimeters) take advantage of the distinctive nucleophilicity of cyanide ions and are more favourable than H-bonding and metal displacement approaches, as the chemical reaction leads to a permanent signal output exhibiting very high selectivity. [9][10][11][12][13][14][15][16][17] Hence, the present endeavour aims to develop a chemodosimeter VDP2 for the optical detection of cyanide ions in an aqueous solution. The probe was designed in such a way as to have a ferrocene moiety because of its extraordinary electrondonating properties, chemical stability, and well-documented electrochemical behaviour.…”

A reaction based carbazole–indolium conjugate probe for the selective detection of environmentally toxic ions

“…The subsequent ndings indicate that the mechanism of detecting cyanide ions by the probe is a nucleophilic addition to the indolium moiety's carbon atom (electron decient) of the probe molecule. 46 Real-time applications…”