Pyrene-Based Fluorescent Probe for “Off-on-Off” Sequential Detection of Cu2+ and CN− with HeLa Cells Imaging

Abstract

The novel pyrene-appended Schiff base probe L with aggregation-induced emissions (AIE) relevant to an increase in water fractions (0–90%) is synthesized and applied in sequentially detecting Cu2+ and CN˗. The pyrene-based probe L firstly induces the excimer formation in the presence of Cu2+. However, the process can be reversed by sequentially adding CN˗, which is demonstrated using the fluorescence “Off-On-Off” response in semi-aqueous media ethanol water (v/v = 7/3) under physiological pH (5 mM HEPES, pH 7.0). The Job’s plot, mass analysis, 1H NMR titrations, and density functional theory (DFT) interrogations confirm the 2:1 stoichiometry of excimer complex L-Cu2+-L*, preferential binding atoms, and CN˗ tuned complex reversibility. Based on the photoluminescence (PL) titration, the association constant of L to Cu2+ is determined as 4.95 × 106 M−1. From standard deviation and linear fittings, the detection limits (LODs) of Cu2+ and CN˗ are estimated as 219 nM and 580 nM, respectively. The practicality of Cu2+ and CN˗ detection is demonstrated using a TLC plate and a blended polymer membrane through which significant color changes under a UV lamp can be monitored. Moreover, utility of the designed probe L towards biological application with low toxicity is demonstrated by detecting Cu2+ and CN˗ inside HeLa cells. The responses of the probe to Cu(II) ions were also verified using living HeLa cells imaging.

Detection of cyanide and sulfide ions by different mechanisms using a fluorescent chemical sensor containing a fluorophore and a potential ligand for metal complexes

“…On the other hand, the chemical displacement approach for the high affinity of Cu 2+ for CN − ions is preferred due to the formation of stable [Cu(CN) x ] 1− x species in the medium. 36–42 Unlike previous studies, in this study, CN − ions acted as additional ligands for the Cu 2+ complex, which can be utilized for detecting CN − ions in the media via enhanced fluorescence.…”

Cy5 Dye Cassettes Exhibit Through-Bond Energy Transfer and Enable Ratiometric Fluorescence Sensing

“…Deep-red cyanine dyes are known to self-aggregate in aqueous solution and form nonfluorescent aggregates. On the other hand, pyrene dyes can form excimers in self-aggregation conditions, − ,− and TPE is also well-known for aggregation induced enhancement (AIE). , To probe the change in fluorescent properties upon dye cassette self-aggregation, we acquired absorption (Figure a–d) and emission (Figures S2–S5) spectra for each dye in water/methanol mixtures. In the case of the relatively hydrophobic dyes, 1P or 1T , the transition from 100% methanol to 99.5% water induced minor spectral changes indicating little formation of dye self-aggregates.…”

“…The propensity of pyrene to form excimers with visible emission is often exploited for fluorescence sensing. − For example, the pyrene-based probe L is known to form an excimer complex ( L 2 ·Cu 2+ ) in the presence of Cu 2+ with “turn-on” fluorescence at 430 nm (Figure a) . By simply mixing “responsive” probe L with non-responsive cassette 2P , we achieved ratiometric sensing of Cu 2+ with a single excitation wavelength of 380 nm.…”

Highly selective and sensitive fluorescent “TURN-ON” furan-based Schiff base for zinc(ii) ion probing: chemical synthesis, DFT studies, and X-ray crystal structure

“…[31][32][33][34] Recently, numerous fluorescein-based cell permeable Zn 2+ sensor molecules have been disclosed. [35][36][37][38][39][40][41][42] The fluorescence approach is excellent for producing various sensor molecules by designing and synthesizing a reactive moiety that is connected to a certain type of metal ion sensor. [43][44][45][46] The fact that the fluorescence quantum yield is low and favourable ensures that the analyte is mostly responsible for the observed fluorescence intensity if the sensor molecule is converted to the fluorescent form.…”