A highly selective colorimetric and ratiometric fluorescent chemodosimeter for detection of fluoride ions based on 1,8-naphthalimide derivatives

Flow-based green ceramics microdevice with smartphone image colorimetric detection for free chlorine determination in drinking water

The residual free chlorine concentration is an important parameter to evaluate the potability of water and the efficiency of disinfection in the water treatment system. As a restricted range of residual free chlorine concentration at all points of the distribution network is needed to ensure efficiency and to avoid deleterious effects, fast and in situ quantification of this specie is important. This work deals with the development and validation of two procedures based on DPD (N,N-diethyl-p-phenylenediamine) and OT (ortho-tolidine, 3,3-dimethylbenzidine) for the determination of residual free chlorine in water by exploiting a flow-based microdevice built with Low Temperature Co-Fired Ceramic (LTCC) technology. The analytical signal was monitored by a smartphone camera through RGB values obtained by a free application (Color Grab®). Under optimized conditions, linear ranges within 0.6-2.5 mg/L and 0.1-2.3 mg/L were obtained for DPD and OT methods, with limits of detection and quantification of 0.023 and 0.077 mg/L (DPD) and 0.026 and 0.089 mg/L (OT). Precision expressed as RSD (2.0 mg/L free chlorine, n = 10), was 1.3 % and 0.7 %, respectively. Both procedures were successfully applied to the analysis of samples from a water treatment plant. The flow-based microdevice coupled to digital-image colorimetry is an innovative, sustainable, and cost-effective analytical tool for in-field chemical analysis.

Visual detection of fluoride ion based on ICT mechanism

A novel chemosensor (H₃NTS) has been designed for a fast and accurate detection of F^- in acetonitrile medium. The UV-Vis, ¹H, ¹³C NMR experiments and computational calculations demonstrate that H₃NTS probe offers a potential colorimetric sensor for discriminating F^- among other relevant anions. The detection limit is as low as 6 μM and a reversible colorimetric switch could be devised by sequential addition of F^-/Ca²⁺. The promising application of H₃NTS is also confirmed in real examples where the concentration of F^- is a critical parameter, e.g., commercial toothpaste, paper strip and gel form analysis of samples.

A 1,8-naphthalimide-based fluorescent probe for selective and sensitive detection of peroxynitrite and its applications in living cell imaging

An “off–on” fluorescent probe for sensitive and selective detection of peroxynitrite was synthesized and showed good photostability and low cytotoxicity.

A novel Ag⁺ cation sensor based on polyamidoamine dendrimer modified with 1,8-naphthalimide derivatives

In this study, 4-amino-1,8-naphthalimide-conjugated polyamidoamine dendrimer was synthesized and characterized and its potentiality as a cation sensor was investigated. 4-Amino-1,8-naphthalic anhydride reacted with polyamidoamine dendrimer and the product was characterized using FTIR, (1)H NMR, (13)C NMR and melting point analysis method. The synthesized compound was applied to detect various cations in water media and N,N-dimethylformamide (DMF) via monitoring the quenching of the fluorescence intensity. Furthermore, various metal cations including Cu(2+), Ni(2+), Zn(2+), Pb(2+),Ca(2+), Ba(2+), Cd(2+), Hg(2+), Fe(2+), Fe(3+) and Ag(+) were tested. The complexes formed between the synthesized compound and metal cations in solution and their effects on Photoinduced Electron Transfer (PET) process were investigated regarding the potential application of the newly-synthesized dendrimer as a colorimetric and fluorescent sensor for such cations. The results clearly confirmed that the 1,8-naphthalimide groups surrounding the central dendrimer core showed strong green fluorescence emission at 553 nm. This effect considerably decreased with the introduction of all cations, except Ag(+) where the fluorescence quenching effect was remarkable and more dominant. Therefore, it can be concluded that the synthesized dye has the potentiality of being a highly sensitive and selective fluorescence sensor for Ag(+) cation.

Fabrication of a miniaturized capillary waveguide integrated fiber-optic sensor for fluoride determination

Fluoride concentration is a key aspect of water quality and essential for human health.

Heteroatom-connected ferrocenyl substituted naphthalimides

A family of heteroatom (oxygen, sulphur and nitrogen) connected ferrocenyl naphthalimides 3a–3f were designed and synthesized by the nucleophilic aromatic substitution and Buchwald coupling reactions.

A switchable electrochemical redox ratiometric substrate based on ferrocene for highly selective and sensitive fluoride detection

A ferrocene based electrochemical redox substrate for highly selective and sensitive fluoride detection in non-transparent solutions.

Two-photon fluorescent probe derived from naphthalimide for cysteine detection and imaging in living cells

A maleimide coupling naphthalimide was reported as new two-photon fluorescent (TPF) probe for cysteine (Cys). The probe was weakly fluorescent itself due to the donor-excited photoinduced electron transfer (d-PET). After reaction with Cys, d-PET process was blocked and fluorescence enhancement of the probe was observed at 470 nm. The d-PET principle was rationalized by theoretical calculations with density functional theory and time-dependent density functional theory. Thiol-maleimide addition between the probe and Cys was confirmed by (1)H NMR and mass spectrum measurements. TPF analysis demonstrated a 24.7-fold emission increase of the probe induced by Cys upon excitation at 760 nm. The two-photon action cross-section of probe-Cys adduct at 760 nm reached 42 GM compared to 1.7 GM for free probe. The probe showed high sensitivity and selectivity to Cys over other potential interferences; especially it had the capability to discriminate Cys from glutathione and homocysteine. Through TPF imaging, the probe was successfully applied in the detection of Cys in living cells.

Imaging of fluoride ion in living cells and tissues with a two-photon ratiometric fluorescence probe

A reaction-based two-photon (TP) ratiometric fluorescence probe Z2 has been developed and successfully applied to detect and image fluoride ion in living cells and tissues. The Z2 probe was designed designed to utilize an ICT mechanism between n-butylnaphthalimide as a fluorophore and tert-butyldiphenylsilane (TBDPS) as a response group. Upon addition of fluoride ion, the Si-O bond in the Z2 would be cleaved, and then a stronger electron-donating group was released. The fluorescent changes at 450 and 540 nm, respectively, made it possible to achieve ratiometric fluorescence detection. The results indicated that the Z2 could ratiometrically detect and image fluoride ion in living cells and tissues in a depth of 250 μm by two-photon microscopy (TPM).

A recyclable, fluorescent, and colorimetric sensor for fluoride anion in water using a crosslinked polymer functionalized with hydroxyl quinolinium

A crosslinked polymer-based recyclable, fluorescent, and colorimetric sensor for F⁻ in water.

Highly selective colorimetric/fluorometric dual-channel fluoride ion probe, and its capability of differentiating cancer cells

A dual-channel naphthalimide-based chemosensor for rapid and sensitive detection of fluoride ion has been developed. Upon addition of F(-), it undergoes deprotonation reaction through H-bonding interactions, and its maximum absorption wavelength is red-shifted for 214 nm to the far-red region, together with drastically quenched fluorescence. In addition, it shows high selectivity toward F(-) anion, thus could be used for practical applications to detecting F(-) in both solution and solid state. Furthermore, the fluorescence of NIM could be enhanced in protein-containing acidic environments, hence NIM could act as lysosome marker to differentiate cancer cells from normal ones in cell imaging.