A selective and ratiometric bifunctional fluorescent probe for Al3+ ion and proton

A new bifunctional probe based on a pyrene-amino acid conjugate for the differential response of Al(3+) and H(+) was demonstrated for the first time. Interestingly, two solvent-dependent sensing mechanisms for Al(3+), which feature a ratiometric change from excimer to monomer in CH(3)OH and a turn-on response in water, are also disclosed.     

A highly selective ratiometric fluorescent chemosensor for Zn2+ ion based on a polyimine macrocycle

A new ratiometric fluorescent chemosensor based on a polyimine macrocycle ligand 1 has been synthesized. The chemosensor can exhibit a pronounced fluorescence response and high selectivity to Zn²⁺ ion over other 15 metal ions, including Cd²⁺. Sensor 1 appears an emission peak at 370 nm. Upon the addition of Zn²⁺ ion, the typical emission peak for 1 at 370 nm is obviously quenched, but a new emission peak at around 470 nm appears and shows a large enhancement due to the formation of a 1:1 Zn²⁺-1 complex. In addition, there is a good linear relationship between the fluorescence ratio I_470nm/I_370nm and the concentration of Zn²⁺, which makes a ratiometric assay of Zn²⁺ ion possible.     

Self-organized fluorescent nanosensors for ratiometric Pb2+ detection

Silica nanoparticles (60 nm diameter) doped with fluorescent dyes and functionalized on the surface with thiol groups have been proved to be efficient fluorescent chemosensors for Pb2+ ions. The particles can detect a 1 microM metal ion concentration with a good selectivity, suffering only interference from Cu2+ ions. Analyte binding sites are provided by the simple grafting of the thiol groups on the nanoparticles. Once bound to the particles surface, the Pb2+ ions quench the emission of the reporting dyes embedded. Sensor performances can be improved by taking advantage of the ease of production of multishell silica particles. On one hand, signaling units can be concentrated in the external shells, allowing a closer interaction with the surface-bound analyte. On the other, a second dye can be buried in the particle core, far enough from the surface to be unaffected by the Pb2+ ions, thus producing a reference signal. In this way, a ratiometric system is easily prepared by simple self-organization of the particle components.     

Naphthalimide-rhodamine based fluorescent probe for ratiometric sensing of cellular pH

The pH values of lysosomes in cancer cells is slightly lower than that in normal cells, which can be used to distinguish cancer cells from normal cells. According to this, a naphthalimide-rhodamine based fluorescent probe(hereafter referred to as RBN) with a pK_a of 4.20 was designed and synthesized for ratiometric sensing of cellular pH via fluorescence resonance energy transfer(FRET), which can respond to different pH precisely through ratiometric fluorescence intensity(Ⅰ_(577)/Ⅰ_(540)). RBN can be employed to distinguish cancer cells from normal cells on the basis of different fluorescent response, in particular, RBN showed excellent water solubility and low cell toxicity, all these are quite significant for potential application in cancer diagnose and therapy.     

A colorimetric and ratiometric fluorescent chemosensor based on furan-pyrene for selective and sensitive sensing Al3+

A new pyrene derivative BF bearing a furan group was synthesized via a one-step reaction as a colorimetric and ratiometric chemosensor for Al³⁺in ethanol-H₂O (9:1,v/v,pH 7.2,HEPES buffer) solution.This chemosensor could selectively recognize Al³⁺ in the presence of other competing ions.Low limit of detection (LOD) and high association constant revealed its superior sensitivity and binding affinity toward Al³⁺.Besides,the probe BF performed perfectly in a reversibility test using EDTA.The mechanism of the interaction has been confirmed by ¹H NMR titration.Importantly,chemosensor BF has also been utilized to detect Al³⁺ on test paper strips,which showed its potential for practical applications.     

Development of ratiometric fluorescent probe for zinc ion based on indole fluorophore

A water-soluble ratiometric fluorescent probe ZID-1 has been developed on the basis of an internal charge transfer (ICT) mechanism. Upon complexation with Zn²⁺ under physiological conditions, ZID-1 exhibits a significant blue shift of 77 nm in the emission spectrum. The fluorescent behavior of ZID-1 suggests that the pyridyl group incorporated into the fluorophore coordinates the metal ion as the fourth ligand and affords an appropriate binding affinity (K_d = 17.1 nM) for the intracellular imaging of Zn²⁺.     

Design of a ratiometric fluorescent probe for benzenethiols based on a thiol-sulfoxide reaction

A novel thiol-sulfoxide reaction based ratiometric probe for benzenethiols was synthesized and evaluated. The probe features a chemospecific reduction over a pH range of 1-10 by benzenethiols with a marked emission color change, enabling the highly selective detection and is promising for applications.     

Synthesis of ratiometric fluorescent nanoparticles for sensing oxygen

A facile reprecipitation-encapsulation method is used for the preparation of ratiometric fluorescent nanoparticles (NPs) for sensing intracellular oxygen. The surface of the NPs is modified in-situ with poly-L-lysine, which renders good biocompatibility and enables easy internalization into living cells. The sensor NPs contain a red fluorescent probe whose fluorescence is sensitive to oxygen with a quenching response of 77 % on going from nitrogen saturation to oxygen saturation, and a reference dye giving a green signal that acts as an oxygen-independent reference. The ratio of the two emissions serves as the analytical information and is sensitive to dissolved oxygen in the 0–43?ppm concentration range. When incorporated into cells, the ratio of the signals increases by 400?% on going from oxygen-saturated to oxygen-free environment.

Thiazole sulfonamide based ratiometric fluorescent chemosensor with a large spectral shift for zinc sensing

A new thiazole sulfonamide (TTP, 1) based Zn²⁺ selective intrinsic chemosensor has been synthesized and investigated. The chemosensor shows a selective fluorescence enhancement (3.0 fold) with Zn²⁺ over biologically relevant cations (Ca²⁺, Mg²⁺, Na⁺, and K⁺) and biologically non-relevant cations (Cd²⁺) in an aqueous ethanol system. It produces an increase in the quantum yield and a longer emission wavelength shift (64 nm) on Zn²⁺ binding with the potential of a ratiometric assay.     

基于香豆素荧光团的高选择性Fe~(3+)荧光分子探针研究

设计合成了四种含有酰胺和酯基结构的香豆素荧光分子探针,其结构通过1H NMR、13C NMR和HRMS进行了表征,并对探针进行了常见金属离子识别性能的研究。发现该类探针对Fe3+产生荧光淬灭性响应,其中7-位带有二乙氨基的2-(7-二乙氨基香豆素-3-甲酰胺基)乙酸乙酯(C3)和3-(7-二乙氨基香豆素-3-甲酰胺基)乙酸丙酯(C4)对Fe3+的淬灭比例达到99.5%和99.6%,可作为识别Fe3+的探针。     

A highly selective colorimetric and ratiometric two-photon fluorescent probe for fluoride ion detection

A naphthalimide-based highly selective colorimetric and ratiometric fluorescent probe for the fluoride ion displayed both one- and two-photon ratiometric changes. Upon reaction with the F(-) (TBA(+) and Na(+) salts) anion in CH(3)CN as well as in aqueous buffer solution, probe 1 shows dramatic color changes from colorless to jade-green and remarkable ratiometric fluorescence enhancements signals. These properties are mechanistically ascribed to a fluoride-triggered Si-O bond cleavage that resulted in a green fluorescent 4-amino-1,8-naphthalimide.     

A chloroacetate based ratiometric fluorescent probe for cysteine detection in biosystems

The specific detection of cysteine (Cys) over homocysteine (Hcy), glutathione (GSH) and other amino acids is of great significance for studying its biological functions as well as for the diagnosis of related diseases. Chloroacetyl group was often used as a reaction site for cysteine fluorescent probes for its sensitivity and selectivity. However, high background fluorescence and low stability are common problems encountered by such probes. Here, four chloroacetyl group based fluorescent probes (C1, C2, C3, and H4) was synthesized for a comparative study. We found that the inefficient quenching ability of chloroacetyl group turned into an advantage when connected with a ratiometric fluorophore. With the modification of chloroacetyl group, probe H4 displayed excellent ratiometric property and great selectivity for Cys, the stability was also improved. Additionally, the probe was successfully applied for quantitative detection of Cys in fetal bovine serum and real-time imaging in living HeLa cells with low toxicity.     

用基于苯并噻二唑衍生物的比率荧光化学传感器检测氟离子

研制了一种用于灵敏、快速地检测溶液中的氟离子的基于苯并噻二唑衍生物的荧光传感器.4,7-二溴-2,1,3-苯并噻二唑与三甲基硅基乙炔通过Sonogashira偶联反应得到二取代的三甲基硅基乙炔苯并噻二唑;将该化合物用于检测氟离子,分析了检测灵敏度和选择性.结果表明,在乙腈和水(V/V=9∶1)混合溶液中,合成的苯并噻二唑衍生物的最大发射波长峰值为455nm(激发波长为376nm);就所测试的F-,Cl-,Br-,I-,ClO4-,AcO-,NO3-,H2PO3-,CN-和HSO4-等阴离子而言,仅F-可以脱除三甲基硅保护基使得该化合物荧光最大发射波长蓝移至435nm,荧光强度降低60%,且最低检测限可达4.5×10-8 mol/L.因此,二取代的三甲基硅基乙炔苯并噻二唑应用于氟离子检测具有很好的灵敏度和选择性.     

A novel "turn-on" fluorescent chemosensor for the selective detection of Al3+ based on aggregation-induced emission

A water-soluble, 'turn-on' fluorescent chemosensor based on aggregation-induced emission (AIE) has been developed. It exhibits rapid response, excellent selectivity, and sensitivity to Al(3+).     

A new ratiometric Ag+ fluorescent sensor based on aggregation-induced emission

The novel tetraphenylethylene(TPE)-based sensor 1 bearing bis(2-pyridin-2-ylmethyl)amine (BPA) units linked with triazole moieties could be obtained by click reaction efficiently. The results show that 1 can demonstrate a Ag⁺-specific emission shift and highly sensitive fluorescent enhancement with a 1:2 binding ratio based on the aggregation-induced emission mechanism. Compound 1 is shown to behave as a ratiometric sensor.     

6-Substituted quinoline-based ratiometric two-photon fluorescent probes for biological Zn2+ detection

New ratiometric two-photon fluorescent probes are developed from 6-substituted quinolines for biological Zn(2+) detection. They show large red shifts and good ratiometric responses upon Zn(2+) binding. They also exhibit high ion selectivities and large two-photon absorption cross sections at nearly 720 nm. Because the new probes are cell-permeable, they can be used to detect intracellular zinc flux under two-photon excitation.     

Design of quinoline-based fluorescent probe for the ratiometric detection of cadmium in aqueous media

A new fluorescent probe,DQCd2,based on 4-piperidinoquinoline has been synthesized as a fluorescent probe for Cd²⁺.It can ratiometrically respond to Cd²⁺ in PBS buffer by a remarkable emission intensity enhancement（88-fold） and wavelength shift（70 nm）.     

A metal–organic gel‐based fluorescent chemosensor for selective Al3+ detection

As an important metal element, aluminium has a significant impact on the environment and human health, and thus the detection of Al³⁺ has become the subject of much research. We synthesized a Ni(II)‐based metal–organic gel (Ni‐MOG), which can serve as an Al³⁺ fluorescence sensor with high selectivity and sensitivity, the limit of detection being calculated to be 0.5 μM. In addition, a composite film was further fabricated by hybridization of this Ni‐MOG with poly(vinyl alcohol). The composite film produced a rapid fluorescence response to Al³⁺ solutions at concentrations above 5 × 10^?5 M in 5 min. The Ni‐MOG composite film can also be successfully applied for the sensitive detection of Al³⁺ in real samples of tap water and seawater. The effective detection of Al³⁺ described in this contribution provides a new insight into water quality monitoring and has promising application value.     

Both visual and ratiometric fluorescent sensor for Zn2+ based on spirobenzopyran platform

A ratiometric fluorescent Zn²⁺ chemosensor, SPQH, based on spirobenzopyran platform, was synthesized. In aqueous HEPES 7.4 buffer solution, upon chelation with Zn(II), SPQH demonstrates high selectivity and subnanomolar sensitivity for zinc ion with 36-fold enhancement in the NIR fluorescence output.     

Developing a novel ratiometric fluorescent probe based on ESIPT for the detection of pH changes in living cells

As an important parameter of intracellular metabolism, pH plays important roles in maintaining normal physiological processes. The abnormal pH could cause disorder of cell function which may cause neurological diseases. Herein, we present two novel ratiometric fluorescent probes to detect pH changes. The probes employed 2-(2′-hydroxyphenyl)benzothiazole as fluorescent platform, and displayed desirable fluorescence response to pH on the basis of excited state intramolecular proton transfer (ESIPT) process. The probe BtyC-1 showed green fluorescence at 546 nm under acidic conditions, while it displayed strong blue fluorescence at 473 nm and weak green fluorescence at 546 nm under alkaline conditions. Biological experiments demonstrated that the probe BtyC-1 could be successfully applied for the ratiometric imaging of cellular pH and the NH₄Cl-induced pH changes in living cells.