Design of a 1,8-naphthalimide-based OFF-ON type bioorthogonal reagent for fluorescent imaging in live cells

A novel 1,8-naphthalimide-based OFF-ON type fluorogenic sydnone (Naph-Syd) as bioorthogonal probe has been developed, which can be triggered by fast cycloaddition reactions with strained alkynes for imaging of biomolecules in cellular environment.     

Design and synthesis of a new fluorescent tripod for chemosensor applications

A new yellow-green fluorescent tripod based 1,8-naphthalimide has been synthesized and characterised. Its photophysical properties have been investigated in organic solvents of different polarity. The effect that the metal ions (Cd²⁺, Co²⁺, Zn²⁺, Mn²⁺, Mg²⁺, Ni²⁺, Pb²⁺, Cu²⁺, Ba²⁺, Fe³⁺ and Ag⁺) produce upon the fluorescent intensity of acetonitrile solutions of the tripod has been discussed viewing its potential applications as a detector for metal cations. The influence of protons on the fluorescence intensity of the tripod in DMF and methanol–water (1:4 v/v) solutions has also been investigated.     

BODIPY based fluorescent turn-on sensor for highly selective detection of HNO and the application in living cells

On the basis of BODIPY platform, a terpyridyl-substituent BODIPY-Copper complex (Cu(II)-BTPY) was rationally designed and synthesized as a redox reaction fluorescent sensor for detecting HNO over reactive oxygen species (ROS) and reactive nitrogen species (RNS) with impressive selectivity in living cells under mild and neutral conditions. The BTPY exhibits relatively high fluorescence quantum efficiency as much as 34.8% and presents large stokes shift, about 62 nm. When a series of transition metal ions were exploited to investigate the fluorescence quench towards BTPY, copper ion (Cu²⁺) gave the optimal result. After the fluorescence of the probe being effectively quenched in the presence of Cu²⁺, it can be in turn recovered through the reduction of Cu²⁺ into Cu⁺ by HNO accompanying with a visually observable fluorescence response. Still, the sensing mechanism was evidently confirmed by EPR and ESI-MS measurement. In addition, the employment of BTPY for imaging dyes was also presented in vivo.     

一种1,8-萘酰亚胺衍生物检测半胱氨酸荧光探针 的合成及其在活细胞和秀丽隐杆线虫中成像中的运用

基于1,8-萘酰亚胺衍生物,构建了一种检测半胱氨酸(Cys)的新型荧光探针TPFC-Acryloyl。光谱研究表明该探针能有效识别Cys且能够在1min内实现快速响应。探针对Cys的检测表现出高选择性,检测限为2.13μmol/L。经荧光光谱和质谱实验确证其检测机理为：Cys与TPFC-Acryloyl分子中的丙烯酸酯发生共轭加成-环化反应,进而羟基裸露的同时释放出黄色荧光。细胞毒性测试表明探针TPFC-Acryloyl的细胞毒性低。此外,该探针还被成功应用于活细胞和秀丽隐杆线虫中Cys的荧光成像。     

Development of a near-infrared fluorescent probe for imaging of endogenous Cu+ in live cells

We have constructed a novel NIR fluorescent turn-on Cu(+) probe suitable for imaging endogenous Cu(+) ions in living cells based on a tricarbocyanine scaffold and a high affinity Cu(+) receptor.     

Development of three novel benzothiazole-based ratiometric fluorescent chemosensor for detecting of hydrazine in serum and gas phase via ESIPT process and different recognition sites

In this article, we have successfully designed and synthesized three novel ratiometric fluorescent probes BTP-LA, BTP-LB and BTP-LN for detection of hydrazine based on benzothiazole-derived fluorophores and different recognition sites. The probes BTP-LA, BTP-LB and BTP-LN displays a good fluorescence ratio emission signals, high selectivity and large emission shifts (>100 nm) toward hydrazine. The three probes BTP-LA, BTP-LB and BTP-LN can be used not only to detect hydrazine in serum, but also to detect gaseous hydrazine in air. More importantly, compared with probes BTP-LB and BTP-LN, BTP-LA has lower saturation concentration (200 µM) and detection limits (1.22 × 10^?7 M) to hydrazine.     

A two-photon fluorescent turn-on probe for imaging of SO2 derivatives in living cells and tissues

SO₂ and its derivatives (bisulfite/sulfite) play crucial roles in several physiological processes. Therefore, development of reliable analytical methods for monitoring SO₂ and its derivatives in biological systems is very significant. In this paper, a FRET-based two-photon fluorescent turn-on probe, A-HCy, was proposed for specific detection of SO₂ derivatives through the bisulfite/sulfite-promoted Michael addition reaction. In this FRET system, an acedan (2-acetyl-6-dialkylaminonaphthalene) moiety was selected as a two-photon donor and a hemicyanine derivative served as both the quencher and the recognition unit for bisulfite/sulfite. A-HCy exhibited excellent selectivity and rapid response to HSO₃⁻ with a detection limit of 0.24 μM. More importantly, probe A-HCy was first successfully applied in two-photon fluorescence imaging of biological SO₂ derivatives in living cells and tissues, suggesting its great potential for practical application in biological systems.     

A novel on-off-on fluorescent chemosensor for relay detection of Fe3+ and PPi in aqueous solution and living cells

A novel on-off-on fluorescence chemosensor BP based on benzothiazole for the relay recognition of Fe³⁺ and PPi was designed and synthesized. The chemosensor BP exhibited a high affinity to Fe³⁺ in the presence of other competing cations. The resultant BP-Fe³⁺ showed excellent recognition ability for PPi via Fe³⁺ displacement approach. The detection limits of BP for Fe³⁺ and BP-Fe³⁺ for PPi were estimated to be 2.59 × 10^?8 M and 8.47 × 10^?8 M, respectively. The low cytotoxicity and good cell-membrane permeability of BP and BP-Fe³⁺ complex makes them capable of Fe³⁺ and PPi imaging in living Hep G2 cells.     

A novel off-on fluorescent probe for specific detection and imaging of cysteine in live cells and in vivo

Cysteine(Cys) plays a pivotal role in many physiological and pathological processes,including detoxification and protein synthesis.The abnormal levels of Cys are linked to many diseases.In this study,a novel red-emitting off-on fluorescent probe Cys-TCF was masterly constructed for discriminative detection of Cys.After a series of experimental assessment,Cys-TCF displayed higher selectivity and sensitivity for Cys over other biothilols with a low detection limit(0.04 μmol/L).More notably,the pro...     

Design and synthesis of a Cu(II)-complex-based carbazole-hemicyanine hybrid for fluorescent sensing of H2S in SDS micellar solution

A novel fluorescent chemosensor HACBA with carbazole-hemicyanine fluorophore as signal reporter and N,N,N'-tri(2-pyridylmethyl)ethylenediamine (TPEA) as binding sites was designed and synthesized. Its assemblies with anionic surfactant sodium dodecyl sulfate (SDS) show improved fluorescence emission stability and enhanced fluorescence intensity. HACBA/SDS system can selectively recognize Cu²⁺, which led to a dramatic fluorescence quenching. The in situ resultant HACBA-Cu(II)/SDS ensemble functioned as a highly selective and sensitive sensor for H₂S with a turn-on fluorescent response. Our results show that the “on-off-on” molecular switch occured through the reversible formation-dissociation reaction between HACBA-Cu(II) complex and HACBA/CuS in the SDS micellar solution, and at least 3 cycles of on-off-on switches were observed.     

Installation of efficient quenching groups of a fluorescent probe for the specific detection of cysteine and homocysteine over glutathione in solution and imaging of living cells

Herein, we report the synthesis and characterisation of a new fluorescent probe 4-(7-nitro-benzo[1,2,5]oxadiazol-4-yl)-benzaldehyde (NBOB) installed with quenching groups for highly selective and sensitive sensing of biothiols. The probe itself is non-fluorescent due to the presence of quenching groups and photoinduced electron transfer (PET) process. Thus, sensitivity of the probe towards thiols was significantly improved by quenching effects. NBOB has been shown to exhibit selective reactivity towards cysteine (Cys) and homocysteine (Hcy) over glutathione (GSH) under stoichiometric conditions. The response mechanism was proved by ¹H NMR, LCMS and theoretical calculation. The probe NBOB has been shown to react with Cys present in Vero cells by fluorescence microscopy.