Fluorescent Biological Label for Recognizing Human Ovarian Tumor Cells Based on Fluorescent Nanoparticles

In this paper, we report a method for recognizing human ovarian tumor(HOT) cells using fluorescent biological label based on core-shell nanoparticles. The luminescent nanoparticles were synthesized with a water-in-oil(W/O)micromulsion technique. The fluorescent silica core-shell nanoparticles modified with anti-HER2 antibody using bifunctional cross-linker glutaraldedhyde targeted the corresponding tumor antigen in the cell surface of the SKOV3 ovarian cancer cells. The specific immunoreactivity of antibody-nanoparticles with cells was characterized by laser scanning microscopy (LSM) and scanning electron microscope (SEM). The results showed that the method offered potential advantages of sensitivity and simplicity due to high binding efficiency between nanoparticles and cells and provided an alternative method for the detection of HOT.     

A BODIPY Based Fluorescent Probe for the Rapid Detection of Hypochlorite

A new boron-dipyrromethene (BODIPY) fluorescent dye aimed at sensitively detecting hypochlorite anion (ClO^?) has been designed, synthesized and characterized. The probe is comprised of a BODIPY fluorophore unit and a ClO^? specific reactive group of amidoxime. The addition of hypochlorite results in a red-shift of absorption and emission spectra of the probe accompanied by a decrease of intensity and spectra changes (A₅₀₀ and 1/I₅₁₂) of the probe can achieve a good linearity to the concentration of ClO^?. The fluorescence probe can react to ClO^? rapidly (within 60 s) in a wide pH range (4–10) with high sensitivity (detection limit of 6.81 μM) and selectivity. The reaction mechanism has been proposed and confirmed by MS analysis, ClO^? anion oxidizes amidoxime moiety to hydroxyl group and hydroxyl group is further oxidized to formyl group in the formation of a corresponding aldehyde compound. In addition, the probe has also been successfully applied to detect ClO^? in tap water and river water samples by spiking a known amount of standard ClO^?.     

A Novel Fluorescent Biosensor for Detection of Silver Ions Based on Upconversion Nanoparticles

In this paper, we report a simple and sensitive fluorescent biosensor for the quantitative analysis of silver ions (Ag⁺) by using NaYF₄:Yb³⁺, Tm³⁺ upconversion nanoparticles (UCNPs). Ag⁺ could oxidize o-phenylenediamine (OPD) to the oxidized OPD (oxOPD) directly. The fluorescence of UCNPs can be significantly quenched by oxOPD through inner filter effects (IFE). Under the optimized conditions, the Ag⁺ concentration is proportional to the changes of the fluorescence intensity of UCNPs. The proposed method shows high selectivity and Ag⁺ could be quantitatively detected in the range of 0 to 0.5 mM with a low detection limit of 33 nM for Ag⁺. The selectivity and sensitivity of the detection can also be satisfactory. More importantly, this method has potential in practical application to detect Ag⁺ in real samples without interference.     

A Novel Ratiometric Fluorescent Mercury Probe Based on Deprotonation-ICT Mechanism

A new NBD-rhodamine dye (1) was developed as a colorimetric and ratiometric fluorescent chemosensor for Hg²⁺ with good selectivity in aqueous ethanol solutions under neutral to basic conditions. Sensor 1 showed absorption at 468 nm and a weak emission at 529 nm (? _F ?=?0.063) in ethanol/aqueous tris buffer (9:1, v/v) of pH 9.17 solution. Bathochromic shifts in both absorption (492 nm) and fluorescence spectra (569 nm, ? _F ?=?0.129), respectively upon addition of 2 equiv. of Hg²⁺ were observed. The ring-opening reaction of the spirolactam form to the corresponding xanthene form was not found. The interaction of Hg²⁺ with chemosensor 1 resulted in the deprotonation of the secondary amine conjugated to the NBD component so that the electron-donating ability of the N atom was enhanced. Deprotonation-ICT mechanism of secondary amines was suggested for the ratiometric fluorescent chemosensing for Hg²⁺.     

Modification-Free Fluorescent Biosensor for CEA Based on Polydopamine-Coated Upconversion Nanoparticles

Journal of Fluorescence - Upconversion nanoparticles (UCNPs) have achieved considerable success in protein sensing in vitro. And aptamer is one of the most frequently used biomolecules to modify...     

A Highly Selective Fluorescent Probe for the Detection of Nitroreductase Based on a Naphthalimide Scaffold

The development of fluorescent probes for nitroreductase (NTR) has received intense attention because of its biological significance and wide application. In this work, a novel fluorescent probe for the detection of NTR in aqueous solution was designed and synthesized on a 1,8-naphthalimide scaffold. In the presence of NTR and nicotinamide adenine dinucleotide (NADH) under physiological conditions, the probe was converted into a 4-hydroxy-1,8-naphthalimide derivative and exhibited a sharp fluorescence enhancement at 550 nm, with a high selectivity for NTR over various analytes. The detection limit for NTR was determined to be 9.8 ng/ml by this probe. Due to its low signal background, this probe showed?>?70-fold fluorescence enhancement. Theoretical calculations revealed that the reason for the fluorescence quenching of this probe is the photoinduced electron transfer (PET) from both the nitrobenzene and morpholine groups to the naphthalimide fluorophore.

     

A Novel Water-soluble Ratiometric Fluorescent Probe Based on FRET for Sensing Lysosomal pH

A new ratiometric fluorescent probe based on Förster resonance energy transfer (FRET) for sensing lysosomal pH has been developed. The probe (RMPM) was composed of imidazo[1,5-α]pyridine quaternary ammonium salt fluorophore as the FRET donor and the rhodamine moiety as the FRET acceptor. It’s the first time to report that imidazo[1,5-α]pyridine quaternary ammonium salt acts as the FRET donor. The ratio of fluorescence intensity of the probe at two wavelengths (I₄₂₄/I₅₈₁) changed significantly and responded linearly toward minor pH changes in the range of 5.4–6.6. It should be noted that it’s rare to report that a ratiometric pH probe could detect so weak acidic pH with pKa = 6.31. In addition, probe RMPM exhibited excellent water-solubility, fast-response, all-right selectivity and brilliant reversibility. Moreover, RMPM has been successfully applied to sensing lysosomal pH in HeLa cells and has low cytotoxicity.     

一种基于C＝N异构化的高选择性镁离子荧光探针

设计合成了荧光传感分子2-羟基-1-萘甲醛缩1-氨基海因(L),通过吸收和荧光光谱研究其对金属离子的识别作用,结果表明该化合物对镁离子表现出高选择性响应,在最大发射波长448nm处,乙腈中加入Mg2+,荧光强度增强30倍,Job曲线表明该受体分子与Mg2+以2∶1计量比配位,并初步探讨了该受体分子与镁离子的结合模式和荧...     

A Colorimetric and Fluorescent Probe Based on Michael Acceptor Type Diketopyrrolopyrrole for Cyanide Detection

A new probe 1 was synthesized by incorporating an α,β-unsaturated ketone to a diketopyrrolopyrrole fluorophore. The probe exhibited a selective and sensitive response to cyanide against other anions. Addition of CN^? aqueous solution to 1 resulted in a rapid color change from pink to light yellow together with a blue shift from 518 to 421 nm, while other anions did not induce any significant color change. Furthermore, the Michael addition of cyanide to 1 elicited 98% fluorescence quenching at 608 nm, which constituted the fluorescence signature for cyanide detection. The detection limit was 0.67 μM using the fluorescence spectra changes, which was far lower than the WHO guideline of 1.9 μM. Moreover, 1-based test strips could successfully detect CN^? solutions.     

Sensitive and Selective Detection of Antibiotic D-Penicillamine Based on a Dual-Mode Probe of Fluorescent Carbon Dots and Gold Nanoparticles

This paper reported a dual-mode probe for D-penicillamine on the basis of pH-mediated gold nanoparticles aggregation and fluorescence resonance energy transfer (FRET) from carbon dots. D-penicillamine is a zwitterionic compound and has different forms depending on specific pH ranges. The thiol group of D-penicillamine has high affinity towards the surface of gold nanoparticles and can replace other surface ligands. When pH values were close to its isoelectrical point (pH(I)), the D-penicillamine capped gold nanoparticles aggregated through hydrogen bonding or electrostatic interactions, resulting in the releasing of carbon dots from gold nanoparticles. The dual-mode probe consisted of fluorescent carbon dots and gold nanoparticles, and the fluorescence of carbon dots was quenched by the attached gold nanoparticles due to the FRET. Then, the fluorescence can be recovered in presence of D-penicillamine due to the gold nanoparticles aggregation in specific pH range. Under the optimum conditions, the probe has linear response for D-penicillamine in the 0.25–1.5 μM concentration range with a detection limit of 0.085 μM. This method provides a potential application in sensitive detection of D-penicillamine.     

A New Pyrazoline-Based Fluorescent Probe for Cu2+ in Live Cells

A new pyrazoline-based probe was synthesized and the structure was determined by using X-ray diffraction analysis. The probe responds to Cu²⁺ in aqueous medium in “turn-off” fluorescent manner with selectivity and sensitivity. Furthermore, the probe could be used for real-time tracking of Cu²⁺ in Hela cells.     

槲皮素作为荧光探针对氟离子的识别作用

槲皮素为天然黄酮类化合物,广泛存在于植物的根、茎、叶、花和果实中。槲皮素作为荧光探针检测氟离子不仅具有较好的选择性和灵敏度,而且与合成的荧光探针比,还具有来源广、环保、无毒等优点。实验将不同阴离子(F-,Cl-,Br-,I-,ClO-₄,H₂PO-₄)分别加入到槲皮素的二甲基亚砜(DMSO)溶液中,考查槲皮素溶液的荧光强度变化。实验发现当加入氟离子后,槲皮素在500 nm处的荧光发射峰的强度降低,发生荧光猝灭,且其猝灭程度随着氟离子浓度的增大而改变,即荧光强度随着氟离子浓度的增大而减小,并呈线性变化。而其他阴离子的加入对槲皮素和槲皮素-氟离子体系的荧光发射强度影响不大,说明其他阴离子不影响槲皮素对氟离子的识别,显示了槲皮素对氟离子具有较好的选择性。由荧光滴定光谱和荧光滴定曲线得到槲皮素对氟离子的滴定方程为：y=-13.36x+173.4,线性关系为R2=0.991,线性范围为1.0×10-6～8.0×10-6 mol·L-1,最低检测限为1.0×10-7 mol·L-1,表明槲皮素对氟离子的识别具有较高的灵敏度。进一步实验表明槲皮素识别氟离子的机理可能是氟离子的加入破坏了溶液体系的氢键,改变了槲皮素分子的共轭状态,发生分子内电荷转移,促使槲皮素荧光猝灭。用该法成功检测了样品中微量氟离子,回收率为100.67%～102.44%,精确度较好,测定结果稳定。     

A Hybrid Coumarin-Semifluorescein-Based Fluorescent Probe for the Detection of Cysteine

A new type of turn-on fluorescent probe CF-AC for the detection of Cys was firstly reported. The probe exhibited an excellent response to Cys with high selectively and sensitivity. In the presence of Cys, two fluorescence emission peaks at 525 nm and 650 nm appeared accompanied by the fluorescence color change from blue to red. Morever, the probe had good biocompatibility and could be successfully used for fluorescence imaging of Cys in MCF-7 cells.     

A Highly Selective Fluorescent Probe for Detection of Biological Samples Thiol and Its Application in Living Cells

Probe 1 was designed and synthesized as a new fluorescent molecular probe for thiols in PBS buffer at physiological condition. This fluorescent molecular probe consists of a thiol reaction moiety bound to a coumarin fluorophore. Its fluorescence quantum yield is low, but a drastic enhancement of fluorescence intensity was observed in the presence of thiols. Possible interference with other analytes was examined. Probe 1 displays a highly selective fluorescent enhancement with thiols, and the probe was successfully applied to thiols determination in intracellular, in human urine and blood samples.     

一种基于部花菁染料的氰离子荧光比率探针

设计合成了荧光探针1,2,2,3-四甲基-4,5-苯并吲哚啉,通过荧光光谱研究了其与CN-的识别和传感作用,结果表明该化合物对CN-具有很高的选择性,同时引起荧光光谱比率的变化。Job曲线表明该探针与CN-是以1∶1计量比作用,并初步探讨了其与CN-的作用模式和荧光变化机理。     

A Dansyl-Rhodamine Ratiometric Fluorescent Probe for Hg<Superscript>2+</Superscript> Based on FRET Mechanism

Based on resonance energy transfer (FRET) from dansyl to rhodamine 101, a new fluorescent probe (compound 1) containing rhodamine 101 and a dansyl unit was synthesized for detecting Hg²⁺ through ratiometric sensing in DMSO aqueous solutions. This probe shows a fast, reversible and selective response toward Hg²⁺ in a wide pH range. Hg²⁺ induced ring-opening reactions of the spirolactam rhodamine moiety of 1, leading to the formation of fluorescent derivatives that can serve as the FRET acceptors. Very large stokes shift (220 nm) was observed in this case. About 97-fold increase in fluorescence intensity ratio was observed upon its binding with Hg²⁺.     

A New Fluorescent Squaraine Probe for the Measurement of Membrane Polarity

The present study was undertaken to evaluate the sensitivity of newly synthesized squaraine dye 1 to the changes in lipid bilayer physical properties and compared it with the well-known dye 2. Partitioning of the dye 1 into lipid bilayer was found to be followed by significant increase of its fluorescence intensity and red-shift of emission maximum, while intensity of the dye 2 fluorescence increased only slightly on going from aqueous to lipidic environment. This suggests that dye 1 is more sensitive to the changes in membrane properties as compared to dye 2. Partition coefficients of the dye 1 have been determined for the model membranes composed of zwitterionic phospholipid phosphatidylcholine (PC) and its mixtures with positively charged detergent cetyltrimethylammonium bromide (CTAB), anionic phospholipid cardiolipin (CL), and sterol (Chol). The spectral responses of the dye 1 in different liposome media proved to correlate with the increase of bilayer polarity induced by Chol and CL or its decrease caused by CTAB. It was concluded that dye 1 can be used as fluorescent probe for examining membrane-related processes.     

A 4-Methylumbelliferone-based Fluorescent Probe for the Sensitive Detection of Captopril

A highly sensitive fluorogenic probe for captopril, 4-methylumbelliferyl-2, 4-dinitrobenzenesulfonate (4-MUDNBS), was designed and synthesized. 4-MUDNBS is a nonfluorescent compound and was synthesized via the one-step reaction of 4-methylumbelliferone (4-MU) with 2,4-dinitrobenzenesulfonyl chloride. Upon mixing with captopril in basic solution, the 2,4-dinitrobenzenesulfonyl group of 4-MUDNBS was efficiently removed and highly fluorescent 4-MU was released, hence leading to the dramatic fluorescence increase of the reaction solution. The fluorescence intensity is linear with captopril concentration in the range 3.0–500 ng mL⁻¹ with a detection limit of 2.2 ng mL⁻¹ (3σ). The effect of substituents on the benzenesulfonyl moiety of the probe is discussed, and the presence of electronegative groups is favorable for the thiolate-induced cleavage reaction. The proposed method has been successfully applied to the captopril determination in pharmaceutical preparations.     

基于亚甲基蓝的近红外荧光探针用于HOCl的特异性检测

次氯酸(HOCl)是一种由过氧化氢和氯离子在髓过氧化物酶(MPO)催化作用下产生的活性氧。由于其在机体抵抗病原体的免疫防御中起着至关重要的作用,因此对HOCl的识别和检测具有非常重要的意义。目前,检测HOCl的方法有电分析法、色谱法、化学发光法和荧光分析法,其中荧光检测法以其简单、快速、高选择性、高灵敏度和实时检测等突出优点引起了许多研究者的兴趣。本文以亚甲基蓝(Methylene blue,MB)为荧光母核,设计合成了一种近红外荧光探针MB-1用于HOCl的特异性检测。该探针可在体外特异性检测HOCl,响应之后,荧光会有显著的增强,同时伴有溶液颜色从无色到蓝色的明显变化。该探针对HOCl具有较高的灵敏度,其检测限为8.2 nmol/L。此外,该探针具有较好的抗干扰能力,为在生理水平上检测HOCl提供了可能。