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Homogeneous immunoassay for alpha-fetoprotein based on the quenching of the fluorescence of quantum dots by antibody labelled with complexed copper ion tags
摘要： A homogeneous fluorescent immunoassay is described for the determination of alpha fetoprotein (AFP) relying on the interaction between copper ion complex and quantum dots (QDs). The copper ion complex-labelled antibody can be employed as a quencher of fluorescence of QDs and capture probe of AFP in homogeneous solution. The labelled antibody is mixed with QDs to form the immune ensemble probe. Upon the addition of AFP, the labelled antibody is stripped away from QDs by antigen-antibody combination leading to the increase in the fluorescence signal. Thus, the determination of AFP can be realized by fluorometry (best measured at excitation/emission wavelengths of 360/520 nm). The fluorescence intensity shows a good linear relationship with the AFP concentration ranging from 40 to 640 ng mL?1, and the LOD is 26 ng mL?1. The proposed method provides a new approach to incorporate metal complexes into QD-based biomolecule sensing.
关键词： Stern-Volmer plot,Metal complex,DTPAA,Copper ion complex-labelled antibody,Fluorescence quenching
更新于2025-11-19 16:46:39
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A new benzimidazole-based selective and sensitive ‘on-off’ fluorescence chemosensor for Cu <sup>2+</sup> ions and application in cellular bioimaging
摘要： Two new twinborn benzimidazole derivates (L and A), which bonded pyridine via the ester space on the opposite and adjacent positions of the benzene ring of benzimidazole respectively, were designed and synthesized. Compound L displayed fluorescence quenching response only towards copper(II) ions (Cu2+) in acetonitrile solution with high selectivity and sensitivity. However, compound A presented 'on–off' fluorescence response towards a wide range of metal ions to different degrees and did not have selectivity. Furthermore, compound L formed a 1:1 complex with Cu2+ and the binding constant between sensor L and Cu2+ was high at 6.02 × 104 M?1. Job's plot, mass spectra, IR spectra, 1H‐NMR titration and density functional theory (DFT) calculations demonstrated the formation of a 1:1 complex between L and Cu2+. Chemosensor L displayed a low limit of detection (3.05 × 10?6 M) and fast response time (15 s) to Cu2+. The Stern–Volmer analysis illustrated that the fluorescence quenching agreed with the static quenching mode. In addition, the obvious difference of L within HepG2 cells in the presence and absence of Cu2+ indicated L had the recognition capability for Cu2+ in living cells.
关键词： fluorescence chemosensor,benzimidazole,cell imaging,copper ion
更新于2025-09-23 15:23:52
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A highly selective “turn-on” fluorescent probe for detecting Cu2+ in two different sensing mechanisms
摘要： A new coumarin-derived hydrazone (1) has been developed as a “turn-on” fluorescent probe for the detection of Cu2+ in two different sensing mechanisms. In anhydrous acetonitrile, the strong fluorescence response of 1 to Cu2+ was mainly attributed to the chelation-controlled C=N isomerisation. Besides, S-donor is indispensable in protecting from the Cu2+-induced fluorescence quenching. In aqueous acetonitrile, 1 as a chemodosimeter can highly selectively sense of Cu2+, which was ascribed to the Cu2+-promoted cyclization reaction affording the strong fluorescent cyclization product (2). The proposed cyclization reaction was confirmed by the single-crystal structure of 2. Furthermore, 1 was utilized for imaging intracellular Cu2+ with good performance.
关键词： Live cell imaging,Fluorescent probe,Copper ion,Coumarin,Cyclization
更新于2025-09-23 15:19:57
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A fluorescent and colorimetric Schiff base chemosensor for the detection of Zn2+ and Cu2+: Application in live cell imaging and colorimetric test kit
摘要： A novel Schiff base chemosensor HMID, ((E)-1-((2-hydroxy-3-methoxybenzylidene)amino)imidazolidine-2,4-dione), have been designed and synthesized. Sensor HMID showed a selectivity to Zn2+ through fluorescence enhancement in aqueous solution. Its detection limit was analyzed as 11.9 μM. Importantly, compound HMID could be applied to image Zn2+ in live cells. Detection mechanism of Zn2+ by HMID was suggested to be an effect of chelation-enhanced fluorescence (CHEF) by DFT calculations. Moreover, HMID could detect Cu2+ with a change of color from colorless to pink. The selective detection mechanism of Cu2+ by HMID was demonstrated to be the promotion of intramolecular charge transfer band by DFT calculations. Additionally, HMID could be employed as a naked-eye colorimetric kit for Cu2+. Therefore, HMID has the ability as a 'single sensor for dual targets'.
关键词： chemosensor,zinc ion,cell imaging,fluorescent,colorimetric,copper ion
更新于2025-09-10 09:29:36
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New fluorescent sensor based on a calix[4]arene bearing two triazole–coumarin units for copper ions: application for Cu2+ detection in human blood serum
摘要： A novel fluorescent chemosensor calix[4]arene L, containing two fluorogenic coumarin units at the lower rim has been synthesized via click reaction. The structure of this chemosensor, was characterized by IR, NMR spectra and elemental analysis. Ion-binding properties of L were investigated in acetonitrile with different metal ions and the recognition process was monitored by fluorescence, UV-Vis and 1H NMR spectral changes. In comparison with other metal ions, chemosensor L showed a specific selectivity toward copper ions. The Job plot analysis revealed that the binding between L with Cu2+ is in 1:1 stoichiometry. The association constant (Ka) for the complex L.Cu2+ was found to be 1.6 × 105 M?1. The limit of detection of the sensor L was determined to be 5.4 × 10?7 M. This sensitive and selective chemosensor was successfully applied for the detection of Cu2+ ions in human blood serum with 90–100% recovery.
关键词： Coumarin units,Blood serum,Calix[4]arene,Fluorescent sensor,Copper ion
更新于2025-09-10 09:29:36
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Highly Sensitive and Selective Photoluminescence Detection of Copper Ions via <i>In Situ</i> Formation of Fluorescent Polydopamine
摘要： Detection of heavy metals via ?uorescence has attracted increasing attention. Herein, we report a novel copper(II) ion (Cu2+) sensor using ?uorescent polydopamine (FPDA). Dopamine is easily oxidized to polydopamine by oxygen in alkaline solution, and oxidized polydopamine does not ?uoresce. However, under a nitrogen atmosphere, FPDA can be produced by adding hydrogen peroxide into a dopamine solution in the presence of Cu2+ ions. The ?uorescence intensity of FPDA is strongly dependent on the concentration of Cu2+ ions. At higher concentrations of Cu2+ ions, the photoluminescence intensity of FPDA also increases at a higher rate. FPDA exhibited a highly sensitive and selective response to Cu2+ ions over other ionic competitors in the biological milieu, achieving a detection limit as low as 1 nmol L?1 (nM). This study shows that the method can be used for monitoring in vivo Cu2+ ions owing to the distinct properties of FPDA such as strong ?uorescence signal and biocompatibility.
关键词： Polydopamine,Copper Ion Detection,Photoluminescence
更新于2025-09-04 15:30:14