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Self-Referenced Ratiometric Detection of Sulfatase Activity with Dual-Emissive Urease-Encapsulated Gold Nanoclusters
摘要： In this study, on the basis of the biomineralization capability of urease, a facile, one-step, and green synthetic method has been proposed for the fabrication of gold nanoclusters (AuNCs). The prepared urease-encapsulated AuNCs (U-AuNCs) exhibited strong red fluorescence emission (λem = 630 nm) with a quantum yield as high as 17%. Interestingly, at a low concentration, the U-AuNC solution was found to be a dual-emissive system with the blue emission of the dityrosine (diTyr) residues of urease and the red emission of the embedded AuNCs. Further experiments demonstrated that p-nitrophenol (PNP) can selectively suppress the 410 nm emission of the diTyr residues of U-AuNCs without affecting the red emission of the U-AuNCs. The fluorescence quenching mechanism between U-AuNCs and PNP was systematically studied, and the leading role of the inner filter effect (IFE) was identified. Additionally, based on the sulfatase-catalyzed hydrolysis of p-nitrophenyl sulfate (PNPS) to release PNP, a self-referenced ratiometric detection method for sulfatase, which plays a crucial role in sulfur cycling, degradation of sulfated glycosaminoglycans and glycolipids, and extracellular remodeling of sulfated glycosaminoglycans, was developed by using dual-emissive U-AuNCs as the signal readout, in which the diTyr residues served as the probe and the AuNCs functioned as the internal reference. This IFE-based ratiometric sensing strategy showed a good linear relationship over the range of 0.01-1 U/mL (R2 = 0.997). The detection limit for sulfatase activity was 0.01 U/mL. The developed protocol was successfully used to detect sulfatase activity in human serum samples. The simplicity, rapidness, low cost, high credibility, good reproducibility, and excellent selectivity of the detection platform serve as an inspiration for further applications of fluorescent AuNCs in chemo/biosensing.
关键词： dityrosine,inner filter effect,gold nanocluster,ratiometric detection,sulfatase
更新于2025-09-23 15:22:29
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Dual-Emitting Quantum Dot Complex Nanoprobe for Ratiometric and Visual Detection of Hg2+ and Cu2+ ions
摘要： Herein we report the use of a dual emitting quantum dot complex (QDC; composed of blue emitting metal-methylsalicylaldimine complex being on the surface of orange emitting Mn2+-doped ZnS quantum dot) for ratiometric and visual detection of Hg2+ and Cu2+ ions - following the alterations in luminescence color, intensity ratio, chromaticity and hue of the QDC.
关键词： Hg2+ ions,Cu2+ ions,ratiometric detection,quantum dot complex,visual detection
更新于2025-09-23 15:21:01
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Colorimetric and dark-field microscopic determination of cadmium(II) using unmodified gold nanoparticles and?based on the formation of glutathione-cadmium(II) complexes
摘要： A colorimetric approach is presented for the determinaton of cadmium(II) using unmodified gold nanoparticles (AuNPs) as a colorimetric probe. The assay is based on AuNP aggregation that is induced by the complexes formed between Cd(II) and glutathione (GSH) in a concentrated solution of NaCl. Unmodified AuNPs are known to aggregate in high-salt medium, but GSH can prevent aggregation. In the presence of Cd(II), it will bind GSH, and this will cause the AuNPs to aggregate as indicated by yellow and red dots under dark-field microscopy observation and the formation of a blue coloration. By monitoring the intensity change of AuNPs (as a ratio of absorbances at 600 and 520 nm), Cd(II) can be quantified with a linear response in the 17 pM to 16.7 nM concentration range and a detection limit of 4.3 pM. The method was successfully applied to the determination of Cd(II) in spiked lake water by the standard addition mode, and the detection limit is 4.5 pM.
关键词： Microscopy,Yellow and red dots,Lake water,Glutathione,Ratiometric detection,Cadmium ion,Gold nanoparticle aggregation
更新于2025-09-23 15:19:57
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A water-stable Eu <sup>III</sup> -based MOF as a dual-emission luminescent sensor for discriminative detection of nitroaromatic pollutants
摘要： A water-stable EuIII-based metal–organic framework (MOF) with dual-emission luminescence behavior, namely {[Eu4(INO)5(μ3-OH)2Cl4(H2O)]·(NO3)·(H2O)5}n (Eu-MOF; HINO = isonicotinic acid N-oxide), was successfully constructed by the solvothermal reaction of Eu3+ ions with the organic ligand HINO. The cationic 3D framework contains microporous channels with accessible Lewis-base sites and NO3? ions as balanced anions, which all contribute to the selective detection of multifarious analytes. This MOF shows ratiometric detection of acetone, Cr2O72? ions, and nitroaromatic compounds (NACs). In particular, it shows great recognition of four NACs in water, representing the first LnIII-MOF which can display distinguishing fluorescence phenomena on NACs rather than relying on the quenching effect. Furthermore, this is also the first example of a MOF-sensor for detecting these explosives discriminatively by ratiometric methods. Additionally, the mechanisms for luminescent responses towards different analytes have been discussed in detail.
关键词： luminescent sensor,dual-emission,ratiometric detection,EuIII-based MOF,nitroaromatic pollutants,water-stable
更新于2025-09-19 17:15:36
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Synergistic effect of fluorescence recovery and enhancement on ultrasensitive visual assay of cyanide anions based on N-Acetyl-L-Cysteine-Capped CdTe quantum dots and carbon dots
摘要： Developing a reliable fluorescent nanosensor for cyanide anions (CN?), with the potential to enable visual discrimination by naked eye, is highly sought after yet is limited by low sensitivity and selectivity. Herein based on the synergistic effect of fluorescence recovery and enhancement, a specific dual-emission nano-system was designed for ultrasensitive detection of CN?, by employing carbon dots (peaking at 443 nm) as a reference and N-acetyl-L-cysteine (NALC)-capped CdTe quantum dots (QDs, peaking at 611 nm) as a reporter. The red fluorescence of CdTe QDs is first quenched by Cu2+ primarily with electron transfer. Upon addition of CN?, coordinates with Cu2+ to form [Cu(CN)n](n?1)? complex, causing the Cu2+ to detach from the QDs, and consequently fluorescence recovery. More importantly, the CN? can undergo a nucleophilic addition reaction with the carbonyl group of NALC ligands, inducing 1.3-fold fluorescence enhancement towards the original QDs while the blue fluorescence of carbon dots remains constant. This results the fluorescence intensity ratios (I611/I443) are proportional to the concentrations of CN? in the ranges of 0.02―10 and 15―80 μM, and an ultra-low detection limit down to 10.35 nM is achieved. By using both Cu2+-promoted complexation and addition reaction as recognition units, the present method also showed excellent selectivity for CN? over other coexisting anions. Especially, we have already demonstrated, by spiked tests, the practicability of monitoring the concentration changes of CN? in both environmental water and cassava samples, and further realized visual monitoring of CN? changes in aqueous solution and test paper.
关键词： Ratiometric detection,Visual identification,Nucleophilic addition,Quantum dots,Turn-on,Cyanide anions
更新于2025-09-16 10:30:52