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Target-responsive ratiometric fluorescent aptasensor for OTA based on energy transfer between [Ru(bpy)3]2+ and silica quantum dots
摘要： A ratiometric fluorescent aptasensor based on energy transfer between [Ru(bpy)3]2+ and silica quantum dots (silica QDs) for assaying OTA was fabricated. The aptamer for OTA was used as the gate to shield the fluorescent reagent [Ru(bpy)3]2+ into mesoporous silica nanoparticle (MSN). In the presence of OTA, the constrained [Ru(bpy)3]2+ was released from MSN due to a target-induced aptamer conformational change. The released [Ru(bpy)3]2+ adsorbed onto the negatively charged silica QDs through electrostatic interaction. This creates appearance of fluorescence from [Ru(bpy)3]2+ at 625 nm and decrease of the fluorescence from silica QDs at 442 nm owing to the energy transfer. The value of FL625nm/FL442nm was in proportion to the concentration of OTA in the range 0.5~100 ng mL?1 with a LOD of 0.08 ng mL?1. Practical applicability of this method was validated by the determination of OTA in flour samples.
关键词： Ochratoxin A,Ratiometric fluorescent sensor,Aptamer,Silica quantum dots,[Ru(bpy)3]2+
更新于2025-09-23 15:19:57
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Dual-emission CdTe quantum dot@ZIF-365 ratiometric fluorescent sensor and application for highly sensitive detection of l-histidine and Cu2+
摘要： L-histidine acts as a semi-essential amino acid, which is medically used in the treatment of gastric ulcer, anemia, allergies. However, the overuse of L-histidine will result in terrible damage to heart disease, slow growth of animals and water pollution in the environment. In addition, Cu2+ pollution is common environmental pollution in the industry. It has the characteristics of high accumulation, migration, and persistence. Given this, through the post-synthesis strategy, CdTe quantum dots (QDs) were the first time to introduce into zeolitic imidazolate framework-ZIF-365 to synthesis dual-emission hybrid material CdTe@ZIF-365 with high quantum yield. TEM mappings and N2 absorption tests are applied to confirm the combination mode between CdTe quantum dots and ZIF-365. It should be noted that CdTe@ZIF-365 can be successfully utilized as a bi-functional ratiometric sensor for highly sensitive discrimination of L-histidine and Cu2+. Firstly, CdTe@ZIF-365 is applied to a fluorescent ratiometric sensor for Cu2+ with high sensitivity (the Ksv value is 2.7417(cid:1)107 [M-1]) and selectivity in the mixed cation ions’ solution. On the other hand, CdTe@ZIF-365 also behaved as the first example for an excellent ratiometric fluorescent senor for L-histidine with high sensitivity (the Ksv value is 6.0507(cid:1)108 [M-1]) and selectivity in the mixed amino acids’ solutions.
关键词： hybrid material,Cu2+,CdTe quantum dots,ratiometric fluorescent sensor,L-histidine
更新于2025-09-23 15:19:57
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Double-Emission Ratiometric Fluorescent Sensors Composed of Rare-Earth-Doped ZnS Quantum Dots for Hg <sup>2+</sup> Detection
摘要： Quantum dots (QDs) are a class of zero-dimensional nanocrystal materials, whose lengths are limited to 2?10 nm. Their unique advantages such as wide excitation spectra, narrow emission spectra, and high quantum yield make their application possible in ?uorescence sensing, wherein QDs such as CdSe, CdTe, and CdS are used. Indeed, QDs have a wide range of applications in ?uorescence sensing, and there have been many reports of applications based on QDs as ion probes. The emission spectra of QDs can be adjusted by changing the size of the QDs or doping them with other ions/elements. However, the high toxicity of Cd and the poor anti-interference ability of single-emission ?uorescent probes greatly limit the applications of QDs in many ?elds. In this paper, ZnS QDs are doped with the rare-earth element Ce to form a low-toxicity double-emission ratiometric ?uorescent sensor, ZnS:Ce, for Hg2+ detection. The results of transmission electron microscopy (TEM), X-ray di?ractometry, X-ray photoelectron spectroscopy, and optical spectroscopy show that ZnS:Ce QDs were successfully synthesized. Under the optimal conditions, the concentration of Hg2+ was in the range of 10?100 μM, which had a linear relationship with the ?uorescence intensity of the ZnS:Ce QDs: the linear correlation coe?cient was 0.998, and the detection limit was 0.82 μM L?1. In addition, the ?uorescent sensor had good selectivity for Hg2+, and it was successfully applied to the detection of Hg2+ in laboratory water samples.
关键词： ZnS:Ce,Hg2+ detection,Quantum dots,ratiometric fluorescent sensor,double-emission
更新于2025-09-23 15:19:57
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A ratiometric fluorescent sensor for sensitive detection of UDG using poly(thymine)-templated copper nanoclusters and DAPI with exonuclease III assisted amplification
摘要： As one of critical base excision repair enzymes, uracil-DNA glycosylase (UDG) can specifically repair uracil-induced DNA damage to maintain the genome integrity of organisms. Moreover, abnormal expression of UDG is related to various cancers and other serious diseases. Therefore, it is essential to accurately and sensitively monitor UDG activity. In this work, a ratiometric fluorescence method using poly-(thymine) DNA template copper nanoclusters (Cu NCs) and 4',6-diamidino-2-phenylindole (DAPI) as the output signals is developed for simple, selective, and sensitive detection of UDG. A double-stranded DNA (dsDNA) consisting of a uracil-containing single chain and a trigger sequence is designed as a substrate dsDNA. Meanwhile, another dsDNA comprising 30 pairs of A-T bases ((AT)30 dsDNA) is designed to be partially complementary to the trigger chain. The (AT)30 dsDNA itself has no blunt or recessed 3’ end and cannot be cut by exonuclease III (Exo III). With the Exo III-assisted amplification, adding UDG results in the success synthesis of red-emissive Cu NCs, while the dsDNAs in the system are hydrolyzed and the fluorescence signal of DAPI is weak. In contrast, without addition of UDG, the fluorescence intensity of Cu NCs is low, while the DAPI emits significantly enhanced fluorescence signal. The proposed method presents a detection limit of 5.0 × 10?5 U mL-1 and can be applied to the Hela cell lysate sample with satisfactory results. Additionally, the kinetic parameter is studied and the UDG inhibition effect is evaluated. In summary, this work provides a potential platform for DNA repair enzyme-related analysis and clinical diagnosis.
关键词： Uracil-DNA glycosylase,Ratiometric fluorescent sensor,Poly-(thymine) templated copper nanoclusters,DAPI,Exo III-assisted amplification
更新于2025-09-19 17:15:36