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An fluorescent aptasensor for sensitive detection of tumor marker based on the FRET of a sandwich structured QDs-AFP-AuNPs
摘要： The detection of alpha-fetoprotein (AFP) is of great importance for hepatocellular carcinoma (HCC) diagnosis, but it needs to be further improved because of poor sensitivity and complicated operating steps. In this paper, a simple and sensitive homogeneous aptasensor for AFP has been developed based on F?rster resonance energy transfer (FRET) where the AFP aptamer labeled luminescent CdTe quantum dots (QDs) as a donor and anti-AFP antibody functional gold nanoparticles (AuNPs) as an acceptor. In the presence of AFP, the bio-affinity between aptamer, target, and antibody made the QDs and AuNPs close enough, thus the fluorescence of CdTe QDs quenched though the FRET between QD and AuNP. The fluorescent aptasensor for AFP showed a concentration-dependent decrease of fluorescence intensity in the low nanomolar range and a detecting linear range of 0.5-45 ng mL?1, with a detection limit of 400 pg mL?1. Moreover, this homogeneous aptasensor is simple and reliable, and obtained satisfying results for the detection of AFP in human serum samples. With more and more aptamers for biomarkers have been selected gradually, this approach could be easily extended to detection of a wide range of biomarkers. The proposed aptasensor has great potential for carcinoma screening in point-of-care testing and even in field use.
关键词： alpha fetoprotein (AFP),fluorescent aptasensor,biomarker,hepatocellular carcinoma,F?rster resonance energy transfer (FRET)
更新于2025-09-23 15:23:52
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Dynamic Emission Tuning of X-ray Radioluminescent Crystalline Colloidal Arrays: Coupling the Optical Stop Band with Sequential F?rster Resonance Energy Transfers
摘要： X-ray radiation exhibits diminished scattering and a greater penetration depth in tissue relative to the visible spectrum and has spawned new medical imaging techniques that exploit X-ray luminescence of nanoparticles. The majority of the nanoparticles finding applications in this field incorporate metals with high atomic numbers and pose potential toxicity effects. Here, a general strategy for the preparation of a fully organic X-ray radioluminescent colloidal platform that can be tailored to emit anywhere in the visible spectrum through a judicious choice in donor/acceptor pairing and multiple sequential F?rster resonance energy transfers (FRETs) is presented. This is demonstrated with three different types of ≈100 nm particles that are doped with anthracene as the scintillating molecule to “pump” subsequent FRET dye pairs that result in emissions from ≈400 nm out past 700 nm. The particles can be self-assembled in crystalline colloidal arrays, and the radioluminescence of the particles can be dynamically tuned by coupling the observed rejection wavelength with the dyes’ emission.
关键词： anthracene,F?rster resonance energy transfer,photonic crystals,X-ray radioluminescence,colloidal crystals
更新于2025-09-23 15:21:21
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Photoinduced charge carrier dynamics in a ZnSe quantum dot-attached CdTe system
摘要： A new nanohybrid material is prepared by attaching CdTe nanoneedles (NNs) to surface-modified ZnSe quantum dots (QDs). The NNs and QDs are prepared by a colloidal synthesis method in an aqueous alkaline medium. The surface modification and the attachment of nanostructures are achieved by a bifunctional ligand 3-mercaptopropionic acid (3-MPA). The band gap of the ZnSe QDs is varied by controlling the size of the QDs in order to get the maximum overlap between the absorption band of the CdTe NNs and the emission band of the ZnSe QDs, which is a prerequisite for effective charge/energy transfer. The possibility of photoinduced charge transfer (PCT) and F?rster resonance energy transfer (FRET) from the donor (QDs) to the acceptor (NNs) has been assessed. Very fast (less than 800 ps) PCT and FRET from QDs to NNs occur because the emission band of QDs overlaps with the absorption band of NNs. The calculated large value of the overlapping integral, J(λ) ～4.5 × 1019 M?1 cm?1 nm4, of the donor and the acceptor bands proves the feasibility of energy transfer. These findings suggest that the ZnSe QDs can exchange photoinduced energy with the CdTe NNs effectively over a wide distance in a CdTe–ZnSe nanohybrid.
关键词： quantum dots,zinc selenide,F?rster resonance energy transfer,cadmium telluride,nanohybrid,charge transfer
更新于2025-09-23 15:19:57
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Deepa??Blue Thiophenea??Based Steric Oligomers as a Lowa??Threshold Laser Gain and Host Material
摘要： Thiophene-based (Th-based) derivatives have received wide attentions in organic optoelectronics due to their excellent and tuneable optoelectrical properties as well as chemical modification. However, the low photoluminescence quantum yield in solid state limits their application in solution-processed light-emitting optoelectronic devices, especially in organic lasers. Herein, a novel blue-emitting steric Th-based fluorophore (MC8-Th) with excellent optical gain behavior for organic laser is reported. Interestingly, MC8-Th neat film exhibits efficient exceptional deep-blue amplified spontaneous emission (ASE) behavior with a remarkably low threshold of 6.0 μJ cm?2 and full-width-at-half-maximum value of 2.6 nm. Furthermore, random laser signals are also obtained with the lowest threshold of 4.1 μJ cm?2 when incorporating the compound into an inert polystyrene (PS) matrix. In addition, low threshold (16 μJ cm?2, fivefold lower than those of F8BT neat films) yellow–green ASE emission (560 nm) is achieved through F?rster resonance energy transfer. Meanwhile, ultrafast transient absorption spectroscopy is deployed here to observe the single-molecular excitonic behavior in solution and PS-blend, intermolecular excited state in neat film, and efficient energy transfer in MC8-Th:F8BT-blend films. As far as known, MC8-Th shows lower threshold ASE/lasing behavior for the Th-based conjugated materials.
关键词： transient absorption spectroscopy,optical gain behavior,organic laser,thiophene-based derivatives,F?rster resonance energy transfer
更新于2025-09-23 15:19:57
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Multia??enzyme detection and ina??situ monitoring of enzyme activity by bending CE using quantum dotsa??based polypeptide substrate
摘要： Multi-enzyme detection and monitoring enzyme activity in situ are significant for the disease to diagnose. This study aims to develop a quantum dots (QDs)-based nanoprobe Cyanine5-DDDLEVLFQFPGLVPRGSGGHHHHHH-QDs (Cy5-LEVLVP-QD), which is able to detect two enzymes inside a bent capillary using CE. Cy5-LEVLVP and QDs were allowed to bind with each other through metal affinity interaction and then injected the Cy5-LEVLVP-QD complex into a capillary with different bends, followed by related enzyme that can cleave the Cy5-LEVLVP peptide. The fluorescence of Cy5 was excited by QDs due to F?rster resonance energy transfer (FRET). By monitoring the peaks produced by the original Cy5-LEVLVP-QD complex and a significant fluorescence change, sensitive analysis of two different enzymes was conducted. Therefore, the novel approach of using capillaries with semicircular bends could prove particularly useful for enzyme investigating in disease.
关键词： CE,enzyme,F?rster resonance energy transfer,peptide,quantum dots
更新于2025-09-23 15:19:57
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Single-molecule F?rster Resonance Energy Transfer Measurement Reveals Dynamic Partially Ordered Structure of the Epidermal Growth Factor Receptor C-tail Domain
摘要： Intrinsically disordered proteins (IDPs) or regions (IDRs) are thought to exhibit unique functionalities without forming ordered structures. However, these molecular mechanisms are not easily elucidated, partly because of the difficultly of measuring structural information. In this study, we applied the alternative laser excitation (ALEX) method and circular dichroism (CD) spectroscopy to investigate the structure of the C-terminal tail (CTT) domain of the human epidermal growth factor receptor (EGFR). The single-molecule distributions of F?rster resonance energy transfer (FRET) obtained by ALEX under solution conditions modified by the addition of potassium chloride (KCl), urea or guanidinium chloride (GdmCl) allowed us to separately examine the influences of charge interactions and secondary structure formation. The CD spectrum analyses indicated the types of included secondary structure. The results suggested that the structure of the CTT is influenced by secondary structure formation, which is principally antiparallel β-sheet, rather than by charge interactions, and that phosphorylation of the major Grb2-binding sites partially denature that secondary structure. Our findings suggest that the EGFR CTT might regulate ligand binding kinetics by local β-sheet formation or by the disruption associated with phosphorylation states.
关键词： Circular dichroism,Epidermal Growth Factor Receptor,F?rster resonance energy transfer,Secondary structure,Intrinsically disordered proteins
更新于2025-09-23 15:19:57
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Nonradiative Energy Transfer in a??Colloidal Quantum Dot Nanoclustera??Dyea?? Hybrid Nanostructures: Computer Experiment
摘要： A computer model of nonradiative electronic excitation energy transfer from nanoclusters of colloidal quantum dots of cadmium selenide to the meso-tetra(3-pyridyl)porphyrin molecule in hybrid nanostructures nanocluster–dye has been constructed and analyzed. The model uses the experimental luminescence and absorption spectra of quantum dots and the dye, takes into account heterogeneity of the properties of quantum dots in nanoclusters and the different location of the dye in the hybrid structure. It has been shown that, in the ideal case, due to such energy transfer, the intensity of the luminescent signal of the dye can be increased by five orders of magnitude. However, this value is significantly reduced due to nonluminescent particles, the presence of a protective ligand shell, a large size distribution of the particles, and the non-optimal geometric structure of the hybrid system.
关键词： porphyrin dye,colloidal quantum dots,F?rster resonance energy transfer,hybrid systems,cadmium selenide,computer simulation
更新于2025-09-19 17:13:59
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Photophysics and electroluminescence of red quantum dots diluted in a thermally activated delayed fluorescence host
摘要： A feasible, universal, and low-cost strategy for quantum dot light-emitting devices (QLEDs) was provided to significantly enhance the electroluminescent performances. The emissive layer consists of organic host materials and quantum dots (QDs), and then the efficient energy transfer process remarkably promotes the device performances. It is confirmed that a highly efficient QLED can be realized by a host–guest system without common hole transport layers. The red device based on the thermally activated delayed fluorescence host and QD guest achieved a peak external quantum efficiency of 7.4%. Further, by simply modifying PEDOT:PSS with poly(4-styrenesulfonic acid), the work-function can be easily elevated, accompanied with the boosted external quantum efficiency to 11.9%. It is believed that such performances originate simultaneously from reduced interfacial fluorescence quenching, elevated work-function and efficient F?rster resonance energy transfer in the host–guest system.
关键词： external quantum efficiency,electroluminescent performances,quantum dot light-emitting devices,QLEDs,thermally activated delayed fluorescence,F?rster resonance energy transfer,host–guest system
更新于2025-09-16 10:30:52
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Hybrid CdSe/CsPbI <sub/>3</sub> quantum dots for interface engineering in perovskite solar cells
摘要： Hybrid CdSe/CsPbI3 quantum dots (QDs) are selected for incorporation between the perovskite film and the hole transport layer (HTL). Owing to the high absorption coefficient and the suitable band gap of CsPbI3, an optimized energy level structure can be expected. Besides, energy transfer could be realized due to the overlap between the emission spectrum of CdSe QDs and the excitation spectrum of CsPbI3 QDs. Hence, CdSe/CsPbI3 QDs can serve as an interface layer to promote interfacial charge extraction and enhance light harvesting ability simultaneously. Compared with pristine perovskite solar cells (PSCs), hybrid CdSe/CsPbI3 QD incorporated PSCs achieve 21% enhancement in power conversion efficiency (PCE). The enhancement of PCE can be ascribed to the ultrafast charge carrier dynamics and F?rster resonance energy transfer (FRET) effect. The design of hybrid CdSe/CsPbI3 QDs offers an alternative method for interfacial engineering to enhance optical properties and facilitate the charge transport process in PSCs.
关键词： interface engineering,charge transport,perovskite solar cells,Hybrid CdSe/CsPbI3 quantum dots,F?rster resonance energy transfer
更新于2025-09-16 10:30:52
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F?rster Resonance Energy Transfer between Colloidal CuInS2/ZnS Quantum Dots and Dark Quenchers
摘要： F?rster resonance energy transfer (FRET) using colloidal semiconductor quantum dots (QDs) and dyes is of importance in a wide range of biological and biophysical studies. Here, we report a study on FRET between CuInS2/ZnS QDs and dark quencher dye molecules (IRDye QC-1). Oleate-capped QDs with photoluminescence quantum yields (PLQYs) of 55±4% are transferred into water by using two types of multifunctional polymer ligands combining imidazole groups and specific moieties with amine or methoxy groups as the terminal sites. The resulting water-dispersible QDs show PLQYs as high as 44±4% and exhibit long-term colloidal stability (at least 10 months at 4 °C in the dark) with a hydrodynamic diameter of less than 20 nm. A side-by-side comparison experiment was performed using the amine or methoxy-functionalized QDs for coupling to dark quencher dye molecules. The amine-functionalized QDs bind to the dye molecules via covalent bonds while methoxy-functionalized ones bind only weakly and non-specifically. The progressive quenching of the QD emission and shortening of its photoluminescence decay time upon increasing the number of conjugated dye molecules demonstrate that the QD acts as the energy donor and the dark quencher dye as the energy acceptor in a donor-acceptor FRET pair. The FRET dynamics of the QD-dye conjugates are simulated using two different models based on the possible origin of the multiexponential PL decay of the QDs (i.e., variations in nonradiative or radiative decay rates). The model based on the radiative decay rates provides a better fit of our experimental data and estimates a donor–acceptor distance (6.5 nm) that matches well the hydrodynamic radius of the amine-functionalized QDs.
关键词： dark quencher dye molecules,energy acceptor,multifunctional polymer ligands,CuInS2/ZnS,F?rster resonance energy transfer,colloidal semiconductor quantum dots,energy donor,photoluminescence quantum yields
更新于2025-09-12 10:27:22