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Water Soluble Fluorescent Graphene Nanodots
摘要： Water soluble fluorescent graphene nanodots (GND) have been successfully prepared through a bottom up approach from brominated pyrene via alkaline hydrothermal condensation. FT-IR, UV-Vis, Raman, XRD, AFM, and TEM studies have shown the formation of (cid:2)OH group rich nano-dots having graphene features with an approximate size of 90 nm. Steady state and 3D fluorescence studies have shown efficient fluorescence emission with maximum at 540 nm upon excitation at 450 nm in pH (cid:3) 7. Plasmid deoxyribonucleic acid (plasmid DNA) and bovine serum albumin (BSA) have shown their interaction with GND, which was studied via fluorescence quenching of GND and BSA, respectively. Selective quenching of the Fo¨ rster resonance energy transfer (FRET) of BSA-GND conjugate via ascorbic acid (AA) has been used to construct a calibration curve for AA estimation with a linear range and limit of detection of 34.00–112.00 mmole/L respectively. GND has also shown and 31.343 mmole/L, turn offchemosensing towards concentration-dependent heavy metals like Pb2 +, Cu2 +, Hg2 + and Zn2 +. In-vitromulti-color fluorescence imaging has been observed in GND-labelled HeLa (human cervical cancer) and NIH-3T3 (mouse embryonic fibroblast) cell lines with better uptake by HeLa cells. GND also has shown very high viability for both the cell lines up to the tested concentration of 300 mg/mL.
关键词： fluorescence,graphene nanodots,F?rster resonance energy transfer,brominated pyrene,bovine serum albumin
更新于2025-09-23 15:21:01
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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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Off-Resonance Control and All-Optical Switching: Expanded Dimensions in Nonlinear Optics
摘要： The theory of non-resonant optical processes with intrinsic optical nonlinearity, such as harmonic generation, has been widely understood since the advent of the laser. In general, such effects involve multiphoton interactions that change the population of each input optical mode or modes. However, nonlinear effects can also arise through the input of an off-resonant laser beam that itself emerges unchanged. Many such effects have been largely overlooked. Using a quantum electrodynamical framework, this review provides detail on such optically nonlinear mechanisms that allow for a controlled increase or decrease in the intensity of linear absorption and fluorescence and in the efficiency of resonance energy transfer. The rate modifications responsible for these effects were achieved by the simultaneous application of an off-resonant beam with a moderate intensity, acting in a sense as an optical catalyst, conferring a new dimension of optical nonlinearity upon photoactive materials. It is shown that, in certain configurations, these mechanisms provide the basis for all-optical switching, i.e., the control of light-by-light, including an optical transistor scheme. The conclusion outlines other recently proposed all-optical switching systems.
关键词： absorption,nonlinear optics,all-optical switch,resonance energy transfer,fluorescence,FRET,optical transistor,multiphoton process,laser action,second harmonic generation
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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Human Neutrophil Elastase Activated Fluorescent Probe for Pulmonary Diseases Based on Fluorescence Resonance Energy Transfer Using CdSe/ZnS Quantum Dots
摘要： There is an increasing demand for effective noninvasive diagnosis against common pulmonary diseases which are rising sharply due to the serious air pollution. Human neutrophil elastase (HNE), a typical protease highly involved in pulmonary inflammatory diseases and lung cancer, is a potential predictor for disease progression. Currently, few of HNE-targeting probes is applicable In Vivo due to the limitation in sensitivity and biocompatibility. Herein we reported the achievement of In Vitro detection and In Vivo imaging of HNE, by incorporating the HNE-specific peptide substrate, quantum dots (QDs) and organic dyes into the fluorescence resonance energy transfer (FRET) system. The refined nanoprobe, termed as QDP, could specifically measure the HNE with excellent sensitivity of 7.15 pM at aqueous solution, and successfully image the endogenous and exogenous HNE in living cells. In addition, this nanoprobe enabled the HNE imaging in the mouse models of lung cancer and acute lung injury, and continuously monitored the HNE activity at high temporal and spatial resolution. Most importantly, QDP successfully discriminated the serums of patients with lung diseases from those of the healthy controls based on the HNE activity determination. Overall, this study demonstrates the advantages of FRET system-based nanoprobe in imaging performance and provides an applicable tool for In Vivo HNE detection and pulmonary diseases diagnosis.
关键词： human neutrophil elastase,quantum dots,pulmonary diseases,lung cancer,fluorescence resonance energy transfer
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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Energy Transfer and Spectroscopic Investigation of Dy2O3 Doped Li2O–BaO–GdF3–SiO2 for White Light LED
摘要： LGFDy glasses doped with Dy2O3 (0.1, 0.5, 1.0, 1.5 and 2.0 mol %) were synthesised by conventional melt quenching method and various properties are studied by absorption, Judd–Ofelt analysis, photoluminescence, X-ray excited luminescence, decay curve and CIE color chromaticity measurement. Judd-Ofelt parameters (?2, ?4 and ?6) are valuated form JO theory in order to estimate the radiative parameters of the Dy3+ ion excited states. For white light emission, Yellow/Blue (Y/B) ratio and CIE color coordinates for glasses under study are measured from the emission spectra. The energy transfer from Gd3+ to Dy3+ ions has been studied by exciting the glass with 275 nm photon. The higher value of σ (λp) and βR for 4F9/2 → 6H13/2 transition indicates its more potential use in laser application in yellow region. The correlated color temperature for LGFDy glasses is found to be 4264 K. The decay profile of fluorescent level 4F9/2 for different concentration of Dy3+ ions in the present glasses changes to non-exponential from single-exponential for higher concentration (≥0.5 mol %) of Dy3+ ions. Thus the chemical composition of glass and dopant (Dy3+ ions) concentration strongly influence the energy transfer mechanism. The lifetime non-exponential behavior is well fitted to IH-model for S = 6. The quantum efficiency for LBGFDy05 glass is found to be 86%. The systematic investigation signifies the potential of the studied LGFDy glasses for the laser and white light generation application.
关键词： silicate glasses,dysprosium,decay time,energy transfer,resonance energy transfer
更新于2025-09-19 17:13:59
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Enhancing the organic solar cell efficiency by combining plasmonic and F?rster Resonance Energy Transfer (FRET) effects
摘要： Here, we combine two strategies i.e., F€orster resonance energy transfer and plasmonic effect, to enhance the photovoltaic performance in organic solar cells by introducing gold nanoparticles and squaraine in a binary mixture of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester. In this configuration, the F€orster resonance energy transfer between poly(3-hexylthiophene) and squaraine reduces the electrical loss arising from the exciton recombination in poly(3-hexylthiophene), while gold nanoparticles enable an efficient charge carrier generation in poly(3-hexylthiophene):squaraine mixture as optically confirmed by photoluminescence measurement and transient absorption spectroscopy. The multicomponent organic solar cells demonstrate an enhancement of ~36% in power conversion efficiency over the reference device.
关键词： Organic solar cells,Plasmonic effect,Squaraine,Gold nanoparticles,F€orster resonance energy transfer
更新于2025-09-19 17:13:59
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Principles, mechanisms, and application of carbon quantum dots in sensors: a review
摘要： The Carbon quantum dots (CQDs) as an emerging class of quantum dots (QDs) with advantages such as good photoluminescence (PL) properties, easy synthesis routes, economical synthesis, cheap starting materials, water-solubility, low level of toxicity, chemical stability, and easy functionalization have received great attention during recent years. The CQDs have been used in versatile sensor applications. The CQDs sensors could be ultimately sensitive, and the limit of detection (LOD) for these sensors can reach the nanomolar, picomolar or even femtomolar ranges. The CQDs-based sensors and biosensors work with different mechanisms including fluorescence quenching, static quenching, dynamic quenching, energy transfer, inner filter effect (IFE), photo-induced electron transfer (PET), and fluorescence resonance energy transfer (FRET). The CQDs-based sensors and biosensors have been applied for detection of different species such as metal ions, acids, proteins, biothiols, polypeptides, DNA and miRNA, water pollutants, hematin, drugs, vitamins, and other chemicals. It seems that the CQDs-based sensors and biosensors are promising candidates for high performance and yet accurate sensors in different areas. In this review, the CQDs are introduced, and the synthesis methods and optical properties of the CQDs are discussed. Different types of CQDs-based sensors and biosensors and their working mechanisms are clarified.
关键词： Carbon quantum dots,Sensors,Electrochemiluminescence,Photoluminescnece,Chemiluminescence,Fluorescence resonance energy transfer
更新于2025-09-19 17:13:59