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Yb/Er/Tm tri-doped Na3ZrF7 upconversion nanocrystals for high performance temperature sensing
摘要： Non-contact optical thermometry based on fluorescence intensity ratio (FIR) technique has been widely researched over the past few decades. However, the reported systems exhibit two important shortcomings including the existence of a few interferential signals in addition to the required spectral bands for FIR and the absence of internal standard for reference signal. Herein, only two emission bands of Er3+: 4F9/2→4I15/2 (~673 nm) and Tm3+: 3H4 → 3H6 (~800 nm) are achieved in Yb/Er/Tm tri-doped Na3ZrF7 nano-system. Moreover, the upconversion (UC) emission intensity of Er3+ keeps unchanged with the rising of temperature, which is applied as reference signal; while that of Tm3+ enhances evidently, which is applied as temperature signal. The calculated maximum absolute temperature sensitivity (Sa) and relative temperature sensitivity (Sr) are 0.17 K-1 at 393 K and 1.76 %K-1 at 313 K, respectively.
关键词： Na3ZrF7 nanocrystals,self-reference,rare earth ions,temperature sensor,upconversion
更新于2025-11-14 17:04:02
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Benzo[ghi]perylene & Coronene as Ratiometric Reversible Optical Oxygen Nano-Sensor
摘要： The development of novel single molecular probe based optical ratiometric oxygen sensor with simple fabrication, high sensitivity, and linear response is highly desirable. Herein, benzo[ghi]perylene (BzP) and coronene (Cron) were explored as dual-emissive ratiometric oxygen nano-sensor that displayed linear plots at a low probe concentration (6 μM). The sensor fabrication was simple, and the probes exhibited efficient fluorescence quenching of monomer emission by molecular oxygen. However, the excimer emission of probe remained unaffected. Thus a ratiometric method is developed based on the dual emitting luminophore. The method can be used to estimate dissolved oxygen in liquids and 5 – 100 % of oxygen concentration in gaseous mixtures.
关键词： Coronene,Benzo[ghi]perylene,Oxygen sensing,Excimer emission,Ratiometric sensor,Fluorescence probe
更新于2025-11-14 17:04:02
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Determination of Thiourea by On–Off Fluorescence Using Nitrogen-Doped Graphene Quantum Dots
摘要： A thiourea-detecting fluorescence sensor with Hg2t as a switch was developed using nitrogen-doped graphene quantum dots (N-GQDs). The surface of N-GQDs had many organic functional groups on which Hg2t was effectively bound and turned off the fluorescence of the N-GQDs. The fluorescence of N-GQDs was turned on by the thiol functional group of thiourea that bound strongly with Hg2t and formed Hg2t/thiourea complexes. After constructing the sensor, the experimental conditions and parameters, such as the pH and Hg2t concentration, were investigated and optimized. Under the optimum conditions, the constructed fluorescence sensor showed high sensitivity to thiourea at concentrations from 0.5 to 14 mM with a low detection limit of 41.7 nM. The sensor also exhibited high specificity, excellent stability, and good reproducibility so that the determination of thiourea in various samples had acceptable values with good recoveries from 99% to 106%. The relative standard deviation was less than 4.1% (n ? 3).
关键词： thiourea,Fluorescence,nitrogen-doped graphene quantum dots (N-GQDs),Hg2t,sensor
更新于2025-11-14 17:04:02
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S, N co-doped graphene quantum dots-induced ascorbic acid fluorescent sensor: Design, characterization and performance
摘要： In this work, new detection route for ascorbic acid was designed. First, highly luminescent sulfur and nitrogen doped graphene quantum dots (S,N-GQDs) were prepared via simple hydrothermal method using citric acid and thiourea as the C, N and S sources respectively. The prepared S,N-GQDs are characterized by XRD, HRTEM, FTIR, EDS and PL. Investigations showed that prepared S,N-GQDs have a good photostability and excitation-dependent emission fluorescence. Prepared S,N-GQDs showed maximum excitation wavelength and emission wavelength at 400 and 462nm, respectively. In the following, prepared S,N-GQDs were applied as a photoluminescence probe for detection of ascorbic acid (AA). The designed sensor was based on “off-on” detection mode. The developed sensor had a linear response to AA over a concentration range of 10-500μM with a detection limit of 1.2μM. The regression equation is Y = 0.0014 X+1.2036, where Y and X denote the fluorescence peak intensity and AA concentration, respectively.
关键词： Graphene quantum dots,Quantum confinement,Fluorescence sensor,Nanostructures,Water-soluble vitamin,Quenching
更新于2025-11-14 15:32:45
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Highly Selective Optical Detection of Fe <sup>3+</sup> Ions in Aqueous Solution Using Label-Free Silicon Nanocrystals
摘要： Highly brightness amine-terminated silicon nanocrystals (Si NCs) have been utilized in a simple and rapid assay for the highly selective and sensitive detection of Fe3+ via quenching of their strong blue luminescence, without the need for analyte-specific labeling groups. Sensitive detection of Fe3+ is successfully demonstrated, with a linear relationship observed between luminescence quenching and Fe3+ concentration from 5 × 10?6 to 900 × 10?6 m and a limit of detection of 1.3 × 10?6 m. The Si NCs show excellent selectivity toward Fe3+ ions, with no quenching of the luminescence signal induced by the presence of Fe2+ ions, allowing for solution phase discrimination between the ionic species in different charge states.
关键词： nanocrystal,sensor,iron,optical detection
更新于2025-11-14 15:32:45
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N-arylated bisferrocene pyrazole for dual-mode detection of hydrogen peroxide: AIE-active fluorescent “turn on/off” and electrochemical non-enzymatic sensor
摘要： A series of new N?arylated bisferrocene pyrazole (D-π-A-π-D) chromophores have been synthesized by the Chan?Lam cross-coupling (1, 2) and Buchwald–Hartwig amination (3, 4) reactions. The compounds 1-4 were characterized with the aid of analytical and spectroscopic methods. The solvatochromism behaviour of compounds (1, 3) showed positive solvatochromism and later (2, 4) exhibited negative solvatochromism. The compounds 1-4 interestingly showcased high-enhanced fluorescent intensity in their aggregate state while in the solution state they exhibited low fluorescent intensity behaviour. The origin of enhanced emission in the aggregated state is due to a restriction of intramolecular rotation, especially in the ratio of mixture 40:60 (CH3CN/H2O). The aggregation-induced emission(AIE) properties were utilized to detect the H2O2 which show quick response in a linear range of 10-50 μM with a detection limit of 38.8 nM (1) and 15.9 nM (3). Furthermore, the electrochemical reduction of hydrogen peroxide in the same linear range as above showed and a limit of detection (3σ) of 14.4 mM (1) and 11.6 mM (3).
关键词： Dual-mode detection of H2O2,Electrochemical non?enzymatic sensor,AIE-active luminogens
更新于2025-11-14 15:29:11
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Understanding the performance of a paper‐based UV exposure sensor: The photodegradation mechanism of brilliant blue FCF in the presence of TiO <sub/>2</sub> photocatalysts in both the solid‐state and solution
摘要： Rationale: The decolouration of brilliant blue FCF by the action of TiO2 under UV exposure has been recently reported as the basis of a paper-based sensor for monitoring UV sun exposure. The mechanism of brilliant blue FCF photodegradation in the presence of the photocatalyst and the resulting photoproducts are thus far unknown. Methods: The UV initiated photodegradation of brilliant blue FCF in the presence of TiO2 for both the aqueous and the solid state was investigated. Degradation in the solid state was observed using matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-MS). Decomposition of the dye in the aqueous state was analysed using liquid chromatography mass spectrometry (LC/MS) and ultraviolet-visible (UV-Vis) spectroscopy. Results: After UV radiation exposure, the brilliant blue FCF base peak [M1-H+NH4]+ (m/z calc. 766.194 found 766.194) decreased in the LC/MS chromatogram with a concomitant appearance of BB-FCF decomposition products involving the sequential loss of the N-ethyl- and N-methylbenzene sulfonate (MBSA) groups, assigned as [M2+H]+ (-MBSA, calc. 579.163 found 579.162), [M3+H]+ (-MBSA, -Et, calc. 551.131 found 551.131), [M4+H]+ (-2MBSA, calc. 409.158 found 409.158), [M5+H]+ (-2MBSA, -Et, calc. 381.127 found 381.127). Ions [M2+H]+ and [M3+H]+ were also identified in the photodegradation products using MALDI-MS. Observation by UV-vis indicated a decrease in the solution absorbance maxima and an associated blue-shift upon UV exposure in solution. Conclusion: The LC/MS analysis indicated two main oxidation processes. The most obvious was attack of the N-methylene, eliminating either ethyl or MBSA groups. The presence of the hydroxylated decomposition product M13 ([M13+H]+ calc. 595.157, found 595.157) supported this assignment. In addition, the detection of photoproduct M8, proposed to be 3-((ethylamino)methyl)benzenesulfonic acid ([M8+H]+ calc. 216.069 found 216.069), indicates an aryl-oxidative elimination. The absence of the aryl-hydroxy products normally expected to accompany the formation of M8 is proposed to be due to TiO2 binding catechol-like derivatives, which are then removed upon filtration.
关键词： TiO2,UV sensor,Photodegradation,Brilliant blue FCF
更新于2025-11-14 15:25:21
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The Self-Assembly of Cu-In-S Quantum Dots with Aggregation-Induced Emission into 3D Network Triggered by Cation and Its Application as A Novel Metal-Enhanced Fluorescent Nanosensor for Detecting Zn (Ⅱ)
摘要： A novel self-assembly phenomenon triggered by Zn2+ of Cu-In-S quantum dots with aggregation-induced emission effect was presented in this paper. Hydrophilic Cu-In-S quantum dots with aggregation-induced emission effect were successfully prepared. They were monodisperse spherical nanoparticles with the diameter of 2.8 ± 0.4 nm and had weak fluorescence in aqueous solution. However, the solution emitted strong fluorescence after addition of Zn2+. The results of TEM and SEM indicated the monodisperse quantum dots self-assembled into 3D networks of Cu-In-S quantum dots-Zn2+, which hindered the motion of quantum dots. Besides, the Zn2+ in the mixture passivated the surface defects. The phenomenon also proved by florescence lifetime and XPS. Thus the radiation decay decreased and followed by strong fluorescent emission. Interestingly, the degree of aggregation was proportional to the amount of Zn2+ and the fluorescent intensity. Based on this interesting phenomenon, a novel metal enhanced fluorescent nanosensor for detecting Zn2+ was established. The results demonstrated the proposed method had a good selectivity and linearity in the concentration range of 0-800 nmol?L-1 with a limit of detection of 1.99 ppb. These results showed a promising future in the field of metal-enhanced fluorescent probes of the Cu-In-S quantum dots.
关键词： Surface defects,Metal-enhanced sensor,Quantum dots,Restriction of motion,Aggregation-induced emission
更新于2025-11-14 15:23:50
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Lossy Mode Resonance Generation by Graphene Oxide Coatings onto Cladding-Removed Multimode Optical Fiber
摘要： In this work, we have studied the suitability of graphene oxide-based thin films to be not only excellent sensitive coatings but also lossy mode resonance (LMR)-generating materials. Thin films of graphene oxide (GO) and polyethylenimine (PEI) fabricated by means of layer-by-layer assembly were selected in this study. Two optical fiber devices with 8 and 20 bilayers of the LMR-generating coating were fabricated and characterized as refractometers. Both devices show no hysteresis and high sensitivity, improving previously reported values. This research opens very promising and exciting possibilities in the field of optical fiber sensors based on LMR, strategically including specific recognition groups to the device surface to exploit this high sensitivity for monitoring a range of target analytes. The carboxylate functional groups at the edges of the GO sheets should provide excellent attachment sites for the required coupling chemistry to realize such devices.
关键词： optical fiber sensor,thin films,Dip-assisted layer by layer,lossy mode resonance,refractometer,graphene oxide
更新于2025-11-14 15:19:41
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Upconversion fluorescent nanoparticles based-sensor array for discrimination of the same variety red grape wines
摘要： In this research, a novel fluorescent sensor array based on upconversion nanomaterials (UCNPs) for the discrimination of the same variety red grape wines from different manufacturers was developed. The sensor array was composed of six elements: one positively charged UCNPs modified with guanidine groups (UCNPs@GDN), two negatively charged UCNPs modified with sulfonic acid groups (UCNPs@SO3H) and phosphonic acid groups (UCNPs@PO(OH)2), respectively, and their mixture 1 (UCNPs@GDN + UCNPs@SO3H), mixture 2 (UCNPs@GDN + UCNPs@PO(OH)2) and mixture 3 {UCNPs@GDN + UCNPs@SO3H + UCNPs@PO(OH)2}. The discrimination mechanism is mainly attributed to the emission of those upconversion fluorescent nanoparticles being quenched by organic ingredients that usually exist in red grape wines. The discrimination of red grape wines was carried out by employing UCNPs@GDN, UCNPs@SO3H and UCNPs@PO(OH)2 in pH = 7.0 HEPES buffer, the mixture 1 and mixture 2 in pH = 9.0 PBS buffer, and mixture 3 in pH = 6.0 Tris–HCl buffer. Principal component analysis (PCA) of the data obtained from our established array showed obvious distinction among the nine red grape wines from different manufacturers. The present work is expected to inspire more marvellous research in the fields of UCNPs and red grape wines identification.
关键词： red grape wines,fluorescence quenching,sensor array,upconversion nanoparticles,discrimination
更新于2025-11-14 15:18:02