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Facile synthesis of yellow emissive carbon dots with high quantum yield and their application in construction of fluorescence-labeled shape memory nanocomposite
摘要： Synthesizing carbon dots (CDs) with efficient long-wavelength emissions (i.e., yellow- to red light) generally suffer from sophisticated approaches, time-consuming process, harsh conditions, and requirement of organic solvent; also, a further limitation of the resulting CDs is relatively low quantum yield (QY) in aqueous solution. Herein, novel yellow emitting CDs (Y-CDs) with a considerable QY of 62.8% were synthesized from a precursor comprising resorcinol and o-phenylenediamine via a facile microwave method. To probe the fluorescence mechanism, another typical resorcinol-derived CDs using ethylenediamine as dopant were fabricated as well, showing strong green emission with an absolute QY of 60.6%. Spectroscopic and structural characterizations indicated that the distinct redshift of green to yellow emission depended on the dimension of conjugated sp2-domain and the content of graphitic N heavily, while the excellent QY was highly related to the low proportion of defective sp2 carbon cluster and high nitrogen content within CDs. Moreover, the Y-CDs were confirmed to be capable of introducing additional crosslinking points in poly(vinyl alcohol) (PVA) polymer, which resulted in the Y-CDs-contained nanocomposite behaving superior and tunable water-induced shape recovery performances. Importantly, since being labeled with long-wavelength emission, the responsiveness of PVA/Y-CDs composite will contribute to its versatile utilization in biology-relevant fields.
关键词： shape recovery,fluorescence mechanism,yellow emission,carbon dots,nanocomposite
更新于2025-11-14 15:23:50
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AuxAg1-x Nanocomposites with 40-Fold Emission Enhancement Formed by the Electrostatic Assembly of Gold Nanoclusters and Silver Nanoclusters for Bioimaging and Bioanalysis
摘要： Noble metal nanoclusters (NCs) have been widely used in bioimaging and bioanalysis due to their unique molecular-like structures and good biocompatibility. Bright nanomaterials with high quantum yields are in need for widespread applications. Unfortunately, the weak photoluminescence (PL) of metal NCs hampers their biomedical applications, and thus it is urgent to develop effective routes to enhance their brightness, especially in aqueous solutions. In this work, we reported a facile strategy to prepare highly luminescent AuxAg1-x nanocomposites (x: molar ratio of Au) by electrostatic-induced assembly of non-luminescent glutathione (GSH) stabilized silver NCs (GSH-Ag NCs) and weak orange-emitting GSH stabilized gold NCs (GSH-Au NCs) in aqueous solutions. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), UV-vis absorption spectroscopy and dynamic light scattering (DLS) shed light on the mechanism of PL enhancement. It was found that the positively charged gold nanoclusters and the negatively charged silver nanoclusters formed aggregates by electrostatic force, leading to a 40-fold fluorescence intensity enhancement compared with GSH-Au NCs. This was a novel method to strengthen the fluorescence of nanoclusters with such large enhancement in aqueous solutions. With the molar ratio of Au and Ag changing from 80:1 to 2:3, the emission maximum of the AuxAg1-x nanocomposites could be tuned from 590 to 548 nm. The electrostatic force of the Au0.50Ag0.50 nanocomposites enabled them to respond to pH. The Au0.50Ag0.50 nanocomposites were fluorescent turn-on and turn-off at pH 2.6 and pH 7.5, respectively. In this respect, they can be used as a fluorescent switch and be further used as a general recyclable pH probe in the range of 2.6-7.5. This work will inspire even better strategies to further improve the brightness of noble metal NCs.
关键词： nanocomposites,fluorescent switch,electrostatic force,silver nanoclusters,fluorescence enhancement,gold nanoclusters
更新于2025-11-14 15:23:50
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Aggregation-induced emission (AIE)-active highly emissive novel carbazole-based dyes with various solid-state fluorescence and reversible mechanofluorochromism characteristics
摘要： Three new carbazole-based fluorescent molecules 1-3 functionalized with tetraphenylethene have been successfully synthesized, and these compounds have high thermal stability, and they exhibited different fluorescence in solid states with the superior luminescence quantum yields of 99.04% (1), 98.90% (2) and 39.83% (3). Their aggregation-induced behaviors were explored by the study of photoluminescence spectroscopy. The results showed that luminogens 1-3 exhibited remarkable aggregation-induced emission effect. Furthermore, their distinct mechanical stimulus-responsive fluorescence characteristics were also surveyed by solid-state photoluminescence spectroscopy. Interestingly, the various emitting colors of these luminogens could be changed into the same green, and the repeatabilities of their mechanochromic luminescence behaviors were outstanding, and the powder X-ray diffraction results indicated that the reversible conversion from a crystalline to an amorphous state was responsible for the obvious mechanofluorochromism phenomena of compounds 1-3. This work will be valuable for the exploitation of mechanical-force sensors with typical aggregation-induced emission feature.
关键词： Carbazole,Mechanofluorochromism,Tetraphenylethene,Aggregation-induced emission,Different fluorescence,High thermal stability
更新于2025-11-14 15:23:50
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Glutaraldehyde non-conjugated chitosan polymer fluorophores for selective determination of picric acid via fluorescence resonance energy transfer strategy
摘要： Water-dispersed glutaraldehyde (GA) non-conjugated chitosan polymer fluorophores (GCPF) with quantum yield of 16 % is synthesized by stirring chitosan and GA for 6 h at room temperature in the present work. It is a facile and mild method and fluorescent GCPF can be stabled for two months. Owing to the spectral overlap of fluorescent spectrum of GCPF and absorption spectrum of picric acid (PA), a novel sensitive fluorescent method using fluorescent GCPF for PA detection from 10 nM to 50 μM via fluorescence resonance energy transfer (FRET) strategy is established. The distance between donor of GCPF and acceptor of PA (R0 value) is calculated to be 3.5 nm. FRET method using fluorescent GCPF possesses high sensitivity (LOD of 2.8 nM), and selectivity and fast response within 2 min. Moreover, fluorescent GCPF is also utilized in visual analysis of PA using cotton swabs. Fluorescence quenching effect can be observed by eyes irradiated with 365 nm ultraviolet light at cotton swabs and using GCPF solid on quartz glasses, which paves an effect and wide way for the application of fluorescent GCPF in our daily life.
关键词： Glutaraldehyde non-conjugated chitosan polymer fluorophores (GCPF),picric acid (PA),fluorescence resonance energy transfer (FRET),glutaraldehyde (GA),chitosan
更新于2025-11-14 15:23:50
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Analysis of Fluorescence and Biodegradability of Wastewater
摘要： Three-dimensional fluorescence spectrometer was adopted for the content analysis of different types of organics in coking wastewater before biochemical treatment and through biochemical treatment, and the model of parallel factors was employed to analyze fluorescence components and contents. It was found that tryptophan-like components were the most easily degraded by biology, while humic-like components were the least easily degraded. Meanwhile, it had been seen that the change trends over time of total fluorescence densities of proteinoid fluorescence, and degradable organic fluorescence were highly consistent with that of parameter values of COD, NH3-N in this wastewater after analyzing the trends of the two indexes. It was proved that the three-dimensional fluorescence spectrum method was appropriate for the accurate degradation analysis of wastewater components.
关键词： Coking wastewater,Analysis and evaluation,Biodegradation,Parallel factors model,Three-dimensional fluorescence spectrum
更新于2025-11-14 15:23:50
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Sexing of chicken eggs by fluorescence and Raman spectroscopy through the shell membrane
摘要： In order to provide an alternative to day-old chick culling in the layer hatcheries, a noninvasive method for egg sexing is required at an early stage of incubation before onset of embryo sensitivity. Fluorescence and Raman spectroscopy of blood offers the potential for precise and contactless in ovo sex determination of the domestic chicken (Gallus gallus f. dom.) eggs already during the fourth incubation day. However, such kind of optical spectroscopy requires a window in the egg shell, is thus invasive to the embryo and leads to decreased hatching rates. Here, we show that near infrared Raman and fluorescence spectroscopy can be performed on perfused extraembryonic vessels while leaving the inner egg shell membrane intact. Sparing the shell membrane makes the measurement minimally invasive, so that the sexing procedure does not affect hatching rates. We analyze the effect of the membrane above the vessels on fluorescence signal intensity and on Raman spectrum of blood, and propose a correction method to compensate for it. After compensation, we attain a correct sexing rate above 90% by applying supervised classification of spectra. Therefore, this approach offers the best premises towards practical deployment in the hatcheries.
关键词： Raman spectroscopy,sexing,chicken eggs,fluorescence spectroscopy,shell membrane
更新于2025-11-14 15:18:02
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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
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Multi-stimuli Responsive Supramolecular Gels Based on a D-π-A Structural Cyanostilbene Derivative with Aggregation Induced Emission Properties
摘要： Developing multi-stimuli responsive fluorescent gel materials in a single system remains challenging. Gelator molecules with classical fluorophores suffer from aggregation-caused quenching (ACQ) effect, limiting their applications further. Herein, a novel V-shaped cyanostilbene-based molecule (BAPBIA) with aggregation induced emission (AIE) characteristics and great gelation ability was synthesized and was found to exhibit multi-stimuli responsive behaviors. Reversible gel-sol phase transitions together with emission quenching are realized in response to external stimuli including heating, light and fluoride ion. Especially, the introduction of dimethylaniline group (donor) and cyano group (acceptor) generates a D-π-A structure, further leading to an intramolecular charge transfer (ICT) effect, which enlarges the emission contrast with the variations of the distribution of charge. Thus, upon trifluoroacetic acid (TFA) triggered protonation of dimethylaniline group, not only gel-sol transition but also emission color switching (yellow-to-blue) is achieved due to the loss of the ICT effect. This work paves an easy way to construct fully reversible multi-stimuli responsive fluorescence modulation smart materials.
关键词： supramolecular gels,aggregation induced emission,multi-stimuli responsive,fluorescence switching,cyanostilbene derivative
更新于2025-11-14 15:14:40
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Novel BODIPY-conjugated amino acids: Synthesis and spectral properties
摘要： Three BODIPY-based conjugates with lysine, methionine, and tryptophan bound via amino group were synthesized and characterized. Spectral properties of the compounds were studied and a number of photophysical characteristics were obtained. Bioconjugates investigated are water soluble, which makes them promising markers for various bioobjects.
关键词： conjugation,fluorescence,BODIPY,amino acids,markers
更新于2025-11-14 15:14:40
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Temperature sensitive properties of Eu2+/Eu3+ dual-emitting LaAlO3 phosphors
摘要： In this study, Eu2+/Eu3+ coexisting perovskite LaAlO3 phosphors were synthesized by a traditional high-temperature solid-phase reaction method and investigated via X-ray diffraction data, X-ray photoelectron spectroscopy and temperature-dependent photoluminescence spectra. The Eu2+/Eu3+ coexisting LaAlO3 phosphors exhibit excellent optical temperature sensing characteristics and are potential inorganic materials for temperature detection. The measured maximal absolute temperature sensitivity reaches 0.014 K-1, and the corresponding largest relative temperature sensitivity is 1.193% K-1, which are superior to most of previous reports of that. Meanwhile, the monitored signal peaks are well separated, providing a good signal discriminability. The energy level crossover relaxation of Eu2+ and Struck-Fonger crossover process involving O2–-Eu3+ charge transfer band were used to explain the different temperature-dependent responses of Eu2+ and Eu3+. This work may give new ideas for the future research of optical thermometric materials with high sensitivity and high discriminability.
关键词： Fluorescence intensity ratio,Charge transfer band,Thermometry phosphor,LaAlO3
更新于2025-11-14 15:13:28