Yellow Fluorescence Research Articles

Ratiometric fluorescence determination of carbon disulfide in water using surface functionalized carbon dots

Trace level of CS2 in water causes a serious threat to the environment and living organisms. Thus, the development of reliable methods for its sensitive detection is quite necessary. Herein, we design a dual-emission platform composed of blue and yellow emissive carbon dots (B-CDs and Y-CDs) for ratiometric fluorescence determination of CS2. B-CDs, serving as the indicator, are functionalized by hydrophilic polyethylenimine groups on the surface, which can react with CS2 to produce hydrophobic dithiocarbamate moieties, resulting in the aggregation of nanoparticles and quenching of blue fluorescence. In contrast, Y-CDs without polyethylenimine groups exhibit no reactivity toward CS2 and act as the internal reference. With the increase of CS2 concentration, the blue fluorescence of the sensing platform at 461 nm continually drops, but the yellow fluorescence at 560 nm keeps nearly constant. Correspondingly, the vivid color change from blue-white to yellow can be observed by the naked eyes, realizing the visual detection. There is a linear relationship between the fluorescence intensity ratio (I461/I560) and CS2 concentration in the range of 7.7–1400 μM. The detection limit is as low as 2.3 μM. Furthermore, the sensing platform is successfully applied to monitor CS2 in real water, validating its good practicability.

Synthesis, structure and mechanofluorochromic properties of phenothiazine-S-oxide and phenothiazine-S,S-dioxide derivatives

In this work, two novel luminescent molecules containing distorted phenothiazine-S-oxide and phenothiazine-S,S dioxide skeletons were synthesized by oxidation reactions using different oxidants (m-chloroperoxybenzoic acid, acetic acid /hydrogen peroxide). The target compounds were all confirmed by 1H NMR, 13C NMR and EI-MS. Combined with the results of UV–vis absorption spectra and fluorescence emission spectra, we found that the different oxidation states of S-atom, from sulfide (+2) to sulfoxide (+4) and sulfone (+6), led to the blue, yellow-green and yellowish fluorescence of these compounds in the solid states. Subsequent studies showed that the molecule containing the phenothiazine-S-oxide skeleton exhibited obvious solvatochromism, and the increase of solvent polarity induced a red-shift in the emission wavelength. Moreover, this molecule also exhibited a rare self-recovery mechanochromatic behavior. In addition, these properties were further confirmed by theoretical calculations and X-ray single-crystal diffraction analysis.

Full-Color Emissive D-D-A Carbazole Luminophores: Red to Near-Infrared Mechanofluorochromism, Aggregation-Induced Near-Infrared Emission, and Photodynamic Therapy Application.

The preparation of multi-functionalized luminophores with full-color emission based on an identical core skeleton is a significative but challenging research topic. In this work, eight donor-donor-acceptor (D-D-A) type luminogens based on a central carbazole core bearing a hydrocarbon chain of six carbon atoms are designed by using different kinds of donor and acceptor units on the left and on the right and synthesized in good yields. These D-D-A carbazole derivatives display deep-blue, sky-blue, blue-green, green, yellow-green, yellow, orange and red fluorescence in the solid state, respectively, achieving full-color emission covering the whole visible light range under UV light illumination. Notably, dicyano-functionalized triphenylamine-containing carbazole derivative exhibits rare aggregation-induced near-infrared emission and red to near-infrared mechanofluorochromism with high contrast beyond 100 nm. Furthermore, red emissive luminogen can serve as a potential candidate for cell imaging and photodynamic therapy (PDT). The present work not only provides reference for the construction of full-color emissive systems but also opens a new avenue to the preparation of multi-functionalized luminophores capable of simultaneously applying in near-Infrared mechanical-force sensors and PDT fields.

F, N co-doped carbon nanomaterials for multi-level information encryption: Room-temperature phosphorescence and solid-state fluorescence

The non-radiative transition of triplet excitons limits the emission of room-temperature phosphorescence (RTP). In this paper, F, N co-doped carbon nanomaterials including carbon dot solutions (L-CDs) with cyan fluorescence and solid-state carbon nanowires (S-CNWs) with yellow fluorescence were successfully prepared by the one-pot hydrothermal method. Interestingly, L-CDs@PVA composites with green RTP were obtained by mixing L-CDs with PVA. The RTP production was attributed to F, N related heteroatomic functional groups on the surface of L-CDs. The C-N, CN bonds form lone electron pairs, which promote the electron transition from n→π∗. The F doping reduces the energy gap from the single to the triplet state, which facilitates the inter-system crossing (ISC) process and increases the radiative transition of the triplet exciton to produce RTP. In addition, PVA forms abundant hydrogen bonds with L-CDs to effectively immobilize the luminescence center and isolate atmospheric oxygen, so that L-CDs@PVA has stable phosphorescence emission at room temperature and this phosphorescence is reversible in dry and wet states. In contrast, S-CNWs displayed solid-state yellow fluorescence, but no phosphorescence even though doped into the PVA matrix (S-CNWs@PVA). Therefore, based on the different characteristics of fluorescence and phosphorescence of L-CDs and S-CNWs, a complex, multi-level information encryption method is proposed and the potential applications of S-CNWs powder for fingerprint recording are explored.

Synthesis, Structures, and Properties of π-Extended Phosphindolizine Derivatives.

Dibenzo[b,g]phosphindolizine oxide and three types of benzo[e]naphthophosphindolizine oxides have been synthesized by the ring-closing metathesis of benzo[b]phosphole oxide and naphthophosphole oxides with two olefin tethers. Their molecular structures and properties were revealed by X-ray crystallographic analysis, UV-vis spectroscopy, and electrochemical analysis. The number and position of the benzene rings were found to alter the structural geometry and the HOMO/LUMO energy levels, and their effects were investigated by theoretical calculations. Among the phosphindolizine oxide derivatives investigated, only benzo[e]naphtho[2,3-b]phosphindolizine oxide with the naphthalene ring fused at 2,3-positions showed weak yellow fluorescence with a large Stokes shift.

Dual-template molecularly surface imprinted polymer on fluorescent metal-organic frameworks functionalized with carbon dots for ascorbic acid and uric acid detection

In this work, dual-template molecularly imprinted polymer surfaces imprinted on blue fluorescent Cr-based MOF (Cr-MOF) functionalized with yellow emissive carbon dots (Y-CDs) were prepared using l-ascorbic acid (AA) and uric acid (UA) as templates for simultaneous selective recognition of AA and UA. The as-prepared nanocomposite probe (Y-CDs/Cr-MOF@MIP) contains two recognition site cavities and emits a dual well-resolved fluorescence spectra when excited at 390 nm; blue emission (λem 450 nm) is due to Cr-MOF, and yellow emission (λem 560 nm) is due to Y-CDs. The yellow fluorescence emission of Y-CDs was quenched upon the addition of ascorbic acid, while Cr-MOF’s emission remained unaffected. In the same way, the blue fluorescence emission of the Cr-MOFs was quenched in the presence of uric acid, while the yellow emission remained constant. Both emissions were quenched in a sample containing both AA and UA. This can be exploited to design a dual-template biosensor to detect UA and AA simultaneously. The Y-CDs/Cr-MOF@MIP sensor displayed a dynamic linear response for AA in the range 25.0 µM – 425.0 µM with a detection limit of 1.30 µM, and for UA in the range 25.0 µM – 425.0 µM with a detection limit of 1.10 µM. The dual-target probe Y-CDs/Cr-MOF@MIP was highly selective and sensitive for the detection of UA and AA in human urine samples due to the selectivity of the two recognition sites.

Synthesis and mechanochromic investigations of new cyanopyridone derivatives

In the present work, four new cyanopyridone derivatives bearing terminal long chain alkyloxy substituents were designed and synthesized. All the synthesized target compounds were characterized by IR, NMR and Mass spectrometry. Further, their optical properties were examined in their solution state. The optical study showed that all the compounds can exhibit blue emissive behavior in their solution state and yellow fluorescence in the solid state. Furthermore, the long-tailed target compound showed intriguing fluorescence properties under the applied mechanochromic stimuli. Finally, a simple method of grinding-fuming process confirmed the morphological changes occurring in the studied compound which further resulted in the enhancement of its emission property.

Multi-dimensional dynamic fluorescence readout from laser engineered In2O3 nanowire micropatterns

A laser-irradiated array of In2O3 nanowires presents yellow and blue fluorescence states that can be dynamically altered under UV light for anti-counterfeiting features based upon microscale patterning, color evolution and time-domain encoding.

A fluorescence-based sweat test sensor in a proof-of-concept clinical study for COVID-19 screening diagnosis.

During the corona virus disease 2019 (COVID-19) pandemic period, rapid screening of covid-19 patients has been of great interest by developing a fluorescent sensor for complexation with nonanal, which is a marker for Covid-19 detection in sweat. Solid phase micro-extraction gas chromatography-mass spectrometry (SPME GC-MS) was initially used to quantify nonanal in armpit sweat samples based on an external calibration curve. A sample containing a nonanal content above the threshold of 1.04 μL is expected to be COVID-19 positive with a sensitivity and specificity of 87% and 89%, respectively, validated by comparison with RT-PCR results. For more practical applications, helicene dye-encapsulated ethyl cellulose, namely EC@dyeNH, was applied to screen 140 sweat samples collected from the foreheads of volunteers. The mixed sensor and sweat solution droplets were then visualized and imaged under blacklight. The COVID-19 positive droplets exhibited yellow fluorescence emission, the brightness of which could be measured by using ImageJ in the grey scale. With the optimum color intensity of >73 for positive results, the screening performance was observed with a sensitivity and specificity of 96% and 93%, respectively. The overall test time of this method is approximately less than 15 min. This alternative method offers a promising practical screening approach for the diagnosis of COVID-19 in sweat.

Engineering a Yellow Thermostable Fluorescent Protein by Rational Design.

Thermal green protein (TGP) is an extremely stable, highly soluble synthetic green fluorescent protein. The quantum yield of TGP is lower than the closest related natural fluorescent protein, monomeric Azami-Green. We improved the thermal recovery of TGP through the introduction of a chromophore mutation, Q66E. Furthermore, we developed a yellow thermal protein (YTP) via mutation of histidine 193 to tyrosine. Incorporation of Q66E into YTP (YTP-E) improved chemostability and pH stability. Both YTP and YTP-E have superior thermostability compared to TGP or TGP-E. These proteins offer a new option for green or yellow fluorescence under harsh chemical or thermal conditions.

AIE biofluorescent probe based on twisted cucurbit[14]uril for the detection of Fe(CN)63- anion in solutions and live kidney cells

The kidney is one of the important organs for removing metabolites to maintain the stability of the internal environment. In this study, an AIE effect supramolecular fluorescent probe (TPAPy@tQ[14]) was constructed based on twisted cucurbit[14]uril (tQ[14]) and a triphenylamine derivative (TPAPy) through host-guest interaction. TQ[14] could effectively inhibit the rotation of the TPAPy molecule, which triggered the AIE effect. This effect was manifested as the emission of bright yellow fluorescence. TPAPy@tQ[14] could ultrasensitively detect potential cyanide (K3[Fe{CN}6]) in an aqueous solution at a detection limit as low as 3.28 × 10−7 M. The unique nature of the positive charge of TPAPy@tQ[14] could rapidly cross the glomerular filtration barrier into HK-2 cells. In addition, this probe was successfully applied to distinguish excess Fe(CN)63− in HK-2 cells for cell imaging, providing a new detection method for early clinical identification of acute kidney injury (AKI).

Novel 2-Benzo[d]thiazolyl-4-quinolinylphenol Skeleton-Based Turn-on Fluorescent Probe for H2S Detection and its Multiple Applications in Water Environment, Foodstuffs, and Living Organisms.

Hydrogen sulfide (H2S) has comprehensive contributions to maintaining the normal operation and stability of organisms, and it also occurs in the wastewater environment and is related to the deterioration of foodstuffs. Therefore, developing high-sensitive detection techniques for tracing H2S is promising and meaningful. Inspired by this, a novel nopinone-based fluorescent probe NPS for the recognition of H2S was designed and synthesized with excellent sensitivity, low limit of detection (79 nM), good selectivity, and wide pH range (5-9). NPS could emit strong yellow fluorescence and its emission intensity showed a remarkable augmentation at 520 nm upon the supplement of H2S. Furthermore, the recognition mechanism of NPS for H2S was verified by the HRMS analysis, 1H NMR spectra titration, and DFT computation. What is more, NPS also had broad applications in the monitoring of real water samples, red wine, beer, and eggs samples, which showed its development prospect and value in environmental pollution, foodstuffs quality analysis fields. NPS also was applied to monitor trace exogenous H2S and bioimaging in living cells and zebrafish.

Dual-emissive carbonized polymer dots for the ratiometric fluorescence imaging of singlet oxygen in living cells

Singlet oxygen (1O2) is a type of reactive oxygen species (ROS), playing a vital role in the physiological and pathophysiological processes. Specific probes for monitoring intracellular 1O2 still remain challenging. In this study, we develop a ratiometric fluorescent probe for the real-time intracellular detection of 1O2 using o-phenylenediamine-derived carbonized polymer dots (o-PD CPDs). The o-PD CPDs possessing dual-excitation-emission properties (blue and yellow fluorescence) were successfully synthesized in a two-phase system (water/acetonitrile) using an ionic liquid tetrabutylammonium hexafluorophosphate as a supporting electrolyte through the electrolysis of o-PD. The o-PD CPDs can act as a photosensitizer to produce 1O2 upon white LED irradiation, in turn, the generated 1O2 selectively quenches the yellow emission of the o-PD CPDs. This quenching behavior is ascribed to the specific cycloaddition reaction between 1O2 and alkene groups in the polymer scaffolds on o-PD CPDs. The interior carbon core can be a reliable internal standard since its blue fluorescence intensity remains unchanged in the presence of 1O2. The ratiometric response of o-PD CPDs is selective toward 1O2 against other ROS species. The developed o-PD CPDs have been successfully applied to monitor the 1O2 level in the intracellular environment. Furthermore, in the inflammatory neutrophil cell model, o-PD CPDs can also detect the 1O2 and other ROS species such as hypochlorous acid after phorbol 12-myristate 13-acetate (PMA)-induced inflammation. Through the dual-channel fluorescence imaging, the ratiometric response of o-PD CPDs shows great potential for detecting endogenous and stimulating 1O2in vivo.

Petrographical and geochemical investigation on maturation and primary migration in intact source rock micro-plugs: Insight from hydrous pyrolysis on Woodford Shale

This study proposes a new approach to investigate primary migration in petroleum source rocks under laboratory conditions. It was conducted on organic carbon-rich, type II kerogen-bearing Upper Devonian-Lower Mississippian Woodford Shale. Hydrous pyrolysis was performed on polished source rock micro-plugs at different temperatures. Maceral characteristics are observed before and after the different pyrolysis experiments. Applying this new approach, in situ maceral changes at different maturities are directly visualized at the exact same place after artificial maturation at 300 °C, 320 °C, 330 °C, and 340 °C for 24 h. After each heating step, the surface was cleaned with dichloromethane. The bitumen adsorbed to some of the Tasmanites surfaces leads to the brighter fluorescence color after chemical extraction. Leiosphaeridia alginites are less stable than Tasmanites; they first expand and then shrink during thermal evolution partly leaving empty holes in the matrix. Tasmanites keep a strong yellow fluorescence and start to bituminize at the edge of the particles. Liptodetrinite shows significantly decreasing fluorescence intensities already at low pyrolysis temperature (320 °C) and disappears to a great extent at 330 and 340 °C.

Preparation of fluorescein-modified polymer dots and their application in chiral discrimination of lysine enantiomers.

Fluorescein-functionalized fluorescent polymer dots (F-PDs) were prepared by a facile one-pot method by magnetic stirring under mild conditions based on carboxymethylcellulose (CMC) and fluorescein as the precursors. The obtained F-PDs exhibited a nanoscale size of 3.2 ± 1.1nm, excellent water solubility, and bright yellow fluorescence emission with a fluorescence quantum yield of 12.0%. The fluorescent probe displays rapid and sensitive chiral discrimination for lysine focused on different complexation abilities between lysine enantiomers and Cu2+. The concentration of L-lysine in the range4 to 14mM (R2 = 0.997) wasmeasured by the fluorescence intensity ratio (I513/I429); the exitation wavelength was set to λex = 365nm. The detection limit was 0.28mM (3σ/slope). Importantly, this sensor accurately predicted the enantiomeric excess (ee) of lysine enantiomers at the designed concentration (lysine: 20mM; Cu2+: 10mM) ranges. Theproposed sensor was successfully applied to determineL-lys (recovery: 95.8-101%; RSD: 0.465-3.34%) and ee values (recovery: 98.5-102%; RSD: 2.61-3.21%) in human urine samples using the standard addition method.

Aggregation-Induced Emission Metallocuboctahedra for White Light Devices.

Materials for organic light-emitting devices which exhibit superior emission properties in both the solution and solid states with a high fluorescence quantum yield have been extensively sought after. Herein, two metallocages, S1 and S2, were constructed, and both showed typical aggregation-induced emission (AIE) features with intense yellow fluorescence. By adding blue-emissive 9,10-dimethylanthracene, pure white light emission can be produced in the solution of S1 and S2. Furthermore, due to the remarkable AIE feature and good fluorescence quantum yield in the solid state, metallocages are highly emissive in the solid state and can be utilized to coat blue LED bulbs or integrate with blue-emitting chips to obtain white light. This study advances the usage of metallocages as practical solid-state fluorescent materials and provides a fresh perspective on highly emissive AIE materials.

In Situ Formation of o-Phenylenediamine Cascade Polymers Mediated by Metal-Organic Framework Nanozymes for Fluorescent and Photothermal Dual-Mode Assay of Acetylcholinesterase Activity.

A fluorescent and photothermal dual-mode assay method was established for the detection of acetylcholinesterase (AChE) activity based on in situ formation of o-phenylenediamine (oPD) cascade polymers. First, copper metal-organic frameworks of benzenetricarboxylic acid (Cu-BTC) were screened out as nanozymes with excellent oxidase-like activity and confinement catalysis effect. Then, an ingenious oPD cascade polymerization strategy was proposed. That is, oPD was oxidized by Cu-BTC to oPD oligomers with strong yellow fluorescence, and oPD oligomers were further catalyzed to generate J-aggregation, which promotes the formation of oPD polymer nanoparticles with a high photothermal effect. By utilizing thiocholine (enzymolysis product of acetylthiocholine) to inhibit the Cu-BTC catalytic effect, AChE activity was detected through the fluorescence-photothermal dual-signal change of oPD oligomers and polymer nanoparticles. Both assay modes have low detection limitation (0.03 U L-1 for fluorescence and 0.05 U L-1 for photothermal) and can accurately detect the AChE activity of human serum (recovery 85.0-111.3%). The detection results of real serum samples by fluorescent and photothermal dual modes are consistent with each other (relative error ≤ 5.2%). It is worth emphasizing that this is the first time to report the high photothermal effect of oPD polymers and the fluorescence-photothermal dual-mode assay of enzyme activity.

Aggregation-induced emission active salicylaldehyde hydrazone with multipurpose sensing applications

In this manuscript, the aggregation-induced emission (AIE) behaviour of a Schiff base salicylaldehyde hydrazone (SH) was investigated in DMSO-HEPES mixed solvents. The non-fluorescent SH in pure DMSO becomes a highly yellow-luminescent SH upon increasing the HEPES fraction ≥ 70 % in DMSO. The results of UV–vis, DLS, and SEM investigations supported the formation of SH self-aggregates, which inhibited the intramolecular rotation of SHand activated the excited state intramolecular proton transfer (ESIPT) mechanism toemit a bright yellow fluorescence at 535 nm. The AIEgen SH was applied for the sensing of cations, aldehydes, and nitroaromatics in HEPES buffer (5 % DMSO, 10 mM, pH 7.4) medium. The fluorescence of AIEgen SH was quenched by Cu2+, 2-hydroxy-5-nitrobenzaldehyde, and para-nitrophenol with a limit of detection of 3.74, 0.76, and 1.52 µM, respectively, among the other tested metal ions, aldehydes, and nitroaromatics. The cotton buds coated with the AIEgen SH were designed for the qualitative visual detection of Cu2+. The AIEgen SH was also employed for the detection of Cu2+ in mung bean sprouts. Moreover, the AIEgen SH was used to quantify the selectiveanalytes in a real environmental water sample. Additionally, the AIEgen SH was employed to make yellow fluorescent gel and to visualize latent fingerprints (LFPs) on a non-porous glass slide.

Water-soluble β-cyclodextrin based turn-on amplifying fluorescent probes for sensitive and selective detection of Hg2+/Hg+ ions

In this work, fluorescent β- cyclodextrin (β-CD) based probes containing naphthalimide group were synthesized to realize the specific recognition of Hg2+/Hg+ in aqueous system. Firstly, three small fluorescent molecules (N1, N2 and N3) with -NH2 groups were synthesized from 4-bromo-1, 8-naphthalene anhydride. Secondly, CHCCH2- group was introduced into β-CD by Williamson ether formation reaction. Finally, the target probes (β-CD-PI, β-CD-PY and β-CD-TP) were obtained by Amino-Yne click reaction. These probes can efficiently recognize Hg2+/Hg+. β-CD-PI emits bright yellow fluorescence after binding with Hg2+/Hg+, which is a turn-on fluorescent probe. When the Hg2+/Hg+ concentration exceeds 26 μM, the fluorescence intensity amplifies sharply (20 folds). The hydrophobic parts of the probes aggregated together to form a micelle-like structure due to complexation with Hg2+/Hg+, resulting in special micelle-sensitizing properties. Meanwhile, the HOMO-LUMO energy levels of the probes were calculated by cyclic voltammetry (CV). The probe is expected to be used for the detection of Hg2+/Hg+ in aqueous solutions without any organic solvents.

Rapid self-calibrating fluorescent detection of copper (II) ions in wine with high accuracy

Excessive copper in wine can cause formation of oxidation reactions and affect the quality of wine. Herein, a rapid self-calibrating fluorescence sensing system for the detection of copper (II) ions in wine was developed. The sensing system has a dual-emission peak of 480 nm and 550 nm at the excitation wavelength of 390 nm. Only the yellow fluorescence can be selectively quenched by copper (II) ions. In contrast, the blue fluorescence stays almost constant, resulting in the apparent change of fluorescence image from yellow to blue. The reaction can be completed within 8 s. The sensing system showed a good linear relationship with copper (II) ions concentration in 0–4 μmol/L, with a detection limit of 46.5 nmol/L. Based on this sensing system, a fluorescent dual-tube detection bottle was designed to detect copper (II) ions more conveniently and was successfully applied to detect copper (II) ions in wine.