Yellow-green Fluorescence Research Articles

A novel method for non-invasive detection of aflatoxin contaminated dried figs with deep transfer learning approach

Aflatoxins are the most dangerous mycotoxin produced by Aspergillus fungal species, such as Aspergillus flavus and Aspergillus parasiticus, and can cause various health problems, including liver cancer, in humans. Figs and many agricultural products are affected by aflatoxins. It is crucial to detect it before consumption since it is impossible to clean aflatoxin from contaminated foods. Chromatographic methods are considered the gold standard for aflatoxin detection, but these methods are pretty expensive, time-consuming, and destructive. Therefore, various studies have been conducted on non-invasive aflatoxin detection using optical spectroscopic methods. Specifically, aflatoxin-contaminated figs are sorted manually by employees in production facilities using the Bright Greenish Yellow Fluorescence (BGYF) method under ultraviolet (UV) light. However, accurate and safe manual sorting depends on expertise of employees, along with this long exposure time to UV radiation may cause employees skin cancer and eye disorders. This study presents a deep transfer learning-based approach for non-invasive detection and classification of aflatoxin-contaminated dried figs using images captured under UV light. Pre-trained transfer learning models, such as DenseNet, ResNet, VGG, and InceptionNet, are applied to the dataset, but the accuracy of these models does not outperform the other methods that detect aflatoxin with the BGYF method. Therefore, fine-tuning is performed on the models. As a result, training accuracy of 98.57% and validation accuracy of 97.50% is obtained using the DenseNet169 model. The experimental results show that our proposed method achieves the highest accuracy among other methods. Also, the proposed method shows that deep CNN can be used to automatically, rapidly, and effectively detect aflatoxin-contaminated figs.

Visualization of degradation of injectable thermosensitive hydroxypropyl chitin modified by aggregation-induced emission

The reversible thermosensitive hydroxypropyl chitin (HPCH) has been widely investigated for drug delivery, tissue engineering, wound repair and antibacterial hemostasis. To achieve non-invasive and real-time visualization of in vivo degradation of HPCH, aggregation-induced emission fluorogen (AIEgen) was introduced covalently in HPCH in water to obtain thermosensitive fluorescent hydroxypropyl chitin (FHPCH) avoiding using any organic solvent. The obtained fluorescent FHPCH hydrogel showed strong yellow-green fluorescence feature under UV irradiation, enabling visualization of the hydrogel with reversible thermosensitivity and reliable injectability. The in vitro enzymatic degradation study of FHPCH hydrogel showed that the attenuation of fluorescence intensity well matched with hydrogel weight loss. The injection through a 26-gauge needle for real-time fluorescence imaging in mice indeed indicated that AIE modified injectable thermosensitive FHPCH can be used for non-invasive, continuous and real-time visualization and quantitative analysis of in vivo degradation. This provides a new method for non-invasive real-time monitoring of similar implantable materials.

Turmeric Extract as an Alternative Diagnostic Dye for Fluorescein Dye

A true-experimental type of research in which a range of 10%, 20% and 30% of ophthalmic form of a pre-formulated diagnostic dye using crude extract of curcumin and 1.4% polyvinyl alcohol as a solvent. The pre-formulated ophthalmic dye was tested in 9 mice’s as an animal model for corneal ulcer which is induced by direct contact facilitated with 0.9%NaCl for growth of staphylococcus aureus and 3 mice’s serves as control. The degree of irritancy was also considered by doing “Draize-Eye Irritation Test”. The proposed alternative diagnostic dye was compared to the synthetic fluorescein dye in terms of staining, yellowish-green hyper-fluorescence, draining mechanism, and potential ability to localize area of ulcerations. Ophthalmic parameters was also compared based on the range of concentrations and intensity of yellowish green hyper-fluorescence was analysed through absorption spectrum of wavelength in UV-Visible spectroscopy. All results were gathered and analysed for cause-relationship effect. The study showed that the pre-formulated alternative diagnostic dye can potentially replace the synthetic fluorescein dye in the market. Since, the result of studies revealed that it has a good staining affinity in corneal epithelium, drains through physiological mechanism, can localized corneal ulcerations and practically non-irritant at pH: 4.70. But have less fluorescence due to possible interference in the binding of the curcumin and polyvinyl alcohol, pH level, solvent used, concentrations and presence of other functional groups present in turmeric extract. Thus, requires further studies on how to enhance the yellowish-green fluorescence of curcumin presence and adjustment in some parameters in the formulation of the alternative diagnostic dye.

Zn-MOF74 as a “turn-on” fluorescent chemosensor for recognition and detection of water in acetone and Al3+ in ethanol with high selectivity and sensitivity

Zn-based metal organic framework (Zn-MOF74) was prepared and well characterized. Zn-MOF74 is microporous crystalline framework and has high thermal and chemical stability. Zn-MOF74 displayed selective “turn-on” fluorescence enhancement response towards water in acetone and Al3+in ethanol. Water and Al3+ can induce the bright yellow-green and cyan fluorescence colors, respectively. The fluorescence intensity showed good linear relationship with water content in the range of 0–1.5% (volume percent) and with the concentration of Al3+ in the range of 0–200 μM, the detection limits were 0.045% for water and 0.61 μM for Al3+, respectively. In addition, Zn-MOF74 can be used to intuitively identify Al3+ by naked eyes in the form of test papers. Zn-MOF74 had good recovery of nearly 100% in the detection of Al3+ ions in practical water samples. The hydrogen bonding formation between H2O and O atom broke the coordination bonding between O atoms of hydroxyl on the MOF framework with Zn2+ ions, the electron distribution on MOF framework was changed and thus the fluorescence of MOF was obviously enhanced. The reversible fluorescence change, infrared spectra (IR) and x-ray photoelectron spectroscopy (XPS) demonstrated that fluorescence enhancement of Zn-MOF74 by Al3+ can be ascribed to the complex formation among them. Zn-MOF74 is a good candidate as “turn-on” fluorescence chemosensor for recognition and detection of water and Al3+ in different solvents.

Design, synthesis and properties of twisted D-A-D’ arylamine derivatives with solvatochromism

In this study, three molecules with distorted asymmetric D-A-D' structure were synthesized by one-step nucleophilic substitution reaction using different fluorophores (carbazole, phenoxazine, phenothiazine) as electron donors and benzophenone with distorted conformation as electron acceptor. The target compounds were all confirmed by 1H NMR, 13C NMR and EI-MS. In addition, the molecular skeleton of the target compound containing a phenothiazine donor group was further confirmed by X-ray single-crystal diffraction analysis. Combined with the results of UV–vis absorption spectra and fluorescence emission spectra, we found that the different electron donating ability of donor parts (carbazole, phenoxazine and phenothiazine) led to the blue, green and light yellow fluorescence of these compounds in the solid states. Subsequent studies showed that these three compounds all showed remarkable solvatochromism in different organic solvent due to the intramolecular charge transfer (ICT) effect, and the increase of solvent polarity induces a red-shift in the emission wavelength. The results of mechanochromic properties confirmed that only the compound containing phenothiazine fluorophore showed obvious reversible mechanochromic properties. Compounds containing carbazole and phenothiazine groups showed aggregation-induced enhanced emission (AIEE), while compound bearing phenoxazine showed typical aggregation-induced emission (AIE) behavior. Through powder X-ray diffraction (XRD) analysis experiment, crystal structure analysis and theoretical calculation, the relationship between the structure and properties of these molecules was discussed. Finally, we also preliminarily explored the application of these molecules in biological imaging, which exhibited excellent biocompatibility and cell permeability in living cells. In brief, through reasonable molecular design, the luminescent properties and solvatochromism properties of these compounds can be regulated, which provides a theoretical basis for the rational design of molecules with excellent photophysical properties.

Indirect immunofluorescence assay using embryonated eggs of Toxocara in human toxocariasis diagnosis is unreliable due to autofluorescence nature

Toxocariasis is caused by infection with the nematode species Toxocara canis and Toxocara cati. Serological methods using eggs, larvae and adult worms of Toxocara spp. as antigen have been used for the diagnosis of human toxocariasis. The current study aimed to evaluate indirect immunofluorescence assay (IFA) using embryonated eggs of Toxocara for diagnosis of human toxocariasis. A total of 58 sera including twenty sera from patients with toxocariasis, 20 from healthy persons and 18 from patients with other parasitic infections were collected and used for the study. The embryonated eggs of Toxocara were prepared as antigen. Indirect immunofluorescence assay was performed using the frozen section of uterus containing embryonated T. canis eggs and unembryonated T. cati eggs. All serum samples had a positive reaction using IFA. The eggs of Toxocara as antigen exposed to the serum samples of toxocariasis, other parasitic infections and healthy persons, followed by IFA gave a bright greenish-yellow fluorescence. A number of samples such as eggs of Toxocara, Toxascaris, Trichuris and strongyloides larvae, and adult worm of Ancylostoma exhibited the bright greenish-yellow autofluorescence under fluorescent microscope. IFA using cryocut of embryonated eggs of Toxocara cannot be used for the diagnosis of human toxocariasis due to the existence of autofluorescence of the unembryonated and embryonated eggs, the second stage larva and adult worms of Toxocara spp.

A Fluorescent Linear Conjugated Polymer Constructed from Pillararene and Anthracene.

Over the past few years, conjugated polymers (CPs) have aroused much attention owing to their rigid conjugated structures, which can perform well in light harvesting and energy transfer and offer great potential in materials chemistry. In this article, we fabricate a new luminescent linear CP p(P[5](OTf)2-co-9,10-dea) via the Sonogashira coupling of 9,10-diethynylanthracene and trifluoromethanesulfonic anhydride (OTf) modified pillar[5]arene, generating enhanced yellow-green fluorescence emission at around 552 nm. The reaction condition was screened to get a deeper understanding of this polymerization approach, resulting in an excellent yield as high as 92% ultimately. Besides the optical properties, self-assembly behaviors of the CP in low/high concentrations were studied, where interesting adjustable morphologies from tube to sheet were observed. In addition, the fluorescence performance and structural architecture can be disturbed by the host–guest reorganization between the host CP and the guest adiponitrile, suggesting great potential of this CP material in the field of sensing and detection.

A palmatine-based fluorescent sensor for sensitive fluorometric and smartphone-assisted on-site fluorescent colorimetric detection of water in organic solvents

Water is one of the most important natural resource. However, in some cases, it is imperative to monitor the water content for safety considerations as it is detrimental to the chemical synthesis, drug safety, etc. In this study, palmatine, a natural isoquinoline alkaloid, was proposed as a fluorescent probe for this purpose. Palmatine was demonstrated to be extremely sensitive to water with the obvious fluorescence quenching of it. In light of this phenomenon, the water content in six organic solvents, including acetonitrile, methanol, ethanol, n-propanol, acetone and 1,4-dioxane, could be determined using palmatine as the fluorescent probe, which had wide detection ranges (0–100%) and low detection limits (e.g. 0.08% in ethanol) depending on the individual organic solvents. Moreover, a novel turn-off-(on–off) fluorescent colorimetric probe was constructed based on the combination of palmatine and nitrogen doped carbon dots (N-CDs) (palmatine/N-CDs). The blue fluorescence of N-CDs was quenched by palmatine while the green-yellow fluorescence of palmatine remained; upon interacting with water, the green-yellow fluorescence of palmatine was quenched, while the blue fluorescence of N-CDs recovered. Thus, with the elevated water content, the fluorescent color transitioned from green-yellow to blue, making the visual semi-quantification of water content into a reality. Furthermore, with the assistance of smartphone and APP (Color Acquisition), the quantification of water content could be realized via only photographing. Using palmatine as the fluorescent probe, or palmatine/N-CDs as the fluorescent colorimetric probe, water contents in disinfection alcohol and nitroglycerin injection were accurately determined, and both results agreed well with those of the classical Karl Fischer method. Palmatine was demonstrated to be a potential fluorescent probe for sensing water, and the novel turn-off-(on–off) fluorescent colorimetric probe based on it was promising for the on-site fast detection of water.

Gurzhiite, Al(UO2)(SO4)2F⋅10H2O, a new uranyl sulfate mineral with a chain structure from the Bykogorskoe deposit, Northern Caucasus, Russia

AbstractGurzhiite, ideally Al(UO2)(SO4)2F⋅10H2O, is a new uranyl sulfate mineral from the Bykogorskoe U deposit, Northern Caucasus, Russia. It occurs as fine-grained aggregates forming veinlets up to 50 cm long in cracks of the brecciated rock. Gurzhiite aggregates are composed of small bladed crystals up to 0.1 mm across. Associated minerals include khademite and quartz. Gurzhiite is pale yellow in crystals, lemon yellow in aggregates, transparent with a vitreous lustre and a white streak. It is brittle and has an irregular fracture. Cleavage is good on {001}. The new mineral exhibits a bright yellow–green fluorescence under both longwave and shortwave UV radiation. Mohs hardness is ~2. Dmeas = 2.52(3) g/cm3 and Dcalc = 2.605 g/cm3. The mineral is biaxial (–) with α = 1.528(3), β = 1.538(2), γ = 1.544(3) (589 nm); 2Vmeas= 80(10)° and 2Vcalc = 75.1°. The empirical formula calculated on the basis of 21(O + F) atoms per formula unit (apfu) is Al0.92Zn0.05Fe3+0.03Na0.03U0.95S2.00O9.85F0.99⋅10.16H2O. Gurzhiite is triclinic, with space group P$\bar{1}$, a = 7.193(2), b = 11.760(2), c = 11.792(2) Å, α = 67.20(3), β = 107.76(3), γ = 89.99(3)°, V = 867.7(4) Å3 and Z = 2. The five strongest lines of the powder X-ray diffraction pattern [d, Å (I, %)(hkl)] are: 10.24(100)(001); 5.40(14)($\bar{ 1}\bar{1}$1); 5.11(54)(002); 3.405(11)($\bar{2}$11); and 3.065(11)($\bar{1}\bar{1}$3). The crystal structure of gurzhiite is based upon uranyl sulfate chains of the same type as in bobcookite and svornostite. Between the chains are two types of Al-octahedra – Al1(H2O)6 and Al2F2(H2O)4. The entire structure stability is maintained by a complex network of H bonds. The new mineral honours Russian mineralogist and crystallographer Dr. Vladislav V. Gurzhiy in recognition for his contributions to uranium mineralogy and crystallography.

Key oil accumulation periods of ultra-deep fault-controlled oil reservoir in northern Tarim Basin, NW China

A giant fault-controlled oilfield has been found in the ultra-deep (greater than 6000 m) Ordovician carbonate strata in the northern Tarim Basin. It is of great significance for hydrocarbon accumulation study and oil exploitation to determine the key oil accumulation periods. Based on detailed petrographic analysis, fluid inclusion association (FIA) in calcite samples filling in fractures from 12 wells were analyzed, and key accumulation periods of the strike-slip fault-controlled oilfield was studied by combining oil generation periods of the source rocks, formation periods of the fault and traps, and the fluid inclusion data. (1) There are multiple types of FIA, among them, two types of oil inclusions, the type with yellow fluorescence from the depression area and the type with yellow-green fluorescence from the uplift area with different maturities indicate two oil charging stages. (2) The homogenization temperature of the brine inclusions in FIA is mostly affected by temperature rises, and the minimum temperature of brine inclusions symbiotic with oil inclusions is closer to the reservoir temperature during its forming period. (3) FIA with yellow fluorescence all have homogenization temperatures below 50 °C, while the FIA with yellow-green fluorescence have homogenization temperatures of 70–90 °C tested, suggesting two oil accumulation stages in Middle–Late Caledonian and Late Hercynian. (4) The Middle–Late Ordovician is the key formation period of the strike-slip fault, fracture-cave reservoir and trap there. (5) The oil generation peak of the main source rock of the Lower Cambrian is in the Late Ordovician, and the oil accumulation stage is mainly the Late Ordovician in the depression area, but is mainly the Early Permian in the uplift area. The key oil accumulation period of the strike-slip fault-controlled reservoirs is the Late Caledonian, the depression area has preserved the primary oil reservoirs formed in the Caledonian, while the uplift area has secondary oil reservoirs adjusted from the depression area during the Late Hercynian. Oil reservoir preservation conditions are the key factor for oil enrichment in the strike-slip fault zone of northern Tarim, and the Aman transition zone in the depression is richer in oil and gas and has greater potential for exploration and development.

Mechano-responsive D–A luminogen based on bisarylic methanone derivative with brightly tricolored mechanochromic luminescence

A new luminogen PTZ-BZ-DBF bearing an electron donor phenothiazine unit and an electron acceptor carbonyl group is designed and synthesized. This molecule adopts highly twisted molecular conformation and exhibits intramolecular charge transfer (ICT), effective solid-state luminescence, and high contrast mechanofluorochromic (MFC) properties. The as-prepared powders show bright yellow-green fluorescence. Under conditions of external mechanical stimulation, the color changes to bright orange-red, and a red shift of 87 nm is observed in the emission spectral profile. Meanwhile, the solid-state luminescence efficiency increases from 20.5% to 28.5%. It is different from general MFC materials, when fumed using DCM vapor or annealed at 150 °C, the fluorescence peaks blue shift to approximately 560 nm, and the yellowish-emitting Y-powders are obtained. The ground solids and Y-powders can be converted to the as-prepared solid powders following the process of solvent recrystallization. Thus, tricolor switching is realized. The results obtained using the PXRD and DSC techniques indicate that the MFC phenomenon can be attributed to the process of crystalline-to-amorphous transition. The red shift of the PL spectra is attributed to the planar intramolecular charge transfer (PICT) process induced by conformational planarization in response to external forces.

Study of Morphological Features of Sea Buckthorn Leaves by Luminescent and Stereomicroscopy Methods

Introduction. Sea buckthorn – Hippophaё rhamnoides is a perennial shrub, the fruits of which are a source of carotenoids and are harvested on an industrial scale to obtain a number of drugs. Recently, not only fruits, but also other parts of the plant, such as buds, leaves, shoots and bark, are of increasing interest. It is known that sea buckthorn leaves are rich in compounds such as tannins, polyunsaturated fatty acids and vitamins (C and E). The rich composition of biologically active substances with a sufficient content of components allows us to consider leaves as a new type of medicinal plant material for the further development of various preparations based on them. In addition, the leaves are an annually renewable raw material and it is possible to harvest them on an industrial scale, since this valuable medicinal plant is cultivated everywhere in Russia. Data on the microscopic characteristics of the fruits of sea buckthorn are described in detail in the scientific literature, which cannot be said about the leaves. The scientific literature also does not describe the features of the luminescence of the tissues of the leaves of the sea buckthorn.Aim. The aim of this work was to study the possibility of using the luminescent and stereomicroscopic methods of analysis to determine the main morphological features of the leaves of the sea buckthorn.Materials and methods. Dried whole leaves of a plant of the genus Hippophaës collected in the Voronezh region were used as the object of the study. The study of microdiagnostic signs was carried out according to the State Pharmacopoeia of the XIV RF GPA.1.5.3.0003.15 «Technique of microscopic and microchemical examination of medicinal plants and herbal medicinal products». A stereomicroscopic study was carried out using a Biomed 2 microscope. The luminescence of the tissues of the sea buckthorn leaves was investigated using a luminescent microscope of the Miсromed 3 LUM brand.Results and discussion. Stereomicroscopic analysis of sea buckthorn leaves was carried out. High-resolution volumetric images were obtained in a short period of time. It was found that the characteristic microscopic features of the leaves are the presence of a large number of corymbose hairs along the upper and corymbose-stellate along the lower surfaces, including the vein and petiole (from colorless to white, yellow and dark brown). Single simple stellate hairs are rare. When removing the layer of hairs, the spongy structure of the epidermis of the leaf is visible. The carried out luminescent analysis made it possible to reveal the features of the luminescence of the tissues of the leaves of the sea buckthorn. Diagnostic luminescent features include: the most pronounced yellow glow is observed for the cells of the base of the corymbose hair; the plates that make up the corymbose hairs do not have bright fluorescence; stellate hairs do not have a glow; pronounced yellow-green fluorescence is characteristic of the leaf vein.Conclusion. For the first time, stereomicroscopic and luminescent analyzes of sea buckthorn leaves were carried out and the main morphological features of this type of medicinal plant material and their biometric characteristics were established. The carried out luminescent analysis made it possible to reveal the features of the luminescence of the tissues of the leaves of the sea buckthorn.

Zeolitic imidazolate framework-8 for ratiometric fluorescence sensing tetracyclines in environmental water based on AIE effects

A ratiometric fluorimetric sensing strategy with Zeolitic imidazolate framework-8 (ZIF-8) has been developed for the analysis of tetracycline (TC) in environmental water samples. ZIF-8 with polyhedral structure was synthesized at room temperature exhibiting blue fluorescence at 445 nm. Especially, the as-prepared ZIF-8 could conduct the aggregation-induced emission (AIE) effect in the presence of TC through electrostatic, hydrogen bond, π-π stacking, and coordination interactions. As a result, a strong yellow-green fluorescence appeared and a new fluorescence peak at 505 nm was observed, although the initial fluorescence peak at 445 nm of ZIF-8 was almost unchanged. A ZIF-8-based fluorimetric platform was thereby designed for sensing TC by using ZIF-8 as the fluorescent probe with the peak at 445 nm as the reference and the one at 505 nm as the changing signal, which should increase with the increasing concentrations of TC. Moreover, the quantitative analysis of TC could be carried out through the ratiometric peak intensities of F505/F445, with a detection limit as low as 14.7 nM. Additionally, the ratiometric fluorescent analysis method was successfully employed to detect TC in environmental water samples, indicating that ZIF-8 might be a good luminescent sensor for probing the pollutants in the environmental water.

Twisted phenothiazine-terminated bisarylic methanone π-architecture exhibiting high-contrast mechanofluorochromism

Bisarylic methanone π-architecture PTZ-BZ-DBT with carbonyl group as the acceptor and phenothiazine as the donor was synthesized. Theoretical calculations and photophysical properties in solution demonstrated that the obtained donor-acceptor (D-A) type molecule PTZ-BZ-DBT adopts a molecular conformation of high distortion and significant intramolecular charge transfer (ICT) behavior, which endows it not only with intense solid-state luminescence but also with a high-contrast mechanofluorochromic (MFC) feature. The original as-prepared samples of PTZ-BZ-DBT display bright yellow-green fluorescence. When the as-prepared samples are ground, the ground solid powders exhibit orange-red fluorescence are obtained. Accordingly, during the grinding process, the emission wavelength of the solid powders red shifts from 518 nm of the as-prepared samples to 617 nm of the ground samples, and thus a spectral shift of 99 nm is observed. Different from general MFC materials, if the ground solid powders are fumed by DCM vapor or annealed at 150 °C, the fluorescence peaks blue shift to about 564 nm, and the yellow-emitting Y-powders are gained. However, the ground samples can be converted into the as-prepared solid powders through solvent recrystallization; thus tri-color switching is obtained. The PXRD, fluorescence lifetimes, DSC and the spectral analysis demonstrate that the remarkable MFC nature of PTZ-BZ-DBT is attributed to crystalline-to-amorphous transition. Further, the red shift of the fluorescence band after grinding can be ascribed to the extension of conjugate length and subsequent planar intramolecular charge transfer (PICT) induced by conformational planarization under external forces.

AgVI and Ag/ZnOVI nanostructures from Vateria indica (L.) exert antioxidant, antidiabetic, anti-inflammatory and cytotoxic efficacy on triple negative breast cancer cells in vitro

Human triple-negative breast cancer (TNBC) being an aggressive cancer type accounts for about 15–20% of global breast cancer cases. In the present study, the cytotoxicity of pure silver (AgVI) and silver/zinc oxide (Ag/ZnOVI) nanostructures was evaluated against the TNBC cells. The nanostructures synthesized from a green route using Vateria indica (L.) fruit extract were characterized to scrutinize their formation, crystal phase, size, shape, and surface properties via FTIR, PXRD, FE-SEM coupled with EDS spectroscopy, and BET analysis. The results of the studies have unveiled the formation of 26.43 nm and 20.97 nm sized AgVI and Ag/ZnOVI nanostructures in their purest form. The in-vitro anticancer study performed on human TNBC cells [MDA-MB468] revealed the enhancement in the antiproliferative potentiality of bimetallic Ag/ZnOVI nanostructures from 66.99 ± 0.13 to 79.73 ± 0.23 in comparison to pure AgVI nanostructures. In addition to this, the greenish yellow-fluorescence observed in the TNBC nuclei during the AO-EB staining study manifested the early apoptosis. Furthermore, the anti-inflammatory and cytotoxicity study performed on the human RBC and normal NIH3T3 murine fibroblasts cells proved the biocompatibility and non-toxic nature of the synthesized nanostructures with membrane stabilization percentage up to 94.5 ± 0.001. Additionally, the antioxidant and antidiabetic studies carried out have corroborated the radical scavenging and α-amylase inhibition capability up to 85.87 ± 0.001 and 89.60 ± 0.002 % respectively. Thus the overall results of the study substantiate the superlative antioxidant, antidiabetic, and antiproliferative property of green synthesized AgVI and Ag/ZnOVI nanostructures with excellent biocompatibility.

Multifunctional ratiometric fluorescent sensing platform constructed by grafting various response groups on carbon dots with bromine active site for biosensing and bioimaging

Multifunctional sensing platform with the advantages of simplicity, convenience and efficiency is critical to the improvement of application in biosensing and bioimaging. However, the lack of easily modified scaffold materials seriously hinders its various responsive sensing development. To solve this issue, a novel kind of carbon dots (namely rCDs) with easily modified bromine substitution site was developed by one-step solvothermal treatment of citric acid, ethylenediamine and 4-bromo-1,8-naphthalic anhydride. Benefiting from the maintained structure of naphthalimide structure with bromine substitution site to contribute responsive yellow-green fluorescence emission and the stable blue fluorescence emission from citric acid and ethylenediamine, dual emissive ratiometric sensors based on rCDs could be conveniently fabricated by avoiding the combination of two components with distinct emission wavelength together. As proof, three ratiometric fluorescent probes for sensing formaldehyde (rCDs-FA), HSO3- (rCDs-HSO3-) and pH (rCDs-pH) featuring high stability, selectivity and biocompatibility were simply prepared. Moreover, the as-obtained probes were successfully applied to monitor dynamic variations of formaldehyde, HSO3- and pH changes in living cells. Taken together, the established multifunctional ratiometric fluorescent sensing platform could be simply and effectively regulated through changing the grafted response groups. This work would provide a universal method to design more biosensing or bioimaging platforms by adjusting response groups in the future.

A 3D/3D hetero-interpenetrated MOF with a novel (3,9)-c net and 6-c lcy net for the fluorescence detection of carbaryl.

An exceptional Zn-based MOF material with two-fold hetero-interpenetrated nets consisting of a 3D lcy network and a novel 3D (3,9)-coordinated framework has been constructed. The Zn-based MOF exhibits a rare yellow-green fluorescence and can be used as a fluorescence sensor to detect carbaryl with a detection limit of 4.5 μM.

Highly crystalline covalent organic frameworks for ratiometric fluorescent sensing of trace water in honey and N2 gas

The detection of trace water (H2O) content is important and challenging in food and food-related industries. Herein, highly crystalline two-dimensional covalent organic frameworks (TAPT-BTCA-COF) with yellow-green fluorescence were prepared by using 1,3,5-tris(4-aminophenyl)triazine (TAPT) and 1,3,5-benzenetricarboxaldehyde (BTCA) as precursors. The fluorescence of TAPT-BTCA-COF is sensitive to the solvent polarity due to the intermolecular charge transfer (ICT) effect and can be quenched by trace H2O due to the block of ICT effect by H2O. On this base, TAPT-BTCA-COF is applied for sensing of trace H2O in common organic solvents such as DMF, acetonitrile, THF and acetone with fast response and high sensitivity. The limits of detection for H2O in DMF, acetonitrile, THF and acetone are 0.082 wt%, 0.0053 wt%, 0.0091 wt% and 0.0061 wt%, respectively. Furthermore, a ratiometric fluorescent sensor is proposed by using TAPT-BTCA-COF as the signal probe and red fluorescent tris(2,2′-bipyridyl)ruthenium(II) dichloride as the reference and successfully applied for quantitatively and semi-quantitatively sensing of trace H2O in honey sample and the moisture in N2 gas.

Linear Extension of Anthracene via B←N Lewis Pair Formation: Effects on Optoelectronic Properties and Singlet O2 Sensitization.

The functionalization of polycyclic aromatic hydrocarbons (PAHs) via B←N Lewis pair formation offers an opportunity to judiciously fine-tune the structural features and optoelectronic properties, to suit the demands of applications in organic electronic devices, bioimaging, and as sensitizers for singlet oxygen generation. We demonstrate that the N-directed electrophilic borylation of 2,6-di(pyrid-2-yl)anthracene offers access to linearly extended acene derivatives Py-BR (R=Et, Ph, C6 F5 ). In comparison to indeno-fused 9,10-diphenylanthracene, the formal "BN for CC" replacement in Py-BR selectively lowers the LUMO, resulting in a much reduced HOMO-LUMO gap. An even more extended conjugated system with seven six-membered rings in a row (Qu-BEt) is obtained by borylation of 2,6-di(quinolin-8-yl)anthracene. Fluorinated Py-BPf shows particularly advantageous properties, including relatively lower-lying HOMO and LUMO levels, strong yellow-green fluorescence, and effective singlet oxygen sensitization, while resisting self-sensitized conversion to its endoperoxide.

Synthesis of carbon dots with strong luminescence in both dispersed and aggregated states by tailoring sulfur doping

Carbon dots (CDots), a class of environmentally friendly carbon-based luminescent nanomaterial, have been applied in a wide variety of fields, including bioimaging and light-emitting diodes (LEDs). Prior to these applications, however, CDots usually require modifications because some of its limitations (e.g., the aggregation-induced luminescence quenching) make it difficult to apply in solid state. In order to realize CDots-based multiple applications simultaneously, this paper examines how CDots with a strong greenish-yellow fluorescence in both dispersed and aggregated states are prepared by microwave-assisted heating salicylic acid and thiourea. Based on control testing and the analysis of density functional theory calculations, S element from thiourea is doped into CDots and proves to be critical in governing the photoluminescence (PL) emission color. Featured with excellent biocompatibility and photostability, the dispersed CDots with photoluminescence quantum yields (32%) are able to function as a biological imaging reagent in vitro and in vivo without any side effect. Furthermore, the aggregated CDots also exhibit high photoluminescence quantum yields (26%) and remarkable resistance to organic solvent. These advantages will ensure that S-doped CDots can be applied as a color conversion layer so that white LEDs with different Commission International de L’Eclariage coordinates and tunable color temperature can be fabricated.