Red,green and blue aggregation‐induced emissive carbon dots

As one of the most promising fluorescent nanomaterials, carbon dots (CDs) have been extensively studied for their fluorescent properties in solution. However, research on the synthesis of multicolor solid-state fluorescence (SSF) CDs (from blue to red) is rarely reported. Herein, we used o-phenylenediamine, m-phenylenediamine and p-phenylenediamine with dithiosalicylic acid (DTSA) in the solvothermal reaction using acetic acid as a solvent to obtain aggregation-induced emissive (AIE) CDs of red (620 nm), green (520 nm), and blue (478 nm), respectively. XPS spectra and TEM image show that with the red-shift of luminescence, the particle size and content of C=O of the CDs gradually increases. Finally, based on the non-matrix solid-state multicolor luminescence characteristics of CDs, the application of white light LED devices is realized. Besides, based on the fat-soluble properties of CDs, fingerprint detection applications are realized.     

Photoacoustic imaging-guided chemo-photothermal combinational therapy based on emissive Pt(Ⅱ)metallacycle-loaded biomimic melanin dots

Pt(Ⅱ)-based metallacycles,as an important family of supramolecular coordination complexes(SCCs),have exhibited excellent antitumor activity at the cell level.However,the biomedical applications of Pt(Ⅱ)-based metallacycles for animal studies are still hindered by their poor stability,non-targeted tumour,and lack of detectable feedback for evaluating therapeutic progress.Herein,we propose a strategy that introduces melanin dots as a biomedical platform to load bright-emission Pt(Ⅱ)-based metallacycles,thereby constructing a theranostic agent that enables photoacoustic imaging(PAI)-guided chemo-photothermal combinational therapy.Melanin dots act as a protective carrier to preserve the integrity of Pt(Ⅱ)-based metallacycles before uptake by tumour tissues.Meanwhile,the PAI signal from melanin dots furnishes more comprehensive information on the tumour.Moreover,the heat generated after NIR laser irradiation can not only trigger the apoptosis of tumour cells but also promote the deeper penetration of Pt(Ⅱ)-based SCCs into tumour tissue,thus enhancing the efficiency of chemotherapy.     

Air-stable, room-temperature emissive disilenes with π-extended aromatic groups

π-Conjugated disilenes with 2-naphthyl or 2-fluorenyl groups on the silicon atoms have been synthesized as air-stable emissive red solids using the bulky 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (Eind) groups. The strong π-π* absorptions and distinct emission at room temperature, both in solution and in the solid state, have been observed due to the substantial contribution of the 3p(π)*(Si-Si)-2p(π)*(carbon π-electron system) conjugation.     

Cyanostilbene-based near-infrared emissive platinum(Ⅱ) metallacycles for cancer theranostics

In this work,a near-infrared emissive dipyridyl ligand was synthesized and used to prepare three platinum(Ⅱ) metallacycles with different shapes via metal-coordination-driven self-assembly with different platinum(Ⅱ) precursors.These metallacycles were further used for both cell imaging and cancer therapy,offering a new type of theranostic agents towards cancer treatment.     

Quantum dots on electrodes—new tools for bioelectroanalysis

The review covers recent developments in which quantum dots (QDs) are combined with electrodes for detection of analytes. Special focus will be on the generation of photocurrents and the possibility of spatially resolved, light-directed analysis. Different modes for combining biochemical reactions with QDs will be discussed. Other applications involve the use of QDs as labels in binding analysis. Different methods have been developed for read-out. In addition to photocurrent analysis, voltammetric detection of metals and electrochemiluminescence (ECL) can be used. In the latter, light is the sensor signal. ECL-based systems combine the advantage of very sensitive analytical detection with rather simple instrumentation.

Highly emissive hand-shaped π-conjugated alkynylpyrenes: synthesis, structures, and photophysical properties

Three alkynyl-functionalised, hand-shaped, highly fluorescent and stable emitters, namely, 2-tert-butyl-4,5,7,9,10-pentakis(p-R-phenylethynyl)pyrenes have been successfully synthesized via a Pd/Cu-catalysed Sonogashira cross-coupling reaction. The chemical structures of the alkynylpyrenes were fully characterized by their (1)H/(13)C NMR spectra, mass spectroscopy and elemental analysis. Synchrotron single-crystal X-ray analysis revealed that there is a 1-D, slipped, face-to-face motif with off-set, head-to-tail stacked columns, which are clearly influenced by the single, bulky, tert-butyl group in the pyrene ring at the 2-position. Detailed studies on the photophysical properties in both solutions and thin films strongly indicate that they might be promising candidates for optoelectronic applications, such as organic light-emitting devices (OLEDs) or as models for investigating the fluorescent structure-property relationship of the alkynyl-functionalised pyrene derivatives.     

Magnolol and honokiol included green emissive terbium sol–gel materials and their recognition behaviors

Magnolol and honokiol as pharmaceutical ligands have been introduced into terbium complex systems for the first time and two hybrid organic–inorganic materials were successfully prepared. Both of them can sensitize terbium characteristic green emission effectively based on intra-molecular energy transfer channel. Moreover, they selectively recognized Cu²⁺ and Fe³⁺ through luminescence quenching effects. The photophysical properties and morphological structures were extensively investigated.     

Emerging highly emissive and stable white emitting “phosphores” based on lead-free inorganic halide perovskites

<正>Single materials generating high-efficiency white light emission are of particular interest for lighting. Recently,metal halide perovskite is emerging as a promising candidate for white light emission materials. However, lead halide perovskites showing broad spectrum light emission generally present low luminescence quantum yield and the emission spectrum deviates from the standard white light color co-     

Fluorescence intermittency in blinking quantum dots: renewal or slow modulation?

We study the time series produced by blinking quantum dots, by means of an aging experiment, and we examine the results of this experiment in the light of two distinct approaches to complexity, renewal and slow modulation. We find that the renewal approach fits the result of the aging experiment, while the slow modulation perspective does not. We make also an attempt at establishing the existence of an intermediate condition.     

Three-element doped carbon dots for the detection of p-nitrophenolEI北大核心CSCD

Based on the characteristics that heteroatom doping can improve the luminescence performance of carbon dotsa new type of three-element co-doped carbon dots NSSi-CDswas prepared. The synthesis conditions were optimizedand the morphologystructure and luminescence properties of NSSi-CDs were characterized. NSSi-CDs can emit 450 nm blue fluorescence under excitation at 370 nmand the fluorescence quantum yield reached 11%. The study found that p-nitrophenol PNPhas a strong fluorescence quenching effect on NSSi-CDsand thus a new method for the determination of PNP with NSSi-CDs fluorescent probe was constructed. When the concentration of PNP was in the range of 0.9-60 μµmol/Lit had a good linear relationship with the fluorescence quenching efficiencyF0 /Fand the detection limit was 0.36 μµmol/L. This method was used to determine PNP in actual water samples with good recoveries of 90.6%-95.2%. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Waste-to-wealth: Functional biomass carbon dots based on bee pollen waste and application

Waste utilization is not only the protection of the environment and the practice of green chemistry, but also one of the ways to develop new materials. Herein, we report two biomass carbon dots which prepared from bee pollen waste by one-step hydrothermal method. The new two carbon dots were used in sensing, cell imaging and plant growth regulation. The differences in the structure and properties of the two carbon dots were evaluated by TEM, XPS, TG and various spectroscopic methods. Both two ca...     

Preparation of biomass N-doped carbon dots and detection of tioproninEI北大核心CSCD

Nitrogen-doped carbon dots (N-CDs) were prepared by one-step hydrothermal synthesis with pomegranate seeds as the carbon source and urea as the nitrogen source. Observed by transmission electron microscopy (TEM), average particle size of N-CDs was 20 nm. Observed by atomic force microscopy (AFM), the thickness of N-CDs was 0. 6-1. 4 nm. Fourier transform infra-red (FT-IR) confirmed the presence of water-soluble functional groups such as amino groups on the surface of N-CDs. With the prepared N-CDs as the target fluorophore, Hg2 + can efficiently bind to the surface of N-CDs to form a complex, and achieve static quenching. The addition of tiopronin can bind the Hg2 + in the complex to make the Hg2 + detach from the surface of N-CDs and realize fluorescence recovery. The nano fluorescence switch constructed in this work is more accurate and sensitive than the traditional detection method. The optimum conditions were determined by optimizing the pH value, reaction time, the dosage of N-CDs and Hg2 +. The relative deviation (RSD) was 4. 7%, and the detection limit was 0. 2 μmol/L. The method was used to determine the content of tiopronin in human serum samples with the recoveries of 97. 2%-101. 3%. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Can luminescent quantum dots be efficient energy acceptors with organic dye donors?

We assessed the ability of luminescent quantum dots (QDs) to function as energy acceptors in fluorescence resonance energy transfer (FRET) assays, with organic dyes serving as donors. Either AlexaFluor 488 or Cy3 dye was attached to maltose binding protein (MBP) and used with various QD acceptors. Steady-state and time-resolved fluorescence measurements showed no apparent FRET from dye to QD. We attribute these observations to the dominance of a fast radiative decay rate of the donor excitation relative to a slow FRET decay rate. This is due to the long exciton lifetime of the acceptor compared to that of the dye, combined with substantial QD direct excitation.     

Discrimination of penicillamine enantiomers using β-cyclodextrin modified CdSe/ZnS quantum dots

The authors describe a method for the differentiation of penicillamine (PA) enantiomers by using CdSe/ZnS quantum dots (QDs) modified with β-cylodextrin (β-CD-CdSe/ZnS QDs). Selective enantiorecognition of L-PA and D-PA was accomplished by virtue of selective host-guest interaction between the PAs and the β-CD pockets on the QDs. The fluorescence intensity of the modified QDs decreases in the presence of L-PA. On the contrary, it increases in the presence of D-PA. These findings form the basis for a new method for recognition of PA enantiomers. Under optimized conditions, a linear relationship exists between fluorescence intensity and D-PA concentration in the 0.1 to 5.0 mg L^?1 range, and between 0.8 and 5.0 mg L^?1 for L-PA. Detection limits are 0.06 mg L^?1 for D-PA, and 0.2 mg L^?1 for L-PA. The potential of this method has been demonstrated by the determination of D-PA in pharmaceutical formulations and L-PA in (spiked) environmental samples.

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Graphical abstract Selective and specific enantiorecognition of penicillamine (PA) enantiomers using β-cylodextrin modified CdSe/ZnS quantum dots is described. Fluorescence intensity increases in the presence of D-PA, but it decreases in the presence of L-PA. Results were the basis for analytical applications.

     

Waste-to-wealth: Functional biomass carbon dots based on bee pollen waste and application

Waste utilization is not only the protection of the environment and the practice of green chemistry, but also one of the ways to develop new materials. Herein, we report two biomass carbon dots which prepared from bee pollen waste by one-step hydrothermal method. The new two carbon dots were used in sensing, cell imaging and plant growth regulation. The differences in the structure and properties of the two carbon dots were evaluated by TEM, XPS, TG and various spectroscopic methods. Both two ca...     

Aminophenol-based carbon dots with dual wavelength fluorescence emission for determination of heparin

We describe the preparation of carbon quantum dots (C-dots) by a one-step hydrothermal method starting from o-aminophenol as the precursor. The C-dots exhibit bright both blue fluorescence (with excitation/emission peaks at 300/410 nm and with quantum yield of 0.40) and green fluorescence (420/500 nm; QY 0.28) without any other element doping. The unique emission properties are attributed to a synergistic effect of amino and hydroxy groups on the surface of the C-dots. The C-dots are shown to be viable fluorescent probes for heparin. The positively charged surface amino groups are assumed to interact with sulfate and carboxy groups in heparin via electrostatic interactions and hydrogen bonding. This causes the blue fluorescence of C-dots to be turned off (quenched). Fluorescence is strongest at a pH value of 6. The fluorometric calibration plot is linear in the 10 to 100 nM concentration range, with an 8.2 nM detection limit (at a signal-to-noise ratio of 3).

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Graphical abstract Carbon quantum dots with dual fluorescence emission bands were synthesized and are shown to be a viable fluorescent probe for heparin.

     

Electrochemical enantiorecognition of tryptophan enantiomers based on graphene quantum dots–chitosan composite film

A graphene quantum dots (GQDs)–chitosan (CS) composite film was prepared via successive electrodeposition of GQDs and CS on the surface of a glassy carbon electrode (GCE). The strong interactions between GQDs and CS resulted in the formation of a regular and uniform film, which can be applied in the electrochemical chiral recognition of tryptophan (Trp) enantiomers. CS in the composite film provides a chiral microenvironment, meanwhile, GQDs can amplify the electrochemical signals and improve the recognition efficiency. Due to the synergetic effect of GQDs and CS, chiral recognition of Trp enantiomers is achieved successfully. Compared with previous reports utilizing GQDs in photoluminescent research, this work opens a new avenue for broadening the applications of GQDs in the electrochemically chiral sensors.     

New opportunities in multiplexed optical bioanalyses using quantum dots and donor–acceptor interactions

In this study, we investigated the feasibility of using a novel volatile organic compound (VOC)-based metabolic profiling approach with a newly devised chemometrics methodology which combined rapid multivariate analysis on total ion currents with in-depth peak deconvolution on selected regions to characterise the spoilage progress of pork. We also tested if such approach possessed enough discriminatory information to differentiate natural spoiled pork from pork contaminated with Salmonella typhimurium, a food poisoning pathogen commonly recovered from pork products. Spoilage was monitored in this study over a 72-h period at 0-, 24-, 48- and 72-h time points after the artificial contamination with the salmonellae. At each time point, the VOCs from six individual pork chops were collected for spoiled vs. contaminated meat. Analysis of the VOCs was performed by gas chromatography/mass spectrometry (GC/MS). The data generated by GC/MS analysis were initially subjected to multivariate analysis using principal component analysis (PCA) and multi-block PCA. The loading plots were then used to identify regions in the chromatograms which appeared important to the separation shown in the PCA/multi-block PCA scores plot. Peak deconvolution was then performed only on those regions using a modified hierarchical multivariate curve resolution procedure for curve resolution to generate a concentration profiles matrix C and the corresponding pure spectra matrix S. Following this, the pure mass spectra (S) of the peaks in those region were exported to NIST 02 mass library for chemical identification. A clear separation between the two types of samples was observed from the PCA models, and after deconvolution and univariate analysis using N-way ANOVA, a total of 16 significant metabolites were identified which showed difference between natural spoiled pork and those contaminated with S. typhimurium.     

Surface engineering of carbon dots for highly sensitive α-glucosidase assay and inhibition evaluation

Monitoring α-glucosidase(α-Glu) activity is of great significance for the early diagnosis of type Ⅱ diabetes. Here the blue fluorescent carbon dots(CDs) were integrated with two different recognizing molecules, β-cyclodextrin and phenylboronic acid, for assembling a multifunctional CDs(mCDs) nanoplatform for sensitively analyzing α-Glu and its inhibitors. The hydrolyzed product of 4-nitrophenyl-α-D-glucopyranoside(α-Glu substrate), p-nitrophenol, could efficiently quench the fluorescence of mCDs...