New Fluorophore and Its Applications in Visualizing Polystyrene Nanoplastics in Bean Sprouts and HeLa Cells.

In the domain of environmental science, pollutants of nanoscale plastic dimensions are acknowledged as subjects of intricate significance. Such entities, though minuscule, present formidable challenges to ecological systems and human health. The diminutive dimensions of these contaminants render their detection arduous, thus demanding the inception of avant-garde methodologies. The present manuscript postulates the employment of the tetraphenylethylene functional group with a fused xanthene (TPEF), a distinguished fluorophore, as an exemplary system for the discernment of nanoplastic particulates. The synthesis and characterization of TPEF have been exhaustively elucidated, revealing its paramount fluorescence attributes and inherent affinity for interaction with nanoplastics. When subjected to comparison with TPEF, nanoplastics are observed to manifest a more pronounced fluorescent luminescence than when associated with the conventional Nile Red (NR). Particularly, the TPEF has shown exceptional affinity for polystyrene (PS) nanoplastics. Further, the resilience of nanoplastics within the hypocotyl epidermis of soybeans, as well as their persistence in mung bean sprouts subsequent to rigorous rinsing protocols, has been meticulously examined. Additionally, this investigation furnishes empirical data signifying the existence of nano-dimensional plastic contaminants within HeLa cellular structures. The urgency of addressing the environmental ramifications engendered by these diminutive yet potent plastic constituents is emphatically highlighted in this manuscript. TPEF paves the way for prospective explorations, with the aspiration of devising efficacious mitigation strategies. Such strategies might encompass delineating the trajectories undertaken by nanoplastics within trophic networks or their ingress into human cellular architectures.

In Situ Self-Assembled J-Aggregate Nanofibers of Glycosylated Aza-BODIPY for Synergetic Cell Membrane Disruption and Type†I Photodynamic Therapy.

The in situ self-assembly of exogenous molecules is a powerful strategy for manipulating cellular behavior. However, the direct self-assembly of photochemically inert constituents into supramolecular nano-photosensitizers (PSs) within cancer cells for precise photodynamic therapy (PDT) remains a challenge. Herein, we developed a glycosylated Aza-BODIPY compound (LMBP) capable of self-assembling into J-aggregate nanofibers in situ for cell membrane destruction and type I PDT. LMBP selectively entered human hepatocellular carcinoma HepG2 cells and subsequently self-assembled into intracellular J-aggregate nanovesicles and nanofibers through supramolecular interactions. Detailed studies revealed that these J-aggregate nanostructures generated superoxide radicals (O2 - ⋅) exclusively through photoinduced electron transfer, thus enabling effective PDT. Furthermore, the intracellular nanofibers exhibited an aggregation-induced retention effect, which resulted in selective toxicity to HepG2 cells by disrupting their cellular membranes and synergizing with PDT for powerful tumor suppression efficacy in vivo.

A water-soluble fluorescent organic nano-photosensitizer for the ratiometric detection of mitochondrial G-quadruplexes with photodynamic therapy potential.

We report a water-soluble AIEgen (TPAL) that can self-assemble into fluorescent organic nanoparticles for the ratiometric detection of mitochondrial DNA (mtDNA) parallel G-quadruplexes (G4s) with high selectivity, a low detection limit and photodynamic therapy (PDT) potential.

An AIE-Active NIR Fluorescent Probe with Good Water Solubility for the Detection of Aß1-42 Aggregates in Alzheimer's Disease.

Alzheimer's disease (AD), an amyloid-related disease, seriously endangers the health of elderly individuals. According to current research, its main pathogenic factor is the amyloid protein, which is a kind of fibrillar aggregate formed by noncovalent self-assembly of proteins. Based on the characteristics of aggregation-induced emission (AIE), a bislactosyl-decorated tetraphenylethylene (TPE) molecule TMNL (TPE + malononitrile + lactose), bearing two malononitrile substituents, was designed and synthesized in this work. The amphiphilic TMNL could self-assemble into fluorescent organic nanoparticles (FONs) with near-infrared (NIR) fluorescence emission in physiological PBS (phosphate buffered saline), achieving excellent fluorescent enhancement (47-fold) upon its combination with Aß1-42 fibrils. TMNL was successfully applied to image Aß1-42 plaques in the brain tissue of AD transgenic mice, and due to the AIE properties of TMNL, no additional rinsing process was necessary. It is believed that the probe reported in this work should be useful for the sensitive detection and accurate localization mapping of Aß1-42 aggregates related to Alzheimer's disease.

α-Stereoselective 3-Deoxy-d-manno-oct-2-ulosonoic Acid (Kdo) O-Glycosylation with a p-Toluenethioglycoside Donor by the (p-Tol)2SO/Tf2O Preactivation Strategy.

A convenient and efficient approach was developed to synthesize α-Kdo O-glycosides based on the Tf2O/(p-Tol)2SO preactivation strategy using peracetylated Kdo thioglycoside as a donor. Under the optimized reaction conditions, several O-glycoside products, including α-(2 → 1)-, α-(2 → 2)-, α-(2 → 3)-, and α-(2 → 6)-Kdo products, were stereoselectively synthesized in high yields. Remarkably, a series of aromatic α-Kdo O-glycosides were first and successfully constructed in high yields. An SN2-like mechanism was revealed by DFT calculations and experimental results.

Design and assembly of AIE-active fluorescent organic nanoparticles for anti-counterfeiting fluorescent hydrogels and inks.

Two kinds of AIE-active fluorescent organic nanoparticles were designed and constructed as anti-counterfeiting photoresponsive materials. One is fluorescent organic nanoparticles (TPELs) based on a self-assembly strategy, which were self-assembled from novel amphiphilic tetraphenylethylene (TPE) molecules decorated with a lactose moiety and different photoresponsive tags. The other is polymeric fluorescent organic nanoparticles (F-TPEs) derived from the nanoprecipitation strategy, which utilized pluronic copolymer F127 to encapsulate hydrophobic TPEs without lactosyl modifications. Upon UV light irradiation, these AIE-active materials exhibit different photooxidation behaviors in an aqueous solution to give cyan, orange and green fluorescence emissions, and they were successfully used as an anti-counterfeiting fluorescent hydrogel and ink.

Dual functional amphiphilic sugar-coated AIE-active fluorescent organic nanoparticles for the monitoring and inhibition of insulin amyloid fibrillation based on carbohydrate-protein interactions.

Amyloid-related diseases, such as Alzheimer's disease, are all considered to be related to the deposition of amyloid fibrils in the body. Insulin is a protein hormone that easily undergoes aggregation and fibrillation to form more toxic amyloid-like fibrils. So far, it is still challenging to develop a new protocol to study the ex situ detection and in situ inhibition of amyloid fibrillation. Here, we reported a modular synthetic strategy to construct nine amphiphilic sugar-coated AIE-active fluorescent organic nanoparticles (FONs, TPE2/3/4X, X = G, M or S) with glucosamine (G), mannose (M) or sialic acid (S) as a hydrophilic moiety and tetraphenylethylene (TPE) as a hydrophobic AIE core. The carbohydrate-protein interactions between insulin and TPE2/3/4X were investigated by fluorescence spectroscopy, circular dichroism spectroscopy and transmission electron microscopy. Among the nine FON AIEgens, TPE2G was screened out as the best dual functional FON for the ex situ detection and in situ inhibition of the insulin fibrillation process, indicating that the glycosyl moiety exhibited a crucial effect on the detection/inhibition of insulin fibrillation. The molecular dynamics simulation results showed that the binding mechanism between TPE2G and native insulin was through weak interactions dominated by van der Waals interactions and supplemented by hydrogen bonding interactions to stabilize an α-helix of the insulin A chain, thereby inhibiting the insulin fibrillation process. This work provides a powerful protocol for the further research of amyloid-related diseases based on carbohydrate-protein interactions.

Water-soluble AIE-active fluorescent organic nanoparticles for ratiometric detection of SO2 in the mitochondria of living cells.

We report a water-soluble AIEgen (TYDL) to be self-assembled into fluorescent organic nanoparticles (TYDLs) for specific sensing of SO2 in living hepatoma cells. It is demonstrated that the TYDLs were suitable for ratiometrically detecting endogenous and exogenous SO2 in mitochondria with good selectivity, low detection limit (75 nM) and excellent photostability (>30 min). These findings imply the great potential applications of TYDLs for the diagnosis of SO2-related diseases in cell biology.

Water-soluble AIE-active Fluorescent Organic Nanoparticles: Design, Preparation and Application for Specific Detection of Cyanide in Water and Food Samples.

A dilactosyl-dicyanovinyl-functionalized tetraphenylethene (TPELC) was designed, synthesized and used for ratiometric sensing of cyanide. TPELC was comprised of three moieties (tetraphenylethylene, dicyanovinyl group and lactose unit) in one molecule, making TPELC water-soluble and aggregation-induced emission (AIE)-active and selectively reactive to cyanide. Compared with other reported fluorescent probes containing dicyanovinyl group, TPELC is the first AIE luminogen to be assembled as fluorescent organic nanoparticles (FONs) for sensing of cyanide in water without the use of surfactant or the help of organic solvents based on the nucleophilic addition reaction. The detection mechanism was verified by liquid chromatograph mass spectrometry experiments and by protonation of cyanide to reduce the nucleophilicity of cyanide. In addition, TPELC was used for detection of the cyanide content of food samples and test strips were developed to simplify the detection procedure.

Assembly of Water-soluble AIE-active Fluorescent Organic Nanoparticles for Ratiometric Detection of Hypochlorite in Living Cells.

Hypochlorous acid (HOCl) plays a crucial role in many physiological processes and is widely used as bleach, deodorant and fungicide. In this work, we designed an amphiphilic hydrazone fluorescent molecule THG-1 containing hydrophilic sugar units and hydrophobic tetraphenylethylene unit for ratiometric detection of HOCl with high sensitivity and excellent selectivity based on HOCl-triggered hydrolyzation reaction and aggregation-induced emission (AIE) effect. The detection mechanism was verified by liquid chromatograph mass spectrometry experiments and scanning electron microscope (SEM) tests. Contrast experiments revealed that the numbers of lactose unit and hydrazone linker were essential for assembly of THG-1 and detection of HOCl. In addition, THG-1 was successfully used for imaging of exogenous and endogenous HOCl in living cells.

A BODIPY-carbazole hybrid as a fluorescent probe: the design, synthesis, and discrimination of surfactants and the determination of the CMC values.

Surfactants play important roles in chemical industries and have become well-known environmental pollutants owing to their extensive use in different fields. In this work, we reported a fluorescent probe, namely, BDP-Zn2+ for the discrimination of four kinds of surfactants and the determination of CMC values. BDP-Zn2+ was composed of covalently linked BODIPY, carbazole, N,N-bis(2-pyridylmethyl)ethylenediamine (BPEA) and zinc ions to fabricate a novel push-pull molecular structure. Upon the addition of surfactants, the probe exhibited a turn-on fluorescence response and the emission was enhanced on increasing the surfactant concentrations. This indicated that the fluorescence intensity and the ratios of the emission at 607 nm to that at 514 nm as fingerprints could be used to identify the CMC values of the surfactants. Our current work provides an alternative method to efficiently discriminate different surfactants for the further studies of their physical and chemical functions.

Water-soluble Glucosamine-coated AIE-Active Fluorescent Organic Nanoparticles: Design, Synthesis and Assembly for Specific Detection of Heparin Based on Carbohydrate-Carbohydrate Interactions.

Two water-soluble carbohydrate-coated AIE-activate fluorescent organic nanoparticles TPE3G and TPE4G were designed and synthesized for the detection of heparin. Different from the reported strategy, we not only utilized the general detection mechanism of electrostatic interactions, but also introduced the concept of carbohydrate-carbohydrate interactions (CCIs) to enrich the detection mechanism of heparin. TPE3G can serve as an efficient "turn-on" probe with higher selectivity towards heparin than TPE4G. TEM studies revealed that the micro-aggregated TPE3G was encapsulated with the heparin chain to form a complex self-assemblied composite and emits strong fluorescence. It is believed that the results illustrated in this study provide a novel strategy based on CCls to design water-soluble and more efficient bio-probes for various biological and clinical applications.

A water-soluble AIE-active polyvalent glycocluster: design, synthesis and studies on carbohydrate-lectin interactions for visualization of Siglec distributions in living cell membranes.

In this work, we designed and synthesized an aggregation-induced emission (AIE)-active tetraphenylethene-decorated pseudo-trisialic acid (TPE3S) and validated its high affinity for Siglecs using microscale thermophoresis techniques. TPE3S was a unique binding-on fluorescent trivalent sialocluster which was successfully utilized for the visualization of Siglecs expressed on the surface of mammalian cells.

Water-soluble AIE-Active Fluorescent Organic Nanoparticles: Design, Preparation and Application for Specific Detection of Cysteine over Homocysteine and Glutathione in Living Cells.

Water-soluble ratiometric AIE-active fluorescent organic nanoparticles 2OA-FON for the specific sensing of cysteine over other biothiols are reported. The obtained amphiphilic probe included olefin aldehyde as recognizing unit, tetraphenylethylene as fluorescence reporter and lactose moiety as a hydrophilic group. This work provides a general design strategy based on the introduction of a sugar moiety into a hydrophobic AIEgen to develop ratiometric water-soluble fluorescent organic nanoparticles.

A tetravalent sialic acid-coated tetraphenylethene luminogen with aggregation-induced emission characteristics: design, synthesis and application for sialidase activity assay, high-throughput screening of sialidase inhibitors and diagnosis of bacterial vaginosis.

We report a turn-on tetravalent sialic acid-coated tetraphenylethene luminogen (TPE4S) with excellent hydrophilicity, good stability, high sensitivity and unique selectivity towards sialidases, and the maximum fluorescence enhancement was ∼40 fold. More importantly, TPE4S was successfully utilized for the screening of sialidase inhibitors and diagnosis of bacterial vaginosis.

Boronic acid-based chemical sensors for saccharides.

During the past decades, the interaction between boronic acids-functionalized sensors and saccharides is of great interest in the frontier domain of the interdiscipline concerning both biology and chemistry. Various boronic acid-based sensing systems have been developed to detect saccharides and corresponding derivatives in vitro as well as in vivo, which embrace unimolecular sensors, two-component sensing ensembles, functional assemblies, and boronic acid-loaded nanomaterials or surfaces. New sensing strategies emerge in endlessly with excellent selectivity and sensitivity. In this review, several typical sensing systems were introduced and some promising examples were highlighted to enable the deep insight of saccharides sensing on the basis of boronic acids.

Aggregation-Induced-Emission Materials with Different Electric Charges as an Artificial Tongue: Design, Construction, and Assembly with Various Pathogenic Bacteria for Effective Bacterial Imaging and Discrimination.

Imaging-based total bacterial count and type identification of bacteria play crucial roles in clinical diagnostics, public health, biological and medical science, and environmental protection. Herein, we designed and synthesized a series of tetraphenylethenes (TPEs) functionalized with one or two aldehyde, carboxylic acid, and quaternary ammonium groups, which were successfully used as fluorescent materials for rapid and efficient staining of eight kinds of representative bacterial species, including pathogenic bacteria Vibrio cholera, Klebsiella pneumoniae, and Listeria monocytogenes and potential bioterrorism agent Yersinia pestis. By comparing the fluorescence intensity changes of the aggregation-induced-emission (AIE) materials before and after bacteria incubation, the sensing mechanisms (electrostatic versus hydrophobic interactions) were simply discussed. Moreover, the designed AIE materials were successfully used as an efficient artificial tongue for bacteria discrimination, and all of the bacteria tested were identified via linear discriminant analysis. Our current work provided a general method for simultaneous broad-spectrum bacterial imaging and species discrimination, which is helpful for bacteria surveillance in many fields.

A new method to investigate the catalytic mechanism of YhdE pyrophosphatase by using a pyrophosphate fluorescence probe.

YhdE is a Maf (multicopy associated filamentation) proteins from Escherichia coli which exhibits pyrophosphatase activity towards selected nucleotides, although its catalytic mechanism remains unclear. Herein we used a novel fluorescence probe (4-isoACBA-Zn(II) complex) to characterize the enzymatic properties of YhdE and its mutant, establishing a new method for assaying pyrophosphatase catalytic function. Our results reveal for the first time that the new fluorescence sensor confers high sensitivity and specificity and pyrophosphate (PPi) is the direct catalytic product of YhdE. Crystal structures of a mutant in the active-site loop (YhdE_E33A) show conformational flexibility implicated in the catalytic mechanism of YhdE. ITC experiments and computational docking further reveal that Asp70 and substrate dTTP coordinate Mn2+. Quantum mechanics calculations indicate that YhdE hydrolysis appears to follow a stepwise pathway in which a water molecule first attacks the α-phosphorus atom in the substrate, followed by the release of PPi from the pentavalent intermediate.

Assembly of BODIPY-carbazole dyes with liposomes to fabricate fluorescent nanoparticles for lysosomal bioimaging in living cells.

Two BODIPY-carbazole dye based fluorescent probes BCA and BCAS were designed, synthesized and encapsulated by liposomes to obtain fluorescent nanoparticles BCA-FNP and BCAS-FNP. The fluorescence imaging showed that BCA-FNP was membrane-permeable and capable of localizing lysosomes in living cells.

Boronlectin/Polyelectrolyte Ensembles as Artificial Tongue: Design, Construction, and Application for Discriminative Sensing of Complex Glycoconjugates from Panax ginseng.

Ginsenoside is a large family of triterpenoid saponins from Panax ginseng, which possesses various important biological functions. Due to the very similar structures of these complex glycoconjugates, it is crucial to develop a powerful analytic method to identify ginsenosides qualitatively or quantitatively. We herein report an eight-channel fluorescent sensor array as artificial tongue to achieve the discriminative sensing of ginsenosides. The fluorescent cross-responsive array was constructed by four boronlectins bearing flexible boronic acid moieties (FBAs) with multiple reactive sites and two linear poly(phenylene-ethynylene) (PPEs). An "on-off-on" response pattern was afforded on the basis of superquenching of fluorescent indicator PPEs and an analyte-induced allosteric indicator displacement (AID) process. Most importantly, it was found that the canonical distribution of ginsenoside data points analyzed by linear discriminant analysis (LDA) was highly correlated with the inherent molecular structures of the analytes, and the absence of overlaps among the five point groups reflected the effectiveness of the sensor array in the discrimination process. Almost all of the unknown ginsenoside samples at different concentrations were correctly identified on the basis of the established mathematical model. Our current work provided a general and constructive method to improve the quality assessment and control of ginseng and its extracts, which are useful and helpful for further discriminating other complex glycoconjugate families.