Rapid Preparation of Long-Wavelength Emissive Carbon Dots for Information Encryption Using the Microwave-Assisted Method.

The synthesis of long-wavelength emission fluorescent carbon dots is not common, and it is even more difficult to quickly synthesize within 10 min. In this experiment, yellow, orange, and red B, N codoped fluorescent carbon dots were successfully synthesized using a microwave-assisted method with o-phenylenediamine as the carbon-nitrogen source, boric acid as the boron source, and potassium chloride as the catalyst in just 7 min. Based on the different contents of B, N element doping, there are differences in their surface structures, resulting in differences in the luminescence properties of the synthesized carbon dots. Long-wavelength carbon dots can avoid interference from the blue fluorescence of filter papers and have a clearer display in information encryption. Therefore, three types of carbon dots were mixed with PVP to produce fluorescent inks, and anticounterfeiting and encryption patterns were designed on the filter paper, displaying different fluorescence information under sunlight and UV light. In addition, the rich fluorescent colors were combined ingeniously to enable secondary encryption of information in the form of binary codes that increase the difficulty of decoding. These indicate that the three synthesized long-wavelength carbon dots have good application prospects in information encryption.

Microwave synthesis of chitosan-based carbon dots for Al3+ detection and biological application.

Yellow fluorescent carbon dots (Y-CDs) were prepared via microwave method using chitosan and o-phenylenediamine as the main raw materials. The obtained Y-CDs possesses good water solubility, excellent biocompatibility and luminous stability. During the microwave pyrolysis carbonization process, the surface of Y-CDs was modified with the functional groups such as amino and carboxyl, which can bind to Al3+ by forming complexes, further improving the selectivity and sensitivity of the Al3+ detection. And the fluorescence of Y-CDs was quenched by Al3+ by static quenching process. More importantly, Y-CDs as fluorescent sensor was further applied for the determination of Al3+ in the real water samples with high reliability and accuracy. In addition, Y-CDs present potential application in biological imaging. The cultivated zebrafish embryos with Y-CDs displayed clearly in vivo uptake and metabolic fluorescence images, further confirming its low toxicity and excellent biocompatibility.

Developmental neurotoxicity of PFOA exposure on hiPSC-derived cortical neurons.

PFOA is a legacy Per- and Polyfluorinated Substances (PFAS), a group of chemicals widely used in various industrial applications and consumer products. Although there has been a voluntary phase out of PFOA since 2005, it is still widely detected in various water supplies. A growing body of evidence suggests an association between PFOA exposure, particularly during developmental stages, with increased risks of neurodegenerative diseases (NDs). The neurotoxic mechanism of developmental PFOA exposure, however, remains poorly understood. Utilizing human induced-pluripotent stem cell (hiPSC)-derived cortical neurons, we investigated the effect of PFOA exposure prior to differentiation and assessed changes in neuronal characteristics, transcriptome, and neurodegeneration markers mimicking a Developmental Origin of Health and Disease (DoHAD) paradigm. Exposure to PFOA before neuron differentiation resulted in persistent alterations in nuclear morphology, neuronal network, and calcium activity. RNA sequencing analysis further revealed transcriptomic changes aligning with Alzheimer's Disease (AD) after PFOA exposure. These observations were further corroborated by alterations in tau phosphorylation markers, the presence of fibrillar tau, an increase in liquid droplets, and a decrease in RNA translational efficiency characterized using a battery of biochemical assays. Taken together, our results revealed persistent deficits of key neuronal characteristics induced by pre-differentiation PFOA exposure, suggesting impairments in several AD-related pathways that can together contribute to the elevation of AD risk after pre-differentiation PFOA exposure.

Elevated parkinsonism pathological markers in dopaminergic neurons with developmental exposure to atrazine.

Atrazine (ATZ) is one of the most used herbicides in the US and a known endocrine disruptor. ATZ is frequently detected in drinking water, especially in Midwestern regions of the United States, exceeding the EPA regulation of maximum contamination level (MCL) of 3 ppb. Epidemiology studies have suggested an association between ATZ exposure and neurodegeneration. Less, however, is known about the neurotoxic mechanism of ATZ, particularly for exposures at a developmental stage. Here, we exposed floor plate progenitors (FPPs) derived from human induced pluripotent stem cells (hiPSCs) to low concentrations of ATZ at 0.3 and 3 ppb for two days followed by differentiation into dopaminergic (DA) neurons in ATZ-free medium. We then examined the morphology, activity, pathological protein aggregation, and transcriptomic changes of differentiated DA neurons. We observed significant decrease in the complexity of neurite network, increase of neuronal activity, and elevated tau- and α-synuclein (aSyn) pathologies after ATZ exposure. The ATZ-induced neuronal changes observed here align with pathological characteristics in Parkinson's disease (PD). Transcriptomic analysis further corroborates our findings; and collectively provides a strong evidence base that low-concentration ATZ exposure during development can elicit increased risk of neurodegeneration.

Pre-differentiation GenX exposure induced neurotoxicity in human dopaminergic-like neurons.

GenX, also known as hexafluoropropylene oxide dimer acid (HFPO-DA) was introduced as a safer alternative to perfluorooctanoic acid (PFOA) in 2009. After nearly two decades of applications there are increasing safety concerns about GenX due to its association with various organ damages. Few studies, however, have systematically assessed the molecular neurotoxicity of low-dose GenX exposure. Here, we evaluated the effects of pre-differentiation exposure of GenX on dopaminergic (DA) -like neurons using SH-SY5Y cell line; and assessed changes in epigenome, mitochondrion, and neuronal characteristics. Low dose GenX exposure at 0.4 and 4 µg/L prior to differentiation induced persistent changes in nuclear morphology and chromatin arrangements, manifested specifically in the facultative repressive marker H3K27me3. We also observed impaired neuronal network, increased calcium activity along with alterations in Tyrosine hydroxylase (TH) and α-Synuclein (αSyn) after prior exposure to GenX. Collectively, our results identified neurotoxicity of low-dose GenX exposure in human DA-like neurons following a developmental exposure scheme. The observed changes in neuronal characteristics suggest GenX as a potential neurotoxin and risk factor for Parkinson's disease.

Iridescent coating of graphene oxide on various substrates.

Two-dimensional nanomaterials have been incorporated into coating layers for exceptional properties in mechanic toughness, electronics, thermology and optics. Graphene oxide (GO), however, was greatly hindered by its strong adsorption within visible wavelength and hereby the intrinsic dark color at the solid state. Herein, we found a unique aqueous mixture of GO containing sodium dodecyl sulfate and l-ascorbic acid. It enabled to produce iridescent coating layers with tunable thickness of 0.3-50 µm on both hydrophilic and hydrophobic substrates (e.g., glass, aluminum foil, polytetrafluoroethylene), through brushing, liquid-casting, dipping and writing. Their iridescence could be further tuned by incorporating MXene nanosheets. And their mechanical properties could be enhanced by certain synthetic polymers (e.g., polyvinyl alcohol and polyethylene glycol). Their sensitivity to heat, laser and water also benefited to pattern the coating layers. Furthermore, by controlling laser intensity, the domain color could be changed (e.g., green to blue). Thus, this study may pave a new pathway of producing iridescent coatings of graphene oxide in a large scale for practical applications.

Chitosan and κ-carrageenan-derived nitrogen and sulfur co-doped carbon dots "on-off-on" fluorescent probe for sequential detection of Fe3+ and ascorbic acid.

This study develops a high sensitive and selective "on-off-on" fluorescent probe for sequential detection of iron ion (Fe3+) and ascorbic acid (AA) based on nitrogen and sulfur co-doped carbon dots (N, S-CDs), which were synthesized by using chitosan and κ-carrageenan as raw materials through one-step hydrothermal protocol. The synthesized N,S-CDs possess particularly high quantum yield (QY = 59.31%), excellent stability and excitation dependent behavior, showing great potential for practical applications. Furthermore, N,S-CDs provided high selectivity and strong anti-interference to Fe3+ due to its fluorescence quenching performance, revealing a wide linear concentration range from 1 to 100 µM for the detection of Fe3+ ion with an extremely low limit of detection of 57 nM, and presented reliable and accurate results in actual sample detection of Fe3+. The overall fluorescence quenching mechanism of N,S-CDs with Fe3+ was due to the formation of N,S-CDs/Fe3+ initiated to the aggregation and electron transfer of N,S-CDs, resulting in the static quenching of fluorescence. More interestingly, AA could reduce Fe3+ to Fe2+ and efficaciously recover the quenched fluorescence of N,S-CDs/Fe3+. N,S-CDs/Fe3+ as "turn-on" fluorescent probe was further applied for detecting AA in a linear range of 0.5-90 µM with a detection limit of 38 nM.

Chitosan-derived N-doped carbon dots for fluorescent determination of nitrite and bacteria imaging.

N-doped carbon dots (N-CDs) were successfully synthesized via simple one-step hydrothermal carbonization using chitosan as carbon and nitrogen sources. The obtained N-CDs contained a variety of functional groups on the NCDs surface, and exhibited excitation-independent behavior and strong blue fluorescence with a relatively higher fluorescence quantum yield (QY = 35%). It also presented excellent water solubility, resistance to pH change, high ion strength and UV irradiation. Since the fluorescence of the N-CDs could be selectively quenched by NO2-, they could act as a fluorescent sensor for the determination of NO2- in real tap water and lake water samples with a wide linear range (1-500 µM) and low detection limit (0.1 µM). They could also be used for bacterial imaging as multicolor fluorescent probes. The results indicated that N-CDs could be a promising candidate material for biomedical applications.

Clinical and imaging predictors of impaired myocardial perfusion in symptomatic patients after percutaneous coronary intervention: insights from dynamic CT myocardial perfusion imaging.

BACKGROUND: We aimed to investigate the relationship between baseline clinical characteristics and postprocedural myocardial perfusion as determined by dynamic computed tomography myocardial perfusion imaging (CT-MPI). METHODS: We retrospectively included consecutive symptomatic post percutaneous coronary intervention (PCI) patients, who underwent dynamic CT-MPI + coronary CT angiography (CCTA) and who were revealed to have patent stents on previously revascularized lesions. Myocardial blood flow (MBF) was measured for stented territories and reference territories. Various baseline clinical and angiographic parameters were tested for the association with reduced MBF of stented territories. RESULTS: A total of 81 patients with 96 stented vessels were included in the analysis. The mean effective doses of radiation for the whole integrated CT protocol (calcium score + dynamic CT-MPI + CCTA) was 4.89±1.14 (2.58-6.93) mSv. Overall, 49 stented vessels had reduced MBF (75.3±17.2 mL/100 mL/min) within related territories, whereas 47 stented vessels had normal MBF (138.6±20.5 mL/100 mL/min). Peak levels of high-sensitivity cardiac troponin I (hs-cTnI), N-terminal pro-B-type natriuretic peptide (NT-pro-BNP), high-sensitivity C-reactive protein (hs-CRP), and glucose were significantly higher, while preprocedural thrombolysis in myocardial infarction (TIMI) flow grade was lower in participants with reduced MBF of stented territories. Acute myocardial infarction (AMI) also predominantly presented in participants with decreased MBF after revascularization. According to multivariate analysis, peak hs-cTnI level was the strongest predictor [adjusted hazard ratio (HR): 4.548, P=0.003] for decreased myocardial perfusion, followed by TIMI flow grade, AMI, stenotic extent, and NT-pro-BNP. CONCLUSIONS: The baseline hs-cTnI peak level was the strongest predictor for decreased myocardial perfusion after revascularization, followed by AMI, stenotic extent, and NT-pro-BNP.

Facile and Green Fabrication of Carrageenan-Silver Nanoparticles for Colorimetric Determination of Cu2+ and S2.

In the present work, silver nanoparticles (AgNPs) were prepared by a simple and green method using carrageenan as reducing and capping agent. The as-synthesized carrageenan-AgNPs was demonstrated as an effective duel colorimetric sensing for selective and sensitive recognition of Cu2+ and S2-, which could be used to detect these ions with naked eyes. In addition, the possible sensing mechanism was that Cu2+ ions caused serious aggregation of carrageenan-AgNPs, which led to the color change of carrageenan-AgNPs. AgNPs were etched by S2- forming Ag2S, which played an important role in the determination of S2- ions. Furthermore, it has been successfully applied to the determination of Cu2+ and S2- in tap water and lake water, showing its great potential for the analysis of environmental water samples.

Facile Synthesis of Nitrogen-Doped Carbon Quantum Dots with Chitosan for Fluorescent Detection of Fe3.

A facile, economical, and one-step hydrothermal method was used to prepare highly luminescent nitrogen-doped carbon quantum dots (N-CQDs) with chitosan as both carbon and nitrogen sources. The as-prepared N-CQDs have an average size of 2 nm and exhibit excitation wavelength-dependent fluorescence with a maximum excitation and emission at 330 and 410 nm, respectively. Furthermore, due to the effective quenching effect of Fe3+ ions, the prepared N-CQDs can be used as a fluorescent sensor for Fe3+ ion-sensitive detection with a detection limit of 0.15 µM. The selectivity experiments revealed that the fluorescent sensor is specific to Fe3+ even with interference by high concentrations of other metal ions. Most importantly, the N-CQD-based Fe3+ ion sensor can be successfully applied to the determination of Fe3+ in real water samples. With excellent sensitivity and selectivity, such stable and cheap carbon materials are potentially suitable for the monitoring of Fe3+ in environmental application.

Facile synthesis of chitosan-gold nanocomposite and its application for exclusively sensitive detection of Ag+ ions.

This article reported a simple, green approach for preparing uniform gold nanoparticles (AuNPs) with chitosan as reducing and stabilizing agent in aqueous media. Furthermore, a simple, rapid, sensitive colorimetric method was developed for the detection of Ag+ ions using the as-prepared chitosan functionalized gold nanoparticles (CS-AuNPs) as a probe. The added Ag+ could first interact with the Au core to form a metallic bond, and then reduced by chitosan and deposited on the surface of AuNPs, leading to the formation of alloy Au-Ag core-shell NPs. The characteristic surface plasmon resonance (SPR) peak of CS-AuNPs at 520 nm was blue-shifted and the color of the solution changed from pink to orange with the Ag+ addition. Ag+ could be well determined ranging from 1.0 to 100 µM with detection limit of 0.13 µM. Additionally, this method displayed high sensitivity, selectivity and could be applied to the detection of Ag+ ions in water samples.

Facile Synthesis of IrCu Microspheres Based on Polyol Method and Study on Their Electro-Catalytic Performances to Oxygen Evolution Reaction.

The development of Ir-based catalyst with high efficiency for oxygen evolution reaction (OER) in acidic conditions is of great significance to the development of clean energy, but it still remains a significant challenge for shape controlled synthesis of Ir-based catalysts. This article presented a facile one-pot synthesis method that is based on polyol method for preparing IrCu microspheres. In the process of synthesis, formaldehyde solution and ethylene glycol were used as reducing agent and solvent, respectively, while poly(vinylpyrrolidone) was used as surfactant and dispersant, and all of them played important roles in the successful synthesis of Ir-Cu microspheres. The Ir-Cu microspheres, as synthesized, showed well sphere shape and smooth surface, while their alloy features were quite clear and the composition could be adjusted. Benefitting from the synergistic electronic effect between the Iridium and Cupric atoms from the alloy, the IrCu0.77 microspheres exhibited excellent electrocatalytic activity towards OER in 0.1 M HClO4 electrolyte, and to achieve 10 mA cm-2, IrCu0.77 microspheres only required the overpotential of 282 mV, which was much lower than that of commercial Ir/C catalysts.

Non-Chloride in Situ Preparation of Nano-Cuprous Oxide and Its Effect on Heat Resistance and Combustion Properties of Calcium Alginate.

With Cu2+ complexes as precursors, nano-cuprous oxide was prepared on a sodium alginate template excluded of Cl- and based on which the calcium alginate/nano-cuprous oxide hybrid materials were prepared by a Ca2+ crosslinking and freeze-drying process. The thermal degradation and combustion behavior of the materials were studied by related characterization techniques using pure calcium alginate as a comparison. The results show that the weight loss rate, heat release rate, peak heat release rate, total heat release rate and specific extinction area of the hybrid materials were remarkably lower than pure calcium alginate, and the flame-retardant performance was significantly improved. The experimental data indicates that nano-cuprous oxide formed a dense protective layer of copper oxide, calcium carbonate and carbon by lowering the initial degradation temperature of the polysaccharide chain during thermal degradation and catalytically dehydrating to char in the combustion process, and thereby can isolate combustible gases, increase carbon residual rates, and notably reduce heat release and smoke evacuation.

Preparation of CdTe/Alginate Textile Fibres with Controllable Fluorescence Emission through a Wet-Spinning Process and Application in the Trace Detection of Hg2+ Ions.

Fluorescent textile fibres (FTFs) are widely used in many industrial fields. However, in addition to fibres with good fluorescence, fibres with excellent colour controllability, structural stability and appropriate mechanical strength still need to be developed. In this work, CdTe/alginate composite FTFs are prepared by taking advantage of the interactions between CdTe nanocrystals (NCs) and alginate macromolecules via a wet-spinning machine with a CaCl2 aqueous solution as the coagulation bath. CdTe NCs were chemically fixed in the fibre due to the interactions among surface ligands, macromolecules and coagulators (calcium ions), which ensured the excellent dispersity and good stability of the fibres. Förster resonance energy transfer (FRET) between NCs in the fibre was found to be restricted, which means that the emission colour of the fibres was totally controllable and could be predicted. Other properties of alginate fibres, such as flame retardance and mechanical strength, were also well preserved in the fluorescent fibres. Finally, FTFs showed good selectivity toward trace Hg2+ ions over other metallic ions, and the detection could be identified by the naked eye.

Facile Synthesis of Pd Nanocubes with Assistant of Iodide and Investigation of Their Electrocatalytic Performances Towards Formic Acid Oxidation.

This article presents a facile, one-pot method using the aqueous phase for the synthesis of high-quality Pd nanocubes. In this study, Pd chloride was used as the precursor, sodium iodide as capping agent, and poly(vinylpyrrolidone) as surfactant and reducing agent. The effects of different halogens on the morphology of Pd nanocrystals were investigated. The results showed that, in this synthesis system, the selection and proper amount of sodium iodide was essential to the preparation of high-quality Pd nanocubes. When iodide was replaced by other halogens (such as bromide and chloride), Pd nanocrystals with cubic morphology could not be obtained. In addition, we have found that NaBH4 can be used to efficiently remove inorganic covers, such as iodide, from the surface of Pd nanoparticles as synthesized. The Pd nanoparticles obtained were employed as electro-catalysts for formic acid oxidation, and they exhibited excellent catalytic activity and good stability towards this reaction.

An Alginate Hybrid Sponge with High Thermal Stability: Its Flame Retardant Properties and Mechanism.

The worldwide applications of polyurethane (PU) and polystyrene (PS) sponge materials have been causing massive non-renewable resource consumption and huge loss of property and life due to its high flammability. Finding a biodegradable and regenerative sponge material with desirable thermal and flame retardant properties remains challenging to date. In this study, bio-based, renewable calcium alginate hybrid sponge materials (CAS) with high thermal stability and flame retardancy were fabricated through a simple, eco-friendly, in situ, chemical-foaming process at room temperature, followed by a facile and economical post-cross-linking method to obtain the organic-inorganic (CaCO3) hybrid materials. The microstructure of CAS showed desirable porous networks with a porosity rate of 70.3%, indicating that a great amount of raw materials can be saved to achieve remarkable cost control. The sponge materials reached a limiting oxygen index (LOI) of 39, which was greatly improved compared with common sponge. Moreover, with only 5% calcium carbonate content, the initial thermal degradation temperature of CAS was increased by 70 °C (from 150 to 220 °C), compared to that of calcium alginate, which met the requirements of high-temperature resistant and nonflammable materials. The thermal degradation mechanism of CAS was supposed based on the experimental data. The combined results suggest promising prospects for the application of CAS in a range of fields and the sponge materials provide an alternative for the commonly used PU and PS sponge materials.

A Simple and Fast Method to Synthesize Cubic Iridium Nanoparticles with Clean Surface Free from Surfactants.

Cubic Iridium nanoparticles without any surfactants on the surface have been synthesized successfully in this work. The process of synthesis was quite simple by just injecting one drop of 400 µL solution containing Iridium precursor onto Cu foil (1 cm × 1 cm), and through galvanic reaction between the Ir precursor and Cu foil, the cubic Iridium nanoparticle could be obtained quite quickly (<30 s). The Cu foil played the roles of both reducing agent and substrate. This method could also be employed to synthesize cubic nanoparticles of other Pt-group metals such as Rh. By employing this method, cubic metal nanoparticles with surfactant-free surfaces could be produced economically and efficiently, and as a result, a realistic relationship between structure and catalytic activity could be established.

Highly Efficient Flame Retardant Hybrid Composites Based on Calcium Alginate/Nano-Calcium Borate.

Hybrid composites with low flammability based on renewable calcium alginate and nano-calcium borate were fabricated using an in situ method through a simple, eco-friendly vacuum drying process. The composites were characterized by X-ray diffractometry (XRD), Fourier transform infrared spectrum (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The combustion behavior and flammability of the composites were assessed by using the limiting oxygen index (LOI) and cone calorimetry (CONE) tests. The composites showed excellent thermal stability and achieved nonflammability with an LOI higher than 60. Pyrolysis was investigated using pyrolysis⁻gas chromatography⁻mass spectrometry (Py-GC-MS) and the results showed that fewer sorts of cracking products were produced from the hybrid composites compared with the calcium alginate. A possible thermal degradation mechanism of composites was proposed based on the experimental data. The combined results indicate that the calcium borate had a nano-effect, accumulating more freely in the hybrid composites and contributing significantly to both the solid phase and gas phase, resulting in an efficient improvement in the flame retardancy of the composites. Our study provides a novel material with promising potentiality for flame retardant applications.