Probe Material Research Articles

Flexible Soft X-Ray Image Sensors based on Metal Halide Perovskites With High Quantum Efficiency.

Soft X-ray imaging is a powerful tool to explore the structure of cells, probe material with nanometer resolution, and investigate the energetic phenomena in the universe. Conventional soft X-ray image sensors are by and large Si-based charge coupled devices that suffer from low frame rates, complex fabrication processes, mechanical inflexibility, and required cooling below -60°C. Here, a soft X-ray photodiode is reported based on low-cost metal halide perovskite with comparable performance to commercial Si-based device. Nanothrough network electrodeminimized the optical loss due to the shadowing of insensitive layers, while a multidimensional perovskite heterojunctionis generated to reduce the photo-generated carrier loss. This strategy promoted a record quantum efficiency of 8×103% without cooling, several orders of magnitude greater than the previously achieved. Flexible and curved soft X-ray imaging arrays are fabricated based on this high-performance device structure, demonstrating stable soft X-ray response and sharp imaging capabilities. This work highlights the low-cost and efficient perovskite photodiode as a strong candidate for the next-generation soft X-ray image sensors.

Measurements of K-edge and L-edge extended x-ray absorption fine structure at the national ignition facility (invited).

High-energy-density laser facilities and advances in dynamic compression techniques have expanded access to material states in the Terapascal regime relevant to inertial confinement fusion, planetary science, and geophysics. However, experimentally determining the material temperature in these extreme conditions has remained a difficult challenge. Extended X-ray Absorption Fine Structure (EXAFS), referring to the modulations in x-ray absorption above an absorption edge from photoelectrons' interactions with neighboring atoms, has proven to be a versatile and robust technique for probing material temperature and density for mid-to-high Z elements under dynamic compression. The current platform at the National Ignition Facility has developed six configurations for EXAFS measurements between 7 and 18keV for different absorption edges (Fe K, Co K, Cu K, Ta L3, Pb L3, and Zr K) using a curved-crystal spectrometer and a bright, continuum foil x-ray source. In this work, we describe the platform geometry, x-ray source performance, spectrometer resolution and throughput, design considerations, and data in ambient and dynamic-compression conditions.

Development of a thermal diagnostic system for the SPARC tokamak.

The SPARC tokamak will have scrape-off layer parallel heat fluxes on the order of GW/m2. Managing power exhaust of this magnitude will be mandatory for a reactor-scale device. To enable this mission, a thermal diagnostic suite will be deployed to measure the in-vessel structural temperatures to ensure they do not exceed their design limits and to determine the spatial distribution and magnitude of energy deposited onto the first wall. Thermocouples and fiber Bragg gratings have been selected for their environmental compatibility and proven useful on other fusion devices. High-density thermocouple arrays in the divertor will have two spring-loaded thermocouples per divertor target tile, which are being used as calorimeters, and will look to resolve the temperature distribution within the tile due to a swept or static strike point. All systems will need to survive the vacuum vessel bake, set at a minimum plasma facing surface temperature of 350 °C, which presents a particularly challenging environment for the fiber-based subsystem. Along with this temperature design requirement, all the materials in the primary vacuum need to be ultra-high vacuum compatible, able to handle the expected neutron and gamma radiation, as well as tritium exposure, all of which restrict material options. Finally, due to the expected activated environment in SPARC, there will be little chance to replace defective sensors, so system resilience is ensured through toroidal redundancy, probe material selection, and mitigating the impact of common-mode failures. Initial testing of sensors show that intershot structural measurements are sufficiently captured with the raw output, but intrashot measurements of the plasma facing material requires model-based interpretive tools.

Electrochemiluminescence immunoassay system based on PCN-224-Mn and gold-platinum bimetallic nanoflowers for sensitive detection of ochratoxin A

In this work, a novel Electrochemiluminescence Immunosensor was constructed using PCN-224-Mn and gold-platinum nanoflowers (AuPt NFs) for the ultrasensitive detection of ochratoxin A (OTA). PCN-224 modified with Mn (II) was synthesized as a probe material. The interaction efficiency of PCN-224 with S2O82− was also greatly improved. AuPt NFs were used as the substrate material for the electrodes. It has favorable biocompatibility, large specific surface area and can bind more antigen. Also greatly increased the electroactive surface area and conductivity of the electrode. OTA was detected using a competitive immunoassay strategy, in which OTA in the sample competes with the encapsulated antigen for a finite number of antibodies. ECLIA for the detection of OTA was designed to be highly sensitive, with a linear range from 0.0002 ng mL−1 to 1000 ng mL−1 and a LOD as low as 0.067 pg mL−1. In addition, it was evident from the electrochemical analyses that PCN-224-Mn had a stronger and more stable ECL signal compared to the plain PCN-224. The successful preparation of specific, sensitive and reproducible ECL immunosensors confirms the great promise for the detection of OTA or other small molecule mycotoxins.

A Magnesium Organic Framework Fluorescent Sensor for Selective Detection of Nitrofuran Antibiotics and Inorganic Pollutants

ABSTRACTA novel 3D magnesium‐based metal organic framework (Mg‐MOF) has been solvothermally synthesized using 5‐(pyridin‐4‐yl)isophthalic acid. The ligand has demonstrated to preserve two types of coordination modes depending on the connection mode of the pyridine group. The uncoordinated pyridine groups provide Lewis base sites (LBSs), whereas the coordinated ones promote to form a rarely reported eight‐connected tetranuclear Mg clusters. Benefiting from the multinuclearity with high number of connections, the framework keeps good performance of high thermal stability until 500°C. Furthermore, the framework exhibits potential open metal sites (OMSs) benefiting from the terminal coordinated water groups of the metal clusters. Owing to the abundant active sites, the Mg‐MOF exhibits good sensitivity to nitrofuran antibiotics and Cr2O72−, with high KSV (at 104 M−1 level) and low limit of detection (LOD) values (∼10−6 M). Density functional theory (DFT) investigation reveals that the interchange of the HOMO–LUMO energy levels of the framework and antibiotics is responsible for the sensing activity. In addition, the Mg‐MOF is greatly recyclable in five cycles while maintaining the structural rigidity and sensing activity, making it a promising luminescence probe material.

Highly efficient electrochemiluminescent properties of porphyrin-based metal-organic framework Zn-TCPP and its immunoassay application to the detection of ochratoxin A

BackgroundOchratoxin A (OTA) is a group of mycotoxins that are widely distributed in food and feed and are closely associated with human health, so it is particularly important to detect OTA in cereal-based foods. Porphyrins and their derivatives have been widely investigated for their excellent electrochemical luminescence properties. Tetrakis 4-carboxyphenyl) porphyrin (TCPP) has limited applications because of its tendency to aggregate in water. ResultsTo enhance the luminescence efficiency of TCPP, the porphyrin can be immobilized as an organic ligand in a metal-organic framework. This allows the preparation of a novel zinc-porphyrin-based MOF (Zn-TCPP nanorods), which in turn provides highly efficient and stable cathodic ECL signals. Herein, an ultra-sensitive electrochemiluminescence immunoassay was proposed using Zn-TCPP nanorods as high-efficiency luminophores and Bi2S3@Au nanoflowers as electrode substrate materials for the detection of ochratoxin A in foodstuffs. Zn-TCPP has a strong and stable signal, and has been used as an immunosensor probe material. The Bi2S3@Au nanoflowers was used to decorate the glass carbon electrode and support for antibody immobilization due to its good electrical conductivity and large specific surface area. Under the optimized conditions, the constructed immunosensor could realize the sensitive detection of ochratoxin A in the detection range of 0.0004 ng mL−1 to 500 ng mL−1 with the detection limit as low as 0.13 pg mL−1. In addition, the sensing platform has been used for the detection of OTA in wheat flour and feed. SignificanceHence, it is worth believing that this strategy can pave a bright research direction for the detection of ochratoxin A or other small molecule mycotoxins content in foods, as well as contributing to the further study of MOF in the field of ECL.

Water-Soluble Photoluminescent Ag Nanoclusters Stabilized by Amphiphilic Copolymers as Nanoprobe for Hypochlorite Detection

Luminescent Ag nanoclusters (Ag NCs) are a promising probe material for sensing and bioimaging applications. However, the intrinsic obstacle of poor water stability and photostability greatly restrict their practical application in biological systems. Herein, we report the intracellular hypochlorite (ClO−) detection with amphiphilic copolymer-modified luminescent Ag NCs with good biocompatibility and photostability. The Ag NCs were synthesized by using chemically inert hydrophobic ligands and then modified with an amphiphilic (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(poly(ethylene glycol))-2000]) (DSPE-PEG-2000) and sodium dodecyl sulfonate (SDS) for phase transfer. It was found that the approach of the removal of organic solvents during the phase transfer has remarkable influences on the properties of the Ag NCs, including their size, luminescence property, and aqueous stability. Furthermore, the silver core of Ag NCs could be oxidatively damaged by ClO−, thereby causing photoluminescence (PL) quenching. The ClO−-induced PL quenching was specific over the other common reactive oxygen species (ROS) as well as some common interferences. Finally, they have been successfully applied as a fluorescent nanoprobe for detecting exogenous and endogenous ClO− in living cells.

Effects of ash formation during co-firing refuse-derived fuel with coal on initial superheater material degradation

ABSTRACT Refuse-derived fuel (RDF) has significant potential as a co-firing fuel in power plants. However, its different characteristics from coal, particularly the high chlorine (Cl) concentration in the ash deposits, can degrade metal elements during combustion. This study aims to investigate the effect of adding RDF to coal on the initial degradation of materials caused by ash deposits during combustion. This research is conducted on a laboratory scale using a drop tube furnace to simulate pulverized coal boiler conditions, analyzying ash deposits, mineral transformations, and evaluating the microstructure of the probe material. The results show that the chlorine content in the R-10 at 0.035 wt% substantially affects the initial degradation of 18Cr-Ni during combustion. The oxide layer begins to degrade in the second hour due to ash deposits, reaching 2.38 μm. The presence of Ca (1.11%), K (1.66%), Na (4.46%), and Cl (0.42%) increases to 1.12% on the metal surface, gradually attacking the substrate area and forming cavities. Degradation increases linearly up to probe-8, resulting in a thickness loss of 3.81 μm and a significant reduction in chromium content, which decreases by 12.54%. These findings highlight the importance of understanding the impact of chlorine levels in RDF, which can aggressively attack and corrode metals.

Indirect Voltammetry Detection of Non-Electroactive Neurotransmitters Using Glassy Carbon Microelectrodes: The Case of Glutamate

Glassy carbon (GC) microelectrodes have been successfully used for the detection of electroactive neurotransmitters such as dopamine and serotonin through voltammetry. However, non-electroactive neurotransmitters such as glutamate, lactate, and gamma-aminobutyric acid (GABA) are inherently unsuitable for detection through voltammetry techniques without functionalizing the surface of the microelectrodes. To this end, we present here the immobilization of the L-glutamate oxidase (GluOx) enzyme on the surface of GC microelectrodes to enable the catalysis of a chemical reaction between L-glutamate, oxygen, and water to produce H2O2, an electroactive byproduct that is readily detectable through voltammetry. This immobilization of GluOx on the surface of bare GC microelectrodes and the subsequent catalytic reduction in H2O2 through fast-scan cyclic voltammetry (FSCV) helped demonstrate the indirect in vitro detection of glutamate, a non-electroactive molecule, at concentrations as low as 10 nM. The functionalized microelectrodes formed part of a four-channel array of microelectrodes (30 μm × 60 μm) on a 1.6 cm long neural probe that was supported on a flexible polymer, with potential for in vivo applications. The types and strengths of the bond between the GC microelectrode surface and its functional groups, on one hand, and glutamate and the immobilized functionalization matrix, on the other hand, were investigated through molecular dynamic (MD) modeling and Fourier transform infrared spectroscopy (FTIR). Both MD modeling and FTIR demonstrated the presence of several covalent bonds in the form of C-O (carbon–oxygen polar covalent bond), C=O (carbonyl), C-H (alkenyl), N-H (hydrogen bond), C-N (carbon–nitrogen single bond), and C≡N (triple carbon–nitrogen bond). Further, penetration tests on an agarose hydrogel model confirmed that the probes are mechanically robust, with their penetrating forces being much lower than the fracture force of the probe material.

Degradation of the protective layer on stainless steel by chlorine variation under high-temperature conditions

This study investigates the impact of various chlorine (Cl) content ratios on the degradation of 304 stainless steel during co-combustion of coal with solid recovered fuel (SRF) at a combustion temperature of 1250 °C. The research specifically focuses on the corrosion potential at 550 °C, which represents the temperature in the superheater area of a power plant. High-temperature corrosion experiments are conducted in a laboratory-scale drop tube furnace to observe initial corrosion during combustion. Analyses include visual examination, mineral analysis, microstructure-based metal analysis, and corrosion rate determination. The results show significant degradation at Cl contents higher than 0.09 wt%. The usual carbide formation at the grain boundaries in 304 stainless-steel does not occur in the short-term tests, as indicated by Cr content remaining above 12 % and Cl content less than 0.06 wt%. In addition, material degradation is due to the Cl reacting with alkali content, damaging the oxide layer and causing pits in the cross-section area of the probe material. This research provides insights into the critical role of Cl in metal degradation and identifies the optimum Cl amount suitable for coal blending in power plants.

An Eu (III)-functionalized covalent organic framework fluorescent probe for specific detection of Flumequine based on pore restriction and antenna effect

The overuse of quinolone antibiotics has led to a series of health and environmental issues. Herein, we combine the distinct luminescence properties of Eu3+ with the unique structure of covalent organic frameworks (COFs) to develop a precise and sensitive fluorescent probe for detecting Flumequine (Flu) in water. Eu3+ is thoroughly anchored into the channels of COFs as recognition sites, while the synthesized probe material still maintains its intact framework structure. The unique structure of COFs provides excellent support and protection for Eu3+. Therefore, COF-Eu can rapidly bind with Flu which can transfer the absorbed energy to Eu3+ through an “antenna effect”, resulting in red fluorescence. Moreover, there is a good linear relationship between Flu concentration in the range of 0–30 µM, with a detection limit of 41 nM. Simultaneously, the material maintains remarkable reproducibility, with its performance remaining almost unchanged after five cycles of use. Remarkably, the probe demonstrates excellent Flu recovery rates in real samples. This study provides a viable approach for the recognition of flumequine in the environment through a customized fluorescence detection method.

A methodological approach to assess the ropy character of stirred acid dairy gels based on the measure of adhesiveness.

This work aims to evaluate the potential and limits of adhesiveness measurement using a texturometer to assess the ropiness of acid dairy gels for starter selection. Commercial yogurts of various formulations and textures were used to assess the ability of adhesiveness to detect ropiness and to compare different probes' performance. Chemically acidified gels using different concentrations of glucono-delta-lactone (GDL) were tested to determine the effect of pH on adhesiveness. In addition, acidified (GDL) milk containing 3 EPS-producing adjunct strains were produced to evaluate the detection of ropy strains using adhesiveness, compared with an inoculation loop stretching test. The adhesiveness of commercial yogurts was mainly impacted by its formulation. Visually ropier commercial yogurts with high protein and fat contents presented higher adhesiveness. Globally, adhesiveness analysis was not impacted by probe material, but larger probes resulted in higher adhesiveness values. The addition of adjuncts increased the adhesiveness of GDL gels compared with the controls. Results between inoculation loop stretching test and adhesiveness were similar, except for Lactobacillus. delbrueckii lactis LMA-1511 which exhibited high adhesiveness but no threading with the loop stretching test. When varying GDL concentration, adhesiveness increased with decreasing pH until pH 4.45, and remained stable until pH 4.18. In the pH zone from 4.18 to 4.45, differences in adhesiveness could indicate the presence of a ropy strain. This method is promising for industries as a quality control or screening method for starter cultures due to its simplicity and the availability of texturometers.

Recent Development and Advancement in Quantum Dots in Pharmaceutical and Biomedical Fields for the Delivery of Drugs

Abstract: Nanoscale semiconductors known as quantum dots (QDs) are essential for drug testing because they bridge the gap between nanotechnology and the testing of drugs. QDs are a valuable tool in theranostics and treatment because of their unique physicochemical features. Due to their photoluminescence and electronic properties, including broad and continuous absorption spectra, narrow emission spectra from visible to near-infrared wavelengths, and long-lasting and high brightness, they are suitable probe materials for use in (bio)sensing (immunological) platforms. Several studies use QDs due to their optical, magnetic, electrical, photochemical, and biological features that allow them to be employed in various scientific domains. When utilized in drug delivery systems, fluorescent markers, such as QDs, can track the metabolism of drugs in the human body. Many medicinal applications, such as disease diagnosis and medication research, can benefit from these fluorescent tests. In this review article, the application of QD in drug delivery and immunoassay sensing has been described in detail.

Loneliness in emerging adulthood: A qualitative study using cultural probes and in-depth interviews

BackgroundLoneliness has become a great public health concern in the Western world, with emerging adults being particularly vulnerable. Prolonged loneliness in emerging adults is associated with poor mental health such as symptoms of depression and anxiety that may have negative implications for health and well-being in later life. AimTo explore and gain a deeper understanding of how loneliness develops over time and how it is experienced by emerging adults in their everyday life. MethodsThe study is a thematic analysis of qualitative data consisting of cultural probes and in-depth interviews. Participants were recruited through targeted advertising on social media. During a week, participants aged 18 to 25 years old completed a cultural probe comprising open and evocative activities. These activities provided an opportunity for participants to explore their day-to-day existence, thereby contributing to the portrayal of their individual stories concerning loneliness in everyday life. After reviews of the cultural probes, in-depth interviews were conducted. ResultsParticipants were 21 emerging adults (mean age 21.3), three men and 18 women. Following thematic analysis of the cultural probe material and interview data, three overarching themes were conceptualized: 1) The many faces of loneliness, 2) The interplay between low self-esteem, intrusive thoughts, and mental health in shaping loneliness, and 3) The duality of coping strategies. ConclusionThe findings from this qualitative study offer in-depth insights into the experience of loneliness among emerging adults, highlighting its multifaceted nature and interplay with mental health. Participants' narratives revealed a duality of coping strategies, where engaging in distracting activities provided temporary relief but perpetuated long-term loneliness, and attempts to reconnect with others were sometimes hindered by past experiences. The findings contribute to a richer understanding of loneliness during this pivotal life phase, with implications for interventions needed to address social disconnectedness, thereby contributing to the broader conversation on mental health and well-being.

Magnetic Susceptibility Modeling of Magic-Angle Spinning Modules for Part Per Billion Scale Field Homogeneity

Magic-angle spinning (MAS) solid-state NMR methods are crucial in many areas of biology and materials science. Conventional probe designs have often been specified with 0.1 part per million (ppm) or 100 part per billion (ppb) magnetic field resolution, which is a limitation for many modern scientific applications. Here we describe a novel 5-mm MAS module design that significantly improves the linewidth and line shape for solid samples by an improved understanding of the magnetic susceptibility of probe materials and geometrical symmetry considerations, optimized to minimize the overall perturbation to the applied magnetic field (B0). The improved spinning module requires only first and second order shimming adjustments to achieve a sub-Hz resolution of 13C resonances of adamantane at 150 MHz Larmor frequency (14.1Tesla magnetic field). Minimal use of third and higher order shims improves experimental reproducibility upon sample changes and the exact placement within the magnet. Furthermore, the shimming procedure is faster, and the required gradients smaller, thus minimizing thermal drift of the room temperature (RT) shims. We demonstrate these results with direct polarization (Bloch decay) and cross polarization experiments on adamantane over a range of sample geometries and with multiple superconducting magnet systems. For a direct polarization experiment utilizing the entire active sample volume of a 5-mm rotor (90 µl), we achieved full width at half maximum (FWHM) of 0.76 Hz (5 ppb) and baseline resolved the 13C satellite peaks for adamantane as a consequent of the 7.31 Hz (59 ppb) width at 2% intensity. We expect these approaches to be increasingly pivotal for high-resolution solid-state NMR spectroscopy at and above 1 GHz 1H frequencies.

Fabrication of chitosan-based fluorescent hydrogel membranes cross-linked with bisbenzaldehyde for efficient selective detection and adsorption of Fe2+

Chitosan, as a natural biomass material, is green, recyclable, sustainable and well biocompatible. The molecular chain is rich in active groups such as amino and hydroxyl groups, and its preparation of fluorescent probes has the advantages of biocompatibility and efficient detection performance. In this study, a bis(benzaldehyde) (BHD) fluorescent functional molecule was designed. Then a series of fluorescent chitosan-based hydrogel films (CSBHD) were prepared using chitosan as raw material and BHD as cross-linking agent. As a fluorescent probe for metal ions, CSBHD was able to efficiently detect Fe2+ with a linear correlation of fluorescence intensity in the range of 0–160 μM, and the limit of detection (LOD) was 0.55 μM. Moreover, it has excellent adsorption performance for Fe2+ ions, with a maximum adsorption capacity of 223.5 g/mg at 500 mg/L Fe2+ concentration. Finally, we characterised the structure and microscopic morphology of CSBHD films and found that CSBHD as a hydrogel film has a high cross-linking density, good water resistance, excellent thermal stability, strong resistance to swelling, and excellent stability in cycling tests. Hence, it has great potential for application in adsorption and detection of Fe2+ ions. It also provides a good strategy for the application of chitosan based fluorescent probe materials in environmental monitoring and heavy metal ion adsorption.

Tailored different sizes of quantum dot nanobeads for sensitive and quantitative detection based on the competition fluorescence-linked immunosorbent assay platform

Highly stable and multicolor photoluminescent (PL) quantum dots (QDs) have attracted widespread attention as ideal probe materials in the field of in vitro diagnostics (IVD), especially the fluorescence-linked immunosorbent assay (FLISA), due to their advantages of high-throughput, high stability, and high sensitivity. However, the size of QDs as fluorescent probes have significant effects on antigen-antibody performance. Therefore, it is critical to design suitable QDs for obtain excellent quantitative detection-based biosensors. In this paper, we prepared different sizes of aqueous QDs (30 nm, 116 nm, 219 nm, and 320 nm) as fluorescent probes to optimize the competitive FLISA platform. The SARS-CoV-2 neutralizing antibody (NTAB) assay was used as an example, and it was found that the size of the QDs has a significant impact on the antigen-antibody binding efficiency and detection sensitivity in competitive FLISA platform. The results showed that these QD nanobeads (QBs, ∼219 nm) could be used as a labeled probe for competitive FLISA, with half-maximal inhibitory concentration (IC50) of 1.34 ng/mL and limit of detection (LOD) of 0.21 pg/mL for NTAB detection. More importantly, the results showed good specificity and accuracy, and the QB219 probe was able to efficiently bind NTAB without interference from other substances in the serum. Given the above advantages, the nanoprobe material (∼200 nm) offers considerable potential as a competitive FLISA platform in the field of IVD.

Coalescing clusters unveil regimes of frictional fluid mechanics

The coalescence of droplets is essential in a host of biological and industrial processes, where it can be a crucial limiting factor and a convenient tool to probe material properties. Controlling and understanding this phenomenon relies on theoretical models of droplet coalescence, and classical solutions for the time evolution of contacting drops (such as analytical solutions to the Stokes equation) have proven invaluable for understanding the behavior of many simple liquids. In many systems, especially biological systems on substrates, there are an increasing number of examples of discrepancies between known solutions to continuum models and experimental results. By combining computational and theoretical analyses, we show that there is an unexplored family of dry hydrodynamic or frictional coalescence processes: those governed by a highly dissipative coupling to the environment. This leads to a universality class of coalescing behavior, with unique scaling laws and time-invariant parametrizations for the time evolution of coalescing drops. To demonstrate this, we combine particle-based simulations and both continuum and boundary-integral solutions to hydrodynamic equations, which we then understand in the context of a generalized Navier-Stokes-like equation. Our work suggests a theoretical basis for further studies of coalescence, as well as other fluidlike phenomena in these friction-dominated systems, and significantly alters the interpretation of related experimental measurements. Published by the American Physical Society 2024

Rapid detection of hypobromous acid by a tetraphenylethylene-based turn-on fluorescent AIE probe and its applications

BackgroundSimilar to hypochlorous acid (HClO), hypobromous acid (HBrO) is one of the most notable reactive oxygen species (ROS). Overexpression of HBrO is linked to various diseases causing organ and tissue loss. Due to HBrO's role in the oxidation of micropollutants, real-time monitoring of HBrO in water-based systems is essential. Tetraphenylethylene (TPE)-based organic aggregation-induced emission luminophores (AIEgens) are an emerging category of fluorescent probe materials that have attracted considerable attentions. However, AIE probes are rarely applied to detect HBrO. Developing faster, more precise, and more sensitive AIE probes is thus crucial for detecting biological and environmental HBrO. ResultsA small molecule fluorescent probe 4-(1,2,2-triphenylvinyl)benzamidoxime (SWJT-21) was synthesized for the sensitive and selective detection of hypobromous acid (HBrO) based on aggregation-induced emission (AIE). The amidoxime unit of SWJT-21 would undergo an oxidation reaction with HBrO, leading to a structure differentiation between the probe and the product, and therefore the turn-on fluorescence by the AIE effect. The probe could recognize hypobromous acid rapidly (less than 3 s) in high aqueous phase (99 % water) with a turn-on fluorescence response. It was determined that the limit of detection for HBrO was 5.47 nM. Moreover, SWJT-21 demonstrates potential as a test strip for the detection of HBrO. SWJT-21 was also successfully used for the monitoring of HBrO in water samples and for the detection of endogenous/exogenous HBrO in living cells and zebrafish. SignificanceA special AIE fluorescence turn-on probe SWJT-21 based on tetraphenylethylene was designed for detecting HBrO in the environmental and biological systems. This probe has an extremely low detection limit of 5.47 nM and is able to detect HBrO in 99 % aqueous phase in less than 3 s.

ZnO nanoflakes decorated graphene oxide acting as an efficient platform for precise detection of uric acid via rhodamine fluorescence quenching

Herein, we report 2D based nanocomposite of metallic architectures as probe material for the detection of uric acid (UA). In brief, ZnO nanoflakes are grown on the basal surface of graphene oxide (GO/ZnO-NF), which eventually influences the fluorescence intensity of Rhodamine B (Rh) with varying concentrations of UA. This nanocomposite was synthesized at a low cost with optimized one-step hydrothermal process. It was observed that the transfer of electrons between GO/ZnO-NF and Rh resulted in the oxidation of UA, corroborating significant quenching of fluorescence intensity of Rh. This conjecture was later applied for the quantitative analysis of UA, affirming gradual quenching of fluorescence as a factor of UA concentration in the range of (50 µM – 8*103 µM) with a detection limit of 5.4 µM. Our fluorescent-based sensor was effective for the serum sample without losing its sensitivity, selectivity and analytical performance. Based on these findings, we anticipate that this simple, non-enzymatic, robust, inexpensive method can be a useful tool for diagnostics and biomedical applications.