Simple synthesis of silver nanocluster composites AgNCs@PE-g-PAA by irradiation method and fluorescence detection of Cr^(3+)

Silver nanoclusters(AgNCs)are a new type of nanomaterials with similar properties to molecules and unique applications.The applications of AgNCs can be significantly expanded by combining them with different matrix materials to obtain AgNC composites.Using irradiation techniques,we developed a simple two-step method for preparing silver nanocluster composites.First,polyacrylic acid(PAA)chains were grafted onto the surface of a PE film as templates(PE-g-PAA).Subsequently,silver ions were reduced in situ on the surface of the template material to obtain the AgNC composites(AgNCs@PE-g-PAA).The degree of AgNC loading on the composite film was easily controlled by adjusting the reaction conditions.The loaded AgNCs were anchored to the carboxyl groups of the PAA and wrapped in the graft chain.The particle size of the AgNCs was only 4.38±0.85 nm,with a very uniform particle size distribution.The AgNCs@PE-g-PAA exhibited fluorescence characteristics derived from the AgNCs.The fluorescence of the AgNCs@PE-g-PAA was easily quenched by Cr^(3+)ions.The composite can be used as a fluorescence test paper to realize visual detection of Cr^(3+).

Fluorescence Turn-On/Off Responses of In(Ⅲ)-MOF to Short-Chain Perfluorocarboxylic Acids

Short-chain perfluorocarboxylic acids(PFCAs) are a class of persistent organic pollutants that are widely used as substitutes for long-chain PFCAs. However, they also pose a non-negligible risk to ecosystems. In this study, we demonstrated that a fluorescent metal–organic framework(MOF)(named V-101) constructed from In^(3+)and an aromatic-rich tetratopic carboxylate ligand 5-[2,6-bis(4-carboxyphenyl) pyridin-4-yl] isophthalic acid(H4BCPIA) exhibited highly efficient turn-off and turn-on fluorescence responses toward five short-chain PFCAs in water and methanol, respectively. The limits of detection of V-101 toward five short-chain PFCAs are down to μg/L level, and it showed good anti-interference abilities toward short-chain PFCAs in the presence of common metal ions. The major mechanisms associated with fluorescence responses were molecular collisions and interactions between V-101 and short-chain PFCAs. This work demonstrates that the structure variety of MOFs imparts them with the potential of MOFs in the detection of short-chain PFCAs for pollution control.

Determination of Diphenytriazol (DL111-IT) in Rabbit Plasma by High-Performance Liquid Chromatography with Fluorescence Detection

Aim To develop an HPLC method with fluorescence detection for the assay ofDL111-IT in rabbit plasma. Methods DL111-IT and internal standard glybenzcyclamide in rabbit plasmawere extracted with chloroform. The determination was performed on a Diamonsil ODS-C_(18) column(150 mm x 4.6 mm, 5 μm) with a mobile phase of acetonitrile and 0.025 mol·L^(-1) diammoniumhydrogen phosphate buffer (pH 5.0, adjusted by phosphoric acid) (60:40, V/V) at a flow-rate of 1.0mL·min^(-1) . Fluorescence detector was operated at excitation wavelength of 250 nm and emissionwavelength of 332 nm. Results The calibration curve in plasma was linear from 1.00 - 20.00ng·mL^(-1) ( r = 0.999 6, n = 5). The method afforded average extracting recoveries of 85.3% ±1.3%, 84.9% ± 2.7% and 85.8% ± 1.8%, and the average method recoveries were 99.5% ±0.4%, 102.1%± 1.8% and 101.3% ± 2.4% for the high (20.00 ng·mL^(-1)) , middle (10.00 ng·mL^(-1)) and low (1.00 ng·mL^(-1)) check samples, respectively. The intra-day (n = 5) and inter-day (n = 5) precisions(RSD) were less than 3.0% and 7.0%, respectively. The limit of detection and quantitation for themethod were 0.3 ng·mL^(-1) (S/N = 3) and 1 ng·mL^(-1) (S/N = 10, RSD<7.0%) plasma sample,respectively. Conclusion The developed method was accurate, sensitive, simple and could be used forpharmacokinetic study of DL111- IT.

Review on the application of upconversion nanomaterials in heavy metal detection

As a widespread element,heavy metals have a significant impact on human health and threaten human health.It is of great significance to develop analytical technologies that can detect heavy metal ions quickly and accurately.In comparison to conventional fluorescent materials such as organic dyes,quantum dot(QD)labels,and carbon quantum dots(CD),fluorescence detection technology utilizing lanthanide(Ln)ion-doped upconversion nanoparticles(UCNPs)stands out due to its distinctive attributes.These include a notably reduced autofluorescence background,enhanced tissue penetration capabilities,biocompatibility with cellular tissues,and minimal photodamage inflicted on biological samples.The utilization of this technology has garnered considerable attention across multiple fields.In the domain of heavy metal detection,traditional laboratory methods necessitate costly instrumentation and a fully equipped laboratory,involving intricate sample processing procedures and protracted detection periods,as well as a demand for skilled personnel.In contrast,the implementation of this material offers rapid and cost-effective detection,significantly mitigating the technical barriers for operators.Consequently,this represents an exceptional avenue to curtail expenses and broaden the scope of detection within the analytical process.This paper reviews the research progress of UCNPs in the detection of heavy metal ions,encompassing a brief elucidation of the luminescence principle of upconversion nanomaterials and commonly used detection principles.Additionally,it provides a detailed overview of the research status of several common non-metal ions and essential heavy metals.Furthermore,it summarizes the current focal points in UCNP detection and discusses the challenges and prospects associated with it.

Determination of fluorinated quinolone antibacterials by ion chromatography with fluorescence detection

For preparing fluorinated quinolone antibiotic medicine locally used in stomatology, simultaneous determination of norfloxacin, ciprofloxacin, and enoxacin was carried out by multiphase ion chromatography with fluorescence detection. Quinolone antibiotics were separated by Dionex OmniPac PAX-500 column with an eluent of 15 mmol/L H2SO4 and 35% methanol （v/v） at a flow-rate of 1.0 ml/min and detected with fluorescence with excitation and emission wave lengths of 347 ran and 420 ran respectively. The detection limits （S/N=3） of norfloxacin, ciprofloxacin and enoxacin were 50, 105 and 80 ng/ml respectively. The relative standard deviations of retention time, peak area and peak height were less than 1.1% and good linear relationship resulted. The developed method was applied to pharmaceutical formulations and biological fluids.

The Development of A Fluorescence Polarization Immunoassay for Aflatoxin Detection

A fluorescence polarization immunoassay （FPIA） was developed for the analysis ofaflatoxins （AFs） using an anti-aflatoxin B1 （AFB1） monoclonal antibody and a novel fluorescein-labeled AFB1 tracer. The FPIA showed an IC50 value of 23.33 ng/mL with a limit of detection of 13.12 ng/mL for AFB1. The cross-reactivities of AFB1, AFB2, AFG1, AFG2, AFM1, and AFM2 with the antibody were 100%, 65.7%, 143%, 23.5%, 111.4%, and 2%, respectively. The group-specificity of anti-AFB1mAb indicated that the FPIA could potentially be used in a screening method for the detection of total AFs, albeit not AFG2 and AFM2. The total time required for analyzing 96 samples in one microplate was less than 5 rain. This study demonstrates the potential usefulness of the FPIA as a rapid and simple technique for monitoring AFs.

New HPLC Method with Experimental Design and Fluorescence Detection for Analytical Study of Antihypertensive Mixture,Amlodipine and Valsartan

New HPLC method was developed for determination of amlodipine and valsartan in their binary mixture as a part of routine control of combined formulations. The method was validated to meet official requirements including selectivity, stability, linearity, precision and accuracy. Chromatography was carried out using a LiChrospher RP-18 column, a mixture containing acetonitrile, phosphate buffer of pH 3.5 and methanol (45:45:10, v/v/v) and new fluorescence detection at 255 nm for excitation and 448 nm for emission. The effect of methanol content, pH of the buffer, flow rate, detection wavelengths and column temperature was estimated in robustness study, according to a plan defined by the Plackett-Burman design. For identification of significant effects, both graphical and statistical methods were used. Ro-bustness for dissolution test was checked estimating the effects of paddle speed, temperature and pH of dissolution medium. The method was proved to complying with all official guidelines. Therefore, it is suitable for determination of amlodipine and valsartan in their binary mixtures for different analytical and pharmaceutical purposes.

Determination of Amino Acids in an Individual Erythrocyteby Capillary Electrophoresis with Intracellular FITC-derivatization and Laser-induced Fluorescence Detection

A novel approach for analysis of amino acids in individual erythrocytes was established. In this method, the derivatization reagent was introduced into the living cells by electroporation. After derivatization, the amino acids in a single cell were determined by capillary electrophoresis with laser-induced fluorescence detection.

A smartphone-based automated fluorescence analysis system for point-of-care testing of Hg(Ⅱ)

This work demonstrates a smartphone-based automated fluorescence analysis system(SAFAS)for point-of-care testing(POCT)of Hg(Ⅱ).This system consists of three modules.The smartphone module is used to provide an excitation light source,and to collect and analyze fluorescent images.The dark box module is applied to integrate the desired optical elements and offers a dark environment.The cost of the integrated dark box mainly includes the upper cover,box body,lower bottom,¯xture and some optical elements which is about$109.The chip module is used for fluorescence sensing,which is composed of an upper plate,bottom plate and cloth-based chip.Due to the integration of multiple smartphone functions,the SAFAS eliminates the need for additional power sources,light sources and analysis systems.The dark box and upper and bottom plates are made by 3D printer.The cloth-based chip(about$0.005 for each chip)is fabricated using the wax screenprinting technique,with no need for expensive and complex fabrication equipments.To our knowledge,the cloth-based microfluidic fluorescence detection method combined with smartphone functions is first reported.By using optimal conditions,the designed system can realize the quantitative detection of Hg(Ⅱ),which has a linear range of 0.001–100μgmL^(-1)and a detection limit of 0.5 ngmL^(-1).Additionally,the SAFAS has been successfully applied for detecting Hg(Ⅱ)in actual water samples,with recoveries of 100.1%–111%,RSDs of 3.88%–9.74%,and fast detection time of about 1 min.Obviously,the proposed SAFAS has the advantages of high sensitivity,wide dynamic range,acceptable reproducibility,good stability and low cost.Therefore,it is believed that the presented SAFAS has great potential to perform the POCT of Hg(II)in different water samples.

Research of Confocal Laser Induced Fluorescence Detection System for Micro-fluidic Chip

The characteristics such as signal noise ratio（SNR） and sensitivity of the fluorescence detection system for micro-fluidic chip influence the performance of the whole system extremely. The confocal laser induced fluorescence detection system is presented. Based on the debugging of optical and circuit modules, the results of detecting the samples are given and analyzed theoretically, and the improved project is put forward.

Fluorescence detection of Europiumdoped very small superparamagnetic iron oxide nanoparticles in murine hippocampal slice cultures

In the late 1980s,superparamagnetic iron oxide nanoparticles（SPIO）moved into focus as contrast agents in magnetic resonance imaging（MRI）,due to their strong relaxivity and resulting higher resolution of images.At the time,no one anticipated their high potential in basic research or for medical diagnostic andtreatment. Since then, SPIO have been evaluated notonly as spe- cific markers for MRI, but also for cell labeling and tracking （Li et al., 2013）.

Droplet microfluidic chip for precise monitoring of dynamic solution changes

In this work,an automated microfluidic chip that uses negative pressure to sample and analyze solutions with high temporal resolution was developed.The chip has a T-shaped channel for mixing the sample with a fluorescent indicator,a flow-focusing channel for generating droplets in oil,and a long storage channel for incubating and detecting the droplets.By monitoring the fluorescence intensity of the droplets,the device could detect changes in solution accurately over time.The chip can generate droplets at frequencies of up to 42 Hz with a mixing ratio of 1:1 and a temporal resolution of 3–6 s.It had excellent linearity in detecting fluorescein solution in the concentration range 1–5μM.This droplet microfluidic chip provides several advantages over traditional methods,including high temporal resolution,stable droplet generation,and faster flow rates.This approach could be applied to monitoring calcium ions with a dynamic range from 102 to 107 nM and a detection limit of 10 nM.

Synthesis of Carbon dots from Biomass Chenpi for the Detection of Hg^(2+)

Biomass-derived carbon dots(C-dots)are considered a very important carbon material in metal ion detection of their small environmental impact,simple preparation process,and relatively low cost.A green approach for synthesizing biomass-derived C-dots from Chenpi using a hydrothermal method without further processing is proposed in the present study.The as-synthesized C-dots show excellent fluorescence properties,superior resistance to UV irradiation photobleaching,and high photostability in salt-containing solutions.The C-dots were used in the form of label-free fluorescent probes for sensitively detecting Hg^(2+)selectively.The outcome relationship behaved linearly and was established based on a given range between 10–300 nM concentration,with a detection limit of 7.0 nM.This green strategy obtains a high C-dot quantum yield of 10.8%and satisfactory results in detecting Hg^(2+)in actual water samples.

Fluorescence analysis of antibiotics and antibiotic-resistance genes in the environment: A mini review

Antibiotics,as widely used antibacterial drug,exist in various environmental media.Antibiotic residues can affect biological metabolism and lead to bacterial resistance and the formation of antibiotic-resistance genes,posing a threat to human health and ecological safety.Establishing efficient detection methods for antibiotics and antibiotic-resistance genes has great environmental significance.Fluorescence detection methods,due to their fast response,high sensitivity and specificity,and low-cost,are widely used in chemical and biological sensing.This review first summarizes the pre-treatment methods for different types of environmental samples,and then focuses on the recent advances of fluorescence methods for the detection of antibiotics and antibiotic-resistance genes.Finally,main challenges and future research directions of fluorescence methods for antibiotic and antibiotic-resistance genes detection are discussed.This review highlights the promising prospect of fluorescence methods in-situ detection and monitoring of antibiotics and antibiotic-resistance genes,and provides guidance for the construction of overall risk assessment system of environmental media.

Unveiling size-fluorescence correlation of organic nanoparticles and its use in nanoparticle size determination

Quantitatively establishing the correlation between nanoparticle size and fluorescence is essential for understanding the behavior and functionality of fluorescent nanoparticles(FNPs).However,such exploration focusing on organic FNPs has not been achieved to date.Herein,we employ the use of supramolecular polymeric FNPs prepared from tetraphenylethylene-based bis-ureidopyrimidinone monomers(bis-UPys)to relate the size to the fluorescence of organic nanoparticles.At an equal concentration of bis-UPys,a logarithmic relationship between them is built with a correlation coefficient higher than 0.96.Theoretical calculations indicate that variations in fluorescence intensity among FNPs of different sizes are attributed to the distinct molecular packing environments at the surface and within the interior of the nanoparticles.This leads to different nonradiative decay rates of the embedded and exposed bis-UPys and thereby changes the overall fluorescence quantum yield of nanoparticles due to their different specific surface areas.The established fluorescence intensity-size correlation possesses fine universality and reliability,and it is successfully utilized to estimate the sizes of other nanoparticles,including those in highly diluted dispersions of FNPs.This work paves a new way for the simple and real-time determination of nanoparticle sizes and offers an attractive paradigm to optimize nanoparticle functionalities by the size effect.

Removal and fluorescence detection of antibiotics from wastewater by layered double oxides/metal-organic frameworks with different topological configurations

Owing to the serious potential side-effects on the environment and human health,the rapid detection and removal of antibiotics have become an important research focus.In this work,four zinc-based metal-organic frameworks(MOFs)with different functional groups,i.e.,Zn-MOF,Zn-MOF-CH_(3),Zn-MOF-NO_(2),Zn-MOF-COOH,were utilized for the construction of LDO/MOF composite materials with a nickel-iron-cobalt-based layered double oxide,NiFeCo-LDO.The results showed that the LDO/MOF composites not only had high sensitivity in detecting sulfonamide and quinolone antibiotics,but also had an appreciable ability to adsorb them from wastewater.The maximum adsorption capacities of all the four types of LDO@Zn-MOFs to all antibiotics can at least reach 150 mg/g,and the limits of detection in relation to all four antibiotics were at least as low as 100μg/L.Our work suggested the dual-function extraction performance can be attributed to the synergistic effects between the LDO and the MOFs.Moreover,the strong ferromagnetism derived from the LDO provided great convenience for the separation and regeneration of the LDO/MOF composites.

Enhanced fluorescence sensing of tetracycline with Ti_(2)C quantum dots

Ti_(2)C quantum dots(QDs)with rich surface functional groups have been synthesized using a hydrothermal method,and used to detect tetracycline(Tc)based on enhanced fluorescence.The interaction between the surface functional groups of Ti_(2)C QDs and Tc enhanced the fluorescence of Tc at 514 nm,which is used to detect Tc quickly and accurately.Under optimal conditions,the fluorescence intensity was linear to the concentration of Tc in the range of 50.0–30.0μM,with a detection limit of 21.6 nM.Furthermore,the Tc-Ti_(2)C QDs detection system was evaluated for detection of Tc in milk and artificial urine.This study demonstrates a new and simple strategy for Tc detection,which is important for food safety and human health.

新型液相色谱-荧光检测法测定药物剂型和人血浆中的他达拉非和盐酸达泊西汀(英文)

Tadalafil(TAD)and dapoxetine HCl(DAP)are recently co-formulated and both show native fluorescence.Therefore,a novel,accurate,specific and sensitive reversed-phase high performance liquid chromatographic method with fluorescence detection was developed and validated for their separation and quantitation in dosage form and human plasma using avanafil as an internal standard(IS).Separation was achieved using isocratic elution within 7.0 min on C18column and acetonitrile-0.15%triethylamine(40∶60,v/v;pH 4)as a mobile phase.The flow rate was 1.0 mL/min and the detection was time-programmed at 330,410 and 370 nm for TAD,DAP and IS,respectively,after excitation at 236 nm.The linear ranges from 0.01 to 30.00μg/mL for each drug with the limits of detection of 4.20 and 7.20 ng/mL for TAD and DAP,respectively.The method was validated in accordance to the International Conference on Harmonization(ICH)guidelines and was successfully applied to spiked human plasma with mean recoveries of 98.17%and 98.83%for TAD and DAP respectively.

Temperature-dependent photoluminescence of highly luminescent water-soluble CdTe quantum dots

Highly luminescent water-soluble CdTe quantum dots （QDs） have been synthesized with an electrogenerated precursor. The obtained CdTe QDs can possess good crystallizability, high quantum yield （QY） and favorable stability. Furthermore, a detection system is designed firstly for the investigation of the temperature-dependent PL of the QDs. ？2009 Yu Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.