Fluorescence Detection Research Articles

Fluorescence detection of superoxide anion with CsPbBr3 perovskite quantum dots in aqueous media

Among reactive oxygen species, the superoxide radical anion (O2−) is of particular interest due to its involvement in oxidative stress-related diseases and environmental pollutants. Through solution-phase strategy mediated by ligands, colloidal spherical and water-stable perovskite quantum dots (PQDs) of cesium lead bromide (CsPbBr3) were fabricated by functionalizing with D-tartaric acid (D-TA) (namely, CsPbBr3@D-TA PQDs), exhibiting exceptional photoluminescence quantum yield of 29.88 % and intense emission peak at 522 nm when excited at 380 nm. The as-fabricated CsPbBr3@D-TA PQDs showed strong durability and displayed bright green fluorescence when exposed to 365 nm UV radiation. The emission peak of CsPbBr3 PQDs at 522 nm was completely quenched by O2−, showing wider linear range from 0.125 to 25 µM with a detection limit of 39.82 nM. Moreover, CsPbBr3@D-TA PQDs were also applied for bio-imaging of yeast cells. The CsPbBr3@D-TA PQDs-based fluorescence approach holds great potential for sensing of O2− in real samples.

Detection of Tn-antigen in breast and prostate cancer models by VVL-labeled red dye-doped nanoparticles.

Aim: Fluorescence detection of breast and prostate cancer cells expressing Tn-antigen, a tumor marker, with Vicia villosa lectin (VVL)-labeled nanoparticles.Materials & methods: Breast and prostate cancer cells engineered to express high levels of Tn-antigen and non-engineered controls were incubated with VVL-labeled or unlabeled red dye-doped silica-coated polystyrene nanoparticles. The binding to cells was studied with flow cytometry, confocal microscopy, and electron microscopy.Results: Flow cytometry showed that the binding of VVL-labeled nanoparticles was significantly higher to Tn-antigen-expressing cancer cells than controls. Confocal microscopy demonstrated that particles bound to the cell surface. According to the correlative light and electron microscopy the particles bound mostly as aggregates.Conclusion: VVL-labeled nanoparticles could provide a new tool for the detection of Tn-antigen-expressing breast and prostate cancer cells.

Development of a new high performance liquid chromatography-fluorescence detection (HPLC-FL) method for the determination of biogenic amines in frozen fish sold in markets

<p class="MsoNormal" style="text-align:justify;line-height:200%"><span lang="EN-GB" style="font-size:12.0pt;line-height:200%;font-family:"Times New Roman","serif"; mso-fareast-font-family:"Times New Roman";mso-ansi-language:EN-GB;mso-fareast-language: ZH-CN">It is now possible to measure the biogenic amines histamine, tryptamine, putrescine, cadaverine, spermidine, spermine, and tyramine in an easy, accurate, and selective manner. Dansyl chloride was used to purify the analytes, and high-performance liquid chromatography with detection of fluorescence was utilized for separating them. This is a useful method for identifying and measuring biogenic amines in fish samples in a selective manner. The C18 (250 mm × 4.6 mm × 5 μm) column was used for the separation by chromatography. A mobile phase comprising acetonitrile and phosphate buffer (pH=4.0) (60:40, v/v) was used at an average flow rate of 0.9 mL/min. The technique relied on utilizing fluorescence detection to determine the derivative </span><span style="font-size:12.0pt;line-height:200%;font-family: "Times New Roman","serif"">(λ<sub>ex</sub>=230 nm, λ<sub>em</sub>= 350 nm) </span><span lang="EN-GB" style="font-size:12.0pt;line-height:200%;font-family:"Times New Roman","serif"; mso-fareast-font-family:"Times New Roman";mso-ansi-language:EN-GB;mso-fareast-language: ZH-CN">The suggested method's linearity was examined between 0.01 and 50 μg/mL </span><span style="font-size:12.0pt;line-height:200%;font-family:"Times New Roman","serif"">(r<sup>2</sup>=0.9996). </span><span lang="EN-GB" style="font-size:12.0pt;line-height:200%;font-family: "Times New Roman","serif";mso-fareast-font-family:"Times New Roman";mso-ansi-language: EN-GB;mso-fareast-language:ZH-CN">In compliance with ICH criteria, the method was verified with respect to accuracy, precision, repeatability, specifity, robustness, and detection and quantification limitations. The suggested technique has been effective in tracking the production of biogenic amines in specimens of fish that can be purchased frozen in marketplaces. It was discovered that the recommended approach worked well for routinely analyzing fish sample biogenic amine analyses.<o:p></o:p></span></p>

Engineering Phi29-DNAP Variants for Customized DNA Hydrogel Materials.

DNA hydrogels, which hold potential for use in medicine, biosensors, and tissue engineering, can be produced through enzymatic rolling circle amplification (RCA) using phi29 DNA polymerase (DNAP). This paper introduces new DNAP variants designed for RCA-based DNA hydrogel production, featuring enzymes with modified DNA binding, enhanced thermostability, reduced exonuclease activity, and protein tags for fluorescence detection or specific immobilization. We evaluated these enzymes by quantifying DNA output via quantitative PCR (qPCR) and assessing hydrogel mechanical properties through micromechanical indentation. The results showed that most variants generated similar DNA amounts and hydrogels with comparable mechanical properties. Additionally, all variants successfully incorporated non-natural nucleotides, such as base-modified dGTP derivatives and 2'-fluoro-dGTP, during RCA. This study's robust analytical approach offers a strong foundation for selecting new enzymes and producing DNA hydrogels with tailored material properties.

Comparison of Survivin Determination by Surface-Enhanced Fluorescence and Raman Spectroscopy on Nanostructured Silver Substrates.

Survivin belongs to a family of proteins that promote cellular proliferation and inhibit cellular apoptosis. Its overexpression in various cancer types has led to its recognition as an important marker for cancer diagnosis and treatment. In this work, we compare two approaches for the immunochemical detection of survivin through surface-enhanced fluorescence or Raman spectroscopy using surfaces with nanowires decorated with silver nanoparticles in the form of dendrites or aggregates as immunoassays substrates. In both substrates, a two-step non-competitive immunoassay was developed using a pair of specific monoclonal antibodies, one for detection and the other for capture. The detection antibody was biotinylated and combined with streptavidin labeled with rhodamine for the detection of surface-enhanced fluorescence, while, for the detection via Raman spectroscopy, streptavidin labeled with peroxidase was used and the signal was obtained after the application of 3,3',5,5'-tetramethylbenzidine (TMB) precipitating substrate. It was found that the substrate with the silver dendrites provided higher fluorescence signal intensity compared to the substrate with the silver aggregates, while the opposite was observed for the Raman signal. Thus, the best substrate was used for each detection method. A detection limit of 12.5 pg/mL was achieved with both detection approaches along with a linear dynamic range up to 500 pg/mL, enabling survivin determination in human serum samples from both healthy and ovarian cancer patients for cancer diagnosis and monitoring purposes.

Exploration of glyoxals’ level changes in endoplasmic reticulum during ferroptosis by a photocaged fluorescent probe

Both ferroptosis and elevated glyoxals (e.g. methylglyoxal and glyoxal), are associated with endoplasmic reticulum stress, but their correlations, in particular, how level of glyoxals changes in endoplasmic reticulum during ferroptosis remains unclear. In this work, a new photoactivatable fluorescent probe Photo-ER-GOS was developed to study level changes of glyoxals in endoplasmic reticulum during ferroptosis via in situ photodecaging and fluorescence detection, avoiding potential interference from glyoxals in cytosol. The probe contains a photolabile nitrobenzyloxymethyl group functioned both as the reactivity blocking group and the fluorescence quenching group, which linked to the guanidino group of NAP-DCP-3, the active endoplasmic reticulum-targeting fluorescent probe for glyoxals previously developed in our lab. It was found that the level of glyoxals in endoplasmic reticulum increases significantly during erastin-induced ferroptosis in RAW 264.7 cells via comparison of relative fluorescence intensity increases. The endoplasmic reticulum glyoxal level increase was also confirmed by the Ultra Performance Liquid Chromatography-Mass Spectrum studies. In contrast, no significant change of level of glyoxals in endoplasmic reticulum was found in staurosporine-induced apoptosis, suggesting that upregulated glyoxals in endoplasmic reticulum may be a previously overlooked characteristic of ferroptosis. Erastin-induced level increase of glyoxals was also found in zebrafish. The caged probe Photo-ER-GOS thus provides a useful chemical tool to study GOS levels changes in endoplasmic reticulum.

A novel dual-ligand copper-based nanoflower for the colorimetric and fluorescence detection of 2,4-dichlorophenol, epinephrine and hydrogen peroxide

BackgroundNanozymes have the advantages of cost effective, simple synthesis, high durability and stability, and have been widely used in various fields. However, only a few nanomaterials with multiple enzyme-like activity have been reported, and most of the currently developed nanozymes are usually used in colorimetric or fluorescence analysis depending on a single colorimetric or fluorescence signal output. In this study, a copper-based dual-ligand biomimetic nanoflower (Cu-MN) was constructed, which demonstrated potential multiple enzyme-like activity, and was applied to the multi-mode detection of 2,4-dichlorophenol (2,4-DP), epinephrine (EP), and H2O2. ResultsThe laccase-like activity of Cu-MN can catalyze the conversion of 2,4-DP and EP, resulting in the formation of red and yellow-brown oxidation products with distinct UV absorption peaks at 510 nm and 485 nm, respectively. Furthermore, the fluorescence emission peak at 426 nm of Cu-MN can be dynamic quenched during substrate oxidation due to the fluorescence internal filtration effect (IFE). Therefore, a dual-mode analysis method was constructed to detect 2,4-DP and EP by fluorescence and ultraviolet colorimetry, which was successfully applied in natural lake water and rabbit plasma analysis, respectively. Furthermore, a colorimetric sensing strategy based on the peroxidase-like activity of Cu-MN was developed and successfully applied to the monitoring of H2O2 in hydrogen peroxide disinfectant. Additionally, the visualization analysis method was also established by RGB reading of the smartphone. Significance and noveltyIn brief, inspired by the fluorescence characteristics of 2-aminoterephthallc acid and the imidazole group of 2-methylimidazole, a novel copper-based dual-ligand biomimetic nanoflower (Cu-MN) was prepared and used to establish multi-mode method for the detection of 2,4-DP, EP, and H2O2, which opens up new avenues for its applications in bioanalysis and environmental monitoring.

Glibenclamide reverses cardiac damage and NLRP3 inflammasome activation associated with a high refined sugar diet

Increased energy intake from carbohydrates has been associated with major cardiovascular outcomes. Mice fed a highly-refined carbohydrate (HC) diet develop cardiac hypertrophy and inflammation. During cardiac injury, NLRP3 inflammasome is activated which results in a local inflammatory response. In this study, we hypothesized that a nom-hypoglycemic dose of glibenclamide may reverses sugar diet-induced cardiac damage by NRLP3 inflammasome inhibition. Mice were fed the HC diet for eight weeks and divided into a group treated with glibenclamide (20 mg/kg, gavage) and another with vehicle for four weeks. Afterward, hearts were excised for morphometric analysis and ex vivo function determination. NLRP3 inflammasome activation was investigated by western blotting and in situ fluorescent detection of reactive oxygen species (ROS) and active caspase-1. The HC diet promotes heart hypertrophy and collagen deposition, which were reverted by glibenclamide without ameliorating HC diet-induced insulin resistance. Changes in cardiac performance were observed in vivo by invasive catheterization and in Langendorff-perfused hearts due to the HC diet, which were prevented by glibenclamide. Hearts from HC diet mice had increased levels of NLRP3 and cleaved IL-1β. Glibenclamide reversed ROS production and caspase-1 activity induced by HC diet. These findings suggest glibenclamide's cardioprotective effects on heart damage caused by the HC diet are related to its inhibitory action on the NLRP3 inflammasome.

An intelligent and portable fiber optic real-time fluorescence detection system for pathogenic microorganisms detection

The detection of pathogenic microorganisms poses an increasingly serious challenge to food safety. This paper proposes an intelligent fiber optic fluorescence sensing system for detection of pathogenic microorganisms. The system integrates light-emitting diodes and fiber optic sensing arrays. Compact and multi-channel detection is achieved by this kind of design. Environmental parameters such as temperature, humidity, and location are intelligently analyzed together with sampled fluorescence signal, which successfully achieved a high accuracy detection result without affected or interfered by environmental parameters. A Radial Basis Function Neural Network (RBFNN) algorithm is utilized for intelligent analysis and prediction of pathogenic microorganisms’ concentration with environmental parameters. Under different environmental parameters, the system has successfully detected African swine fever virus or salmonella in real-time with high accuracy and sensitivity. Since location of the sensing system can be determined by GPS module integrated in the system, the change of pathogenic microorganisms with different locations can be determined even during transportation. This innovative solution provides a convenient and accurate method for high accurate on-site real time sensing of pathogenic microorganisms.

Establishment of a platform based on dual RPA combined with CRISPR/Cas12a for the detection of Klebsiella pneumoniae and its KPC resistance gene.

Carbapenem resistant Klebsiella pneumoniae (CRKP) can cause serious hospital- and community-acquired infections. Treatment for CRKP infection is limited, resulting in prolonged hospitalization and high consultation costs. The KPC genotype has the highest detection rate of CRKP, and its mortality rate is higher than the overall mortality rate of CRKP. However, traditional testing methods have disadvantages such as long time and reliance on complex and sophisticated instruments, which are not conducive to rapid screening for CRKP. Therefore, this study aimed to establish a detection platform for early screening of CRKP so that effective antimicrobial therapy could be administered promptly to prevent the widespread spread of CRKP. We integrated dual RPA with CRISPR/Cas12a to establish a dual platform for the detection of K. pneumoniae (Kp) rcsA-specific gene and KPC resistance gene. Four result reading methods were established, including fluorescence detection (FD), blue light irradiation detection (BLID), ultraviolet irradiation detection (UID), and lateral flow test strips (LFTS). For the rcsA gene, the LOD of FD was 1 × 10pg/μL, and the other three methods could detect 1 × 101pg/μL of bacterial DNA. As for the KPC gene, four resultant readout methods were able to detect 1 × 102pg/μL of bacterial DNA. In 59 clinical strains tested, the dual RPA-CRISPR/Cas12a detection of the rcsA had 100% sensitivity, specificity, and accuracy compared to the culture method. Compared with the drug sensitivity test, the sensitivity of dual RPA-CRISPR/Cas12a detection for the KPC was 85.71%, the specificity was 100%, and the accuracy was 94.92%. In summary, our dual RPA-CRISPR/Cas12a platform proved to be rapid, precise, and convenient for the efficient detection of Kp with KPC in the laboratory or at the point of care.

A-326 Testing for Multidrug-Resistant Acinetobacter baumannii with a Microfluidic Device

Abstract Background Multidrug-resistant (MDR) Acinetobacter baumannii in hospitals contribute to high mortality rates and entail expensive infection control procedures. Conventionally, species and resistance determination of MDR bacteria is performed by mass spectrometry and labor-intensive phenotypical assays in clinical microbiology laboratories. Some institutions also apply time-consuming and expensive whole genome sequencing for in-depth resistance and transmission analysis. In contrast, faster and more cost-efficient MDR typing can be achieved by on-site application of real-time PCR-based point-of-care tests (POCTs) that target species- and resistance-specific genes and enable rapid screening of large sample sizes. Methods To construct a real-time PCR-based POCT system for species and resistance determination of MDR A. baumannii, we selected two species-specific genes (rpoB, OXA-51-like) and 18 resistance genes found in MDR A. baumannii (OXA-23-like, OXA-24/40-like, OXA-51-like, OXA-58-like, OXA-143-like, mcr, ADC, NDM, GIM, VIM, IMP, GES, PER, TEM, SHV, VEB, CTX-M, KPC) as targets. For each gene, one to six sets of primers and fluorophore-labeled probes that amplify conserved genetic regions were designed and their functionality was tested in vitro. Parallel, a fully automated system comprising microfluidic chips and a bench-top analyzer able to perform DNA extraction and real-time PCR starting from swab eluate was developed. Results All oligonucleotides tested so far reliably detected 100 to 100,000 copies of DNA extracted from MDR bacteria in single- and multiplex experiments in vitro. Tests with the microfluidic system showed that lysis of different bacterial species could be accomplished via sonication on a membrane located on the microfluidic chip. In addition, chip implementation of all PCR reagents like lyophilized master mix as well as primers and probes was successful and can be stored on chip at least one year. So far, the system delivered detectable fluorescence signals within one hour when performing test runs with bacteria eluted from swabs. Conclusions A real-time PCR-based Point-of-Care screening platform was developed for the detection of antibiotic-resistant A. baumannii from various patient sample materials starting directly from swabs, which detects colonization/infection and at the same time the relevant resistance genes within about an hour.

Determination of adalimumab by HPLC with fluorescence detection using the König reaction

Monoclonal antibody drugs (mAb) are widely used to treat various diseases. Keeping quality of mAbs is crucial to maximize efficacy and minimize adverse effects. To this end, mAb content in the drug product must be precisely quantified. As methods for the determination of mAbs, absorbance measurement at 280 nm, the ligand binding assay based on ELISA, or the LC-MS/MS method based on the surrogate peptide approach is usually used. However, these methods have drawbacks in terms of selectivity, reliability, and cost, respectively. The present method is based on the surrogate peptide approach where a peptide specific to the mAb is determined by a post-column derivatization LC system with fluorescence detection and the König reaction, which is usually used for the detection of cyanide and its derivatives. The detection mechanism was the production of cyanide from the surrogate peptide by chloramine T and the generated cyanide was detected by the König reaction. In this study, adalimumab was used as a model target protein. The calculated LOD and LOQ of the present method were 0.31 μg/mL and 0.94 μg/mL, respectively. The intra-day accuracies and precisions were 127.1 % and 2.94 % for 5 μg of adalimumab and 101.6 % and 10.2 % for 50 μg of adalimumab, respectively. The inter-day accuracies and precisions were 121.8 % and 5.71 % for 5 μg of adalimumab and 101.8 % and 6.98 % for 50 μg of adalimumab, respectively. Our quantitatively determined amount of adalimumab in Humira® was in good agreement with the specified value. This method only requires a conventional LC system, not an LC-MS/MS system. By extending the application of the König reaction, we open the door to a new surrogate peptide approach for the determination of proteins including monoclonal antibody drugs.

Red-emitting carbon dots for fluorescent and smartphone-assisted dual-mode detection of Cu(II), Hg(II), and Fe(III) and investigation of the sensing mechanism

Red-emitting carbon dots (R-CDs) have triggered ever-increasing interest in biochemical sensing due to their deep tissue penetration and minimal biological auto-fluorescence interference. Herein, dual-emitting intrinsic R-CDs are fabricated and well-characterized. R-CDs display ratiometric and colorimetric sensing properties for heavy metal ions (HMIs, Cu2+, Hg2+, and Fe3+), with the corresponding detection limits of 24.5, 74.2, and 170 nM, respectively. Additionally, smartphone imaging colorimetry based on red-green-blue (RGB) value variations is employed to achieve real-time and on-site detection of these HMIs. Crucially, discrimination of these HMIs is facilitated by principal component analysis. Furthermore, R-CDs demonstrate effective optical sensing of these HMIs in tap/lake water and human urine with satisfactory recoveries (95.82–104.8 %). The underlying mechanism of optical sensing, which involves metal ion-triggered aggregation-induced quenching, is elucidated by spectroscopic, morphological analysis, and quantum mechanical calculations. This work presents a feasible real-time approach for the fluorescent and smartphone-assisted dual-mode detection of HMIs.

Evaluation of thiamine and riboflavin in different varieties of rice grown in Kurigram district, Bangladesh

ContextRice is indeed a staple food in many parts of the world, including Bangladesh. This research aimed to evaluate the two essential vitamin levels in different processed rice sunned, parboiled, cooked sunned, cooked parboiled, and washed cooked rice. ObjectiveThe study focused on analyzing the thiamine (vitamin B1) and riboflavin (vitamin B2) contents in 10 different varieties of paddy samples grown in the Kurigram district of Bangladesh. MethodsA high performance liquid chromatographic (HPLC) technique assembled with fluorescence detector was employed for these analyses. Two calibration curves were generated to analyze vitamin B1 and B2 (for thiamine the regression coefficient, r2 = 0.9992 and riboflavin r2 = 0.9989). The study demonstrated a recovery rate of 96.88 % for vitamin B1 and 104.24 % for vitamin B2. Overall, these findings provide valuable insights into the vitamin B1 and B2 contents across different rice samples. Results and conclusionThe results showed that the parboiled samples had the highest thiamine content, ranging from 342.50 ± 0.3 to 673.0 ± 7.5 μg/100 g, compared to the sunned samples, which had a range of 209.5 ± 0.3 to 337.4 ± 4.3 μg/100 g. Conversely, the sunned samples had the highest riboflavin content, ranging from 26.4 ± 0.2 to 59.6 ± 0.3 μg/100 g, while the parboiled samples had a range of 3.0 ± 0.1 to 26.6 ± 0.01 μg/100 g. Additionally, it was observed that the steaming process increased the thiamine content and reduced the riboflavin content in parboiled rice samples but decreased both the thiamine and riboflavin in sunned rice samples. Another study showed a gradual decrease in the levels of both vitamins B1 and B2 in sunned, cooked sunned and washed cooked sunned rice samples. SignificanceThese findings provide valuable insights into the impact of processing methods, such as parboiling and steaming, on the thiamine and riboflavin contents in rice. The results suggest that parboiled rice may be a preferable choice for individuals seeking higher thiamine content in their diet, while sunned rice may contain higher levels of riboflavin. The results shed light on the nutritional profiles of different rice varieties and highlight the potential impact of processing techniques on the vitamin content of rice.

Visual and fluorescent detection of Moraxella catarrhalis by multiple cross displacement amplification-based assay

Moraxella catarrhalis (M. catarrhalis), once considered as a harmless commensal bacterium, is now recognized as a significant pathogen associated with human mucosal infection. Hence, development of rapid, accurate, and user-friendly detection method is crucial for effective control and management of M. catarrhalis infections. Here, we introduce the M. catarrhalis MCDA-FRT assay, a novel diagnostic approach based on multiple cross displacement amplification (MCDA) for the visual and fluorescent (FRT) detection of M. catarrhalis. This innovative method amplifies the target sequence through MCDA reaction and provides results through the visual observation of a fluorescent signal when exposed to blue light. The generation of the fluorescent signal is facilitated by the cleavage of the restriction endonuclease Nb.BsrDⅠ. The M. catarrhalis MCDA-FRT assay can efficiently detect M. catarrhalis at a temperature of 65 °C in 40 min. It exhibits a remarkable sensitivity of 35 fg of M. catarrhalis genomic DNA, with a specificity of 100%. Furthermore, the assay accurately identified all M. catarrhalis-infected clinical samples tested. In conclusion, the M. catarrhalis MCDA-FRT assay showcases outstanding performance in terms of simplicity, sensitivity, and specificity, which can be used as a promising diagnostic tool for the swift and reliable detection of M. catarrhalis in both field and basic medical settings.

Copper nano metal-organic framework paper-based sensor for dual optical detection of biogenic amines to evaluate the food freshness

The improvement of food safety and the reduction of food loss and waste require the development of new bioanalytical tools that provide chemical information about the composition of food that is of great value for improving traceability and extending the shelf life of food. Herein, a Cu-based metal-organic framework has been synthesized and immobilized onto cellulose paper disks for colorimetric and fluorescent detection and quantification of biogenic amines in food. The color of the nano metal-organic framework changes from green to brown in the presence of low amounts of biogenic amine vapors. Also, the fluorescence emission of the nano metal-organic framework greatly decreases after exposing the cellulose disks to amine vapors. The developed sensing paper disk exhibits a quick response to the presence of volatile biogenic amines, very low detection limits, and great selectivity. Also, the paper sensor was used for real-time monitoring of biogenic amines in bass samples at different temperature conditions, being a highly valuable method for evaluating food freshness and safeguarding food safety.

Monitoring of cyanogenic compounds behavior during the manufacturing process of sweetened bean paste

To ensure food safety, food business operators must eliminate or reduce hazardous factors in manufacturing processes by implementing effective process controls. Since some beans are known to contain cyanogenic compounds, their distribution and use are permitted only as a raw bean paste material. Therefore, from the perspective of Hazard Analysis and Critical Control Points (HACCP), the purpose of this study is to demonstrate the validity of establishing CCPs and to determine the cyanogenic compounds in intermediate products for effectively managing hazardous substances in the manufacturing process. The previously reported method, post-column HPLC with fluorescence detection, was used for determine cyanogenic compounds in CCPs.While free cyanide ions were only detected at CCP#1, cyanoglycoside analysis was crucial throughout the manufacturing process. Results indicated a decrease in cyanoglycoside concentration as manufacturing progressed, with levels below 10 ppm in the final product. Notably, cyanoglycosides decreased significantly during the shibukiri process (soaking, boiling, and discarding water). The concentration of cyanogenic compounds in raw beans were below the regulated 500 ppm, and the concentrations in the final product were below regulated 10 ppm. In conclusion, it was found that proposed method is very useful for HACCP management to monitor the decrease of cyanide compounds in the manufacturing process.

3D track extraction from a fluorescent nuclear track detector via machine learning and an application to diagnostics of laser-driven ions.

We have developed an ion diagnostic method for laser-driven ion acceleration experiments that uses fluorescent nuclear track detectors (FNTDs). An FNTD records the particle tracks as color centers and does not require chemical etching, unlike CR-39 track detectors. The color centers are observed using a confocal laser microscope, and 3D particle tracks can be obtained by changing its focal position. The intensity of the color centers corresponds to the energy deposited by the ions. The nuclides of the ions can be determined from the intensity distribution of the color centers as a function of depth and the distance between the stopping point and the surface of the detector. To extract the intensity distribution, we must track the same ion tracks in the depth-layered microscopic images from the surface to the stopping point, even if they overlap with those of other ions. In addition, since an FNTD is sensitive not only to ions but also to electrons and photons, we must identify ion tracks among those from the latter particles. To analyze a statistical number of ion tracks, it is necessary to automate these processes. We have thus developed a method for automated ion detection and 3D tracking that relies on a support vector classifier and a kernelized correlation filter. This method was tested on a laser ion acceleration experiment performed using the J-KAREN-P laser. The method automatically detects ion tracks on FNTDs and tracks them in the depth direction. The training data are sampled from the Heavy-Ion Medical Accelerator in Chiba.

A Fluorescent Probe for Hydrazine Based on 4-hydroxycoumarin with High Selectivity and Sensitivity

Background: Therefore, the development of reliable analytical techniques with high selectivity and sensitivity to detect hydrazine is required for the protection of human health and safety. Objectives: Traditional methods for detecting N2H4 are frequently time-consuming, less accurate, and unsuitable for the analysis of living systems. Numerous fluorescent probes for hydrazine have been produced and gained some valuable results recently. The creation of a simple fluorescent probe for hydrazine detection is the goal of this project Method: In this study, 300 µL of probe 3-methyl-2-oxo-2H-chromen-7-yl propionate (MOCP) was mixed with an equivalent amount of the solution of each analyte to obtain the measurement solution. Following a 10-minute room temperature incubation period, the fluorescence spectra of the resultant solution were recorded. Results: The fluorescence intensity of the probe was noticeably enhanced when N2H4 was added to the probe, but almost no fluorescence enhancement was observed when other competitive ions were added. Conclusion: A hydrazine fluorescent probe based on 4-hydroxycoumarin fluorophore was developed. The probe MOCP displayed high sensitivity and selectivity for hydrazine, with a color change from colourless to blue for detection by the naked eye. Moreover, it demonstrated a low detection limit of 20 nM and a fast reaction time of 30 s.

DNA-linked composite probe for the sensitive detection of Salmonella typhimurium in milk

Milk was favored for its nutrient richness which resulted in foodborne bacteria contamination along the production and transportation chain. Hence, there is an urgent necessary to develop high-sensitivity detection assays for early warning of bacteria-contaminated milk. Herein, a fluorescence composite probe that can bind with Salmonella typhimurium (S. typhi) was designed and prepared through a DNA bridge linking several fluorescence single probes. With the assistance of immuno-magnetic beads (IMBs) which can recognize S. typhi, IMBs/S. typhi/composite probe formed and separated from undiluted pure milk with high efficiency. As a result, the S. typhi ranging from 50-1 × 106 CFU/mL can be converted to a detectable fluorescence signal. The detection limit was calculated to be 11 CFU/mL. Meanwhile, the average recovery of S. typhi spiked in pure milk samples and milk powder samples were 95.9 % and 92.9 %, respectively. The strong anti-interference ability also made the assay an effective and promising alternative strategy for rapidly and accurately screening S. typhi in milk and milk powder.