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Deep-groove ball bearings for the eAxles of electric vehicles must adapt to higher rotational speed conditions because the speed of eAxle motors have been increasing as the size and weight of the motors decrease. Therefore, understanding the oil-lubricated conditions inside ball bearings at high rotational speeds is essential for optimizing their design for eAxles. To clarify the oil-lubricated conditions inside ball bearings at these high speeds, a new test apparatus was developed. This apparatus is capable of simultaneously measuring the friction torque of deep-groove ball bearings, the oil-film thickness on the rolling balls, and observing the oil distributions inside the bearings at rotational speeds up to 20,000 min-1. The oil-film thickness was measured using threewavelength optical interferometry, and the oil distribution was observed using fluorescence. It was found that the oil-film thickness became constant at rotational speed conditions exceeding approximately 7,700 min-1. Oil starvations were observed on the raceway around the rolling ball, and these regions increased with increasing rotational speeds. Additionally, in the deepgroove ball bearing with a crown-shaped cage, the oil was mainly supplied to the rolling balls from the inner ring side through the space between the cage claws that held the ball. Moreover, the amount of mixed air tended to increase as the rotational speed increased to approximately 7,700 min-1. Those oil starvations and increasing air in oils were considered to be factors that prevent the increase in oil-film thickness. The findings of the reported study will contribute to the development of multibody dynamic technology for high-speed ball bearings necessary in electric vehicles. [ABSTRACT FROM AUTHOR]

Pilot-ignition Otto marine engines are known for greatly reduced emissions of air pollutants (sulphur oxides, nitrogen oxide, particulates) compared to marine diesel engines. However, lubricating oil emissions still are about one order of magnitude higher than in land-based systems. To identify reduction potentials, a better understanding of oil emission mechanisms has to be gained. For this purpose, mass spectrometric oil emission measurements and fluorescence lubricating film thickness measurements were performed on a medium-speed marine engine. With the fluorescence measuring system, the varying lubricating oil film on the cylinder wall can be visualised and analysed in sub-crank-angle resolution. By applying the developed calibration method to the measurement data, the oil film thickness can be determined in µm. It is shown that the oil film left by the piston rings on the liner as it moves down is almost halved after ignition compared to during intake stroke. The authors have further been able to detect and time operating point dependent ring rotation and investigations show a connection between ring rotation and cylinder liner temperature distribution. Aligning ring gaps allow blow-by to happen. This and other high intensity events such as engine knock, load shedding or the transition from diesel-mode to gas-mode, heavily disturb the oil layer and cause peaking oil emissions. [ABSTRACT FROM AUTHOR]

Article presented describes a comprehensive study using chlorophyll fluorescence induction (CFI) as a non-destructive method for assessing phytophagous damage, particularly by cruciferous fleas, in oilseed radish (Raphanus sativus l. var. oleiformis Pers.) during early developmental stages. This method has been adapted for ecological monitoring and has implications for building ecological prognostic models. Several key parameters were measured and analyzed in relation to environmental stressors and plant damage according to the basic indicators of the chlorophyll fluorescence induction curve (CFI) in relation to different gradations of cotyledon damage in the interval 'traces of damage-70% damage' for three varieties. Typical CFI curves of cotyledons for different varieties of oilseed rape with different degrees of damage were constructed and its reliability (factor-dispersion and correlation schemes) was evaluated in the practice of indirect identification of adaptive plant response to stress caused by pest damage with the assessment of the interaction of this damage with environmental parameters of the environment at different levels of stressfulness of the year from the standpoint of hydrothermal moisture regimes. This made it possible to expand the possibility of building ecological prognostic models for assessing the stress response systems of plant development in case of their damage in the early stages of growth processes. A decrease in the basic criteria of the chlorophyll fluorescence curve (F0, Fpl, Fm, Fst) in the range of 20.78–34.56% in the conjugate system damage degree-environmental stress of the period was established. This led to a decrease in the cotyledon water potential (Lwp) in the range of 3.7–41.2%, the plant viability index (RFd) in the range of 8.3–40.1%, and an increase in the indicator of endogenous (stress) factors (Kef) by 6.5–36.4%. Based on these studies, the possibility of using the chlorophyll fluorescence method for ecological and entomological analysis of the stress response of plants to the degree of damage to the primary assimilative cotyledonous tissues of plants at different levels of hydrothermal support during their growth period was proved.

The article presented describes a comprehensive study using chlorophyll fluorescence induction (CFI) as a non-destructive method for assessing phytophagous damage, particularly by cruciferous fleas, in oilseed radish (Raphanus sativus l. var. oleiformis Pers.) during early developmental stages. This method has been adapted for ecological monitoring and has implications for building ecological prognostic models. Several key parameters were measured and analyzed in relation to environmental stressors as well as plant damage, according to the basic indicators of the chlorophyll fluorescence induction curve (CFI) in relation to different gradations of cotyledon damage in the interval 'traces of damage - 70% damage' for three varieties. Typical CFI curves of cotyledons for different varieties of oilseed rape with different degrees of damage were constructed and its reliability (factor-dispersion and correlation schemes) was evaluated in the practice of indirect identification of adaptive plant response to the stress caused by pest damage with the assessment of the interaction of this damage with environmental parameters of the environment at different levels of stressfulness of the year from the standpoint of hydrothermal moisture regimes. This made it possible to expand the possibility of building ecological prognostic models for assessing the stress response systems of plant development in case of their damage in the early stages of growth processes. A decrease in the basic criteria of the chlorophyll fluorescence curve (F0, Fpl, Fm, Fst) in the range of 20.78-34.56% in the conjugate system damage degree-environmental stress of the period was established. This led to a decrease in the cotyledon water potential (Lwp) in the range of 3.7-41.2%, the plant viability index (RFd) in the range of 8.3-40.1%, and an increase in the indicator of endogenous (stress) factors (Kef) by 6.5-36.4%. On the basis of these studies, the possibility of using the chlorophyll fluorescence method for ecological and entomological analysis of the stress response of plants to the degree of damage to the primary assimilative cotyledonous tissues of plants at different levels of hydrothermal support during their growth period was proven. [ABSTRACT FROM AUTHOR]

The presented method was developed to determine the concentration of thymol residues in honey by ultra performance liquid chromatography with a fluorescence detector. The thymol in honey was extracted by 40% acetonitrile-water solution. After centrifugation and filtration, the separation of thymol was performed on an Accucore aQ liquid chromatography column (150 mm×2.1 mm, 2.6 μm) with the gradient elution of acetonitrile and water (containing 0.1% formic acid) as mobile phases, and quantitated by external standard method with fluoresce detector (excitation wavelength 274 nm, emission wavelength 297 nm). A good linear relationship (R2=0.9999) was observed with concentration ranging from 0.01 μg/mL to 3.00 μg/mL. The average recovery of thymol was from 87.4% to 106.9%, the coefficient of variation was between 0.7% and 7.3%, and the limit of quantification was 0.10 mg/kg. The developed method was applied to determine residual thymol in 48 commercial honey samples, and the thylmol was only detected in one sample. The presented method is simple, quick, reliable, and suitable to be used for batch screening and quantitative determination of residual thymol in honey.

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Two rapid detection methods for Salmonella in food were established and compared using recombinase-mediated amplification technology. The primers and probes were designed based on the fimY gene of Salmonella, and the amplified products were detected using the fluorescence method and lateral flow strip method, respectively. A recombinase-mediated isothermal nucleic acid amplification method was constructed to verify the specificity, sensitivity, and detection effect of the two methods on artificially contaminated samples. The two methods constructed in this study were operated at a constant temperature of 39 °C, and the detection time was 30~40 min. These methods have good specificity and no cross-reaction with other common food-borne pathogens, such as Escherichia coli and Staphylococcus aureus. The sensitivity of the lateral flow test strip method reached 1 pg/μL, and the sensitivity of the fluorescence method was 10 pg/μL. The detection results of the artificially contaminated samples were consistent with the detection results of the traditional separation and culture method. Therefore, two rapid, specific and sensitive methods were established in this study for the detection of Salmonella, which provide a confirmed reference value and data to support the rapid screening of Salmonella contamination in food. [ABSTRACT FROM AUTHOR]

Objective Although small red blood cells are a well-known analytical pitfall that could cause artifactual increase of the platelet count, limited information is available on the accuracy of impedance platelet counting in cases with microcytosis. The aim of this study is to assess the accuracy of impedance platelet counting in the presence of small red blood cells, and to establish the optimal mean corpuscular volume (MCV) cutoff to endorse fluorescence platelet counting. Methods In this study, platelet counts estimated by the impedance method on the Sysmex XN9000 analyzer (Sysmex, Kobe, Japan) were compared with those provided by the fluorescence method. The accuracy of impedance platelet counting was assessed. Receiver operating characteristic curve was used to evaluate the performance of MCV in predicting falsely increased platelet counts. Results There was a tendency for the impedance method to overestimate the platelet count in samples with 70 fL < MCV ≤ 80 fL, 60 fL < MCV ≤ 70 fL, MCV ≤ 60 fL. Receiver operating characteristic curve analysis showed that a 73.5fL cutoff of MCV was highly sensitive in predicting falsely increased platelet counts. Conclusion In cases with MCV < 73.5 fL, we strongly suggest that the platelet counts obtained by the impedance method on the Sysmex XN9000 analyzer should be checked and corrected by fluorescence counting. [ABSTRACT FROM AUTHOR]

Salmonella Typhimurium poses a serious threat to human health worldwide, necessitating the development of a rapid, sensitive, and convenient method for S. Typhimurium detection. Nanozymes are considered ideal signal report elements, which are extensively used for developing colorimetric methods. However, single-component nanozymes display low catalytic activity, and colorimetric methods are susceptible to environmental interference, reducing the sensitivity and accuracy of detection results. To address these drawbacks, this study constructed a dual-mode composite nanozyme-based cascade colorimetric-fluorescence aptasensor for S. Typhimurium detection in food. In this study, the composite Fe 3 O 4 @MIL-100(Fe) nanozymes were successful synthesized and demonstrated substantial peroxide-like activity, with 4.76-fold higher specificity activity (SA) than that of Fe 3 O 4 nanozymes. Then, a glucose oxidase (GOx)-Fe 3 O 4 @MIL-100(Fe) cascade reaction was developed for colorimetric detection via an aptamer to facilitate the formation of Fe 3 O 4 @MIL-100(Fe)/ S. Typhimurium/carboxylated g-C 3 N 4 (CCN)-GOx sandwich complexes. Meanwhile, the fluorescence mode was achieved by measuring the fluorescence intensity of the sandwich complexes. In optimum conditions, the dual-mode detection limits (LOD) were 1.8 CFU/mL (colorimetric mode) and 1.2 CFU/mL (fluorescence mode), respectively, with the S. Typhimurium concentration ranging from 10 CFU/mL to 107 CFU/mL. Finally, the feasibility of the dual-mode colorimetric-fluorescence method was validated via three actual samples, yielding recovery rates of 77.32 % to91.17 % and 82.17 % to 103.7 %, respectively. This study successfully develops a composite nanozyme-based cascade colorimetric and fluorescence dual-mode aptasensor for S. Typhimurium detection. It presents several distinct benefits, such as a broader linear range (10–107 CFU/mL), a lower LOD value (1.2 CFU/mL), and more accurate results. More importantly, the proposed dual-mode method displays a low LOD in colorimetric mode, demonstrating considerable potential for S. Typhimurium on-site detection in food. [Display omitted] • A nanozyme cascade reaction was developed to improve the sensitivity of results. • The fluorescence method was introduced to improve the accuracy of results. • This dual-mode detection limits for bacteria were 1.8 and 1.2 CFU/mL, respectively. [ABSTRACT FROM AUTHOR]

Fe 3+ is one of the crucial metal ions in biological systems, and its excess or deficiency in the body can trigger various diseases, posing a serious threat to human health. Moreover, improper handling or disposal of Fe 3+ can lead to water pollution, thereby harming the environment. Therefore, the development of highly selective and sensitive Fe 3+ detection probes is particularly urgent. In this paper, a dual-mode sensor based on sol-gel and fluorescence signal responses was developed for the visual detection of Fe 3+ . The visual sensing method based on the simultaneous response of Fe 3+ -triggered dual signals can minimize the interference from false-positive signals and enhance detection accuracy. The dual-mode sensor, denoted as PAA@CDs, was constructed by incorporating high-brightness (high fluorescence emission intensity) green-yellow carbon dots (CDs) into poly(acrylic acid) (PAA), which possesses a large number of carboxyl functional groups. Based on the interaction of Fe 3+ with the surface functional groups of CDs, nonfluorescent complexes are formed, leading to nonradiative electron transfer, which induces fluorescence quenching and produces a fluorescence signal visible to the naked eye. Additionally, the interaction of Fe 3+ with the carboxyl groups of PAA triggers the cross-linking of PAA, causing a sol-gel phase change signal. Consequently, the PAA@CDs exhibit a dual-response signal in Fe 3+ detection. Based on the fluorescence method, the linear detection range of PAA@CDs for Fe 3+ is 0.05-2.60 mM with a limit of detection (LOD) of 5.14 μM. Meanwhile, using the sol-gel method, the linear detection range is 0.02-2.20 mM, and the LOD is 42.5 μM. Furthermore, the PAA@CDs probes can be successfully applied to the detection of Fe 3+ in real water samples, demonstrating their potential value in the analysis of real samples containing multiple ions.

Background and objective Segmentectomy has gradually become one of the standard surgical methods for small pulmonary nodules with early lung cancer on imaging. This study aimed to investigate the perioperative outcomes of patients who underwent uniport video-assisted thoracoscopic surgery (VATS) segmentectomy for identifying the intersegmental boundary line (IBL) by the near-infrared fluorescence imaging with intravenous indocyanine green (ICG) method or the modified inflation-deflation (MID) method and assess the feasibility and effectiveness of the ICG fluorescence (ICGF)-based method. Methods We retrospectively analyzed the perioperative data in total 198 consecutive patients who underwent uniport VATS segmentectomy between February 2018 and August 2020. With the guidance of preoperative intelligent/interactive qualitative and quantitative analysis-three dimensional (IQQA-3D), the targeted segment structures could be precisely identified and dissected, and then the IBL was confirmed by ICGF-based method or MID method. Clinical effectiveness and postoperative complications of the two methods were evaluated. Results An IBL was visible in 98% of patients by the ICGF-based group, even with the low-doses of ICG. The ICGF-based group was significantly associated with the shorter IBL clear presentation time [(23.59±4.47) s vs (1,026.80±318.34) s] (P0.05). Conclusion The ICGF-based method could highly accurately identify the IBL and make anatomical segmentectomy easier and faster, and therefore has the potential to be a feasible and effective technique to facilitate the quality of uniport VATS segmentectomy.

Lead，as a heavy metal，is widely used in industrial production，which has a significant impact on the environment and human health. The development of lead ion detection strategies is necessary in recent research areas. Compared with traditional detection methods，the fluorescence method has the advantages of high sensitivity and good selectivity. Therefore，the fluorescence method is often used for qualitative or quantitative analysis of heavy metal ions in actual samples such as water bodies. This review summarizes the research progress on fluorescence detection of lead ions，including fluorescent dyes，fluorescent nanomaterials and fluorescent biomaterials even fluorescent proteins. In addition，an outlook of future development trends and challenges of fluorescence detection is also prospected. [ABSTRACT FROM AUTHOR]

Background: Changes in platelet count are associated with a variety of diseases and treatments. Measuring it gives better insight into the expected outcome. Our aim was to evaluate the accuracy of three methods for platelet count in hyperlipidemia samples. Methods: Sixty non-lipid whole bloods from 60 individuals were included: 20 in low platelet count group, 20 in medium platelet count group, and 20 in high platelet count group. Then, 400 μL plasma was exchanged with 400 μL fat emulsion. Platelet count was measured after replacement by three methods, impedance method (Plt-I), optical method (Plt-O), and fluorescence method (Plt-F). Results: In the low platelet count group with fat emulsion plasma exchange, except for Plt-O, other methods showed the predefined acceptance criterion (± 10%) covered the mean bias and 95% CI of proportional bias (slope) which were obtained from Bland-Altman plot and Passing-Bablok algorithm, respectively. In medium and high platelet count group with fat emulsion plasma exchange, the predefined acceptance mean bias and criterion of 95% CI of proportional bias (slope) and intercept were met only in Plt-F. In the medium platelet count group, the mean bias was -1.600% and the 95%CI of slope and intercept were 1.000 (0.815 to 1.071) and -0.500 (-12.831 to 23.907), respectively. In the high platelet count group, the mean bias was -2.250% and the 95%CI of slope and intercept were 1.071 (0.974 to 1.225) and -33.8142 (-113.703 to 8.339), respectively. Conclusions: Our results show that the Plt-F can more accurately reflect the true platelet count of lipemia specimens compared with Plt-I or Plt-O. [ABSTRACT FROM AUTHOR]

In this study, nitrobenzene was used as dummy template to synthesize a type of specific molecularly imprinted microspheres for chloramphenicol, and 4‐nitroaniline was coupled with three fluorophores to synthesize three fluorescent tracers. Then a competitive fluorescence method was developed on a conventional microplate for detection of chloramphenicol in chicken and pork samples. This method contained only one sample‐loading step, so one assay was finished within 30 min. The IC50 was 1.8 ng/ml, and the limit of detection was 0.06 ng/g. The recoveries from chloramphenicol‐fortified blank meat samples were in the range 67.5–96.2%. Furthermore, this method could be recycled three times. The detection results for some real meat samples were identical to that of a LC–MS/MS method. Therefore, this method could be used as a practical tool for routine screening for the residue of chloramphenicol in large number of meat samples. [ABSTRACT FROM AUTHOR]

In this study, molecularly imprinted microspheres of a type capable of recognising amantadine and rimantadine were first synthesised, and three fluorescent tracers based on dansyl chloride, fluorescein isothiocyanate and 5-carboxytetramethylrhodamine were also synthesised. These reagents were used to develop and optimise a direct competitive fluorescence method on conventional 96-well microplate for detection of the two analytes. Results showed that this method achieved simple operation procedure, rapid assay process (30 min), high sensitivity (limits of detection 0.04–0.05 ng mL−1) and acceptable recycle performance (five times). After optimisation of several parameters, this method was used to detect amantadine and rimantadine in chicken muscle samples. Their recoveries from standards fortified blank samples were in the range of 62.3–93.7%. The analysis results for some real chicken samples were consistent with a confirmatory LC-MS/MS method. Therefore, this method could be used as a rapid, simple and accurate tool for routine screening the residues of amantadine and rimantadine in a large number of chicken muscle samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • A framework nucleic acids (FNAs) fluorescent nanoprobe was constructed. • The detection of multiple DNA repair enzymes in living cells was realized. • This method exhibits good selectivity and high sensitivity. • The FNAs enter the cell autonomously and image UDG and APE1. DNA repair enzymes play pivotal roles in DNA damage repair. Imaging multiple DNA repair enzymes in living cells is significant for DNA damage repair-related biological study and disease diagnosis. Here, we constructed a framework nucleic acids (FNAs) fluorescent nanoprobe for imaging multiple DNA repair enzymes in living cells. Uracil DNA glycosylase (UDG) and human apurinic/apyrimidinic endonuclease 1 (APE1) were used as the target analytes. Two double-stranded DNA probes (dsDNA1 and dsDNA2) were designed. dsDNA1 contained four uracil (U) bases for UDG recognition and was labeled with black hole quencher2 (BHQ2) /cyanine5 (Cy5). dsDNA2 contained one apurinic/apyrimidinic (AP) site for APE1 recognition and was labeled with black hole quencher1 (BHQ1) /fluorophore carboxyfluorescein (FAM). To obtain the FNAs fluorescent nanoprobe, dsDNA1 and dsDNA2 were attached to two vertices of a DNA tetrahedron (a type of FNAs). Under the action of UDG and APE1, dsDNA1 and dsDNA2 were both dissociated, generating fluorescence of Cy5 and FAM. Among them, Cy5 indicated the activity of UDG and FAM indicated the activity of APE1. This method had good sensitivity to UDG and APE1, and the detection limits were 0.0012 U/mL and 0.057 U/mL, respectively. This method also exhibited high selectivity for UDG and APE1. When the FNAs fluorescent nanoprobe was endocytosed, it had little toxicity to normal and cancer cells. Furthermore, this method successfully achieved multiple imaging UDG and APE1 in cancer cells. This study provides a novel strategy for imaging multiple DNA repair enzymes and holds great potential in biological applications and clinical diagnosis. [ABSTRACT FROM AUTHOR]

Luminescent materials encapsulated into zeolite imidazole framework-8 (ZIF-8) as fluorescent probes are widely applied to detect the various analytes. Notably, these analytes react with Zn2+ through the coordination, oxidation, or acidification of 2-methylimidazole (2-MIM) to cause the degradation of ZIF-8 shell, which enormously constraints the improvement of the sensor sensitivity and selectivity. Herein, we have rationally designed the new way to collapse the shell of ZIF-8 entrapped with copper nanoclusters (CuNCs@ZIF-8) triggered by p-benzoquinone. It is worth noting that p-benzoquinone reactions with 2-MIM through hydrogen bonding interaction. As a proof-of-concept, a sensitive method for the detection of hydroquinone (HQ) is developed based on the degradation of CuNCs@ZIF-8 because HQ is easily oxidized to p-benzoquinone. The limit of detection (LOD) is estimated as low as 76 nM. Importantly, this method is highly selective for HQ over other dihydroxybenzene isomers. Inspired by the generation of HQ from hydrolysis of α-arbutin as a substrate for α-glucosidase (α-Glu), we have further proposed a straightforward α-Glu activity assay. LOD is down to 0.003 U/mL, which is lower than most of other α-Glu activity assays. Moreover, the inhibition effect of acarbose and three kinds of natural flavonoids including baicalein, silibinin, and apigenin on α-Glu activity is measured with IC 50 values of 37, 155, 1940, and 2930 nM, respectively. The synergistic and antagonistic inhibition effect of α-Glu activity is also evaluated by binary combination with three types of flavonoids. This approach provides a promising strategy in clinical diagnosis and anti-diabetic drug screening. [Display omitted] • A novel strategy is designed to decompose CuNCs@ZIF-8 shell induced by p-benzoquinone. • LOD is as low as 76 nM and 0.003 U/mL for hydroquinone and α-glucosidase activity, respectively. • This system is not only applied to detect IC 50 value for many inhibitors but also inhibitory effect of binary mixtures. [ABSTRACT FROM AUTHOR]

The exposure of micro- and nanoplastics (MNPs) via medical device is still unknown to us. Herein, a visual quantitative detection of polyvinyl chloride (PVC) MPs and a fluorescent quantitative detection of PVC NPs were developed. To overcome the aggregation of PVC NPs, sodium dodecylbenzene sulfonate was used as the stabilizer of PVC NPs. The brand-new disposable PVC infusion tubes were found to carry PVC MPs with the average total number (ATN) of 931.4 particles and PVC NPs with the average mass of 0.040 μg, respectively. For four typical infusion fluids such as 0.9% sodium chloride, 5% glucose, 5% sodium bicarbonate, hydroxyethyl starch 40 sodium chloride, the released PVC MPs and NPs were ranged from 1003.6 ∼ 3494.6 particles and 0.042 ∼ 0.087 μg, respectively in stimulating normal infusion scenario (room temperature 4 h). The released PVC MPs and NPs were also increased with the infusion duration and temperature. The released PVC MPs are mainly in granular form, accounting for 38 ∼ 49% of the total PVC MPs. Our findings indicate PVC MNPs can enter the blood vessel directly with the infusion fluids during intravenous infusion and the PVC MNPs exposure risk towards patients deserves more attention. [Display omitted] • SDS was used as the stabilizer to overcome the aggregation of PVC NPs. • PVC NPs was quantitatively detected by a facile fluorescent method as common solution. • The brand-new disposable PVC infusion tubes were found to carry PVC MPs and NPs. • PVC MPs and NPs were released in stimulating infusion scenario. • The granular PVC MPs account for 38 ∼ 49% of the total released PVC MPs. [ABSTRACT FROM AUTHOR]

Objective: to assess the efficacy of fluorescence sentinel lymph node (SLN) detection with indocyanine green (ICG) in patients with cervical cancer.Materials and methods. We analyzed the results of examination and treatment in 80 patients with morphologically verified stage IA1–IIA1 cervical cancer. All patients underwent laparoscopic surgery with fluorescence SLN detection with ICG using a high-resolution infrared camera.Results. SLNs were detected in 78 out of 80 patients (97.5 %); the rate of bilateral SLN detection was 80.0 % (64 out of 80). SLNs were not identified in 2 patients only (2.5 %). The majority of SLNs (99 out of 176; 56.28 %) were located in the internal group of lymph nodes, near to the common iliac artery bifurcation. Eleven out of 80 patients (13.75 %) were found to have pelvic lymph node metastasis. SLN metastatic lesions were observed in 10 out of 80 patients (12.5 %), whereas only one participant had non-SLN metastasis. Therefore, the sensitivity of the fluorescence method with ICG was 98.75 %.Conclusion. Fluorescence SLN mapping with ICG in patients with stage IA1–IIA1 cervical cancer is an effective diagnostic method allowing SLN topical diagnosis, intraoperative restaging, and correction of the treatment strategy.

Concentration-dependent photoluminescence carbon dots (CDs) have been successfully synthesized through the one-step hydrothermal treatment of o-phthalic acid and ethylenediamine. The CDs possessed higher fluorescence quantum yield, up to 39.22%, exhibiting distinguished optical property, water solubility, and stability. The CDs that emit strong blue-green fluorescence can visually identify and determine tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC). TC quenched the fluorescence of CDs at 500 nm owing to the inner filter effect; OTC behaved similarly, but the emission wavelength of CDs was red-shifted to 515 nm. Inversely, once CTC was introduced to CDs solution, the fluorescence increased and the emission peak was blue-shifted to 450 nm. Bandgap transition and electrostatic interaction were proposed to be the mechanisms for the detection of OTC and CTC by CDs. Wide linear relationships were established for TC, OTC, and CTC with the limits of detection to be 50 nM, 36 nM, and 373 nM, respectively. Furthermore, the nanoscale probe constructed by this system has been applied to detect tetracyclines (TCs) in complex samples with satisfying recoveries (93.2–114%) and was designed as a portable test strip sensor for visually on-site TCs of honey sample screening. Accordingly, the preparation process of the nano fluorescent probe is simple and environmentally friendly, and the probe has a specific recognition ability for tetracyclines. The synthesized CDs in this work provide a new orientation for fast, effective, and visual real-time detection of tetracycline in actual samples. [ABSTRACT FROM AUTHOR]

Herein, we report a new probe for the determination of the concentration of NF-κB p50, one kind of DNA-binding transcription factors (TFs), by using Exonuclease III (Exo III)-aided amplification and gold nanoparticle mediated fluorescence intensity. Since TFs play critical roles in various biological processes, the detection of TFs can provide a lot of useful biological information for studding gene expression regulation related disease. In our system, in the presence of transcription factor, Exo III based amplification reaction was trigged. This enzymatic digestion results in the release of intermediate DNA and ultimately liberating the fluorophore (which, separated from the quencher of AuNP and BHQ2, now fluoresces). The released intermediate DNA then hybridizes with another strand3, whence the cycle starts anew. So, the fluorescence intensity reflects the NF-κB p50 concentration with a detection limit of 1.32 pM. Importantly, this method might be further extended to selectively detect various dsDNA-binding proteins by simply changing the binding-site sequences of strand1/strand2 duplex probes. Schematic presentation of the probe for ultrasensitive detection of NF-κB p50. In this probe, AuNP was employed as the frame and fluorophore Cy3 was used as the signal output element. Image 1 • We report a new strategy here for detecting NF-κB p50 concentration. • This strategy coupled DNA duplexes on AuNP surface with Exo III-aided amplification technique. • This strategy exhibits a good sensitivity with a limit of detection (LOD) of 1.32 pM. • This strategy has the potential for screening transcription factor inhibitors for drug research and development. [ABSTRACT FROM AUTHOR]

The detection of miRNA in cells is difficult owing to its substantially low cellular content. Therefore, developing a highly sensitive sensor to detect cellular miRNA remains a significant challenge. Herein, we report an enzyme-assisted biosensor with target cycle amplification that can trigger the unlocking of locked hairpin probes for sensitive and robust let-7a gene detection. In the research, three kinds of hairpin probes were skillfully designed. The hairpin probe comprises a complementary sequence of a target, primer, and recognition site of Nt. Bbv CI restriction endonucleases. In addition, the alternating synergistic impact of polymerase and the nicking enzyme generates considerable triggers to unlock the locked hairpin probe LH1, consequently triggering a subsequent circulating strand displacement reaction to form a stable H1–H2 double strand to ensure sufficient distance between a fluorophore on H1 and a quenching group on bolt DNA (bDNA), and resulting in the recovery of fluorescence. Furthermore, this process does not require complicated operation procedures and instruments, and the target gene let-7a can be sensitively detected. Specifically, the detection limit of the biosensor is as low as 160 fM, and its linear range is 0.5 pM–250 nM. Moreover, this biosensor can be employed to detect let-7a in human serum with good selectivity. [Display omitted] • An enzyme-assisted fluorescent sensing system was proposed for the detection of the miRNA Let-7a. • The sensitivity of miRNA Let-7a fluorescence detection was further enhanced by target cyclic amplification. • Ultrasensitive enzyme-assisted fluorescent detection limit of Let-7a was estimated to be as low as 160 fM. • The biosensor has good specificity and excellent detection capabilities in a complex substrate environment. [ABSTRACT FROM AUTHOR]

A rapid, cost-effective and quencher-free fluorescence-based analytical method for sensitive detection of l -cysteine (Cys) based on 2-aminopurine (2-AP) labeled DNA probe and exonuclease I (Exo I) activity was developed. 2-AP labeled DNA probe includes two thymine (T)-T mismatches, which can bind with Hg2+ to form T-Hg2+-T pairing bases, resulting in stable hairpin with five base pairs in its stem. The target Cys can remove Hg2+ from the stem of the hairpin probe based on the high affinity of Cys with Hg2+, leading to the unfolding of the hairpin probe. At last, by adding Exo I, the resulted single-stranded DNA (ssDNA) will be digested to release free 2-AP with strong fluorescence. Under the optimal conditions, the sensing system exhibited a good and wider linear range from 0.4 to 400 nM (R2 = 0.997) and a detection limit as low as 0.16 nM for Cys. Furthermore, other amino acids without reductive sulfur group did not generate obvious change in fluorescence signals. Finally, the sensor can be used in diluted real samples with a good recovery rate, showing promising application in food, environmental and medical analysis. Image 1 • A simple, cost-effective and fluorescent method for Cys detection using 2-AP modified DNA probe was developed. • This assay owns high selectivity, low detection limit of 0.16 nM and wider linear range of 0.4–400 nM. • This method operates in manner of "mix, incubate and detect" and the analytical process is fast. [ABSTRACT FROM AUTHOR]

A simple and rapid detection strategy for vitamin B12 (VB12) was established based on label‐free silicon quantum dots (SiQDs); the detection mechanism was additionally investigated. SiQDs were synthesized using a one‐step microwave method, and their fluorescence was stronger than that synthesized using the hydrothermal method. SiQDs fluorescence was quenched using VB12 due to the inner filter effect (IFE), which was demonstrated using ultraviolet (UV) absorption spectra, fluorescence lifetime, transmission electron microscopy and zeta potential analysis. Subsequently, quercetin (Que) and doxorubicin (Dox) with absorption peaks that overlapped the excitation or emission peaks of SiQDs respectively were used as control groups to investigate the quenching mechanism. Results showed that quenching efficiency was related to the level of overlap between the adsorption peak of the quencher and the excitation or emission peaks of SiQDs. A greater level of overlap caused a higher quenching efficiency. Therefore, the sensitive quenching of VB12 for SiQDs was due to the synergistic effect of the synchronous overlap between the absorption peak of VB12 with the excitation and emission peaks of SiQDs. Fluorescence quenching efficiency increased linearly in the 0.5 to 16.0 μmol·L−1 VB12 concentration range, and the detection limit was 158 nmol·L−1. In addition, SiQDs were applied to determine VB12 in tablets and human urine samples with satisfactory recoveries ranging from 97.7 to 101.1%. [ABSTRACT FROM AUTHOR]

Ion sensor properties of the carboxamide and carbothioamide compounds carrying 4-quinolone group were investigated by means of emission spectrometry in methanol-water (1:1). The compounds were selectively complexed with Cu2+, Pd2+, and Fe3+ among many metal ions. The complex stoichiometry and the stability constant were determined by fluorimetric measurements. The carboxamide compound having phenyl group (QPO) showed sensitivity for Fe3+ ion with a linear range between 0.1 and 0.7 mg/L. The new method was applied in the determination of iron in the spiked tap water samples and the sandy-soil reference material. A modified standard addition method was used to remove the matrix effect. Limit of detection was 0.03 mg/L for the Fe3+ determination method. The carboxamide compound with benzyl group (QBO) showed sensitivity for Cu2+ ion with linear range 0–0.4 mg/L. There was no matrix effect for copper determination in the spiked tap water samples. The detection limit of the method for Cu2+ ion was 0.05 mg/L. The quantification limits of the methods were low enough to determine iron and copper amount in drinking water samples according to EPA. [ABSTRACT FROM AUTHOR]

In his study, we report a fluorescence method for homogeneous detection of influenza A (H1N1) DNA sequence based on G‐quadruplex‐NMM complex and assistance‐DNA (A‐DNA) inhibition. The quadruplex‐based functional DNA (QBF‐DNA), composed of a complementary probe to the target H1N1 DNA sequence and G‐rich fragment, was designed as the signal DNA. The A‐DNA consisted of two parts, one part was complementary to target H1N1 DNA and the other part was complementary to the signal DNA. In the absence of target H1N1 DNA, the G‐rich fragment of QBF‐DNA can form G‐quadruplex‐NMM complex, which outputted a fluorescent signal. With the presence of target H1N1 DNA, QBF‐DNA, and A‐DNA can simultaneously hybridize with target H1N1 DNA to form double‐helix structure. In this case, the A‐DNA partially hybridized with the QBF‐DNA, which inhibited the formation of G‐quadruplex‐NMM complex, leading to the decrease of fluorescent signal. Under the optimum conditions, the fluorescence intensity was inversely proportional to the concentration of target H1N1 DNA over the range from 25 to 700 pmol/L with a detection limit of 8 pmol/L. In addition, the method is target specific and practicability, and would become a new diagnostic assay for H1N1 DNA sequence and other infectious diseases. Highlights: A fluorescence method for homogeneous detection of influenza A (H1N1) DNA sequence based on G‐quadruplex‐NMM complex and assistance‐DNA inhibition is developed. [ABSTRACT FROM AUTHOR]

Abstract It is important to establish sensitive and simple analysis methods for adenosine 5′‑triphosphate (ATP). A label-free fluorescent probe for the determination of ATP was constructed based on glutathione modified silver nanoclusters (AgNCs/GSH). AgNCs/GSH showed aggregation-induced emission enhancement (AIEE) property in the organic solvent. The effects of metal ions on the fluorescence of AgNCs/GSH were also studied. Only zinc ion enhanced the fluorescence of AgNCs/GSH obviously. This was because Zn2+ coordinated with AgNCs/GSH to cause the aggregation of AgNCs/GSH, which was sufficiently proved by TEM. With the addition of ATP, Zn2+ bound with ATP through Zn O P bond and the binding between Zn2+ and AgNCs/GSH was inhibited. Hence the fluorescence of AgNCs/GSH was decreased with increasing the ATP concentration. The fluorescence response was linear in the ATP concentration range of 1–110 μM, and the detection limit was 0.8 μM. Then this method was successfully applied for determining ATP in the samples of human urine and rat serum, the recoveries were in the range of 97.6%–103%. Graphical abstract Unlabelled Image Highlights • A label-free fluorescent probe for ATP is constructed based on AgNCs/GSH with AIEE property. • Only Zn2+ causes aggregation and fluorescence enhancement of AgNCs/GSH, which is proved by TEM and fluorescence spectra. • The detection method for ATP is simple, fast, and has the practical application in detecting biological samples. [ABSTRACT FROM AUTHOR]

The mechanism of interaction between cefonicid sodium and pepsin was investigated by various spectroscopic methods and molecular docking. Cefoncid sodium quenched the intrinsic fluorescence of pepsin at pH of 2.0 to form a new complex in a 1:1 binding mode driven by Van der Waals and hydrogen bonds. The mechanism of quenching was static. The results of molecular docking indicated that the cefonicid sodium-binding site was located in the active site of pepsin. The protein binding rates of cefonicid sodium in gastric juice was calculated and the binding model was established. It is concluded that cefonicid sodium is not suitable for oral administration. [ABSTRACT FROM AUTHOR]

Abstract Human alkyladenine DNA glycosylase (hAAG) is an important protein enzyme which can specifically recognize and initiate the repair of a variety of alkylated purines and hypoxanthine, and the dysregulation of hAAG activity is associated with various human diseases. Although there are several methods focusing on hAAG detection, they share common defects such as time-consuming protocols, laborious operation or requirement of expensive analytical instruments. Herein, taking advantage of the high amplification efficiency of hyperbranched signal amplification and the low background signals by modifying NH 2 at 3' terminus of hairpin substrate and signal probe to prevent the terminal deoxynucleotidyl transferase (TdT)-activated nonspecific amplification, a fluoresence method for sensitive detection of hAAG was established using TdT-activated Endonuclease IV (Endo IV)-assisted hyperbranched signal amplification. This method exhibits high sensitivity with a limit of detection of 0.090 U/mL for pure hAAG and shows a large dynamic range of 3 orders of magnitude from 0.1 to 50 U/mL, and it can be applied for accurate detection of hAAG in complicated HeLa nuclear extract. Moreover, the method can be used for discrimination of hAAG from other DNA glycosylases, holding great potential in hAAG-related biomedical research and clinical diagnosis. Graphical abstract fx1 Highlights • A fluoresence method is introduced to detect hAAG based on hyperbranched signal amplification. • The method shows high sensitivity with a detection limit as low as 0.090 U/mL for hAAG. • The hAAG activity detection can be finished about 100 min. • The method can be applied for the detection of hAAG in HeLa nuclear extract. [ABSTRACT FROM AUTHOR]

Highlights • A fluorescence-based method for analysis of sulfide is presented. • The method shows high selectivity and sensitivity toward sulfide. • The applicability of the method was demonstrated via analysis of real samples. Abstract With the rapid growth of agricultural and industrial sectors, a significant quantity of sulfide is released into water resources systems at an increasing rate. This has caused serious environmental problems, which calls for the development of sensitive and selective methods for determining sulfide in environmental samples. In this report, we employed carbon dots (C-dots) as fluorescence emitters and measured the decrease in their fluorescence intensity caused by Ag 2 S formation. Instead of having free Ag+ cation (which can interact with many other species besides sulfide) in the C-dot solution, we used iodide (I−) to convert Ag+ to one of the least soluble silver salts (i.e., AgI). While AgI interacts with sulfide to form Ag 2 S (because of the lower solubility of Ag 2 S), it remains stable against many other anions, thereby offering the method high selectivity. Under optimized experimental conditions, the developed method enabled quantifying sulfide in the range of 1–10 μM with the low detection limit of 0.48 μM. The applicability of the method was demonstrated by successful analysis of sulfide in a mineral water, a hot spring water, and an industrial wastewater sample. [ABSTRACT FROM AUTHOR]

Uracil-DNA glycosylase (UDG) is pivotal in maintaining genome integrity and aberrant expressed UDG is highly relevant to numerous diseases. Sensitive and accurate detecting UDG is critically significant for early clinical diagnosis. In this research, we demonstrated a sensitive UDG fluorescent assay based on rolling circle transcription (RCT)/CRISPR/Cas12a-assisted bicyclic cascade amplification strategy. Target UDG catalyzed to remove uracil base of DNA dumbbell-shape substrate probe (Sub UDG) to produce an apurinic/apyrimidinic (AP) site, at which Sub UDG was cleaved by apurinic/apyrimidinic endonuclease (APE1) subsequently. The exposed 5′-PO 4 was ligated with the free 3′-OH terminus to form an enclosed DNA dumbbell-shape substrate probe (E-Sub UDG). E-Sub UDG functioned as a template can actuate T7 RNA polymerase-mediated RCT signal amplification, generating multitudes of crRNA repeats. The resultant Cas12a/crRNA/activator ternary complex activated the activity of Cas12a, causing a significantly enhanced fluorescence output. In this bicyclic cascade strategy, target UDG was amplified via RCT and CRISPR/Cas12a, and the whole reaction was completed without complex procedures. This method enabled sensitive and specific monitor UDG down to 0.0005 U/mL, screen corresponding inhibitors, and analyze endogenous UDG in A549 cells at single-cell level. Importantly, this assay can be extended to analyze other DNA glycosylase (hAAG and Fpg) by altering the recognition site in DNA substrates probe rationally, thereby offering a potent tool for DNA glycosylase-associated clinical diagnosis and biomedical research. Schematic of the RCT/Cas12a-assisted bicyclic cascade amplification strategy for uracil-DNA glycosylase activity. [Display omitted] • A sensitive fluorescent assay based on RCT/CRISPR/Cas12a-assisted cascade amplification strategy was demonstrated for UDG. • The assay can be extended to analyze other DNA glycosylase by altering the recognition site in DNA substrates. • The strategy confers the assay with the feature of low background and high signal-to-noise ratio. • The method offers a potent tool for DNA glycosylase-associated clinical diagnosis and biomedical research. [ABSTRACT FROM AUTHOR]

Steady state fluorescence measurements have been used for the investigation of interaction between the bovine serum albumin (BSA) and fluorescence probes: 3-hydroxy-2,4- bis[(3-methyl-1,3-benzoxazol-2(3H)-ylidene)methyl]cyclobut-2-en-1-one (SQ6), 3-hydroxy- 2,4-bis[(3-methyl-1,3-benzothiazol-2(3H)-ylidene)methyl]cyclobut-2-en-1-one (SQ7) and 3-hydroxy-2,4-bis[(1,3,3-trimethyl-1,3-dihydro-2H-indol-2-ylidene)methyl]cyclobut-2-en-1-one (SQ8). The binding constant between bovine serum albumin and squarine dyes has been determined by using both the Benesi-Hildebrand and Stern-Volmer equations. The negative value of free energy change indicates the existence of a spontaneous complexation process of BSA with squarine dyes.

In this paper, a FRET (Forster resonance energy transfer) based fluorescence method was developed for the quickly detection of ochratoxin A (OTA) in agricultural products ( e.g. , flour and beer). A highly fluorescent nitrogen doped carbon dots (CD) were served as energy donor, the DNA and MCH (6-mercapto-1-hexanol) modified Ag nanoparticles were served as energy acceptor in the FRET system. OTA can be detected in a concentration range between 10 and 5000 nM, the limit of detection is 8.7 nM. This method has three advantages: (1) an enhanced fluorescent intensity can be acquired by utilizing the nitrogen doped CD synthesized by one-step approach without sophisticated modification of nanoparticles; (2) OTA detection was accomplished quickly (less than 30 min) by using MCH as assistant molecule; (3) an extended OTA detection linear range was acquired, which may facilitate the OTA detection in real agricultural samples, and is helpful for solving food safety problems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel fluorometric assay toward alkaline phosphatase activity (ALP) was proposed. • Resorcinol monophosphate ester (RME) was developed as a new substrate and synthesized simply via a two-step routine. • The mechanism is RME was converted to resorcinol, reacting with dopamine to form strong a fluorescent product. • ALP activity could be determined with high sensitivity and selectivity. • The assay was validated for verifying pasteurization of milk products. Alkaline phosphatase (ALP) is an indicator of sterilization efficacy of milk products and its activity monitoring is essential for ensuring food safety and controlling product quality. Here, a novel fluorometric method for the determination of ALP activity based on resorcinol monophosphate ester (RME) as a new substrate was proposed to verify pasteurization of milk products. RME was cheap and was simply and novelly synthesized by a two-step method using resorcinol (RC) as the raw material. The mechanism is, after dephosphorylation, RME was transformed to RC, which subsequently react with dopamine (DA) to form a strong fluorescent product, azamonardine. It has a fluorescence emission wavelength at 461 nm under the optimal excitation at 418 nm. The results show that under the optimum conditions, there is a good linear relationship between ΔF (the variation of fluorescence intensity) and ALP activity over 0–5000 mU/L. High sensitivity was achieved (detection limit of 17.34 mU/L) because of high quantum yield of the products and catalytic activity of ALP and the recovery rate is 96.8–106.1%. Compared with national and international standard methods, the detection procedures are simple, just adding RME and DA solution to milk with buffer solution. Our method was successfully applied for ALP activity detection in milk products. Moreover, the catalyst of ALP and the reaction of RME and dopamine are pH dependent, and thus the reaction time could be kept identical by terminating the reaction through adding acids. With high sensitivity, high selectivity, simple operation, and wide linear range, our assay will find more practical applications in food analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • CQD/Dex/PVA nanocomposites are prepared by low-cost green technique. • Glucose sensing by "switch-OFF" fluorescence mechanism. • Highly selective for sensing of glucose in presence of interfering sugars. • Very low detection limit of 61.1 μM. • Glucose contents in human blood serums are compared with commercial glucometer. Herein, carbon quantum dot (CQD) doped dextran/polyvinyl alcohol (PVA) (CQD/Dex/PVA) nanocomposites are synthesized for in vivo detection of glucose by non-enzymatic "switch-OFF" fluorescence mechanism in real human blood serums. Highly functional, dispersible and stable CQD is obtained from aloe vera by carbonization and a facile solution mixing technique is adopted for the preparation of CQD/Dex/PVA nanocomposites. It is noticed that hydrogen bonding between –OH group of glucose and that of the dextran and PVA quenches the fluorescence intensity of the nanocomposite. The synthesized CQD/Dex/PVA nanocomposite is highly selective for sensing of glucose in presence of other interfering sugars which proves its suitability to be implemented in complex biological environment. This biosensing technique exhibits linear range from 0.27 mM to 1.72 mM, R2 = 0.986 and a low detection limit of 61.1 μM. The measurements of glucose content in twelve real human blood serums are done and compared with commercial glucometer with satisfactory recoveries. Considering the high selectivity, sensitivity and accuracy, this "switch-OFF" fluorescence method holds promising application in diabetes management. [ABSTRACT FROM AUTHOR]

In this paper, an ultra-sensitive and highly selective label-free fluorescent aptasensor was developed for the rapid detection of Hg(II), using water soluble cysteamine-capped CdTe/ZnS quantum dots (cysteamine@CdTe/ZnS QDs) as an luminescent probe and a single strain DNA aptamer designed to specifically bind to Hg(II) ions. Negative charge aptamers could aggregate the cationic cysteamine@CdTe/ZnS core/shell quantum dots, so the fluorescence quenching occurred. When Hg(II) ions, as a target, were added to the quantum dots solution, the aptamers with thymine (T)-rich sequences were selectively bound to the mercury ions. This is due to the powerful affinity of Hg(II) ions to the T bases of the DNA aptamer. It leads to the formation of an Hg (II)-bridged T base pair and the aptamers rearrangement into a hairpin-like structure. In the presence of Hg(II), de-aggregation of the quantum dots was occurs, so the fluorescence intensity was gradually increased with enhancing its concentration. Hg(II) could be measured in the range of 5.0 × 10 −10 to 1.0 × 10 −6 mol L −1 with a low limit of detection, 8.0 × 10 −11 mol L −1 . The fabricated fluorescent aptasensor also demonstrated excellent selectivity for Hg(II) detection, this principal was investigated by theoretical and experimental methods so it was applied lucratively for the determination of Hg(II) in real water and waste water samples. [ABSTRACT FROM AUTHOR]

Lipid content in food strongly influences food perception on the level of textural properties. Lipids in contact with the tongue and palate are substantially responsible for the sensory impact of a product. The aim of this study is to investigate the impact of oil content on the thickness of lipid deposition on oral surface as well as on the mouthfeel perception. The fluorescent probe method was used to study the thickness of lipid deposition on oral surface. We observed an increase in the thickness of lipid deposition depending on the increase of oil content in oil/water dispersions. Clear correlation was shown between the thickness of lipid deposition on oral surfaces and the perception of mouthfeel. A direct measure of undisrupted deposition of food components on oral surface contributes to the understanding of the behaviour of food components in the mouth and their influence on mouthfeel perception.

• The AuNCs based on d -histidine and polylysine was first designed to detect Cr6+. • The detection mechanism was aggregation of AuNCs and FRET between AuNCs and Cr6+. • The proposed fluorescence method possessed high sensitivity and selectivity. • The proposed method possessed feasibility of usage in actual system. Hexavalent chromium (Cr6+) owns hypertoxicity, non-biodegradability, and carcinogenicity, thus the detection of Cr6+ is of paramount significance for environmental monitoring and human health maintenance. Herein, a simple, rapid, and feasible fluorescent method based on gold nanoclusters (AuNCs) was established for determination of Cr6+. The AuNCs was coated by a simple and fast one-pot method using d -histidine (d -His) and polylysine (P-Lys) as stabilizers and reductants, which could be quenched by the addition of Cr6+ owing to the aggregation of AuNCs and fluorescence resonance energy transfer (FRET) between AuNCs and Cr6+. Under the optimal conditions, the fluorescent sensor exhibited good linearity within 10–10000 μg/L with limit of detection of 7.2 μg/L. The developed sensor possessed favorable sensitivity and selectivity. Additionally, the proposed method also had favorable recovery with good precision and accuracy within the actual sample, including celery cabbage, rice, capsule shell, and river water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu2+ and Cys/Hcy/GSH sequential sensing mechanism by Eu-DTPA-bis(AMC) is established. • Concentration of Eu-DTPA-bis(AMC)/Cu2+ has relationship with selection of biothiols. • Eu3+-DTPA-bis(AMC)/Cu2+ shows low LODs for biothiols detection. • Low concentration of Eu-DTPA-bis(AMC)/Cu2+ specifically distinguish Cys from Hcy/GSH. • Eu3+-DTPA-bis(AMC) can be applied to accurately detect Cu2+ and Cys in real samples. In this work, a novel Eu3+-DTPA-bis(AMC) complex with red luminescence was designed and synthesized for sequential detection of Cu2+ and biothiols (Cys/Hcy/GSH) based on the displacement strategy with the good selectivity, high sensitivity, and large Stokes shift (288 nm). The possible detection mechanism was verified by UV–vis, the high-resolution mass spectrometry, and the fluorescence decay curve. The experimental parameters, including the solution pH, the incubation time, the concentration ratio of Eu3+-DTPA-bis(AMC) to Cu2+ and biothiols concentration, were optimized. Under the optimal conditions, it shows a good linear relationship between the concentration (0–10 μM) of Cu2+ and the fluorescence intensity of Eu3+-DTPA-bis(AMC), with a low detection limit of 0.065 μM. The linear range and the limit of detection of the Eu3+-DTPA-bis(AMC)/Cu2+ system for Cys/Hcy/GSH were 2.5–22.5/5–45/5–50 μM and 0.11/0.07/0.05 μM, respectively. Surprisingly, the high or low concentration of Eu3+-DTPA-bis(AMC)/Cu2+ can significantly affect the selectivity of the sensing system to biothiols (Cys/GSH/Hcy). When the concentration of the Eu3+-DTPA-bis(AMC)/Cu2+ system is 10.0 μΜ, it could recognize biothiols (Cys/GSH/Hcy) from other substances, but when the concentration is as low as 3.3 μM, it could further specifically distinguished Cys from Hcy/GSH. Owing to the high anti-interference characteristics, accuracy and specificity, the sensing system was well applied to the cascade detection of Cu2+ in actual environmental samples and Cys in biological and food samples, including FBS, urine, milk, beverage, fresh juice with the satisfactory recoveries from 96.20 to 106.80 %. [ABSTRACT FROM AUTHOR]

Understanding the binding mechanisms of drug–protein interactions is a crucial factor in determining the pharmacokinetics and pharmacodynamics of a drug. In this study, the binding affinity of inosine toward the HSA, as well as the dynamic properties of HSA-inosine complexes was obtained from applying NMR methodology. The changes in proton selective and non-selective relaxation rates suggested that inosine interacts with HSA. The values of normalized affinity indexes and equilibrium constant K provided information about the binding strength, which were in accordance with fluorescence result. The detailed binding mechanisms were obtained through fluorescence method, and the binding mode was displayed using Discovery Studio. Circular dichroism data further confirmed the secondary structure changes in HSA upon inosine addition. This study provided insights on the interactions between inosine and HSA. [ABSTRACT FROM AUTHOR]

Chemosensors are the molecule of abiotic origin that binds with different analyte by covalent or non-covalent interactions to create a change in colour or optical properties. In this context, colorimetric anion sensors are unique, because they detect target anions through visual detection with no sophisticated instrumentation technique. A chromophore or a fluorophore plays a significant role as a signalling unit in chemosensors. A variety of chemosensors designed with organic and inorganic chromophores or fluorophores used for the detection of various analytes. Among them anthraquinone has found significant application in anion recognition and sensing for their important role in various photochemical and colorimetric sensor systems. In this review we summarise the development of chromogenic anion sensors using colorimetric and fluorometric reagent anthraquinone as a signalling unit. We have attempted to cover almost all the reports of modified anthraquinone moiety as anion sensor reported until now. [ABSTRACT FROM AUTHOR]