A sensitive electrochemical aptasensor for zearalenone detection based on target-triggered branched hybridization chain reaction and exonuclease I-assisted recycling.

Traditional methods for detecting antibiotic and mycotoxin residues rely on large-scale instruments, which are expensive and require complex sample pretreatment processes and professional operators. Although aptamer-based electrochemical sensors have the advantages of simplicity, speed, low cost, and high sensitivity, most aptamer-based sensors lack a signal amplification strategy due to their direct use of aptamers as probes, resulting in insufficient sensitivity. To solve the sensitivity problem in the electrochemical detection process, a novel electrochemical sensing strategy was established for ultrasensitive zearalenone (ZEN) detection on the basis of exonuclease I (Exo I) and branched hybridization chain reaction (bHCR) to amplify the signal. The amplification strategy showed excellent analytical performance towards ZEN with a low detection limit at 3.1×10-12 mol/L and a wide linear range from 10-11 to 10-6 mol/L. Importantly, the assay was utilized in the corn powder samples with satisfactory results, holding promising applications in food safety detection and environmental monitoring.

A novel colorimetric assay for sensitive detection of kanamycin based on the aptamer-regulated peroxidase-mimicking activity of Co3O4 nanoparticles.

Kanamycin is used widely in livestock farming due to its antimicrobial properties and low cost, but has led to antibiotic residues in food, which can damage human health. Therefore, there is an urgent need for convenient technology that can be used to detect kanamycin rapidly. We found that Co3O4 nanoparticles (NPs) possessed peroxidase-like activity that catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine to change color. Interestingly, a target-specific aptamer could regulate the catalytic activity of Co3O4 NPs and inhibit this effect through aptamer-target binding. On the basis of a colorimetric assay combined with an aptamer-regulatory mechanism, the linear range for quantitative detection of kanamycin was 0.1-30 µM, the minimum limit of detection was 44.2 nM, and the total time needed for detection was 55 min. Moreover, this "aptasensor" displayed excellent selectivity and could be applied to detect KAN in milk samples. Our sensor might have promising applications for kanamycin detection in animal husbandry and agricultural products.

A fluorescent assay for sensitive detection of kanamycin by split aptamers and DNA-based copper/silver nanoclusters.

Kanamycin was a group of essential antibiotics generally served in treating infections of animals which leached into the environment residual in food, causing health concerns. Thus, selective and sensitive monitoring of kanamycin was significant for food safety. In this work, split aptamers were used as templates to prepare fluorescent Cu/Ag NCs for detection of kanamycin. According to the impressive affinity of the aptamer to kanamycin, two different detection modes were designed using kanamycin aptamer as a recognition molecule, in which one was to combine split aptamer Apt-1 with Apt-2 to form an entangled DNA as a Cu/Ag NCs template, the other was to associate the normal aptamer after encirclement to form Cu/Ag NCs templates. After the addition of kanamycin, the fluorescence signals of the Cu/Ag NCs synthesized in the two modes were both enhanced, but the approach with split aptamer exhibited a superior observable sensitivity than that of the normal type. The detection range showed a well linear relationship between 80 nM and 10 µM when the emission wavelength was 560 nm, and the detection limit was 13.3 nM. In addition, when streptomycin, oxytetracycline, chloramphenicol and chlortetracycline were involved in the selective interference experiment under the same conditions, the fluorescence intensity of the system performed no significant changes. The results demonstrated that this method possessed favorable specificity and selectivity for the assay of kanamycin, proficiently achieving efficient, rapid and sensitive evaluation of kanamycin in the milk samples.

Detection of Pyrophosphate and Alkaline Phosphatase Activity Based on PolyT Single Stranded DNA - Copper Nanoclusters.

The determination of pyrophosphate and alkaline phosphatase activity plays a significant role in medical diagnosis. In this work, a label-free "ON-OFF-ON" fluorescence strategy is developed for the analysis of pyrophosphate and alkaline phosphatase activity. Using PolyT single strand DNA as templates to synthesize fluorescent copper nanoparticles, the coordination effect of pyrophosphoric acid on Cu2+ inhibited the generation of fluorescence. Afterwards, the addition of alkaline phosphatase into hydrolyze pyrophosphoric acid resulted in the release of Cu2+, whereby the fluorescence intensity could be recovered. Thereupon enhanced-sensitivity for alkaline phosphatase was obtained (0.1 mU/L), much better than previously reported methods. Meanwhile, it could be performed directly in homogeneous solution, which was very close to the actual activity level of alkaline phosphatase under physiological conditions. Likewise, satisfactory results were also obtained in specificity assessment, which demonstrated its potential application in clinical diagnosis. Notably, a new, sensitive, low-cost, short-time, and high-sensitivity platform for alkaline phosphatase detection was constructed, and the design of biosensor using DNA-templated Copper nanoclusters (CuNCs) was instructed in this study.

Relationships Among Extreme Sports Participation, Sensation Seeking, and Negative Risky Behaviors of Middle-School Students.

Objective: The aim was to investigate the relationships among extreme sports participation, sensation seeking, and negative risky behaviors (smoking, drinking alcohol, and gambling) for middle-school students. Methods: Using a convenience sampling procedure, all students from a middle school in a district of Chongqing were selected to participate in the survey, which included questions on their extreme sports participation rate, and smoking, drinking alcohol, and gambling behavior. Results: A sample of 2,987 middle-school students participated in this study. The results showed that the proportions of students participating in extreme sports, smoking, drinking alcohol, and gambling were 19.9, 4.8, 18.4, and 3.0%, respectively. There were significant differences between different genders, schools, place of residence, smoking, drinking, gambling, and sensation seeking of the participation rate of students of extreme sports, the rate of boys, junior middle-school students, urban students, smokers, alcohol drinkers, gamblers, and high-sensation-seeking students were relatively higher than that of girls, senior middle-school students, rural students, no-smokers, no-alcohol drinkers, no-gamblers, and low-sensation-seeking students. Alcohol drinking, gambling, and sensation seeking were associated with extreme sports participation, and the students who drank alcohol, who gambled, and who were high sensation seeking were more likely to participate in extreme sports than those who did not drink alcohol, who did not gamble, and who were low sensation seeking. Conclusion: Middle schools should integrate extreme sports education into physical education and risky-behavior education, strengthen relevant knowledge and safety training, and guide students to meet their sensation-seeking needs through participation in extreme sports instead of risky behaviors.

A Sensitive Fluorescent Assay for Tetracycline Detection Based on Triple-helix Aptamer Probe and Cyclodextrin Supramolecular Inclusion.

Herein, an effective pyrene excimer signaled fluorescent biosensor for the determination of tetracycline based on triple-helix aptamer probe (TAP) and supramolecular inclusion of cyclodextrin was reported. The TAP was devised containing an aptamer loop, two DNA segment stems and a triplex-forming oligonucleotide (signal probe) labeled with pyrenes at 5' and 3' ends. The presence of target could result in its binding towards aptamer with a mighty affinity, leading to a conformation change of the TAP and whereupon the release of the signal probe. This liberty of signal probe enabled the formation of pyrene excimer, generating fluorescence signals. Further, signal amplification was fulfilled through the addition of γ-cyclodextrin which could interact with pyrene dimer, thus leading to an enhanced "on-state" of the sensing ensemble. In contrast, when the target was absent, the sensing ensemble remained "off-state" because of the long distance between two pyrene molecules. When the conditions were properly optimized, the increasing signal kept a linear dependence on target concentrations ranging from 5.0 nM to 100 nM, and the detection limit reached as low as 1.6 nM. In this way, a newly-constructed, simple, and economically affordable protocol enjoys desirable efficiency, sensitivity, specificity in biosensing. Also, its universality as another attractive behalf in assaying diverse targets was envisioned with only the need of matched aptamer replacement.

Research of relationship between frailty and gut microbiota on middle-aged and the aged patients with diabetes / 生物医学工程学杂志

Gut microbiota plays an important role in development of diabetes with frailty. Therefore, it is of great significance to study the structural and functional characteristics of gut microbiota in Chinese with frailty. Totally 30 middle-aged and the aged participants in communities with diabetes were enrolled in this study, and their feces were collected. At the same time, we developed a metagenome analysis to explore the different of the structural and functional characteristics between diabetes with frailty and diabetes without frailty. The results showed the alpha diversity of intestinal microbiota in diabetes with frailty was lower.

Novel magnetic Fe3O4/g-C3N4/MoO3 nanocomposites with highly enhanced photocatalytic activities: Visible-light-driven degradation of tetracycline from aqueous environment.

In the present work, a series of magnetically separable Fe3O4/g-C3N4/MoO3 nanocomposite catalysts were prepared. The as-prepared catalysts were characterized by XRD, EDX, TEM, FT-IR, UV-Vis DRS, TGA, PL, BET and VSM. The photocatalytic activity of photocatalytic materials was evaluated by catalytic degradation of tetracycline solution under visible light irradiation. Furthermore, the influences of weight percent of MoO3 and scavengers of the reactive species on the degradation activity were investigated. The results showed that the Fe3O4/g-C3N4/MoO3 (30%) nanocomposites exhibited highest removal ability for TC, 94% TC was removed during the treatment. Photocatalytic activity of Fe3O4/g-C3N4/MoO3 (30%) was about 6.9, 5, and 19.9-fold higher than those of the MoO3, g-C3N4, and Fe3O4/g-C3N4 samples, respectively. The excellent photocatalytic performance was mainly attributed to the Z-scheme structure formed between MoO3 and g-C3N4, which enhanced the efficient separation of the electron-hole and sufficient utilization charge carriers for generating active radials. The highly improved activity was also partially beneficial from the increase in adsorption of the photocatalysts in visible range due to the combinaion of Fe3O4. Superoxide ions (·O2-) was the primary reactive species for the photocatalytic degradation of TC, as degradation rate were decreased to 6% in solution containing benzoquinone (BQ). Data indicate that the novel Fe3O4/g-C3N4/MoO3 was favorable for the degradation of high concentrations of tetracycline in water.

Synergistic adsorption-photocatalytic degradation effect and norfloxacin mechanism of ZnO/ZnS@BC under UV-light irradiation.

Norfloxacin (NOF) is an environmentally harmful and ubiquitous aquatic pollutant with extensive production and application. In this study, a novel composition named carbon-based composite photocatalytic material of zinc oxide and zinc sulphide (ZnO/ZnS@BC) was successfully obtained by the impregnation-roasting method to remove NOF under UV-light. Scanning electron microscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive spectrometer characterised the composition. ZnO/ZnS was successfully decorated on the surface of biochar (BC). The pH, the ZnSO4/PS ratio, and ions and quenchers, were investigated. High removal efficiency was obtained with a pH of 7 and a ZnSO4/PS ratio of 1:1, and the removal ratio of NOF reached 95% within three hours; the adsorption and degradation ratios reached 46% and 49%, respectively. Fe2+ promoted the degradation of NOF, whereas other ions inhibited it, with NO3- showing the strongest inhibitory effect. Three reactive species (tert-butanol, quinone, and ammonium oxala) were identified in the catalytic system. The decreasing order of the contribution of each reactive species was: O2- > ·OH- > h+. Additionally, a recycling experiment demonstrated the stability of the catalyst; the catalytic degradation ratio of NOF reached 78% after five successive runs. Therefore, ZnO/ZnS@BC possessed strong adsorption capacity and high ultraviolet photocatalysis ability.

A nanofiber mat prepared from sulfonated polyaniline for solid-phase extraction of fluoroquinolones from water and biological fluids prior to their quantitation by UPLC-MS/MS.

A bifunctional sulfonated polyaniline nanofiber mat (NFM) was synthesized by oxidative polymerization and by using polyacrylonitrile nanofiber mat (NFM) as the template. The adsorption capacity of the NFM for fluoroquinolones (FQs) is distinctly improved and the adsorption was a spontaneous process. According to theoretical calculations, hydrogen bonding and ion-exchange interaction are the two major kinds of interaction mechanisms between adsorbent and FQs. The adsorption and desorption properties for FQs were systematically evaluated by adsorption isotherms and by thermodynamic and kinetic studies. The results indicate that the NFM is a viable sorbent for FQs because of rapid mass transfer and good adsorption/desorption efficiency. The NFM is re-usable for at least 20 cycles without decline in performance. Following desorption of the FQs with 10% (V/V) formic acid/acetonitrile, they were quantified by UPLC with MS/MS detection. The sorbent was applied to the solid phase extraction of the FQs norfloxacin, ciprofloxacin, ofloxacin, enrofloxacin, danofloxacin, pefloxacin, marbofloxacin, lomefloxacin and difloxacin from water and biological fluids. Figures of merit include (a) low limits of detection (0.5-1.5 ng L-1 for water, 0.016-0.052 µg L-1 for urine and serum), (b) high recoveries from spiked samples (82.3%-109.4%) with low relative standard deviations (1.1%-12.3%); (c) short extraction times (2 min), and (d) low adsorbent dosage (4 mg). Graphical abstractSchematic representation of a bi-functional sulfonated polyaniline nanofiber mat (NFM) for solid phase extraction (SPE) of fluoroquinolones (FQs) in water, urine and serum.

An electrochemical strategy for tetracycline detection coupled triple helix aptamer probe with catalyzed hairpin assembly signal amplification.

Incorporating elements of triple-helix aptamer probes (TAP), catalyzed hairpin assembly (CHA) signal amplification and host-guest recognition, a novel "signal-on" sensing strategy for sensitive electrochemical quantification of tetracycline (TC) was reported unprecedentedly. TAP was formed involving an aptamer loop, two-segment stems and a triplex oligonucleotide serving as trigger probe. Then, the trigger probe would be released from TAP once the target presented due to the conformational variation of TAP induced by aptamer binding event, sparking off the upcoming CHA amplification reaction, in which two coexisting DNA hairpins (H1 and H2 both modified with the electroactive molecules) would hybridize into plentiful H1-H2 double helices. Afterwards, the Exonuclease III was added, demolishing double helices and simultaneously releasing plentiful electroactive molecules which were capable of diffusing onto the electrode surface under the assistance of ß-cyclodextrin due to host-guest recognition, where appreciable signals were enriched and generated. As thus, considerably slight amounts of targets though, emitted trigger probes, yet efficiently engining spectacular CHA cycles of reactions through which amplified signals were yielded, and in turn progressively enabling the sensitive target detection done. Under optimal conditions, the growing signal stayed a linear relation along with the logarithm of the target concentrations ranging from 0.2 nM to 100 nM, the detection limit reaching as low as 0.13 nM. This approach was desirable regarding to sensitivity, detection limit and range, prospectively rendering a service for diverse targets detection by easily replacing the matched aptamer loop of TAP.

Facile combination of beta-cyclodextrin host-guest recognition with exonuclease-assistant signal amplification for sensitive electrochemical assay of ochratoxin A.

Smartly coupling exonuclease-induced target recycling signal amplifications with ß-cyclodextrin host-guest recognition, a novel "signal-on" aptamer sensor for sensitive determination of ochratoxin A (OTA) was proposed for the first time. Firstly, the formation of double-strand DNA (dsDNA) was occurred by hybridizing OTA aptamer with its complementary DNA (cDNA) and as the probe DNA the cDNA at its 3' terminal was labeled with methylene blue (MB). Next, when OTA was present, the aptamer tended to form aptamer-OTA complex with conformation of G-quadruplex instead of aptamer-cDNA duplex, leading to thus the probe DNA separating from dsDNA complex. Then the RecJf exonuclease was added, demolishing partially G-quadruplex structure and releasing a certain number of OTA. Sequentially, those released OTA would continue to react with the rest of aptamer in dsDNA, drawn into development of a new round of G-quadruplex complex, where the target cycling was realized. Meanwhile, as a signal molecule, MB modified on cDNA was liberated along with the cDNA being digested into monoucleotides by RecJf exonuclease, capable of diffusing onto the electrode surface due to host-guest recognition with ß-cyclodextrin, whereupon the signal was enriched and yielded. In this way, cycles of target with continuous output of signal indicators were undergone, in which the detection of target was in return fulfilled with signal amplification owing to the joint endeavor of exonuclease and ß-cyclodextrin. Under the optimal conditions, the raising signal maintained a linear relation with the logarithm of the target concentrations ranging from 10 pg/mL to 10.0 ng/mL and the detection limit reached as low as 3 pg/mL. This brand-new strategy was simple and low-cost but satisfactory in terms of detection limit, range and sensitivity, in all possibility to be applied extensively for diverse targets detection by easily alternating the corresponding aptamers.

Preliminary analysis of clinical efficacy of whole brain simultaneous integrated boost intensity-modulated radiotherapy in patients with brain metastases / 中华放射肿瘤学杂志

Objective To preliminary investigate the clinical efficacy of whole brain simultaneous integrated boost intensity-modulated radiotherapy ( SIB-IMRT ) in patients diagnosed with brain metastases ( BM) . Methods Fifty-two cases of BM admitted to our hospital from January 2016 to December 2017 were equally recruited and randomly divided into the observation and control groups. Patients in the observation group were treated with SIB-IMRT, and those in the control group received conventional whole brain radiotherapy (WBRT).The clinical efficacy and prognosis were statistically compared between two groups. Results The ORR in the observation group was 77％, significantly higher than 27％ in the control group (P=0. 00).The median survival in the observation group was 384 d,significantly longer compared with 211 d in the control group (P=0. 00).All patients in both groups successfully completed corresponding treatment. Acute adverse reactions were mainly 1-2 grade reactions. Conclusions SIB-IMRT is an efficacious and safe treatment of BM,which yields tolerable adverse events and deserves application in clinical practice.

Significance of radiological protection of sensitive organs in non-treated region in body γ-knife treatment / 中华放射医学与防护杂志

Objective To explore the radiation dose from body γ-knife treatment to the nontargeted region's sensitive organs before and after shielding.Methods 20 patients suffering tumors less than 5 cm were selected.Calibrated thermoluminescence dosimeters (TLD) were placed above the sensitive organs,such as lens,thyroid gland and sexual gland,to measure the radiation dose received before shielding.Different plans were prepared for the patients with lung and renicapsule tumors using calibrators of different size.Radiation dose was measured by the aid of water phantom.For selected lungtumor treatment plan,the radiation doses were measured at the same location on the water phantom shielded with and without 1,2 and 4 cm lead,respectively.Results The maximum doses were 1 023.3 mGy for lens,1 235.7 mGy for thyroid gland and 1 176.8 mGy for sexual glands after treatment,respectively,being higher on the left site than the right.The radiation doses to the sensitive organs were higher for the water phatom with more tartgted points,decreasing by 55％-91％ after being covered with 1,2 and 4 cm lead shieldings.There were significant differences in doses received before and after lead shielding (t =14.4,12.9,13.3,P ＜ 0.05).Conclusions In the course of body γ-knife treatment,the additional factors would increase the dose to the sensitive organs.Therefore,it is necessary to provide lead shielding protection to the teenagers and adults with fertility when they undergo body γ-knife treatment.Trial registration Chinese Clinical Trial Registry,ChiCTR-OOC-16008259.

Comparison between sliding window and step and shoot / 医疗卫生装备

Objective To compare and analyze DMLC(Sliding Window,SW)and SMLC(Step and Shoot,SS)for delivering IMRT.Methods 5 patients with nasopharyngeal carcinoma were treated with radical intensity modulated radiation therapy using Varian 23EX and Helios tool on a Varian Eclipse system.Different modalities to deliver IMRT were considered for Sliding Window(SW) and Step and Shoot(SS) techniques using a different number of intensity levels(e.g.5,10 and 20).The total beam-on-time,total delivery time and a number of dose-volume parameters regarding PTV and OARs were considered.Results Comparing with the DVH,it was found that SW was the best of the four modalities in the dose distribution of PTV,but SS was better when considering the protection of OARs.The total beam-on-time(MUs) requirement for SS was 9～23% less than SW,but the total delivery time(in minutes)was about twice as long.Conclusion With the number of intensity level of 10 or more,no differences between SS and SW can be appreciated in the dose distribution of PTV and OARs sparing.Referring to the quality assurance,only leaf position needed to be checked in SS,whereas both leaf position and leaf speed need to be checked in SW,so it is proposed to use SS10 for delivering IMRT.

Social economical status, behaviors and environment as the risk factors of tuberculosis in Chengdu China / 中华流行病学杂志

Objective　To study the risk factors of pulmonary tuberculosis in Chengdu, Southwest China. Methods　A population-based case-control study was used which included 174 cases selected from 12 communities in Chengdu and 174 controls selected from registered population with normal chest radiograph.Cases were active TB patients which were matched for age,sex with controls,then interviewed by trained interviewers using a standardized questionnaire. Results　Social economic status measured by education, occupation and income did not show obvions influence to TB; It found that the active smoking, passive smoking，type of cigarettes and alcohol consumption had no significanct effects on TB during logistic regression analysis. The study showed that a person who was smoking and also alcohol intake had a higher risk to get TB (OR＝6.12, 95%CI=1.15-32.49). Significant association was showed in the Dose-Response Analysis (OR=1.37, 95％CI=1.30-2.30). Crowded living space (OR=1.14, 95%CI=1.05-1.25), degree of darkness (OR=2.18, 95%CI=1.11-4.27) and moisture (OR=4.06, 95%CI=2.25-7.33), poor sanitary (OR=3.03, 95%CI=1.22-4.44), airpollution of working environment, which were filled with dusts (OR=2.35, 95%CI=1.18-4.70) and chemical fumes (OR=5.15, 95%CI=1.44-18.40) were strongly associated with pulmonary tuberculosis. BMI also had strong relationship with TB (OR=4.72, 95%CI=2.68-8.33). Conclusion　Poor environment and exposure to dust and chemical fume under working condition, low BMI, smoking combining alcohol consumption were the risk factors of adult pulmonary tuberculosis in Chengdu, China.

Social economical status, behaviors and environment as the risk factors of tuberculosis in Chengdu China / 中华流行病学杂志

Objective　To study the risk factors of pulmonary tuberculosis in Chengdu, Southwest China. Methods　A population-based case-control study was used which included 174 cases selected from 12 communities in Chengdu and 174 controls selected from registered population with normal chest radiograph.Cases were active TB patients which were matched for age,sex with controls,then interviewed by trained interviewers using a standardized questionnaire. Results　Social economic status measured by education, occupation and income did not show obvions influence to TB; It found that the active smoking, passive smoking，type of cigarettes and alcohol consumption had no significanct effects on TB during logistic regression analysis. The study showed that a person who was smoking and also alcohol intake had a higher risk to get TB (OR＝6.12, 95%CI=1.15-32.49). Significant association was showed in the Dose-Response Analysis (OR=1.37, 95％CI=1.30-2.30). Crowded living space (OR=1.14, 95%CI=1.05-1.25), degree of darkness (OR=2.18, 95%CI=1.11-4.27) and moisture (OR=4.06, 95%CI=2.25-7.33), poor sanitary (OR=3.03, 95%CI=1.22-4.44), airpollution of working environment, which were filled with dusts (OR=2.35, 95%CI=1.18-4.70) and chemical fumes (OR=5.15, 95%CI=1.44-18.40) were strongly associated with pulmonary tuberculosis. BMI also had strong relationship with TB (OR=4.72, 95%CI=2.68-8.33). Conclusion　Poor environment and exposure to dust and chemical fume under working condition, low BMI, smoking combining alcohol consumption were the risk factors of adult pulmonary tuberculosis in Chengdu, China.