scholarly journals Ultrasensitive Densitometry Detection of Cytokines with Nanoparticle-Modified Aptamers

2007 ◽  
Vol 53 (6) ◽  
pp. 1061-1066 ◽  
Author(s):  
Yuan-Yuan Li ◽  
Chi Zhang ◽  
Bo-Sheng Li ◽  
Li-Fan Zhao ◽  
Xiao-bo Li ◽  
...  
Keyword(s):  
Detection Limit ◽  
Serum Concentrations ◽  
Sandwich Complex ◽  
Detection Range ◽  
Factor B ◽  
Cytokine Detection ◽  
Microplate Reader ◽  
Aptamer Assay ◽  
Densitometry Detection ◽  
Better Than

Abstract Background: Aptamers mimic properties of antibodies and sometimes turn out to be even better than antibodies as reagents for assays. We describe the establishment of an ultrasensitive densitometry method for cytokine detection by nanoparticle (NP)-modified aptamers. Methods: The assay simultaneously uses a gold NP–modified aptamer and a biotin-modified aptamer to bind to the target protein, forming a sandwich complex. The absorbance signal generated by the aptamer-protein complex is amplified and detected with a microplate reader. Results: The assay for platelet-derived growth factor B-chain homodimer (PDGF-BB) was linear from 1 fmol/L to 100 pmol/L (R2 = 0.9869). The analytical detection limit was 83 amol/L. The intraassay and interassay imprecision (CVs) was ≤7.5%. Serum concentrations of PDGF-BB determined with the gold NP–modified aptamer assay and with ELISA were not significantly different. Conclusions: The gold NP–modified aptamer assay provides a fast, convenient method for cytokine detection and improves the detection range and the detection limit compared with ELISA.

scholarly journals Single-Atom Cobalt-Based Electrochemical Biomimetic Uric Acid Sensor with Wide Linear Range and Ultralow Detection Limit

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Fang Xin Hu ◽  
Tao Hu ◽  
Shihong Chen ◽  
Dongping Wang ◽  
Qianghai Rao ◽  
...  
Keyword(s):  
Uric Acid ◽  
Detection Limit ◽  
Single Atom ◽  
Practical Application ◽  
Oxidation Of Co ◽  
Renal Disorder ◽  
Detection Range ◽  
Low Detection Limit ◽  
Doped Graphene ◽  
Better Than

Abstract Uric acid (UA) detection is essential in diagnosis of arthritis, preeclampsia, renal disorder, and cardiovascular diseases, but it is very challenging to realize the required wide detection range and low detection limit. We present here a single-atom catalyst consisting of Co(II) atoms coordinated by an average of 3.4 N atoms on an N-doped graphene matrix (A–Co–NG) to build an electrochemical biomimetic sensor for UA detection. The A–Co–NG sensor achieves a wide detection range over 0.4–41,950 μM and an extremely low detection limit of 33.3 ± 0.024 nM, which are much better than previously reported sensors based on various nanostructured materials. Besides, the A–Co–NG sensor also demonstrates its accurate serum diagnosis for UA for its practical application. Combination of experimental and theoretical calculation discovers that the catalytic process of the A–Co–NG toward UA starts from the oxidation of Co species to form a Co3+–OH–UA*, followed by the generation of Co3+–OH + *UA_H, eventually leading to N–H bond dissociation for the formation of oxidized UA molecule and reduction of oxidized Co3+ to Co2+ for the regenerated A–Co–NG. This work provides a promising material to realize UA detection with wide detection range and low detection limit to meet the practical diagnosis requirements, and the proposed sensing mechanism sheds light on fundamental insights for guiding exploration of other biosensing processes.

A rapid and accurate method for screening T-2 toxin in food and feed using competitive AlphaLISA

2021 ◽  
Vol 368 (6) ◽  
Author(s):  
Liwen Zhang ◽  
Qingyu Lv ◽  
Yuling Zheng ◽  
Xuan Chen ◽  
Decong Kong ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Accurate Method ◽  
Detection Methods ◽  
Cereal Crops ◽  
Detection Range ◽  
Highly Sensitive ◽  
Food And Feed ◽  
Good Repeatability ◽  
Feed Samples ◽  
Better Than

ABSTRACT T-2 is a common mycotoxin contaminating cereal crops. Chronic consumption of food contaminated with T-2 toxin can lead to death, so simple and accurate detection methods in food and feed are necessary. In this paper, we establish a highly sensitive and accurate method for detecting T-2 toxin using AlphaLISA. The system consists of acceptor beads labeled with T-2-bovine serum albumin (BSA), streptavidin-labeled donor beads and biotinylated T-2 antibodies. T-2 in the sample matrix competes with T-2-BSA for antibodies. Adding biotinylated antibodies to the test well followed by T-2 and T-2-BSA acceptor beads yielded a detection range of 0.03–500 ng/mL. The half-maximal inhibitory concentration was 2.28 ng/mL and the coefficient of variation was <10%. In addition, this method had no cross-reaction with other related mycotoxins. This optimized method for extracting T-2 from food and feed samples achieved a recovery rate of approximately 90% in T-2 concentrations as low as 1 ng/mL, better than the performance of a commercial ELISA kit. This competitive AlphaLISA method offers high sensitivity, good specificity, good repeatability and simple operation for detecting T-2 toxin in food and feed.

Dosage du Sr-90 dans l'eau des lacs et des rivières du Québec par précipitation avec l'oxine et comptage β

1988 ◽  
Vol 66 (1) ◽  
pp. 174-177 ◽  
Author(s):  
E. Haddad ◽  
L. Zikovsky
Keyword(s):  
Detection Limit ◽  
Surface Waters ◽  
New Method ◽  
The Mean ◽  
Better Than

A new method for the determination of Sr-90 dissolved in surface waters has been developed. It is based on the precipitation of Sr with 8-hydroxyquinoline at pH 11.3 and counting of β particles with energy above 150 keV. The detection limit obtained is 0.5 mBq/L and the mean yield is 28%. The decontamination factors from other β emitters achieved are better than 10 000. This method has been used to measure the Sr-90 in 5 lakes and 5 rivers in Québec and activities ranging from 3 to 15 mBq/L were obtained. This new method is as efficient and reliable as conventional techniques while being less tedious.

Colorimetric Detection of Trace Arsenic(III) in Aqueous Solution Using Arsenic Aptamer and Gold Nanoparticles

2014 ◽  
Vol 67 (5) ◽  
pp. 813 ◽  
Author(s):  
Minglei Yu
Keyword(s):  
Aqueous Solution ◽  
Gold Nanoparticles ◽  
Detection Limit ◽  
Colorimetric Assay ◽  
Colorimetric Detection ◽  
Colour Change ◽  
Colorimetric Sensing ◽  
Detection Range ◽  
Colorimetric Indicator ◽  
Blue Solution

In this study, trace arsenic(iii) (AsIII) in aqueous solution was detected by applying a classical aptamer-based gold nanoparticles colorimetric sensing strategy. An arsenic aptamer was used as a sensing probe and gold nanoparticles as a colorimetric indicator. In the absence of AsIII, the gold nanoparticles were stabilised by the arsenic aptamer and remained dispersed at high NaCl concentrations, displaying a red solution. Contrarily, in the presence of AsIII, the gold nanoparticles were prone to aggregation, owing to the formation of aptamer–AsIII complex between the arsenic aptamer and AsIII, and thus exhibited a blue solution. By monitoring the colour change, a simple and fast colorimetric assay for AsIII was established with a detection range of 1.26–200 ppb and a detection limit of 1.26 ppb. Because this colorimetric assay only involves common reagents and can be assessed visually, it holds great potential for arsenic(iii) monitoring in environment-related and other applications.

AN EXPLORATORY STUDY OF WITKIN'S DIMENSION IN RELATION TO SOCIAL CLASS, PERSONALITY FACTORS AND PIAGETIAN TESTS

1977 ◽  
Vol 5 (1) ◽  
pp. 87-91 ◽  
Author(s):  
P. A. S. Ghuman
Keyword(s):  
Social Class ◽  
Primary Schools ◽  
Social Classes ◽  
Personality Factors ◽  
Cognitive Variables ◽  
Factor B ◽  
Personality Variables ◽  
Significant Difference ◽  
Independence Dimension ◽  
Better Than

The research explores the relationships between the cognitive variables, as measured by Piagetian tests and standard Raven Matrices, and Witkin's Field-dependence/independence dimension (FD-FID). The association between sex, social class, and the personality variables, as assessed by the Children's Personality Questionnaire (CPQ) devised by Porter and Cattell, with the Witkin's dimension is also investigated. The sample consisted of sixty children of 11 to 12 years of age from two primary schools in Wales. The results show that there are significant correlations between Witkin's dimension and the cognitive variables including factor B of CPQ. However, no significant correlations were found between the personality traits and Witkin's dimension. There was a significant difference (p < 0.1) between the two social classes; middle-class children performed better than working-class children; but no significant difference was found between the boys and girls.

A Comparative Study on the Analysis Methods for Chlorophyll-a

2013 ◽  
Vol 726-731 ◽  
pp. 1411-1415 ◽  
Author(s):  
Fei Peng ◽  
Shi Bo Liu ◽  
Hai Yan Xu ◽  
Zhi Qun Li
Keyword(s):  
Detection Limit ◽  
Chlorophyll A ◽  
Water Samples ◽  
Chlorophyll A Fluorescence ◽  
Standard Procedure ◽  
Fluorescence Method ◽  
Monitoring Method ◽  
Detection Range ◽  
Analysis Methods

This paper investigated three chlorophyll-a analysis methods in water sample. The UV-VIS spectrophotometry method followed SL88-2012 standard procedure, the results showed the detection limit of chlorophyll-a was 0.22 μg/L, with the lower detection limit of 1.0 μg/L. The detection range of the vivo chlorophyll-a fluorescence method was 0.1-300μg/L, the ratios of different algae matched that prepared in water samples. The detection limits and quantification limits for HPLC by using UVD and FLD were respectively 0.013 and 0.004 μg/L, 0.040 and 0.013μg/L. FLD was more sensitive than UVD for chlorophyll-a analysis, and the recovery of standard addition was in the range of 90.2% to 103.9% with UVD and FLD. Given the different pretreatment procedures of the sample, equipment conditions, correction and precision, vivo chlorophyll-a fluorescence method was the best on-site monitoring and the emergency monitoring method. Spectrophotometer was suitable for routine laboratory determination of chlorophyll-a, especially for bulk water samples. HPLC method had high precision and sensitivity, so this method applied to the determination of exact requirements, microanalysis and pigment separation.

The Determination of Traces of Bismuth by Solid State Luminescence

1974 ◽  
Vol 52 (10) ◽  
pp. 1942-1944 ◽  
Author(s):  
D. E. Ryan ◽  
H. Rollier ◽  
J. Holzbecher
Keyword(s):  
Detection Limit ◽  
Solid State ◽  
Calcium Oxalate ◽  
Co Precipitation ◽  
State Luminescence ◽  
Better Than

Traces of Bi(III) are determined with good selectivity by measurement of the luminescence (λex = 355 nm; λem = 430 nm) of CaO:Bi phosphor after co-precipitation with calcium oxalate and ignition at 850–900 °C. The detection limit is better than 0.01 μg Bi in 15 mg CaO; bismuth can be quantitatively recovered from 500 ml sample volumes and analysis is possible for 0.02 ng Bi/ml. The method has been successfully applied to the determination of trace amounts of bismuth added to synthetic blood and kidney samples.

scholarly journals MoS2 QDs/8-Armed Poly(Ethylene Glycol) Fluorescence Sensor for Three Nitrotoluenes (TNT) Detection

Biosensors ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 475
Author(s):  
Xiaoyuan Zhang ◽  
Zhiqiang Su
Keyword(s):  
Quantum Dots ◽  
Polyethylene Glycol ◽  
Detection Limit ◽  
Ethylene Glycol ◽  
Hydrazine Hydrate ◽  
Poly Ethylene Glycol ◽  
Fluorescent Properties ◽  
Detection Range ◽  
Poly Ethylene ◽  
Tnt Detection

In this work, ammonia cross-linked 8-armed polyethylene glycol hydrogel material was successfully synthesized and used as a template for synthesizing nanoparticles with fluorescent properties. The 8-armed polyethylene glycol hydrogel template was used to prepare molybdenum disulfide quantum dots (MoS2 QDs). The ammonium tetrathiomolybdate functioned as a molybdenum source and hydrazine hydrate functioned as a reducing agent. The fluorescence properties of the as-prepared MoS2 QDs were investigated. The bursting of fluorescence caused by adding different concentrations of explosive TNT was studied. The study indicated that the synthesized MoS2 QDs can be used for trace TNT detection with a detection limit of 6 nmol/L and a detection range of 16–700 nmol/L. Furthermore, it indicated that the fluorescence-bursting mechanism is static bursting.

scholarly journals Nanostructured copper selenide as an ultrasensitive and selective non-enzymatic glucose sensor

2021 ◽  
Author(s):  
Siddesh Umapathi ◽  
Harish Singh ◽  
Jahangir Masud ◽  
Manashi Nath
Keyword(s):  
Detection Limit ◽  
High Efficiency ◽  
Glucose Sensor ◽  
High Sensitivity ◽  
Copper Selenide ◽  
Glucose Detection ◽  
Applied Potential ◽  
Detection Range ◽  
Low Detection Limit ◽  
Linear Detection

CuSe nanostructures exhibit high-efficiency for glucose detection with high sensitivity (19.419 mA mM−1 cm−2) and selectivity at low applied potential (0.15 V vs. Ag|AgCl), low detection limit (0.196 μM) and linear detection range (100 nM to 40 μM).

scholarly journals ANTI-TYROSINASE ACTIVITY FROM VARIOUS SOLVENTS OF PEANUT SHELL (ARACHIS HYPOGAEA L.) EXTRACTS IN VITRO

2019 ◽  
pp. 150-152
Author(s):  
RISHA FILLAH FITHRIA ◽  
MELLA DWI KRISDIANA ◽  
ETIKA MUSLIMAH ◽  
SARIF MUSYAFA ◽  
NINING SUGIHARTINI
Keyword(s):  
Ethyl Acetate ◽  
Kojic Acid ◽  
Ethyl Acetate Extract ◽  
Ethanol Extract ◽  
Tyrosinase Activity ◽  
Peanut Shell ◽  
Microplate Reader ◽  
Tyrosinase Enzyme ◽  
Better Than

Objective: This study aimed to determine in vitro anti-tyrosinase activity from various solvents of peanut shell extracts and to find out if the activityis better than kojic acid which is a conventional compound used as anti-hyperpigmentation agent.Methods: Extraction was done by maceration method with various solvents of ethyl acetate, n-hexane, and 70% ethanol. Extracts were made into theseries concentration of 25, 50, and 75 μg/ml. Kojic acid with concentration of 50 μg/ml used as positive control and 5% dimethyl sulfoxide used asnegative control. Tyrosinase enzyme will react with L-3,4-dihydroxyphenylalanine substrate to produce dopachrome compound. The absorbance ofdopachrome read by microplate reader at λ = 492 nm. If the absorbance read by the microplate reader is low, means that the inhibition power of thepeanut shell extract against the tyrosinase enzyme is high. Anti-tyrosinase activity seen by the percentage inhibition value. The percentage inhibitionvalue was analyzed with Kruskal–Wallis test followed by Mann–Whitney U-test; all tests were carried out with a confidence level of 95%.Results: The mean of percentage inhibition value of n-hexane extract ranged from 12.44 ± 1.66% to 39.82 ± 1.33%, 70% of ethanol extract rangedfrom 39.98 ± 0.85% to 70.19 ± 1.98%, and ethyl acetate extract ranged from 17.85 ± 0.78% to 60.30 ± 0.97%. Kojic acid has mean percentageinhibition value of 78.19 ± 1.97%. IC50 of ethanol, ethyl acetate, and n-hexane extracts was, respectively, 40.53 μg/ml, 63.49 μg/ml, and 91.95 μg/ml.Ethanol extract contains flavonoid, tannin, and saponin. Ethyl acetate extract contains flavonoid.Conclusion: All various solvents of peanut shell extracts have anti-tyrosinase activity but not better than kojic acid. Ethanol extract with concentrationof 75 μg/ml has the greatest anti-tyrosinase activity.

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