Determination of metal ions by fluorescence anisotropy exhibits a broad dynamic range

1998 ◽  
Author(s):  
Richard B. Thompson ◽  
Badri P. Maliwal ◽  
Carol A. Fierke
Keyword(s):  
Metal Ions ◽  
Fluorescence Anisotropy ◽  
Dynamic Range ◽  
Broad Dynamic Range

scholarly journals A Cell-Free Approach Based on Phospholipid Characterization for Determination of the Cell Specific Unbound Drug Fraction (fu,cell)

2019 ◽  
Vol 36 (12) ◽  
Author(s):  
Andrea Treyer ◽  
Sandra Walday ◽  
Hinnerk Boriss ◽  
Pär Matsson ◽  
Per Artursson
Keyword(s):  
Dynamic Range ◽  
Cell Types ◽  
Drug Binding ◽  
Small Scale ◽  
Intracellular Fraction ◽  
Drug Molecules ◽  
Cellular Assays ◽  
Broad Dynamic Range ◽  
The Impact

Abstract Purpose The intracellular fraction of unbound compound (fu,cell) is an important parameter for accurate prediction of drug binding to intracellular targets. fu,cell is the result of a passive distribution process of drug molecules partitioning into cellular structures. Initial observations in our laboratory showed an up to 10-fold difference in the fu,cell of a given drug for different cell types. We hypothesized that these differences could be explained by the phospholipid (PL) composition of the cells, since the PL cell membrane is the major sink of unspecific drug binding. Therefore, we determined the fu,cell of 19 drugs in cell types of different origin. Method The cells were characterized for their total PL content and we used mass spectrometric PL profiling to delineate the impact of each of the four major cellular PL subspecies: phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) and phosphatidylinositol (PI). The cell-based experiments were compared to cell-free experiments that used beads covered by PL bilayers consisting of the most abundant PL subspecies. Results PC was found to give the largest contribution to the drug binding. Improved correlations between the cell-based and cell-free assays were obtained when affinities to all four major PL subspecies were considered. Together, our data indicate that fu,cell is influenced by PL composition of cells. Conclusion We conclude that cellular PL composition varies between cell types and that cell-specific mixtures of PLs can replace cellular assays for determination of fu,cell as a rapid, small-scale assay covering a broad dynamic range.

Determination of Picomolar Concentrations of Metal Ions Using Fluorescence Anisotropy:  Biosensing with a “Reagentless” Enzyme Transducer

1998 ◽  
Vol 70 (22) ◽  
pp. 4717-4723 ◽  
Author(s):  
Richard B. Thompson ◽  
Badri P. Maliwal ◽  
Vincent L. Feliccia ◽  
Carol A. Fierke ◽  
Keith McCall
Keyword(s):  
Metal Ions ◽  
Fluorescence Anisotropy

DNAzyme self-assembled gold nanoparticles for determination of metal ions using fluorescence anisotropy assay

2010 ◽  
Vol 401 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Bin-Cheng Yin ◽  
Peng Zuo ◽  
Hao Huo ◽  
Xinhua Zhong ◽  
Bang-Ce Ye
Keyword(s):  
Gold Nanoparticles ◽  
Metal Ions ◽  
Fluorescence Anisotropy ◽  
Self Assembled

Application of quantitative EPR

1990 ◽  
Vol 333 (1628) ◽  
pp. 37-48 ◽  
Keyword(s):  
Detection Limit ◽  
Dynamic Range ◽  
Sea Water ◽  
High Sensitivity ◽  
Nitrite Ion ◽  
Spin Concentration ◽  
Analytical Technique ◽  
Broad Dynamic Range ◽  
Aromatic Nitro

Although the high sensitivity and broad dynamic range of EPR make it an attractive analytical technique for species with unpaired electrons, the precision and accuracy of spin concentration measurements have often been low. The marked improvement in quantitative EPR is a result of improvements in instrumentation and greater attention being given to operating procedures. In 1962 the lower limit for the EPR determination of polycyclic aromatic hydrocarbons was reported to be ca . 3|ig. Using the same method these compounds have now been determined down to nanogram levels. Aromatic nitro compounds present at submicrogram levels can also be quantified by EPR. A free radical assay technique has been applied to the determination of drugs in body fluids; a morphine concentration in urine of 0.5 |ig cm -3 is detectable. Molybdenum has been determined in sea water with a relative precision of 4.7 % at the 11 pg 1 -1 level and a detection limit of 0.46 pg 1 -1 . By using the EPR signal of [FeF 6 ] 3- the total iron content of solutions containing Mn II , Fe II and Fe III has been measured, the analytical range being 10 -6 -10 -2 M with a detection limit of 6 x 10 -7 M. Diamagnetic metal ions can be estimated by EPR with the aid of spin-labelled chelating reagents, e.g. Zn II over the linear range 10 -6 -10 -3 M with a detection limit of 5.5 x 10 -7 M. Nitrite ion can be determined by EPR with a precision of 0.9% at the 0.5p.p.m. level.

scholarly journals Multiplex Assays of Luminex for Identification of COVID-19 Antibodies in Patient Serum: Performance Evaluation and Comparison to ELISA

2020 ◽  
Vol 154 (Supplement_1) ◽  
pp. S92-S92
Author(s):  
M S Shapiro ◽  
X Wang ◽  
D R Mendu ◽  
A Firpo
Keyword(s):  
Dynamic Range ◽  
High Titer ◽  
Mount Sinai Hospital ◽  
Antibody Testing ◽  
Luminex Assay ◽  
Multiplex Assays ◽  
Negative Results ◽  
Broad Dynamic Range ◽  
Circulating Antibodies ◽  
Mount Sinai

Abstract Introduction/Objective Mount Sinai Hospital has received emergency use authorization (EUA) from the FDA for Coronavirus Disease 2019 (COVID-19) antibody testing using ELISA. This serological assay detects and titrates the presence of circulating antibodies to COVID-19. Other platforms have aimed to achieve the credentials of the ELISA instrument, including the multiplex assays of Luminex. The platform is known to have a greater throughput (384 wells vs. 96 wells per microplate) and faster processing speed (8 hours vs. 17 hours). Methods Luminex utilizes beads that couple to the same COVID-19 antigens (mRBD and mSpike) which were utilized for the ELISA assay. The beads are read determining the mean fluorescence intensity (MFI). In order to compare the two methods, our study included 61 patients with COVID-19 at Mount Sinai Hospital, to screen and titrate their sera using Luminex, and to correspond the MFI values with the ELISA titers. Results The Luminex assay has achieved the same level of confidence as ELISA. The 61 patients, representing 30 negatives and 31 positives, are consistently identified as such on both platforms. Our data highlights 32% of patients with a low titer (<1:160), 42% of patients with a high titer (1:160 ~ 1:320), and 26% of patients with a very high titer level (>1:320). These titers correlated well with the MFI values. Based on a cutoff of 80,000 MFI, the sensitivity and specificity of the assay is 98% and 85%, respectively, with no overlapping of MFI between positive and negative results. Conclusion Overall, the study has demonstrated that the Luminex is a strong alternative for the ELISA platform. The Luminex highlights the broad dynamic range with no overlapping between positives and negatives. Migration from ELISA to Luminex, a platform with faster and greater throughput, is therefore, highly desirable.

scholarly journals A tandem giant magnetoresistance assay for one-shot quantification of clinically relevant concentrations of N-terminal pro-B-type natriuretic peptide in human blood

2021 ◽  
Author(s):  
Fanda Meng ◽  
Weisong Huo ◽  
Jie Lian ◽  
Lei Zhang ◽  
Xizeng Shi ◽  
...  
Keyword(s):  
Detection Limit ◽  
Giant Magnetoresistance ◽  
Dynamic Range ◽  
Point Of Care ◽  
Sample Volume ◽  
Small Sample ◽  
Broad Dynamic Range ◽  
Gmr Sensors ◽  
Gmr Sensor ◽  
Sample Volume Requirement

AbstractWe report a microfluidic sandwich immunoassay constructed around a dual-giant magnetoresistance (GMR) sensor array to quantify the heart failure biomarker NT-proBNP in human plasma at the clinically relevant concentration levels between 15 pg/mL and 40 ng/mL. The broad dynamic range was achieved by differential coating of two identical GMR sensors operated in tandem, and combining two standard curves. The detection limit was determined as 5 pg/mL. The assay, involving 53 plasma samples from patients with different cardiovascular diseases, was validated against the Roche Cobas e411 analyzer. The salient features of this system are its wide concentration range, low detection limit, small sample volume requirement (50 μL), and the need for a short measurement time of 15 min, making it a prospective candidate for practical use in point of care analysis.

scholarly journals Engineering Cyanobacterial Cell Morphology for Enhanced Recovery and Processing of Biomass

2017 ◽  
Vol 83 (9) ◽  
Author(s):  
Adam Jordan ◽  
Jenna Chandler ◽  
Joshua S. MacCready ◽  
Jingcheng Huang ◽  
Katherine W. Osteryoung ◽  
...  
Keyword(s):  
Cell Division ◽  
Cell Morphology ◽  
Dynamic Range ◽  
Enhanced Recovery ◽  
Downstream Processing ◽  
Crop Species ◽  
Content Type ◽  
Alternative Crop ◽  
Cell Harvesting ◽  
Broad Dynamic Range

ABSTRACT Cyanobacteria are emerging as alternative crop species for the production of fuels, chemicals, and biomass. Yet, the success of these microbes depends on the development of cost-effective technologies that permit scaled cultivation and cell harvesting. Here, we investigate the feasibility of engineering cell morphology to improve biomass recovery and decrease energetic costs associated with lysing cyanobacterial cells. Specifically, we modify the levels of Min system proteins in Synechococcus elongatus PCC 7942. The Min system has established functions in controlling cell division by regulating the assembly of FtsZ, a tubulin-like protein required for defining the bacterial division plane. We show that altering the expression of two FtsZ-regulatory proteins, MinC and Cdv3, enables control over cell morphology by disrupting FtsZ localization and cell division without preventing continued cell growth. By varying the expression of these proteins, we can tune the lengths of cyanobacterial cells across a broad dynamic range, anywhere from an ∼20% increased length (relative to the wild type) to near-millimeter lengths. Highly elongated cells exhibit increased rates of sedimentation under low centrifugal forces or by gravity-assisted settling. Furthermore, hyperelongated cells are also more susceptible to lysis through the application of mild physical stress. Collectively, these results demonstrate a novel approach toward decreasing harvesting and processing costs associated with mass cyanobacterial cultivation by altering morphology at the cellular level. IMPORTANCE We show that the cell length of a model cyanobacterial species can be programmed by rationally manipulating the expression of protein factors that suppress cell division. In some instances, we can increase the size of these cells to near-millimeter lengths with this approach. The resulting elongated cells have favorable properties with regard to cell harvesting and lysis. Furthermore, cells treated in this manner continue to grow rapidly at time scales similar to those of uninduced controls. To our knowledge, this is the first reported example of engineering the cell morphology of cyanobacteria or algae to make them more compatible with downstream processing steps that present economic barriers to their use as alternative crop species. Therefore, our results are a promising proof-of-principle for the use of morphology engineering to increase the cost-effectiveness of the mass cultivation of cyanobacteria for various sustainability initiatives.

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