scholarly journals Detection of Exosomes Using Total Internal Reflected Imaging Ellipsometry

Biosensors ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 164
Author(s):  
Haoyu Liu ◽  
Wei Liu ◽  
Gang Jin
Keyword(s):  
Limit Of Detection ◽  
Biological Fluids ◽  
Surface Proteins ◽  
Surface Markers ◽  
Functional Roles ◽  
Disease Biomarkers ◽  
First Order ◽  
Imaging Ellipsometry ◽  
Interaction Kinetics ◽  
Membrane Bound

Exosomes are a kind of membrane-bound phospholipid nanovesicle that are secreted extensively in a variety of biological fluids. Accumulating evidence has indicated that exosomes not only communicate with cells, but also perform functional roles in physiology and pathology. In addition, exosomes have also elicited a great deal of excitement due to their potential as disease biomarkers. Therefore, requirements for sensitive methods capable of precisely and specifically determining exosomes were needed. Herein, we not only develop a sensing surface to capture exosomes but also compare two surface proteins on exosomes, which are appropriate for detecting exosome surface markers by total internal reflected imaging ellipsometry (TIRIE). Protein G and antibody were immobilized on a thin layer of golden substrate to form the biosensing surface. The bio-interaction between antibodies and exosomes was recorded by the TIRIE in real time. The distance between exosomes adhered on a surface was 44 nm ± 0.5 nm. The KD  of anti-CD9 and exosome was lower than anti-CD63 and exosome by introducing pseudo-first-order interaction kinetics, which suggested that CD9 is more suitable for exosome surface markers than CD63. The limit of detection (LOD) of TIRIE was 0.4 μg/mL. In conclusion, we have proposed a surface for the detection of exosomes based on TIRIE, which can make the detection of exosomes convenient and efficient.

scholarly journals Graphite Studded with Facile-Synthesized Cu2O Nanoparticle-Based Cubes as a Novel Electrochemical Sensor for Highly Sensitive Voltametric Determination of Mebeverine Hydrochloride

Chemosensors ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 35
Author(s):  
Ahmed H. Naggar ◽  
Ahmed Kotb ◽  
Ahmed A. Gahlan ◽  
Mahmoud H. Mahross ◽  
Abd El-Aziz Y. El-Sayed ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Lower Limit ◽  
Electrochemical Behavior ◽  
Cuprous Oxide ◽  
Density Functional ◽  
Limit Of Detection ◽  
Biological Fluids ◽  
Chemical Reduction ◽  
Anodic Stripping Voltammetry ◽  
Mebeverine Hydrochloride

Herein, a feasible chemical reduction method followed by intensive mixing was applied for the preparation of an attractive material based on graphite studded with cuprous oxide nanoparticle-based cubes (Cu2ONPs–C@G). Transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) and cyclic voltammetry (CV) were utilized for characterization. Cuprous oxide nanoparticles (Cu2ONPs), with a diameter range mainly distributed from 4 to 20 nm, aggregate to form microcubes (Cu2ONPs–C) with an average diameter of about 367 nm. Paste electrode was prepared using Cu2ONPs–C@G (Cu2ONPs–C@G/PE) for voltametric quantification of the musculotropic antispasmodic drug: mebeverine hydrochloride (MEB). The electrochemical behavior of MEB was studied using CV, and the optimum analytical parameters were investigated using square wave adsorptive anodic stripping voltammetry (SWAdASV). Moreover, density functional theory (DFT) was used to emphasize the ability of MEB to form a complex with Cu2+, confirming the suggested electrochemical behavior of MEB at Cu2ONPs–C@G/PE. With good stability and high reproducibility, SWAdASV of Cu2ONPs–C@G/PE shows successful quantification of MEB over the concentration range of 5.00 × 10−11–1.10 × 10−9 M with lower limit of detection (LOD) and lower limit of quantification (LOQ) values of 2.41 × 10−11 M and 8.05 × 10−11 M, respectively. Finally, accurate quantification of MEB in dosage forms (tablets) and biological fluids (spiked human urine and plasma samples) was achieved using Cu2ONPs-C@G/PE.

scholarly journals Determination of amino acids in human biological fluids by high-performance liquid chromatography: critical review

Amino Acids ◽  
2021 ◽  
Author(s):  
Grażyna Gałęzowska ◽  
Joanna Ratajczyk ◽  
Lidia Wolska
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
High Performance ◽  
Hplc Analysis ◽  
Limit Of Detection ◽  
Biological Fluids ◽  
Analytical Techniques ◽  
Epidemiological Studies ◽  
Preparation Conditions

AbstractThe quantitation and qualification of amino acids are most commonly used in clinical and epidemiological studies, and provide an excellent way of monitoring compounds in human fluids which have not been monitored previously, to prevent some diseases. Because of this, it is not surprising that scientific interest in evaluating these compounds has resurfaced in recent years and has precipitated the development of a multitude of new analytical techniques. This review considers recent developments in HPLC analytics on the basis of publications from the last few years. It helps to update and systematize knowledge in this area. Particular attention is paid to the progress of analytical methods, pointing out the advantages and drawbacks of the various techniques used for the preparation, separation and determination of amino acids. Depending on the type of sample, the preparation conditions for HPLC analysis change. For this reason, the review has focused on three types of samples, namely urine, blood and cerebrospinal fluid. Despite time-consuming sample preparation before HPLC analysis, an additional derivatization technique should be used, depending on the detection technique used. There are proposals for columns that are specially modified for amino acid separation without derivatization, but the limit of detection of the substance is less beneficial. In view of the fact that amino acid analyses have been performed for years and new solutions may generate increased costs, it may turn out that older proposals are much more advantageous.

scholarly journals Surface-Enhanced Oxidation and Determination of Isothipendyl Hydrochloride at an Electrochemical Sensing Film Constructed by Multiwalled Carbon Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
S. N. Prashanth ◽  
Shankara S. Kalanur ◽  
Nagappa L. Teradal ◽  
J. Seetharamappa
Keyword(s):  
Limit Of Detection ◽  
Biological Fluids ◽  
Differential Pulse ◽  
Electrochemical Sensing ◽  
Good Precision ◽  
Multiwalled Carbon ◽  
Limit Of Quantification ◽  
Surface Enhanced ◽  
Ph Range

The electrochemical behavior of isothipendyl hydrochloride (IPH) was investigated at bare and multiwalled-carbon-nanotube modified glassy carbon electrode (MWCNT-GCE). IPH (55 μM) showed two oxidation peaks in Britton-Robinson (BR) buffer of pH 7.0. The oxidation process of IPH was observed to be irreversible over the pH range of 2.5–9.0. The influence of pH, scan rate, and concentration of the drug on anodic peak was studied. A differential pulse voltammetric method with good precision and accuracy was developed for the determination of IPH in pure and biological fluids. The peak current was found to be linearly dependent on the concentration of IPH in the range of 1.25–55 μM. The values of limit of detection and limit of quantification were noticed to be 0.284 and 0.949 μM, respectively.

SHEDDING OF SURFACE PROTEINS BY PORCINE THYROID CELLS

1980 ◽  
Vol 85 (2) ◽  
pp. 245-251 ◽  
Author(s):  
A. BRENNAN ◽  
P. M. POVEY ◽  
B. REES SMITH ◽  
R. HALL
Keyword(s):  
Cell Surface ◽  
Sodium Dodecyl Sulphate ◽  
Culture Medium ◽  
Cell Metabolism ◽  
Sodium Dodecyl ◽  
Surface Proteins ◽  
Half Time ◽  
Thyroid Cells ◽  
Peptide Cleavage ◽  
Membrane Bound

Isolated porcine thyroid cells were surface-labelled with 125I using the lactoperoxidase technique. Samples of the cells were then cultured and harvested at various intervals for up to 7 days. The labelled proteins remaining on the cells or shed into the culture medium were analysed by electrophoresis on polyacrylamide gels run in sodium dodecyl sulphate. These studies indicated that the several different surface proteins of the thyroid cells were lost from the cell surface at similar rates (half-time of approximately 28 h) as the result, at least in part, of a process which depended on active cell metabolism. In addition, the gel profiles obtained from analysis of both medium and membrane-bound labelled proteins were similar and this suggested that peptide cleavage was not involved in the shedding of the majority of these proteins.

Serological biomarkers of zearalenone exposure in beef heifers receiving anti-mycotoxin additive

2020 ◽  
pp. 1-10
Author(s):  
C. Tonini ◽  
M.S. Oliveira ◽  
E.B. Parmeggiani ◽  
D.A.F. Sturza ◽  
A.O. Mallmann ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Biological Fluids ◽  
Basal Diet ◽  
Beef Heifers ◽  
Efficacy Evaluation ◽  
Limit Of Quantification ◽  
In Vivo Measurement ◽  
Significant Difference ◽  
Serological Biomarkers

The inclusion of anti-mycotoxin additives (AMA) in the diet of production animals has been widely used to avoid mycotoxin exposure. In order to confirm the efficacy of such products in vivo, measurement of mycotoxins and/or their metabolites in biological fluids is preconized. This study aimed at determining the serological biomarkers of zearalenone (ZEN), α-zearalenol, β-zearalenol, α-zearalanol, β-zearalanol (β-ZAL) and zearalanone, to evaluate the efficacy of an AMA in beef heifers. The trial lasted 37 days: 11 days of adaptation, 21 days of actual experiment, and 5 days of regression. Twenty-four heifers were randomly assigned to receive one of the following treatments (n=6/group): (T1) basal diet (control); (T2) basal diet + 5 mg/kg of ZEN; (T3) basal diet + 5 mg/kg of ZEN + 2.5 kg/t of AMA; and (T4) basal diet + 5 mg/kg of ZEN + 5.0 kg/t of AMA. Blood sampling was performed on different days after the diet was given. The samples were centrifuged to obtain the blood serum, and then analysed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). β-ZAL was detected above the limit of quantification both in the unconjugated (>0.60 ng/ml) and conjugated (>0.90 ng/ml) forms. The remaining metabolites presented concentrations under the limit of detection. In the efficacy evaluation of the AMA, there was no significant difference (P>0.05) between the treatments with and without additive at the tested levels of inclusion. Thus, β-ZAL may be employed as a biomarker of ZEN exposure via diet to evaluate the efficacy of an AMA through serological parameters. The technique applied in this study proved to be an adequate alternative for in vivo confirmation of the efficacy of products in adsorbing the toxin.

Lower Limits of Detection for Single Biological Particles Using Impedance Spectroscopy

2005 ◽  
Author(s):  
Pahnit Seriburi ◽  
Ashutosh Shastry ◽  
Angelique Van’t Wout ◽  
John Mittler ◽  
Shih-Hui Chao ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Impedance Spectroscopy ◽  
Minimally Invasive ◽  
Limit Of Detection ◽  
Single Cells ◽  
Lab On A Chip ◽  
Minimally Invasive Approach ◽  
Invasive Approach ◽  
Membrane Bound ◽  
Lower Limits

Single-cell impedance spectroscopy integrated with lab-on-a-chip systems provides a direct and minimally invasive approach for monitoring and characterizing properties of individual cells in real-time. Here we investigate the theoretical potential and limitations of this technique for analyzing single membrane-bound particles as small as 100 nm in diameter. Our theoretical model suggests a lower limit of detection for single cells on the order of a few microns.

scholarly journals Spectrophotometric Determination of Olmutinib in Bulk by Area under Curve and First Order Derivative Methods and its Validation as per ICH guidelines

2019 ◽  
Vol 9 (4-A) ◽  
pp. 349-354
Author(s):  
BALU KHANDARE ◽  
Atish C. Musle ◽  
Sanket S. Arole ◽  
Pravin V. Popalghat
Keyword(s):  
Area Under Curve ◽  
Limit Of Detection ◽  
Order Derivative ◽  
Spectrometric Method ◽  
First Order ◽  
Accuracy And Precision ◽  
Ich Guidelines ◽  
Validation Parameters ◽  
Limit Of Quantitation

Abstract: A simple, precise and economical UV-spectrophotometric method has been developed for the estimation of Olmutinib from bulk. Two methods were developed First method (A) applied was area under curve (AUC) in which the area was integrated in wavelength from 262-272nm. Second method (B) was first order derivative spectrometric method. In this method absorbance at λmin=256.57nm, λmax=282.83nm and zero cross=267.68nm was measured. Calibration curves were plotted for the method by using instrumental response at selected wavelength and concentration of analyte in the solution. In both the methods, linearity was observed in the concentration range of 2-12µg/ml at the λmax=267.68nm. Accuracy and precision studies were carried out and results were satisfactorily obtained. The drug at each of the 80 %, 100 % and 120 % levels showed good recoveries that is in the range of 98.00 to 99.00% for both methods, hence it could be said that the method was accurate. Limit of detection (LOD) and limit of quantitation (LOQ) were determined for the method. The method was validated as per International Conference on Harmonization. All validation parameters were within the acceptable limit. The developed method was successfully applied to estimate the amount of Olmutinib in pharmaceutical formulation.

scholarly journals Streamlined circular proximity ligation assay provides high stringency and compatibility with low-affinity antibodies

2018 ◽  
Vol 115 (5) ◽  
pp. E925-E933 ◽  
Author(s):  
Roxana Jalili ◽  
Joe Horecka ◽  
James R. Swartz ◽  
Ronald W. Davis ◽  
Henrik H. J. Persson
Keyword(s):  
Limit Of Detection ◽  
Biological Fluids ◽  
Protein Detection ◽  
Ease Of Use ◽  
Proximity Ligation Assay ◽  
Quantitative Detection ◽  
High Signal ◽  
Affinity Reagents ◽  
Proximity Ligation ◽  
Assay Format

Proximity ligation assay (PLA) is a powerful tool for quantitative detection of protein biomarkers in biological fluids and tissues. Here, we present the circular proximity ligation assay (c-PLA), a highly specific protein detection method that outperforms traditional PLA in stringency, ease of use, and compatibility with low-affinity reagents. In c-PLA, two proximity probes bind to an analyte, providing a scaffolding that positions two free oligonucleotides such that they can be ligated into a circular DNA molecule. This assay format stabilizes antigen proximity probe complexes and enhances stringency by reducing the probability of random background ligation events. Circle formation also increases selectivity, since the uncircularized DNA can be removed enzymatically. We compare this method with traditional PLA on several biomarkers and show that the higher stringency for c-PLA improves reproducibility and enhances sensitivity in both buffer and human plasma. The limit of detection ranges from femtomolar to nanomolar concentrations for both methods. Kinetic analyses using surface plasmon resonance (SPR) and biolayer interferometry (BLI) reveal that the variation in limit of detection is due to the variation in antibody affinity and that c-PLA outperforms traditional PLA for low-affinity antibodies. The lower background signal can be used to increase proximity probe concentration while maintaining a high signal-to-noise ratio, thereby enabling the use of low-affinity reagents in a homogeneous assay format. We anticipate that the advantages of c-PLA will be useful in a variety of clinical protein detection applications where high-affinity reagents are lacking.

scholarly journals Sensitive Analysis of Idarubicin in Human Urine and Plasma by Liquid Chromatography with Fluorescence Detection: An Application in Drug Monitoring

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5799
Author(s):  
Olga Maliszewska ◽  
Natalia Treder ◽  
IIona Olędzka ◽  
Piotr Kowalski ◽  
Natalia Miękus ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Human Plasma ◽  
Fluorescence Detection ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Biological Fluids ◽  
Internal Standard ◽  
Urine Samples ◽  
Human Plasma And Urine ◽  
Plasma And Urine Samples

A new approach for the sensitive, robust and rapid determination of idarubicin (IDA) in human plasma and urine samples based on liquid chromatography with fluorescence detection (LC-FL) was developed. Satisfactory chromatographic separation of the analyte after solid-phase extraction (SPE) was performed on a Discovery HS C18 analytical column using a mixture of acetonitrile and 0.1% formic acid in water as the mobile phase in isocratic mode. IDA and daunorubicin hydrochloride used as an internal standard (I.S.) were monitored at the excitation and emission wavelengths of 487 and 547 nm, respectively. The method was validated according to the FDA and ICH guidelines. The linearity was confirmed in the range of 0.1–50 ng/mL and 0.25–200 ng/mL, while the limit of detection (LOD) was 0.05 and 0.125 ng/mL in plasma and urine samples, respectively. The developed LC-FL method was successfully applied for drug determinations in human plasma and urine after oral administration of IDA at a dose of 10 mg to a patient with highly advanced alveolar rhabdomyosarcoma (RMA). Moreover, the potential exposure to IDA present in both fluids for healthcare workers and the caregivers of patients has been evaluated. The present LC-FL method can be a useful tool in pharmacokinetic and clinical investigations, in the monitoring of chemotherapy containing IDA, as well as for sensitive and reliable IDA quantitation in biological fluids.

Development, optimization and validation of an absolute specific assay for active myeloperoxidase (MPO) and its application in a clinical context: role of MPO specific activity in coronary artery disease

2020 ◽  
Vol 58 (10) ◽  
pp. 1749-1758 ◽  
Author(s):  
Alessandro Trentini ◽  
Valentina Rosta ◽  
Savino Spadaro ◽  
Tiziana Bellini ◽  
Paola Rizzo ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Specific Activity ◽  
Limit Of Detection ◽  
Biological Fluids ◽  
Consensus Method ◽  
Chronic Obstructive ◽  
Clinical Context ◽  
Artery Disease

AbstractBackgroundMyeloperoxidase (MPO) is an enzyme with a recognized prognostic role in coronary artery disease (CAD), which is also emerging as a promising biomarker for cardiac risk stratification. However, the lack of a consensus method for its quantification has hindered its implementation in clinical practice. The aim of our work was to optimize an absolute sensitive assay for active MPO without external standards, to validate the method in the clinical context of CAD patients, and to estimate the enzyme specific activity.MethodsIn order to determine the MPO concentration using fluorescence readings, this ELISA assay exploits the activity of the enzyme recognized by specific antibodies. The assay was validated in a small cohort of patients that included: healthy subjects (n=60); patients with acute myocardial infarction (AMI, n=25); patients with stable CAD (SCAD, n=25) and a concomitant chronic obstructive pulmonary disease (COPD). Then, total MPO concentration and specific activity (activity/total MPO) were determined.ResultsThe assay showed an intra- and inter-assay coefficient of variation of 5.8% and 10.4%, respectively, with a limit of detection (LoD) of 0.074 μU. Both AMI and SCAD patients had higher active and total MPO than controls (p<0.0001 and p<0.01, respectively). The specific activity of MPO was higher in SCAD patients compared to both controls and AMI (p<0.0001).ConclusionsThe study presents a robust and sensitive method for assaying MPO activity in biological fluids with low variability. Moreover, the determination of the specific activity could provide novel insight into the role of MPO in cardiovascular diseases (CVDs).

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