scholarly journals Electrochemical Immunosensing of ST2: A Checkpoint Target in Cancer Diseases

Biosensors ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 202
Author(s):  
Rebeca M. Torrente-Rodríguez ◽  
Cristina Muñoz-San Martín ◽  
Maria Gamella ◽  
María Pedrero ◽  
Neus Martínez-Bosch ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Magnetic Beads ◽  
Limit Of Detection ◽  
Ductal Adenocarcinoma ◽  
Healthy Individuals ◽  
Electrochemical Immunosensing ◽  
Streptavidin Peroxidase ◽  
Peroxidase Conjugate ◽  
Receptor Family

A magnetic beads (MB)-involved amperometric immunosensor for the determination of ST2, a member of the IL1 receptor family, is reported in this work. The method utilizes a sandwich immunoassay and disposable screen-printed carbon electrodes (SPCEs). Magnetic immunoconjugates built on the surface of carboxylic acid-microsized magnetic particles (HOOC-MBs) were used to selectively capture ST2. A biotinylated secondary antibody further conjugated with a streptavidin peroxidase conjugate (Strep-HRP) was used to accomplish the sandwiching of the target protein. The immune platform exhibits great selectivity and a low limit of detection (39.6 pg mL−1) for ST2, allowing the determination of soluble ST2 (sST2) in plasma samples from healthy individuals and patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) in only 45 min once the immunoconjugates have been prepared. The good correlation of the obtained results with those provided by an ELISA kit performed using the same immunoreagents demonstrates the potential of the developed strategy for early diagnosis and/or prognosis of the fatal PDAC disease.

scholarly journals The Effect of Synthesis Procedure on Hydrogen Peroxidase-Like Catalytic Activity of Iron Oxide Magnetic Particles

2020 ◽  
Vol 10 (19) ◽  
pp. 6756
Author(s):  
Atripan Mukherjee ◽  
Amir M. Ashrafi ◽  
Pavel Svec ◽  
Lukáš Richtera ◽  
Jan Přibyl ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Rapid Detection ◽  
Magnetic Particles ◽  
Limit Of Detection ◽  
Cathodic Potential ◽  
Limit Of Quantification ◽  
Figures Of Merit ◽  
Satisfactory Analysis ◽  
Synthesis Procedure

A comparative study was carried out using magnetic nanoparticles (MNPs) for the fabrication of non-enzymatic sensors for the continuous and rapid detection and monitoring of H2O2. Various MNPs, differing in terms of their synthesis procedure and modification, were synthesized and characterized by different techniques. The electrochemical catalytic activity of the synthesized MNPs toward the reduction in H2O2 was investigated by cyclic voltammetry. The naked MNPs showed the highest catalytic activity among all the synthesized MNPs. The biosensor based on the naked MNPs was then applied in the determination of H2O2 using chronoamperometry. The parameters such as the applied cathodic potential and the amount of MNPs on the developed biosensor were optimized. Moreover, the analytical figures of merit, including reproducibility (RSD = 6.14%), sensitivity (m = 0.0676 µA µM−1), limit of detection (LOD) = 27.02 µmol L−1, and limit of quantification (LOQ) = 89.26 µmol L−1 of the developed biosensor indicate satisfactory analysis. Finally, MNPs were successfully utilized for the determination of H2O2 in milk.

Tropomyosin Analysis in Foods Using an Electrochemical Immunosensing Approach

2021 ◽  
Vol 5 (1) ◽  
pp. 62
Author(s):  
Ricarda Torre ◽  
Maria Freitas ◽  
Estefanía Costa-Rama ◽  
Henri P. A. Nouws ◽  
Cristina Delerue-Matos
Keyword(s):  
Limit Of Detection ◽  
Polyclonal Antibodies ◽  
Analytical Signal ◽  
Food Samples ◽  
Electrochemical Immunosensor ◽  
Screen Printed Carbon Electrode ◽  
Sandwich Type ◽  
Assay Time ◽  
Electrochemical Immunosensing

A screen-printed carbon electrode was used as the transducer for the development of an electrochemical immunosensor for the determination of tropomyosin (a major shrimp allergen) in food samples. Monoclonal and polyclonal antibodies were used in a sandwich-type immunoassay. The analytical signal was electrochemically obtained using an alkaline phosphatase-labelled secondary antibody and a 3-indoxyl phosphate/silver nitrate substrate. The total assay time was 2 h 50 min and allowed the quantification of tropomyosin between 2.5 and 20 ng mL−1, with a limit of detection of 1.7 ng mL−1 The immunosensor was successfully applied to the analysis of commercial food products.

scholarly journals A rapid magnetic bead-based immunoassay for sensitive determination of diclofenac

2021 ◽  
Author(s):  
Alexander Ecke ◽  
Tanja Westphalen ◽  
Jane Hornung ◽  
Michael Voetz ◽  
Rudolf J. Schneider
Keyword(s):  
Water Samples ◽  
Magnetic Beads ◽  
Limit Of Detection ◽  
Cost Effective ◽  
Magnetic Bead ◽  
Enzyme Linked Immunosorbent Assay ◽  
Reference Analysis ◽  
Immunochemical Method ◽  
Synthetic Strategy

Abstract Increasing contamination of environmental waters with pharmaceuticals represents an emerging threat for the drinking water quality and safety. In this regard, fast and reliable analytical methods are required to allow quick countermeasures in case of contamination. Here, we report the development of a magnetic bead-based immunoassay (MBBA) for the fast and cost-effective determination of the analgesic diclofenac (DCF) in water samples, based on diclofenac-coupled magnetic beads and a robust monoclonal anti-DCF antibody. A novel synthetic strategy for preparation of the beads resulted in an assay that enabled for the determination of diclofenac with a significantly lower limit of detection (400 ng/L) than the respective enzyme-linked immunosorbent assay (ELISA). With shorter incubation times and only one manual washing step required, the assay demands for remarkably shorter time to result (< 45 min) and less equipment than ELISA. Evaluation of assay precision and accuracy with a series of spiked water samples yielded results with low to moderate intra- and inter-assay variations and in good agreement with LC–MS/MS reference analysis. The assay principle can be transferred to other, e.g., microfluidic, formats, as well as applied to other analytes and may replace ELISA as the standard immunochemical method. Graphical abstract

scholarly journals SUN-LB95 Developing a Highly Equivalent Non-Competitive Chemiluminescence Immunoassay Aldosterone Measurement to LC/MS

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Fumitoshi Satoh ◽  
Yoshikiyo Ono ◽  
Kei Omata ◽  
Yuta Tezuka ◽  
Hiroaki Yamanami ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Limit Of Detection ◽  
Low Cost ◽  
Antihypertensive Agents ◽  
Measuring Time ◽  
Limits Of Agreement ◽  
Chemiluminescence Immunoassay ◽  
Limit Of Quantitation ◽  
Background Measurement

Abstract Background Measurement of plasma aldosterone and renin concentration, or activity, is useful for selecting antihypertensive agents anddetecting hyperaldosteronism in hypertensive patients. However, it takes several days to get results even if measured by inaccurateradioimmunoassay, or we must accept high-cost LC/MS, and development of a more rapid and accurate substitute has been long hoped. We havedeveloped a novel, fully-automated, high-quantitative noncompetitive chemiluminescence immunoassay (NC-CLEIA) for detecting aldosterone inserum and plasma, and its performance is evaluated as compared to LC/MS measurement. Methods Recently a unique anti-metatype antibody,which recognizes the immunocomplex of aldosterone and its monoclonal antibody, was established. Using this antibody for sensing permittedthe construction of non-competitive assay for the detection of aldosterone. The reaction protocol of novel aldosterone assay is the following. Inthe 1st reaction, aldosterone in patient’s sample is captured on anti-body coated magnetic particles. Alkaline phosphatase-conjugated antimetatypeantibody is added and incubated as 2nd reaction following a wash. Then substrate solution is added after washing immunocomplex.The resulting reaction signals are proportional to the amount of aldosterone in the sample allowing quantitative determination of in serum orplasma sample. The overall reaction is completed within 30 min. Results Limit of blank (LoB), limit of detection (LoD) and limit of quantitation(LoQ) of our NC-CLEIA aldosterone assay were 0.09 ng/dL, 0.21 ng/dL and 0.57 ng/dL, respectively. NC-CLEIA aldosterone measurements werelinearly well correlated with LC/MS aldosterone measurements (N = 130, y = 1.027x - 0.23 ng/dL, Spearman’s ρ = 0.996, P&lt; 0.0001). Bland-Altmanplot analysis between NC-CLEIA and LC-MS/MS of aldosterone revealed a bias of 0.40 ng/dL with the limits of agreement of -4.60 and 5.41 ng/dLwith 95% confidence interval. Conclusion Our novel NC-CLEIA aldosterone assay was well-correlated and had only a very low bias with LC-MS/MSmethod and also was able to accurately quantify low level samples even in essential hypertension patients. This aldosterone assay can be a most equivalent to LC-MS/MS measurement with a low cost of 12 $ and a short measuring time of 30 minutes.

SERUM TRIIODOTHYRONINE DETERMINATION BY SATURATION ANALYSIS

1973 ◽  
Vol 72 (4) ◽  
pp. 714-726 ◽  
Author(s):  
A. Burger ◽  
B. Miller ◽  
C. Sakoloff ◽  
M. B. Vallotton
Keyword(s):  
Ionic Strength ◽  
Limit Of Detection ◽  
Improved Method ◽  
Accuracy Of Measurement ◽  
Tracer Amount ◽  
The Mean ◽  
Physiological Values ◽  
Hyperthyroid Patients ◽  
Solvent Blank

ABSTRACT An improved method for the determination of serum triiodothyronine (T3) has been developed. After addition of a tracer amount of the hormone, T3 was extracted from 1 ml serum under conditions of pH and ionic strength which favoured T3 extraction (89%) over thyroxine (T4) extraction (58%). Chromatography of the extracted material on Sephadex LH-20 separated T3 completely from residual T4. The T3 eluate was dried, then re-dissolved in 0.5 ml NaOH 0.04 n. To 0.2 ml duplicate aliquots, a standard amount of TBG was added for the competitive protein analysis. After one hour incubation at 4°C, separation of bound from free T3 was achieved on small Sephadex G-25 columns. Overall recovery was 67 ± 10.8% and correction for the loss was made. The solvent blank was 37 ± 27 (sd) ng/100 ml. Accuracy of measurement of known quantities of T3 added to serum was 98.4%. The coefficient of variation within the assay was 6.2% and between the assays it was 11.4%. The limit of detection (0.1 ng) corresponded to a concentration of 25 ng/100 ml. T4 added to serum did not interfere with T3 determination until high non-physiological values were reached. The mean ± sd serum T3 in 54 euthyroid subjects was 153 ± 58 ng/100 ml and in 24 hyperthyroid patients it was 428 ±186 ng/100 ml; 4 out of the 24 hyperthyroid values were within 2 sd of the mean euthyroid group. All the values found in the euthyroid group were well above the limit of detection of the method.

Spectrophotometeric Determination of Trifluoperazine HCL in Pure Forms and Pharmaceutical Preperations

2017 ◽  
Vol 9 (5) ◽  
Author(s):  
Mohammad Hamzah Hamzah ◽  
Rawa M M Taqi ◽  
Muna M. Hasan ◽  
Raid J. M. Al-Timimi
Keyword(s):  
Standard Method ◽  
Limit Of Detection ◽  
Molar Absorptivity ◽  
Dosage Forms ◽  
Oxidizing Agent ◽  
Optimum Conditions ◽  
Limit Of Quantification ◽  
Cerium Ion ◽  
Blank Solution

A simple and accurate spectrophotometric method for the determination of Trifluoperazine HCl in pure and dosage forms was developed. The method is based on the reaction between Trifluoperazine HCl and p-chloroaniline in the presence of cerium ion as oxidizing agent which lead to the formation of violate color product that absorbed at a maximum wavelength 570nm while the blank solution was pink. Under the optimum conditions a linear relationship between the intensity and concentration of TRF in the range 4-50μg/ml was obtained . The molar absorptivity 3.74×103 L.mol-1.cm-1 , Limit of detection (2.21μg/ml), while limit of quantification was 7.39μg/ml. The proposed analytical method was compared with standard method using t-test and F-test , the obtained results shows there is no significant differences between proposed method and standard method. Based on that the proposed method can be used as an alternative method for the determination of TRF in pure and dosage forms.

Fast Method for the Determination of Residual Solvents in Radiopharmaceutical Products

2017 ◽  
Vol 68 (4) ◽  
pp. 666-670 ◽  
Author(s):  
Mirela Mihon ◽  
Catalin Stelian Tuta ◽  
Alina Catrinel Ion ◽  
Dana Niculae ◽  
Vasile Lavric
Keyword(s):  
Gas Chromatography ◽  
Control Method ◽  
Limit Of Detection ◽  
The Body ◽  
Biologically Active ◽  
Injection Technique ◽  
Fast Method ◽  
Residual Solvent ◽  
Residual Solvents

The aim of this work was the development and validation of a fast analytical method to determine the residual solvents content in radiopharmaceuticals such as: 18F-Fluorodeoxyglucose (18F-FDG), 18F-Fluoroestradiol (18F-FES), 18F-Fluorothymidine (18F-FLT),18F-Fluoromisonidazole (18F-FMISO). Radiopharmaceuticals are radioactive preparations for medical purposes used in nuclear medicine as tracers in diagnostic imaging and treatment of certain diseases. Positron Emission Tomography (PET) is a medical imaging technique that consists in introducing into the body of a small amount of a biologically active chemical compound labelled with a short lived positron-emitting radioisotope (18F, 11C, 68Ga). Residual solvents are critical impurities in radiopharmaceuticals that can affect labelling, stability and physicochemical properties of drugs. Therefore, the determination of these solvents is essential for quality control of radiopharmaceuticals. Validation of the control method for residual solvents by gas chromatography is referred by the European Pharmacopoeia using a special injection technique (head space). The parameters of the method, which comply with International Conference on Harmonization guidelines, are: accuracy, precision, linearity, limit of detection, limit of quantification and robustness. The proposed method (direct gas chromatography injection) proved to be linear, precise, accurate and robust. Good linearity was achieved for all the solvents and correlation coefficients (R2) for each residual solvent were found more than 0.99.

Indirect Determination of Amikacin by Gold Nanoparticles as Redox Probe

2020 ◽  
Vol 17 ◽  
Author(s):  
Mansureh Alizadeh ◽  
Mandana Amiri ◽  
Abolfazl Bezaatpour
Keyword(s):  
Gold Nanoparticles ◽  
Bacterial Infections ◽  
Limit Of Detection ◽  
Pharmaceutical Preparation ◽  
Cathodic Peak ◽  
Easy Method ◽  
Peak Current ◽  
Indirect Determination ◽  
Tract Infections

: Amikacin is an aminoglycoside antibiotic used for many gram-negative bacterial infections like infections in the urinary tract, infections in brain, lungs and abdomen. Electrochemical determination of amikacin is a challenge in electroanalysis because it shows no voltammetric peak at the surface of bare electrodes. In this approach, a very simple and easy method for indirect voltammetric determination of amikacin presented in real samples. Gold nanoparticles were electrodeposited at the surface of glassy carbon electrode in constant potential. The effect of several parameters such as time and potential of deposition, pH and scan rates on signal were studied. The cathodic peak current of Au3+ decreased with increasing amikacin concentration. Quantitative analysis of amikacin was performed using differential pulse voltammetry by following cathodic peak current of gold ions. Two dynamic linear ranges of 1.0 × 10−8–1.0 × 10-7 M and 5.0 × 10−7–1.0 × 10-3 M were obtained and limit of detection was estimated 3.0× 10−9 M. The method was successfully determined amikacin in pharmaceutical preparation and human serum. The effect of several interference in determination of amikacin was also studied.

Optimum HPLC Conditions for Determination of Dibucaine HCL, Fluocortolone Pivalate and Fluocortolone Caproate by Using Experimental Design

2018 ◽  
Vol 15 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Bürge Aşçı ◽  
Mesut Koç
Keyword(s):  
Experimental Design ◽  
Flow Rate ◽  
Mobile Phase ◽  
High Performance ◽  
Limit Of Detection ◽  
Pharmaceutical Preparations ◽  
Acid Mixture ◽  
Solution Stability ◽  
Uv Detector

Introduction:This paper presents the development and validation of a novel, fast, sensitive and accurate high performance liquid chromatography (HPLC) method for the simultaneous quantitative determination of dibucaine HCl, fluocortolone pivalate and fluocortolone caproate in pharmaceutical preparations.Experiment:Development of the chromatographic method was based on an experimental design approach. A five-level-three-factor central composite design requiring 20 experiments in this optimization study was performed in order to evaluate the effects of three independent variances including mobile phase ratio, flow rate and amount of acid in the mobile phase.Conclusion:The optimum composition for mobile phase was found as a methanol:water:acetic acid mixture at 71.6 : 26.4 : 2 (v/v/v) ratio and optimum separation was acquired by isocratic elution with a flow rate of 1.3 mL/min. The analytes were detected using a UV detector at 240 nm. The developed method was validated in terms of linearity, precision, accuracy, limit of detection/quantitation and solution stability and successfully applied to the determination of dibucaine HCl, fluocortolone pivalate and fluocortolone caproate in pharmaceutical topical formulations such as suppositories and ointments.

Novel palladium(II) selective membrane electrode based on 4-[(5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl]benzene-1,3-diol

2010 ◽  
Vol 75 (5) ◽  
pp. 563-575 ◽  
Author(s):  
Moslem Mohammadi ◽  
Mehdi Khodadadian ◽  
Mohammad K. Rofouei
Keyword(s):  
Limit Of Detection ◽  
Membrane Electrode ◽  
Aqueous Samples ◽  
Selective Determination ◽  
Poly Vinyl Chloride ◽  
Selective Membrane ◽  
Ph Range ◽  
Palladium Content ◽  
Methyl Benzene

A plasticized poly(vinyl chloride) membrane electrode based on 4-[(5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl]benzene-1,3-diol (L) for highly selective determination of palladium(II) (in PdCl42– form) is developed. The electrode showed a good Nernstian response (29.6 ± 0.4 mV per decade) over a wide concentration range (3.1 × 10–7 to 1.0 × 10–2 mol l–1). The limit of detection was 1.5 × 10–7 mol l–1. The electrode has a response time of about 20 s, and it can be used for at least 2 months without observing any considerable deviation from Nernstian response. The proposed electrode could be used in the pH range of 2.5–5.5. The practical utility of the electrode has been demonstrated by its use for the estimation of palladium content in aqueous samples.

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