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Objectives Type I IFN (IFN-I) activation is a prominent feature of primary SS (pSS), SLE and SSc. Ultrasensitive single-molecule array (Simoa) technology has facilitated the measurement of subfemtomolar concentrations of IFNs. Here we aimed to measure IFN-α2 in serum from pSS, SLE and SSc using a Simoa immunoassay and correlate these levels to blood IFN-stimulated gene (ISG) expression and disease activity. Methods Serum IFN-α2 was measured in patients with pSS (n = 85 and n = 110), SLE (n = 24) and SSc (n = 23) and healthy controls (HCs; n = 68) using an IFN-α Simoa assay on an HD-X analyser. IFN-I pathway activation was additionally determined from serum by an IFN-I reporter assay and paired samples of whole blood ISG expression of IFI44, IFI44L, IFIT1, IFIT3 and MxA by RT-PCR or myxovirus resistance protein 1 (MxA) protein ELISA. Results Serum IFN-α2 levels were elevated in pSS (median 61.3 fg/ml) compared with HCs (median ≤5 fg/ml, P Conclusion Simoa serum IFN-α2 reflects blood ISG expression in pSS, SLE and SSc. In light of IFN-targeting treatments, Simoa could potentially be applied for patient stratification or retrospective analysis of historical cohorts.

Inducible T-cell costimulator (ICOS) is a homodimeric protein expressed on the surface of activated T-cells that is being investigated as a potential therapeutic target to treat various cancers. Recent studies have reported aberrant increases in the soluble form of ICOS (sICOS) in human serum in disease-state patients, primarily using commercial ELISA kits. However, results from our in-house immunoassay did not show these aberrant increases, leading us to speculate that commercial sICOS ELISAs may be prone to interference. We directly tested that hypothesis and found that one widely used commercial kit yields false-positives and is prone to human anti-mouse antibody (HAMA) interference. We then analyzed a panel of healthy, cancer, chronic hepatitis C virus, systemic lupus erythematosus, and diffuse cutaneous systemic sclerosis human serum using our in-house immunoassay and reported the measured sICOS concentrations in these populations. Since even well characterized immunoassay methods are prone to non-specific interference, we also developed a novel sICOS LC-MS/MS method to confirm the results. Using these orthogonal approaches, we show that sICOS is a low abundance soluble protein that cannot be measured above approximately 20 pg/mL in human serum.

Effective public-health measures and vaccination campaigns against SARS-CoV-2 require granular knowledge of population-level immune responses. We developed a Tripartite Automated Blood Immunoassay (TRABI) to assess the IgG response against the ectodomain and the receptor-binding domain of the spike protein as well as the nucleocapsid protein of SARS-CoV-2. We used TRABI for continuous seromonitoring of hospital patients and healthy blood donors (n=72’222) in the canton of Zurich from December 2019 to December 2020 (pre-vaccine period). Seroprevalence peaked in May 2020 and rose again in November 2020 in both cohorts. Validations of results included antibody diffusional sizing and Western Blotting. Using an extended Susceptible-Exposed-Infectious-Removed model, we found that antibodies waned with a half-life of 75 days, whereas the cumulative incidence rose from 2.3% in June 2020 to 12.2% in mid-December 2020 in the population of the canton of Zurich. A follow-up health survey indicated that about 10% of patients infected with wildtype SARS-CoV-2 sustained some symptoms at least twelve months post COVID-19 and up to the timepoint of survey participation. Crucially, we found no evidence for a difference in long-term complications between those whose infection was symptomatic and those with asymptomatic acute infection. The cohort of asymptomatic SARS-CoV-2- infected subjects represents a resource for the study of chronic and possibly unexpected sequelae.

Substrate photopatterning has provided versatile applications in biomedical fields. Herein, an universal and efficient photoligation reaction has been used to prepare a patterned capture substrate for a sandwich SERS immunoassay. Photoirradiation induces mild and efficient immobilization of antibodies at the desired region of a gold surface, and the antibody-antigen interaction helps the substrate to capture the antigens in solution specifically. After exposing to SERS probes, i.e., the gold nanoparticles labelled with both antibodies and intrinsically strong Raman reporters, multiple quantitative SERS determination of antigens can be achieved with high sensitivity and specificity. The limit of detection can be as low as 10−12 mol/L for four kinds of cancer biomarkers, which provides a promising method for the construction of highly sensitive and high-throughput SERS detection chip and the application of in vitro diagnosis.

Chemiluminescence immunoassay (CLIA) has always been a great challenge in detecting cardiac troponin I (cTnI) in whole blood samples without centrifugation because of the interference of red blood cells and low sensitivity. In this study, the antigens and erythrocytes in the blood were captured by the antibodies immobilized on the magnetic particles, recognized by another biotin-conjugated cTnI antibody and detected by streptavidin/acridine aster-conjugated polychloromethylstyrene microspheres (PCMS). After magnetic separation, the supernatant was transferred and measured. No significant difference was noted between the cTnI concentrations of the serum samples, plasma samples and whole blood. The prepared PCMS provided more functional areas to conjugate streptavidin and acridinium ester, so the immunoassay has highly sensitive, the limits of blank at 0.012 ng/mL, and functional sensitivity at 0.019 ng/mL with a CV of 20%, and 0.058 ng/mL with a CV of 10%. Total precision of any sample type ranged from 2.62%~5.67%. The assay was linear over the studied range of 0.01–50.00 ng/mL, and no hook effect was found when cTnI concentrations reached 1900 ng/mL. No significant interference was noted with the potential endogenous interfering substances. Compared with the commercial kit (Abbott assay kit), the correlation coefficient was 0.9859. A washing-free CLIA was established for the rapid detection of cTnI in human whole blood, using erythrocyte capture antibodies-conjugated magnetic nanoparticles for eliminating the influence of erythrocytes and PCMS for signal amplification, which showed great potential in clinical application.

Antigen tests for severe acute respiratory coronavirus 2 sometimes show positive lines earlier than their specified read time, although the implication of getting the results at earlier time is not well understood. This study aimed to evaluate the clinical utility of an antigen test by evaluating the time period to get positive results and by comparing the test sensitivity with that of a digital immunoassay (DIA) test.We prospectively collected additional nasopharyngeal samples from patients who had already tested positive for SARS-CoV-2 by reverse transcription PCR. The additional swab was used for an antigen test, QuickNavi™-COVID19 Ag, and the time periods to get positive results were measured. The sensitivity of QuickNavi™-COVID19 Ag was also compared with that of a DIA.In 84 of 96 (87.5%) analyzed cases, the results of QuickNavi™-COVID19 Ag were positive. The time to obtain positive results was 15.0 seconds in median (inter quartile range: 12.0-33.3, range 11-736), and was extended in samples with higher cycle thresholds (Ct) (p32.QuickNavi™-COVID19 Ag immediately showed positive results in most cases, and the time to a positive reaction may have indicated the viral load. In addition, the sensitivity of the test was comparable to the DIA.

The objective of the study was to improve the treatment of acute obstructive bronchitis in infants by optimizing the anti-inflammatory therapy based on the evaluation of its clinical, immunological and molecular genetic efficiency. Materials and methods. We have carried out a comprehensive examination of 80 children aged 6 months to 3 years with acute obstructive bronchitis. Patients were divided into two groups: children of the first group (n = 40) received systemic glucocorticosteroids, children of the second group (n = 40) were treated with inhaled glucocorticosteroids. Before and after the treatment, in all children we have studied the content of IFN-γ, IL-4 and IL-13 in the blood serum using enzyme linked immunosorbent assay, the concentration of total IgE — by means of electrochemiluminescent immunoassay. The level of expression of the transcription factor NF-κB in peripheral blood lymphocytes was determined using flow cytometry. Results. Transcription factor NF-κB, having almost the same effect on the concentration of IFN-γ and IgE in the blood serum, determines the characteristics of inflammation, mainly local, in acute obstructive bronchitis. Glucocorticosteroid therapy leads to the disappearance of NF-κB influence on the content of proinflammatory cytokines. Inhaled glucocorticosteroids, in addition, help to reduce the concentration of IgE in the blood serum and inhibition of the activity of pro-inflammatory intracellular cascades that, at high clinical efficacy and safety profile, justifies the appropriateness of their use in the treatment of acute obstructive bronchitis in infants as pathogenetic therapy.

Objective Cervical cancer (CC) is a major public health problem in women, and its early detection can help reduce morbidity and mortality. The objective of this study was to compare serum levels of soluble major histocompatibility complex class I-related chain A (sMICA) levels in various body fluids between women diagnosed with CC and healthy women.Methods A case-control study was conducted at a tertiary care hospital and a cancer center in Kolhapur, India. Overall, 150 individuals (100 CC patients and 50 healthy women) participated after providing informed written consent. Demographic data, histopathology history, parity, and tumor, node, and metastasis (TNM) staging data were collected. Pap smears, saliva, blood, and urine samples were collected. Pap smears were examined microscopically, and sMICA levels in all samples were determined by enzyme-linked immunoassay (ELISA).Results The mean age of women with cervical cancer was 49.86±8.18 years. Squamous cell carcinoma (70%) was the most common histological variant in CC patients. Serum soluble sMICA levels differed significantly with parity and TNM staging (P

Background The measurement of plasma concentrations of retinol binding protein is a component of nutritional assessment in neonatal intensive care. However, serial testing in newborns is hampered by the limited amount of blood that can be sampled. Limitations are most severe with preterm infants, for whom close monitoring may be most important. Methods We developed an assay to quantify retinol binding protein using trypsin digestion and liquid chromatography-tandem mass spectrometry, which requires a serum or plasma volume of 5 µl. Additionally, we validated the method according to current recommendations and performed comparison with a standard nephelometry platform in clinical use. Results The assay demonstrated linearity from below 1 mg/dL (0.48 µM) to more than 20 mg/dL (9.7 µM), and an imprecision of 11.8% at 0.43 mg/dL (0.21 µM). The distribution of results observed with the new method was different when compared with nephelometry. Conclusion Liquid chromatography-tandem mass spectrometry facilitated testing a smaller sample volume, thereby increasing the ability to monitor key nutritional markers in premature infants. The differences in results compared with a commercially-available nephelometric assay revealed questionable results for lower concentrations by immunoassay.

Ratiometric fluorescence immunoassay is known as a spectrofluorimetric variant for sensitive and quantitative analyses of biomarkers. However, there are few comparative studies between it and the traditional, single-wavelength-based immunoassay. In this work, a ratiometric fluorescence immunoassay was designed via the fluorescence resonance energy transfer (FRET) in a system comprising MnO2 nanosheets, o-phenylenediamine (OPD), and fluorescent carbon nanodots (FCNs). The MnO2 nanosheet oxidizes OPD, producing a fluorescence peak at 580 nm, while FCNs exhibit a fluorescence peak at 490 nm. Under the effect of FRET, the fluorescence at 580 nm increases significantly while the fluorescence at 490 nm is reduced. The FRET effect was confirmed by our fluorescence lifetime measurements. We optimized the experimental conditions that include solution pH, OPD concentration, and reaction time. By electrostatically coating the MnO2 nanosheets with antibody molecules and using the resultant materials as a detection probe, the ratiometric fluorescence sensing was extended to the detection of alpha fetoprotein (AFP) in human serum samples on a 96-well titer plate. Our ratiometric fluorescence immunoassay possesses a good dynamic range (from 0.14 to 130.43 pM). The detection limit was estimated to be 0.13 pM (0.009 ng/mL), which is 7.6-fold lower than that of the single-wavelength-based immunoassay. The measurement results of serum samples from healthy and patient donors are highly comparable to those measured by chemiluminescence for the same donors, demonstrating the viability for serological assays of important cancer markers.

Serum hepatitis B core-related antigen (HBcrAg) and surface antigen (HBsAg) are surrogate markers of intrahepatic covalently closed circular DNA. The measurement range of the current HBcrAg assay is relatively narrow. Thus, we examined the potential of HBcrAg and HBsAg measured by ultrasensitive assays for predicting hepatocellular carcinoma (HCC) development in patients with chronic hepatitis B treated with entecavir (ETV). We conducted a retrospective cohort study of 180 patients who received ETV for >1 year. All patients had hepatitis B e-antigen negativity at baseline. Serum HBcrAg and HBsAg levels at baseline and year 1 were measured in all patients by ultrasensitive assays using immunoassay for total antigen including complex by pretreatment (iTACT) technology. During the median follow-up of 11.0 years, 22 patients developed HCC (11.8/1,000 person-years). Baseline HBsAg levels were not associated with HCC development during ETV treatment. However, high HBcrAg levels at baseline and at year 1 were significantly associated with HCC development (log-rank test; P < 0.001). In 110 patients (61.1%) with ≥4.0 log U/mL at baseline (high HBcrAg cohort), HBcrAg declined to ≤2.9 log U/mL at year 1 in 25 patients (22.7%). The adjusted hazard ratio for HCC incidence was significantly lower in patients with HBcrAg ≤2.9 log U/mL at year 1 than in those in the high HBcrAg cohort. Conclusion: Measurement of HBcrAg by ultrasensitive assay has better potential for predicting HCC during antiviral treatment than the current HBcrAg assay.

A commutability confirmation test for the blood aldosterone measurement was performed on liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) as a designated comparison method (DCM) and four chemiluminescent enzyme immunoassay (CLEIA) measurement procedures based on metrological traceability. A conventional radioimmunoassay (RIA) and two measurement procedures of CLEIA which obtains RIA equivalent values were also compared. The relationship between the DCM value and the CLEIA value with respect to 120 pg/mL of the RIA value, which is the screening criterion of primary aldosteronism (PA) was clarified. For the correlation test, 75 samples of patient serum and plasma were used. Regression analysis revealed that the standardized LC-MS/MS and four CLEIA measurement procedures were in good agreement. This is the effect of measurement specificity and calibration using by certified reference material (CRM). The median of the LC-MS/MS corresponding to 120 pg/mL of RIA was 48.5 pg/mL. In the mean of standardized four CLEIA values corresponding to the 48.5 pg/mL of LC-MS/MS value was 47.51 pg/mL and the standard deviation (SD) was 2.93 pg/mL. However, the correlation between the RIA value and the RIA equivalent of the two measurement procedures by CLEIA differed depending on the measurement procedure. This is due to the influence of RIA measurement performance. Standardized CLEIA measurements are suitable for routine measurement procedure. When converting the LC-MS/MS equivalent value by the standardized CLEIA to the conventional RIA value, it is necessary to use the conversion formula.

Elevated blood biotin levels may interfere with some biotin-streptavidin immunoassays, used in clinical laboratories to aid diagnosis. The objective of this study was to determine the prevalence of elevated blood biotin levels in three at risk patient cohorts, where misclassification of disease status would have a high clinical impact. This retrospective, single-center study screened residual, de-identified plasma samples (N = 700) from adult patients undergoing routine thyroid stimulating hormone (TSH) (n = 500), procalcitonin (PCT) (n = 100), or human immunodeficiency virus (HIV) (n = 100) testing using the Elecsys® BRAHMS PCT (Roche Diagnostics), Access TSH (3rd IS) (Beckman Coulter Inc), and ARCHITECT HIV Ag/Ab Combo (Abbott Laboratories) immunoassays, respectively, for elevated levels of biotin (quantified by gas chromatography-time of flight mass spectrometry). Patients taking biotin supplements were included and dosages recorded from medical records. In the overall study cohort, blood biotin levels ranged 0.1-21.3 ng/mL; 44.3% (310/700) of samples were

The purpose of the present work was to study effectiveness for early pregnancy diagnosis in cattle of the new enzyme immunoassay (EIA) sandwich kit commercially available based on the measurement of pregnancy-associated glycoproteins (PAGs). 120 Holstein-Friesian cattle of mixed age and parity were comprised from different dairy herds. The pregnant females (n = 68) were diagnosed by ultrasonography at day 35-40 after artificial insemination and confirmed by transrectal exploration at 2-3 months after AI. The non-pregnant females (n = 52) were housed in the absence of males during the experimental period. Blood samples were collected from coccygeal vessels of females into EDTA tubes. The serum was obtained by centrifugation and the serum was stored at - 20 C until assay. The PAG concentrations in pregnant and non-pregnant females were determined in serum by EIA kit. The reproducibility inter- and intra-assay of the PAG-EIA is satisfactory (2.78 and 13.19 %, respectively). The accuracy ( 94.8 %) and the test of parallelism were largely acceptable. No cross-reaction was observed with the different hormones tested at different dilutions. PAG-EIA system gave 100 % sensitivity and negative predictive values. Whereas, specificity and positive predictive value were 91.93 and 71.15 %, respectively. The accuracy of pregnancy diagnosis by PAG-EIA was 87.5 %. In conclusion, the present study shows clearly that the EIA kit can be used to measure PAG in serum cows for the detection of gestation in Algeria. Therefore, this alternative technique could be recommended to replace the radioactive methods in immunoassays to improve the reproductive performances and an efficient tool for reproductive management of dairy cattle.

Aim: In response to the COVID-19 pandemic, Regeneron developed the anti-SARS-CoV-2 monoclonal antibody cocktail, REGEN-COV® (RONAPREVE® outside the USA). Drug concentration data was important for determination of dose, so a two-part bioanalytical strategy was implemented to ensure the therapy was rapidly available for use. Results & methodology: Initially, a liquid chromatography-multiple reaction monitoring-mass spectrometry (LC-MRM-MS) assay, was used to analyze early-phase study samples. Subsequently, a validated electrochemiluminescence (ECL) immunoassay was implemented for high throughput sample analysis for all samples. A comparison of drug concentration data from the methods was performed which identified strong linear correlations and for Bland-Altman, small bias. In addition, pharmacokinetic data from both methods produced similar profiles and parameters. Discussion & conclusion: This novel bioanalytical strategy successfully supported swift development of a critical targeted therapy during the COVID-19 public health emergency.

Supplemental Digital Content is Available in the Text., Background: Busulfan is an alkylating agent used in allogeneic hematopoietic stem cell transplantation for various malignant and nonmalignant disorders. Therapeutic drug monitoring of busulfan is common because busulfan exposure has been linked to veno-occlusive disease, disease relapse, and failed engraftment. The authors developed an automated immunoassay, along with stable calibrators and controls, and quantified busulfan in sodium heparin plasma. Methods: The authors evaluated a homogenous nanoparticle immunoassay, the MyCare Oncology Busulfan Assay Kit (Saladax Biomedical, Inc), for precision, sensitivity, accuracy, and linearity on an open channel clinical chemistry analyzer; they compared the method with 2 mass spectrometry methods (liquid chromatography–tandem mass spectrometry and gas chromatography/mass spectrometry), using anonymized, remnant patient samples. Results: The coefficients of variation for repeatability and within-laboratory precision were ≤9.0%. The linear range was 150–2000 ng/mL; samples up to 6000 ng/mL can be measured with sample dilution. Measured values deviated by ≤14% from assigned values. Comparison between validated mass spectrometry methods resulted in a correlation coefficient R ≥ 0.995. Conclusions: The MyCare Busulfan Assay Kit shows the precision, accuracy, linearity, and test range for performing busulfan concentration measurements in sodium heparin plasma on routine clinical chemistry analyzers.

This study aimed to evaluate whether insulin could be measured in the saliva of pigs and if its concentration changes in some physiological conditions. For this purpose, a validation of an automated heterologous immunoassay for measuring insulin in the saliva of pigs was performed. In addition, the possible changes of salivary insulin concentration in sows after food intake and during gestation and lactation were studied. The evaluated immunoassay was able to detect insulin in the saliva of pigs in a precise and accurate way when species-specific calibrators were used. There was no correlation in insulin concentrations between serum and saliva. Insulin concentrations showed a significant increase in the saliva of sows after feeding. Sows at farrowing and lactation presented higher salivary insulin levels as compared with those in gestation. In conclusion, the results showed that insulin could be measured in the saliva of pigs, and changes in its concentration can be detected due to food intake and different physiological conditions.

A rapid and sensitive immunoassay for the simultaneous detection of thiabendazole (TBZ) and carbendazim (CBZ) was developed by using magnetic nanoparticles (MNPs) and two-color upconversion nanoparticles (UCNPs). The anti-thiabendazole and anti-carbendazim antibody were linked to NaYF4:Yb, Tm (emission at 474 nm) and NaYF4:Yb, Er (emission at 542 nm) UCNPs as multicolor signal probe, respectively. The thiabendazole and carbendazim coating antigen were connected to magnetic microspheres as capture probe, respectively. Based on a competitive format, capture probes compete with analytes to combine corresponding signal probes. Under excitation at 980 nm, the formed competitive immune-complex fluorescent signal at 474 and 542 nm indicates the concentration of thiabendazole and carbendazim, respectively. Under the optimal conditions, the 50% inhibiting concentration (IC50) and limit of detection (LOD, IC10) were 2.21 and 0.083 ng/mL for thiabendazole and 1.18 and 0.075 ng/mL for carbendazim, respectively. The average recoveries of thiabendazole and carbendazim in foods, including oyster mushroom, shiitake mushrooms, oranges and orange juice, ranged from 83.6 to 100.9% with the coefficient of variance (CV) of 1.0–9.8% for thiabendazole and ranged from 89.6 to 105.9% with the CV of 2.5 to 9.1% for carbendazim. This multiplexed analysis format has potential applications for rapid, efficient detection of multiple food risk factors.

A sensitive biosensor capable of detecting trace concentrations of several cancer biomarkers in clinical samples is critical for early detection of cancer because different cancer biomarkers may be expressed at different stages of cancer. Previous multiplex studies using microarrays or color-coded beads had limited multiplex detection in a single well, and difficulty in optimizing and unifying the incubation parameters for all tests made in different wells had posed challenges to small sample size and lengthened assay time. Herein, we proposed a novel approach to achieve multiplex analysis on a single three-dimensional porous calcium alginate bead. Because of the high surface area to volume ratio of the calcium alginate immuno-bead, the sensitivity and linear dynamic range of the as-proposed multiplex analysis method are significantly improved. Based on the direct sandwich immunoassay principle, dual-capturing antibodies were encapsulated into a single 3D porous calcium alginate bead as a proof-of-concept for multiplexity detection of serum-HER2 and serum-CA125 breast cancer biomarkers. High sensitivity was attained, with LODs of 0.004 ng mL−1 for serum HER2, and 0.005 U mL−1 for serum CA125, both of which are below the clinical cutoff values, enabling for early breast cancer diagnosis. Stability tests revealed that the 3D immuno-beads were stable at 4 °C and room temperature (25 °C) for at least 14 days. Most importantly, the results obtained using the developed system were in good agreement with those obtained using standard methods while analyzing real clinical samples. In addition, the analysis required only approximately 30 min, which was much less time than typical ELISA techniques. When endogenous interferences were introduced, no cross-reactivity was observed. We anticipate this approach to be potentially used in the multiplex assays and biosensors.

OBJECTIVE To identify serum protein biomarkers that might distinguish patients with early inflammatory arthritis (IA) with psoriatic arthritis (PsA) from those with rheumatoid arthritis (RA) and may be used to support appropriate early intervention. METHODS The serum proteome of patients with PsA and patients with RA was interrogated using nano-liquid chromatography mass spectrometry (nano-LC-MS/MS) (n = 64 patients), an aptamer-based assay (SomaScan) targeting 1,129 proteins (n = 36 patients), and a multiplexed antibody assay (Luminex) for 48 proteins (n = 64 patients). Multiple reaction monitoring (MRM) assays were developed to evaluate the performance of putative markers using the discovery cohort (n = 60 patients) and subsequently an independent cohort of PsA and RA patients (n = 167). RESULTS Multivariate machine learning analysis of the protein discovery data from the 3 platforms revealed that it was possible to differentiate PsA patients from RA patients with an area under the curve (AUC) of 0.94 for nano-LC-MS/MS, 0.69 for bead-based immunoassay measurements, and 0.73 for aptamer-based analysis. Subsequently, in the separate verification and evaluation studies, random forest models revealed that a subset of proteins measured by MRM could differentiate PsA and RA patients with AUCs of 0.79 and 0.85, respectively. CONCLUSION We present a serum protein biomarker panel that can separate patients with early-onset IA with PsA from those with RA. With continued evaluation and refinement using additional and larger patient cohorts, including those with other arthropathies, we suggest that the panel identified here could contribute to improved clinical decision making.

Analytical tests/devices that are used outside laboratory settings are required to have a very simple analytical protocol to get clearance by regulatory authorities. This study describes sink/float magnetic immunoassays, a new type of rapid, mix-and-observe, instrument-free tests for the detection of biomarkers in untreated biological samples that are very simple and might meet the simple-to-use criterion of authorities to be used in the field. These tests can tell whether an analyte is above or below a predetermined level within 25-45 minutes based on the sinking or floating of a mm-sized sphere on the surface of which an immunoassay that uses reporter antibodies conjugated to superparamagnetic nanoparticles is performed. This manuscript describes the theory and proof-of-concept applications of sink/float magnetic immunoassays for the detection of C-Reactive Protein, anti-Treponema pallidum antibodies and E. coli bacteria.

Immunoassays are a powerful diagnostic tool and are widely used for the quantification of proteins and biomolecules in medical diagnosis and research. Enzyme-linked immunosorbent assay (ELISA) is the most commonly used immunoassay format and allows the detection of biomarkers at a very low concentration. The diagnostic platforms such as enzyme immunoassay (EIA), chemiluminescence (CL) assay, polymerase chain reaction (PCR), flow cytometry (FC), and mass spectrometry (MS) have been used to identify molecular biomarkers. However, these diagnostic tools requiring expensive equipment, long testing time, and qualified personnel that is not always available in small local hospitals with limited resources. The lateral flow immunoassay (LFIA) platform was developed for rapidly obtaining laboratory results and to make urgent decisions in emergency medicine, as well as the recently introduced concept of testing at the site of care (point-of-care, POC). The simultaneous measurement of different substances from a single sample called multiplex assays have become increasingly significant for in vitro quantification of multiple analytes in a single sample, thereby minimising cost, time, and volume. In multiplex immunoassays, the ligands are immobilized either in planar format (flat surface) or on microspheres in suspension that binds to target analytes in sample. The multiplex technology has established itself in proteomic networks and pathways, validation of genomic discoveries, and in the development of clinical biomarkers. In the present review article, various types of monoplex/simplex and complex/multiplex immunoassays have been analysed that are increasingly being applied in laboratory medicine. Also, some advantages and disadvantages of these multiplex assays have also been included such as experimental animals, in vitro tests using cell lines and tissue samples, 3-dimensional modelling and bioprinting, in silico tests, organ-on-chip, and computer modelling.

Clenbuterol is a β-adrenergic receptor agonist that can be used as a bronchodilator for the treatment of respiratory diseases or as an additive feed in livestock to improve conversion rate of lean meat. However, the residue of clenbuterol in food can be a threat to human health. Therefore, it is important to monitor clenbuterol in foods. In this paper, a fluorescence inner filtration immunoassay (FIFI) method for the detection of clenbuterol was developed based on the principle of immunoreactive competitive method and the theory of fluorescence quenching, which was constructed from a fluorescence-quenching detection system and a separation system of magnetic immunization. In the magnetic immunization separation system, the detection antigen competes with the biotin-labeled antigen for binding to colloidal gold-labeled clenbuterol antibody and the immunocomplex is enriched by streptavidin- and biotin-specific reactions on the surface of magnetic beads. The remaining complex as a fluorescence quencher in the detection system after centrifugation, and rhodamine 6G acts as a fluorescence agent. The quantitative detection of clenbuterol was accomplished by achieving fluorescence quenching under excitation light irradiation. The standard solutions of clenbuterol in the range of 0.03–5.0 ng/mL exhibited good correlation (r = 0.9996) with the fluorescence intensity, with limit of detection 0.01 ng/mL and recoveries ranging from 98.1 to 101.2%. Moreover, there was no significant difference between the results obtained after testing valid samples by FIFI and ELISA. Therefore, our developed method is sensitive and efficient, simple to operate, and has great potential for on-site detection of clenbuterol.

Objectives The core cerebrospinal fluid (CSF) biomarkers; total tau (tTau), phospho-tau (pTau), amyloid β 1-42 (Aβ 1-42), and the Aβ 1-42/Aβ 1-40 ratio have transformed Alzheimer’s disease (AD) research and are today increasingly used in clinical routine laboratories as diagnostic tools. Fully automated immunoassay instruments with ready-to-use assay kits and calibrators has simplified their analysis and improved reproducibility of measurements. We evaluated the analytical performance of the fully automated immunoassay instrument LUMIPULSE G (Fujirebio) for measurement of the four core AD CSF biomarkers and determined cutpoints for AD diagnosis. Methods Comparison of the LUMIPULSE G assays was performed with the established INNOTEST ELISAs (Fujirebio) for hTau Ag, pTau 181, β-amyloid 1-42, and with V-PLEX Plus Aβ Peptide Panel 1 (6E10) (Meso Scale Discovery) for Aβ 1-42/Aβ 1-40, as well as with a LC-MS reference method for Aβ 1-42. Intra- and inter-laboratory reproducibility was evaluated for all assays. Clinical cutpoints for Aβ 1-42, tTau, and pTau was determined by analysis of three cohorts of clinically diagnosed patients, comprising 651 CSF samples. For the Aβ 1-42/Aβ 1-40 ratio, the cutpoint was determined by mixture model analysis of 2,782 CSF samples. Results The LUMIPULSE G assays showed strong correlation to all other immunoassays (r>0.93 for all assays). The repeatability (intra-laboratory) CVs ranged between 2.0 and 5.6%, with the highest variation observed for β-amyloid 1-40. The reproducibility (inter-laboratory) CVs ranged between 2.1 and 6.5%, with the highest variation observed for β-amyloid 1-42. The clinical cutpoints for AD were determined to be 409 ng/L for total tau, 50.2 ng/L for pTau 181, 526 ng/L for β-amyloid 1-42, and 0.072 for the Aβ 1-42/Aβ 1-40 ratio. Conclusions Our results suggest that the LUMIPULSE G assays for the CSF AD biomarkers are fit for purpose in clinical laboratory practice. Further, they corroborate earlier presented reference limits for the biomarkers.

Although, cancer is considered as a localized disease in its premature stages, in certain types of cells, it results in metastasis, which accounts for over 90% of the total cancer deaths in the wor...

We have identified a clinical need for a sensitive, specific, flexible, comprehensive and affordable analytical technology to efficiently detect polydrug use. In addition, the current standard practice of surveilled urine sampling is uncomfortable for the patient; hence, more patient-friendly sample collection methods are requested. To fill these needs, we have developed and validated a high-throughput liquid chromatography–high-resolution mass spectrometry (LC--HRMS) method for the analysis of drugs of abuse (DoA) in oral fluid (OF). The method covers a panel of 71 substances including traditional DoA, prescription narcotics and new psychoactive substances (NPS), with a guaranteed limit of identification of 99.7%), sensitivity (>99.7%) and specificity (100%). Most analytes had a high process efficiency during the salting-out liquid–liquid extraction sample preparation and no or only a minor matrix effect during the analysis. We have implemented this method in clinical routine and present data from 18,579 OF samples collected during routine patient treatment in mainly psychiatric and addiction clinics in West Sweden between September 2020 and June 2021. Seventy-one percent of the samples were positive and a total of 41,472 DoA findings were detected. Amphetamine (27%), buprenorphine (25%), nordiazepam (18%) and alprazolam (16%) were most prevalent. New psychoactive substances were detected in 189 samples (1.0%). The occurrence of polydrug use was common; 34% of the positive samples contained three analytes or more and 12% six or more. To the best of our knowledge, this is the first method for comprehensive analysis of DoA in OF using LC--HRMS and the largest dataset published on the detection of DoA in OF. With the current complex and variable drug use pattern, this broad, cost-effective and reliable method has largely replaced immunoassay screening in urine in our laboratory.

COVID-19 has become a planetary emergency which is seriously threatening human health. Comparative studies can shed light on the molecular mechanisms of the formation of humoral antiviral immunity in persons who have undergone the disease and have been vaccinated against the SARS-CoV-2 virus. Serum levels of biomarkers of inflammation and cytokine storm (procalcitonin, sCD14, sLBP, sTREM1, IL-6, IL-8, IL-10, sWnt5a, TNFα and TNFβ) were determined by enzyme immunoassay. We studied the relationship between the content of biomarkers in blood serum with low and high concentrations of antiviral antibodies, indirect indicators of which are the values of the positivity coefficient (CP). A significant increase in the serum levels of sTREM1, IL-6, and procalcitonin was found in persons with a high CP level after infection. A significant increase in IL-6 and PCT was revealed in persons vaccinated with the Sputnik V vaccine, both with a low level of CP and with a high one. In vaccinated individuals with a low CP level, a significant increase in the sTREM1 content was also observed. It has been shown that the content of sCD14 (presepsin) is significantly lower in vaccinated individuals, both with low and high CP, compared with donors. When studying the correlations between CP and serum biomarkers in vaccinated individuals, a weak inverse correlation was found for sLBP (r = –0.465) and IL-6 (r = –0.437), as well as an average inverse correlation for sTREM1 (r = –0.508).

Coronavirus disease 2019 (COVID‐19) manifests with high clinical variability and warrants sensitive and specific assays to analyze immune responses in infected and vaccinated individuals. Using Single Molecule Arrays (Simoa), we developed an assay to assess antibody neutralization with high sensitivity and multiplexing capabilities based on antibody‐mediated blockage of the ACE2‐spike interaction. The assay does not require live viruses or cells and can be performed in a biosafety level 2 laboratory within two hours. We used this assay to assess neutralization and antibody levels in patients who died of COVID‐19 and patients hospitalized for a short period of time and show that neutralization and antibody levels increase over time. We also adapted the assay for SARS‐CoV‐2 variants and measured neutralization capacity in pre‐pandemic healthy, COVID‐19 infected, and vaccinated individuals. This assay is highly adaptable for clinical applications, such as vaccine development and epidemiological studies., Using Single Molecule Arrays (Simoa), we developed a simple neutralization assay based on antibody‐mediated blockage of the ACE2‐spike interaction. This assay can assess antibody neutralization with high sensitivity and multiplexing capabilities. We used this assay to profile neutralization capacity in patients infected with SARS‐CoV‐2 and vaccinated individuals and show that this assay is useful for various clinical applications.

Bioengineered yeast bio-nanomaterials termed nanoyeasts displaying antibody single-chain variable fragments (scFvs) against diagnostic targets are a promising alternative to monoclonal antibodies (mAbs). A potential limitation for translating nanoyeasts into diagnostic tools is batch-to-batch variability. Herein, we demonstrate a systematic approach for cost-efficient production of highly specific nanoyeasts that enabled accurate dengue virus (DENV) detection by immunoassay (2.5% CV). Yeasts bioengineered to surface express DENV-specific scFvs (up to 66% of the total cell population) were fragmented into nanoyeast fractions trialing sonication, bead beating, and high-pressure disruption methods. Nanoyeast fractions from sonication had optimal target binding, uniform particle size (±89 nm), were stable, and retained diagnostic activity for 7 days at 37 °C compared to traditional mAbs that lost activity after 1 day at 37 °C. We engineered a panel of nanoyeast scFvs targeting DENV nonstructural protein 1 (NS1): (i) specific for serotyping DENV 1-4 and (ii) cross-reactive anti-DENV scFvs that are suitable for "yes/no" diagnostic applications. We demonstrate highly specific nanoyeast scFvs for serotyping DENV. We show that nanoyeast scFvs specifically detect NS1 in simulated patient plasma with a limit of detection of 250 ng/mL, the concentration found in infected patients.

Rapid and automated detection of acute myocardial infarction (AMI) at its developing stage is very important due to its high mortality rate. To quantitatively diagnose AMI, Myo, CK-MB, and cTnI are chosen as three biomarkers, which are usually detected through an immunosorbent assay, such as the enzyme-linked immunosorbent assay. However, the approach poses many drawbacks, such as long detection time, the cumbersome process, the need for professionals, and the difficulty of realizing automatic operation. Here, a multichannel digital microfluidic (DMF) thermal control chip integrated with a sandwich-based immunoassay strategy is proposed for the automated, rapid, and sensitive detection of AMI biomarkers. A miniaturized temperature control module is integrated on the back of the DMF chip, meeting the temperature requirement for the immunoassay. With this DMF thermal control chip, sample and reagent consumption are reduced to several microliters, significantly alleviating reagent consumption and sample dependence, and the automated and multichannel detection of biomarkers can be achieved. In this work, the simultaneously noninvasive detection of the human serum sample containing the three biomarkers of AMI is also achieved within 30 min, which improves the diagnostic accuracy of AMI. Due to the features of automation and miniaturization, the multichannel immunosensor can be used in community hospitals to increase the speed of diagnosis of patients with various acute diseases.

Background As thyroid-stimulating immunoglobulins (TSI) are a sign of Graves' disease (GD), measuring TSI titers is becoming increasingly important for GD diagnosis. This study evaluated the diagnostic accuracy of a new fully automated TSI immunoassay (Immulite™ TSI assay) in GD patients and compared it to the third generation thyroid-stimulating hormone receptor antibody (TRAb) electrochemiluminescence assay (Elecsys Anti-TSHR assay). Additionally, clinical characteristics associated with responsiveness to methimazole in patients with newly diagnosed GD were preliminarily explored. Methods This study involved 324 subjects, comprising patients with untreated GD (GD-UT), Graves’ ophthalmopathy (GO) patients, GD patients who had been treated for > 12 months (GD-T), autoimmune thyroiditis (AIT) patients, and healthy subjects (HS). The Immulite™ TSI and Elecsys Anti-TSHR assay were performed on all samples. According to their responsiveness to methimazole, the GD-UT patients were divided into rapid and slow responder groups, and their clinical characteristics were compared. Results A receiver operating characteristic (ROC) curve analysis of GD-UT patients showed that the optimal TSI cut-off value was 0.57 IU/L. Logistic regression revealed that age and initial FT4 and TSI levels in the middle-dose methimazole group were related to a rapid response, while the initial FT4 level, but not TSI, in the high-dose group was also associated with a rapid response. Conclusions The clinical diagnostic performance of the Immulite™ TSI assay for diagnosing GD was comparable to that of the Elecsys Anti-TSHR assay. The initial FT4 and TSI levels can be used as predictors of the responsiveness to methimazole in patients with newly diagnosed GD.

Jianwei Wang,1,2,&ast; Lili Yu,1,3,&ast; Yulong Sun,4,&ast; Liangming Zhang,1,3 Mingshu Tu,1,3 Liqing Cai,1,3 Xiaoqing Yin,3,5 Xiaojie Pan,1,6 Tao Wang,4 Yi Huang1,3,7,8 1Provincial Clinical College, Fujian Medical University, Fuzhou, 350001, People’s Republic of China; 2Department of Clinical Laboratory, Fujian Provincial Hospital South Branch, Fuzhou, 350008, People’s Republic of China; 3Department of Clinical Laboratory, Fujian Provincial Hospital, Fuzhou, 350001, People’s Republic of China; 4Shanghai Liangrun Biomedicine Technology Limited Company, Shanghai, 200000, People’s Republic of China; 5Integrated Chinese and Western Medicine College, Fujian University of Traditional Chinese Medicine, Fuzhou, 350001, People’s Republic of China; 6Department of Thoracic Surgery, Fujian Provincial Hospital, Fuzhou, 350001, People’s Republic of China; 7Central Laboratory, Fujian Provincial Hospital, Fuzhou, 350001, People’s Republic of China; 8Center for Experimental Research in Clinical Medicine, Fujian Provincial Hospital, Fuzhou, 350001, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Yi Huang; Tao Wang Email hyi8070@126.com; wangtao@microdiag.comPurpose: Our pilot study has shown that cystatin SN (CST1) protein is highly expressed in esophageal squamous cell carcinoma (ESCC) tissues. We intend to develop a chemiluminescent enzyme immunoassay (CLEIA) available for serum CST1 detection and define the diagnostic value of CST1 detection for early ESCC patients, and establish a panel of CST1 with traditional tumor markers to improve the diagnostic sensitivity for early ESCC.Methods: Detection performance of CLEIA for CST1 was evaluated by linearity, detection limit, accuracy, precision, anti-interference and stability. Diagnostic performance of CST1 for early ESCC was evaluated by detecting CST1 of 112 early ESCC, 107 esophageal benign lesions (EBL), and 151 healthy controls (HC). CEA, CYFRA21-1 and SCC-Ag were detected by chemiluminescence immunoassay (CLIA).Results: The linear range and detection limit of CLEIA for CST1 were 6.25– 400 pg/mL and 1.35 pg/mL, respectively; the average recovery rate was 102.65%; CVs of intra-batch precision and inter-batch precision were < 1/4 TEa and < 1/3 TEa, respectively; 8 interferents including 7 common interferents and CST4 had no interference on CST1 detection; stability evaluation showed good sample and reagent stability. The level and positive rate of CST1 in early ESCC group were significantly higher than those in EBL/HC groups (P< 0.05). The diagnostic sensitivity of CST1 for early ESCC was 31.25% (specificity 92.64%, AUC 0.654). The diagnostic sensitivity of traditional tumor markers ranged from 16.07% to 28.57%, at > 93.0% specificity, and SCC-Ag showed the highest AUC (0.709). Combination of CST1 and CEA, SCC-Ag exhibited the highest AUC up to 0.736 (sensitivity 49.11%, specificity 89.53%).Conclusion: CLEIA has excellent detection performance for CST1. CST1 might be a prospective serological biomarker for early diagnosis of ESCC, while combination of CST1 and CEA, SCC-Ag might improve the early diagnostic performance.Keywords: esophageal squamous cell carcinoma, cystatin SN, chemiluminescence enzyme immunoassay, methodological evaluation, early diagnosis

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody assays have high clinical utility in managing the pandemic. We compared antibody responses and seroconversion of coronavirus disease 2019 (COVID-19) patients using different immunoassays. Methods We evaluated 12 commercial immunoassays, including three automated chemiluminescent immunoassays (Abbott, Roche, and Siemens), three enzyme immunoassays (Bio-Rad, Euroimmun, and Vircell), five lateral flow immunoassays (Boditech Med, SD biosensor, PCL, Sugentech, and Rapigen), and one surrogate neutralizing antibody assay (GenScript) in sequential samples from 49 COVID-19 patients and 10 seroconversion panels. Results The positive percent agreement (PPA) of assays for a COVID-19 diagnosis ranged from 84.0% to 98.5% for all samples (>14 days after symptom onset), with IgM or IgA assays showing higher PPAs. Seroconversion responses varied across the assay type and disease severity. Assays targeting the spike or receptor-binding domain protein showed a tendency for early seroconversion detection and higher index values in patients with severe disease. Index values from SARS-CoV-2 binding antibody assays (three automated assays, one LFIA, and three EIAs) showed moderate to strong correlations with the neutralizing antibody percentage (r=0.517-0.874), and stronger correlations in patients with severe disease and in assays targeting spike protein. Agreement among the 12 assays was good (74.3%-96.4%) for detecting IgG or total antibodies. Conclusions Positivity rates and seroconversion of SARS-CoV-2 antibodies vary depending on the assay kits, disease severity, and antigen target. This study contributes to a better understanding of antibody response in symptomatic COVID-19 patients using currently available assays.

Background and aims Long-term kinetics of anti-RBD IgG and neutralizing antibodies were analyzed in a cohort of COVID-19 naive health care workers (HCW) undergoing SARS-CoV-2 vaccination. Methods An anti-RBD IgG immunoassay and a surrogate virus neutralization test (sVNT) were performed at different time points up to 6 months after vaccination in 57 HCWs. Values of anti-RBD IgG predicting an high neutralizing bioactivity (>60%) were also calculated. Results Mean (range) values of anti-RBD IgG were 294.7 (11.6–1554), 2583 (398–8391), 320.4 (42.3–1134) BAU/mL at T1 (21 days after the 1st dose [T0]), T2 (30 days after the 2nd dose) and T3 (+180 days after T0), respectively. Mean (range) percentages of neutralization (NS%) were 24 (0–76), 86 (59–96) and 82 (52–99) at T1, T2 and T3, respectively. Anti-RBD IgG values and NS% were positively correlated at T2 and T3 while anti-RBD IgG value predicting a NS% > 60 markedly differed at T2 and T3 (594 vs. 108 BAU/mL, respectively). Conclusion While a high neutralizing bioactivity was maintained at least 6 months after vaccination in almost all individuals, the mean values of anti-RBD-IgG showed a marked decline at 6 months. The absolute value of anti-RBD IgG is a poor marker of neutralizing bioactivity.

Over 30,000 protein-protein interactions with pathological implications have been identified; yet, discovering and investigating drugs that target these specific interactions is greatly limited by the inability to monitor native protein-protein interactions (PPIs) efficiently. The two most frequently used tools to monitor PPIs, resonance-energy transfer (RET) assays and protein complementation assays (PCA), face significant limitations. RET assays have a narrow working range of 10 to 50 A, while PCA require permanent attachment of a reporter probe to a protein of interest by chemical conjugation or genetic engineering. We developed a non-invasive assay platform to measure PPIs without modifications to the proteins of interest and is functional at a greater working range than RET assays. We demonstrate our approach by monitoring the EGFR-HER2 heterodimerization on relevant cell surfaces, utilizing various EGFR- and HER2-specific binders (e.g., Fab, DARPin, and VHH) fused with small fragments of a tri-part split-luciferase derived from NanoLuc®. Following independent binding of the binder fusions to their respective targets, the dimerization of EGFR and HER2 induces complementation of the luciferase fragments into a functional native structure, producing glow-type luminescence. We have confirmed the functionality of the platform to monitor EGFR-HER2 dimerization induction and inhibition. Statement of Significance We describe a platform technology for rapid monitoring of protein-protein interactions (PPIs). Our approach is uses a luciferase split into three parts – two short peptide “tags” and a large third fragment. Each of the short peptides can be fused to antibodies which bind to domains of a target antigens which orients the two tags and facilitates refolding of an active enzyme. To our knowledge this is the first example of a split-enzyme used to monitor PPIs without requiring any modification of the target proteins. We demonstrate our approach on the important PPI of HER2 and EGFR. Significantly, we quantify stimulation and inhibition of these partners, opening the possibility of using our approach to assess potential drugs without engineering cells.

We aimed to generate an unbiased estimate of the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in 4 urban counties in Utah, USA. We used a multistage sampling design to randomly select community-representative participants >12 years of age. During May 4–June 30, 2020, we collected serum samples and survey responses from 8,108 persons belonging to 5,125 households. We used a qualitative chemiluminescent microparticle immunoassay to detect SARS-CoV-2 IgG in serum samples. We estimated the overall seroprevalence to be 0.8%. The estimated seroprevalence-to-case count ratio was 2.5, corresponding to a detection fraction of 40%. Only 0.2% of participants from whom we collected nasopharyngeal swab samples had SARS-CoV-2–positive reverse transcription PCR results. SARS-CoV-2 antibody prevalence during the study was low, and prevalence of PCR-positive cases was even lower. The comparatively high SARS-CoV-2 detection rate (40%) demonstrates the effectiveness of Utah’s testing strategy and public health response.

Paramagnetic microspheres can be used in planar array fluorescence immunoassays for single or multiplex screening of food contaminants. However, no confirmation of the molecular identity is obtained. Coated blade spray (CBS) is a direct ionization mass spectrometry (MS) technique, and when combined with triple quadrupole MS/MS, it allows for rapid confirmation of food contaminants. The lack of chromatography in CBS, though, compromises the specificity of the measurement for unequivocal identification of contaminants, based on the European Union (EU) regulation. Therefore, a rapid and easy-to-use immuno-magnetic blade spray (iMBS) method was developed in which immuno-enriched paramagnetic microspheres replace the coating of CBS. The iMBS-MS/MS method was fully optimized, validated in-house following the EU 2021/808 regulation, and benchmarked against a commercial lateral flow immunoassay (LFIA) for on-site screening of DA. The applicability of iMBS-MS/MS was further demonstrated by analyzing incurred mussel samples. The combination of immunorecognition and MS/MS detection in iMBS-MS/MS enhances the measurement's selectivity, which is demonstrated by the rapid differentiation between the marine toxin domoic acid (DA) and its structural analog kainic acid (KA), which cannot be achieved with the LFIA alone. Interestingly, this first-ever reported iMBS-MS/MS method is generic and can be adapted to include any other immuno-captured food contaminant, provided that monoclonal antibodies are available, thus offering a complementary confirmatory analysis approach to multiplex immunoassay screening methods. Moreover, thanks to its speed of analysis, iMBS-MS/MS can bridge the logistics gap between future large-scale on-site testings using LFIAs and classical time-consuming confirmatory MS analysis performed in official control laboratories.

Introduction. The aim of the work was development of enzyme immunoassay for detecting I and II types of shiga-like toxins and assessment of it diagnostic properties. Materials and methods. For the research, we used hybridomas producing monoclonal antibodies to shiga-like toxins of types I and II, obtained at the branch of the Federal State Budgetary Institution “48 Central Research Institute” of the Ministry of Defense of Russian Federation (Kirov); BALB/c mice; shiga-like toxins of types I and II. Hybridoma cells were cultured in culture flasks and in the peritoneal cavity of BALB/c mice. Monoclonal antibodies were isolated from ascitic fluids by precipitation with a saturated solution of ammonium sulfate, followed by purification by ion exchange chromatography. The obtained preparations of monoclonal antibodies were used to develop enzyme immunoassay for the detection of shiga-like toxins of types I and II. Specific components of enzyme immunoassay were freeze-dried in a protective environment. Results. As a result of research, preparative quantities of monoclonal antibodies against I and II types of shiga-like toxins were obtained and purified; selection of monoclonal antibodies for sorption on the solid phase and for the synthesis of immunoperoxidase conjugates was carried out. Conclusion. Experimental enzyme immunoassay allowing to identify 1 ng/ml I and II types of shiga-like toxins in «sandwich»-ELISA was developed.

The xMAP food allergen detection assay (xMAP FADA) is an advanced multiplex immunoassay with multiple antibodies for each of 15 target food allergens and gluten, allowing for signal confirmation and antigenic profiling to occur in a single analysis. Botanicals used as spices are complex matrices for allergen analysis because they can exhibit inherent cross-reactivity with antibodies employed by the assays. Preliminary examinations of botanicals revealed chili peppers to have notably high levels of cross-reactivity with Brazil nut and hazelnut antibody bead sets in the xMAP FADA. This in-depth investigation of 29 pre-ground and whole chili peppers indicated Brazil nut and hazelnut cross-reactivity to be consistent among most members of genusCapsicum, although cross-reactive signals generated by chili peppers were distinguishable from signals indicative of target allergen detection. Using the requirements that complementary antibodies used in the assay generated positive responses and that the various secondary end points were characteristic of the target analytes, xMAP FADA reactivity to chilis of the genus Capsicum was categorized as cross-reactivity instead of confirmed detection of target allergenic foods.

Cytokine storm, known as an exaggerated hyperactive immune response characterized by elevated release of cytokines, has been described as a feature associated with life-threatening complications in COVID-19 patients. A critical evaluation of a cytokine storm and its mechanistic linkage to COVID-19 requires innovative immunoassay technology capable of rapid, sensitive, selective detection of multiple cytokines across a wide dynamic range at high-throughput. In this study, we report a machine-learning-assisted microfluidic nanoplasmonic digital immunoassay to meet the rising demand for cytokine storm monitoring in COVID-19 patients. Specifically, the assay was carried out using a facile one-step sandwich immunoassay format with three notable features: (i) a microfluidic microarray patterning technique for high-throughput, multiantibody-arrayed biosensing chip fabrication; (ii) an ultrasensitive nanoplasmonic digital imaging technology utilizing 100 nm silver nanocubes (AgNCs) for signal transduction; (iii) a rapid and accurate machine-learning-based image processing method for digital signal analysis. The developed immunoassay allows simultaneous detection of six cytokines in a single run with wide working ranges of 1–10,000 pg mL–1 and ultralow detection limits down to 0.46–1.36 pg mL–1 using a minimum of 3 μL serum samples. The whole chip can afford a 6-plex assay of 8 different samples with 6 repeats in each sample for a total of 288 sensing spots in less than 100 min. The image processing method enhanced by convolutional neural network (CNN) dramatically shortens the processing time ∼6,000 fold with a much simpler procedure while maintaining high statistical accuracy compared to the conventional manual counting approach. The immunoassay was validated by the gold-standard enzyme-linked immunosorbent assay (ELISA) and utilized for serum cytokine profiling of COVID-19 positive patients. Our results demonstrate the nanoplasmonic digital immunoassay as a promising practical tool for comprehensive characterization of cytokine storm in patients that holds great promise as an intelligent immunoassay for next generation immune monitoring.

A novel ultrasensitive electrochemiluminescence (ECL) immunoassay based on Au/CaCO3 was proposed for detecting ochratoxin A (OTA) in coffee. Au/CaCO3 nanocomposites synthesized using waste eggshells as the template with a large surface area and excellent electrochemical properties were applied for immobilizing a large amount of Ru(bpy)3 2+ and conjugating a high-affinity nanobody (prepared by the phage display technique). Coupling of the Au/CaCO3 nanocomposites and nanobody technologies provided an ultrasensitive and highly selective ECL immunosensor for OTA detection in the range of 10 pg/mL-100 ng/mL with a low detection limit of 5.7 pg/mL. Moreover, the as-prepared ECL immunosensor showed excellent performance and high stability. Finally, the proposed ECL sensor was applied to analyze OTA in coffee samples, confirming the desirable accuracy and practical applicability potential. Overall, this work presents a new nanomaterial for fabricating the sensing interface of immunosensors by harnessing natural waste as the source and a method for detecting toxic OTA in foods.

Although there are several reports in the literature of SARS‐CoV‐2 infection in cats, few SARS‐CoV‐2 sequences from infected cats have been published. In this study, SARS‐CoV‐2 infection was evaluated in two cats by clinical observation, molecular biology (qPCR and NGS), and serology (microsphere immunoassay and seroneutralization). Following the observation of symptomatic SARS‐CoV‐2 infection in two cats, infection status was confirmed by RT‐qPCR and, in one cat, serological analysis for antibodies against N‐protein and S‐protein, as well as neutralizing antibodies. Comparative analysis of five SARS‐CoV‐2 sequence fragments obtained from one of the cats showed that this infection was not with one of the three recently emerged variants of SARS‐CoV‐2. This study provides additional information on the clinical, molecular, and serological aspects of SARS‐CoV‐2 infection in cats., This study provides additional information on the clinical, molecular, and serological aspects of SARS‐CoV‐2 infection in cats.

Objective – integral analysis of effectiveness of anti-epidemic measures applied towards employees of the Amur gas processing plant assigned for rotational work under conditions of COVID-19 pandemic.Materials and methods. Sero-epidemiological study included a questionnaire survey of 1461 workers who arrived through the “clean corridor” in the Amur Region, followed by sampling of biological material (blood and respiratory smears). Testing of blood sera for the presence of antibodies to SARS-CoV-2 of two classes (IgM and IgG) was carried out applying enzyme immunoassay. Using PCR, respiratory smears were examined for the presence of the agent RNA in them. Statistical processing of the results obtained was carried out using conventional methodsResults and discussion. The presence of antibodies of the IgG class was revealed in (4.7±0.55) % of cases. In a small cohort (1.7±0.34 %) of practically healthy individuals, asymptomatic infection was detected, confrmed either by a positive PCR result (0.76±0.23 %), or by the detection of IgM antibodies (1.0±0.08 %). On the basis of the study carried out by the Federal Service for Surveillance in the Sphere of Consumer Rights Protection and Human Welfare on August 01, 2020, “Temporary recommendations on the procedure for admitting to work on a rotational basis under the risk of COVID-19 spread in the Amur Region” were approved. These recommendations set out the algorithm for observation of incoming workers and the order for triage of shift workers after testing by ELISA and PCR. The results of the study demonstrate the effectiveness of anti-epidemic measures related to ensuring the procedure for admission to work on a rotational basis under the risks of the spread of COVID-19.

Agricultural product contamination by endocrine-disrupting compounds (EDCs) residues is an international public health issue and requires continuously stringent administration. A high-throughput biotin-streptavidin-amplified enzyme-linked immunosorbent assay (BA-ELISA) for detection of progesterone (P4) has been established to be applied in determining milk samples. Under experimental optimization, BA-ELISA based on anti-P4-specific antibody (P4-pAb-based BA-ELISA) showed a linear range from 0.44 to 31.06 ng/mL. The IC50 was 3.68 ng/mL, and the limit of detection (LOD) was 1.25 × 10−1 ng/mL, with negligible cross-reactivities on structural P4 analogues. The signal amplification system enhanced sensitivity on account of strongly supramolecular affinity between biotin and streptavidin. Good recoveries ranged from 87.81 to 113.11%, and low coefficient of variation (below 9.75%) of the immunoassay validated the feasibility and applicability to monitor P4 in milk samples. Milk samples with different spiked levels were tested by both the established P4-pAb-based BA-ELISA and liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS). Our results, combined with the advantages of specific antibodies, elucidated that P4-pAb-based BA-ELISA is an applicable method for routine screening analysis of P4.

We developed a novel surface‐enhanced Raman scattering (SERS)‐based SARS‐CoV‐2 assay platform using hollow Au nanostars to realize high‐sensitivity diagnosis of SARS‐CoV‐2. The assay was performed using SARS‐CoV‐2 lysate as the target in a wide dynamic range with virus concentrations ranging from 0 to 104 PFU/ml and has a limit of detection (LOD) of 5.1 PFU/ml. This LOD value shows 100 times and 10 times better sensitivity compared to the LODs measured on the same sample using a commercially available rapid kit and enzyme‐linked immunosorbent assay, respectively. Therefore, we believe that this SERS‐based SARS‐CoV‐2 assay platform has high diagnostic accuracy for early or asymptomatic infected patients with low virus concentrations. Furthermore, the probability of a false‐negative diagnosis is likely to be very low., A new magnetic bead‐based SERS assay platform was developed to overcome the sensitivity limit of the commercially available SARS‐CoV‐2 immunodiagnostic kits. A novel hollow gold nanostars (HAuNSs), with a high enhancement factor and good stability, was employed for the detection of nucleocapsid protein from SARS‐CoV‐2. The assay could be performed in a wide dynamic range with virus concentrations ranging from 10−2 to 104 PFU/ml and showed an LOD value of 5.1 PFU/ml using this platform.

In this study, we report a new method to prepare highly sensitive monoclonal antibody against α-zearalanol (ZAL) based on a similar antigen determinant structure. Zearalanone (ZAN), structural analogs of ZAL, was modified by oximation to obtain ZAN-O. ZAN-O was then coupled with bovine serum albumin using 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (EDC) to synthesise the artificial complete antigen ZAN-O-BSA. ZAN-O-BSA was used to immunise the BALB/c mice. The splenocytes of the immunised mice were fused with myeloma NS0 cells. During the process of cell fusion, ZAL was used as an inhibitor instead of ZAN to screen the hybridoma cell lines that can secrete monoclonal antibodies against ZAL. The sensitivity (half inhibitory concentration, IC50) of the prepared monoclonal antibody was 0.475 ng/ml, the limit of detection (LOD) was 0.050 ng/ml, the linear range of detection was 0.066-3.399 ng/ml, the affinity constant Kaff was 6.18×107 l/mol, the cross-reactivity rate with structural analogues, such as β-zearalanol, α-zearalenol, β-zearalenol, ZAN and zearalenone were 28.07, 13.16, 15.83, 60.28 and 7.95% respectively. The cross-reactivity with other mycotoxin and carrier proteins were all less than 0.05%. The prepared monoclonal antibody can be used to establish a highly sensitive immunoassay for the detection of ZAL.

Detection of antinuclear antibodies (ANA) by immunofluorescence assay (IFA) is increasingly substituted by multiplex bead-based immunoassay (MBA) and line-blot immunoassay (LIA). This study is to compare the diagnostic performance of MBA and LIA ANA assays on clinically characterized patient samples.A total of 728 serum samples from 385 patients with systemic autoimmune rheumatic diseases (SARD), 204 patients with non-SARD diseases, and 139 apparently healthy subjects were tested with the BioPlex 2200 ANA Screen and EuroLine ANA Profile 3 as the representative MBA and LIA technologies and HEp-2 ANA IFA. Clinical data were collected independent of laboratory analysis and later related to the ANA test results. The clinical diagnostic performances were analyzed using Analyse-it software.The MBA demonstrated higher area under curve (AUC) compared to LIA (0.814 vs 0.761, p = 0.002) and HEp-2 IFA (0.814 vs 0.771, p = 0.008). The MBA and LIA ANA methods showed higher specificity (83.8% and 77.0% vs 67.6%, p 0.001 and p = 0.005) but lower sensitivity (79.0% and 75.3% vs 86.5%, p 0.001) compared to HEp-2 IFA. The MBA and LIA ANA revealed substantial to excellent agreements on specific antinuclear antibodies except anti-dsDNA, with the total agreement from 92.3 to 99.9% and Cohen's kappa from 0.71 to 0.98. The MBA demonstrated significantly higher sensitivity (58.1% vs 19.8%, p 0.001) and comparable specificity (95.9% vs 97.5%, p = 0.221) on anti-dsDNA assay for the diagnosis of SLE compared to LIA.The MBA and LIA ANA assays have higher specificity but lower sensitivity compared to HEp-2 IFA. There are good agreements between MBA and LIA ANA for the specific antinuclear antibodies except for anti-dsDNA. The MBA ANA demonstrated better assay performance compared to LIA as the MBA possesses higher sensitivity and specificity in the diagnosis of SARD. Key Points • The multiplex bead-based immunoassay (MBA) ANA outperformed line-blot immunoassay (LIA) and traditional HEp-2 IFA. • There are good agreements between the MBA BioPlex 2200 ANA Screen and LIA EuroLine ANA Profile 3 for the most of specific antinuclear antibodies except anti-dsDNA. • Additional anti-dsDNA testing is suggested when EuroLine ANA Profile 3 is used for the aid of SLE diagnosis and management. • The positive predictive value of both multiplex ANA assays can be substantially increased without significantly affecting negative predictive value by using at least two specific antinuclear antibodies for reporting a positive ANA result.

Background: Cryptosporidium species are intestinal parasites that infect both humans and animals; it causes cryptosporidiosis which usually resulted to diarrhea especially among those with impaired immunity. It was observed that enzyme linked immunosorbent assay (ELISA) be ascertain was never been used as one of the techniques in the detection of Cryptosporidium parvum antigen in Maiduguri, Borno state. Materials and Methods: Four hundred stool and blood samples were collected in four selected hospitals in the study area. Stool samples were analyzed by Enzyme link immunosorbent assay to detect fecal Cryptosporidium antigen, while the blood samples were analyzed with Partec sysmex ® flow cytometric machine for CD4 T-lymphocyte counts. Results: Demographically, female are 275 while male 125 in number. The result of the stool samples have shown that, of the four hundred samples, seventy nine (79) patients were positive for Cryptosporidium species with an infection rate of 19.8%. According to gender, females have the highest infection rate of 14.25% while males 5.5%.based on age, patients between the ages of 20-39 have the highest prevalence of 9.5% followed by 40-59 with 7.5% and lastly 0-19 and >60 old are1.25 and 1.5% respectively. Traders (businessmen and women) demonstrated the highest infection rate of 8.0% followed by housewives 6.25%, civil servants 4.25% and lastly student and farmer with 1.0 and 0.25% respectively. In terms of CD4-T-lymphocyte count, those with CD4 500 with 4.5%. on the bases of clinical details, the results have shown that patients with diarrhea has a prevalence of 13.0% while those without diarrhea has 6.75%, however, according to the hospitals the patients attended, the result has that, USUMH has 7.0%.Followed by UMTH 6.5%, SSHM 3.75%, and MSMH 2.5% respectively. Conclusion: It was concluded that those with cd4 count bellow 200 are at risk of contacting the parasites and hence is one of the causes of diarrhea among HIV patients. It is recommended that proper hygiene practice should be encouraged.

Given the great harm of pesticide residues to the environment and public health, exploring ultrasensitive and low-cost methods for their quantitative analysis becomes intensely necessary. Herein, we proposed a double-functionalized gold nanoparticle (AuNP) probe as a signal amplification immunoassay for the detection of acetochlor (ATC), metolachlor, and propisochlor. The AuNP was modified with IgG and fluorophore-labeled duplex DNA by a polyadenine-based freezing method. The quenched fluorescence can be effectively recovered via duplex-specific nuclease (DSN) with excellent cleaving activity. This approach provided limits of detection (LODs) down to 0.03 ng/mL for ATC, 0.10 ng/mL for metolachlor, 0.14 ng/mL for propisochlor, and 0.08 ng/mL for their mixture. The average recoveries of ATC, metolachlor, and propisochlor were 93.0-106.6% from a corn sample, which are in good agreement with the commercial kit (R2 = 0.9995). This "turn-off" fluorescence immunoassay presents considerable potential in the analysis of chloroacetamide herbicide due to its simple process of probe preparing and ultrahigh sensitivity.

PURPOSE The Immulite® thyroid stimulating immunoglobulin (TSI) immunoassay is a relatively new commercial assay that has shown good diagnostic accuracy in Graves' hyperthyroidism (GH). However, its clinical utility in thyroid-associated orbitopathy (TAO) is less clear. The purpose of this study was to assess the diagnostic accuracy of the Immulite® TSI immunoassay for TAO and investigate the associations between TSI and other clinical measures. METHODS One hundred and forty patients that had been diagnosed with GH within the previous 12 months were recruited. Identification and grading of TAO were performed at enrolment and serum samples were analysed using the Immulite® TSI immunoassay. RESULTS Of the 140 participants recruited, 75 (53.6%) had TAO. Age, sex and time since GH diagnosis were similar between those with and without TAO (p ≥ 0.300). TSI level tended to decrease with increasing time from GH diagnosis (Spearman's ρ - 0.28, 95% CI - 0.43, - 0.12). TSI levels were higher among those with than those without TAO (median 4.0 vs. 2.7 IU/L, respectively, p = 0.037). There was no correlation between TSI level and inflammatory index score (ρ = 0.14, 95% CI - 0.03, 0.30) or clinical severity (p = 0.527) among those with TAO. TSI level showed poor diagnostic accuracy for TAO (area under the receiver operating characteristic curve 0.60, 95% CI 0.51, 0.70). CONCLUSIONS Although Immulite® TSI level was higher in the presence of TAO, it showed poor diagnostic accuracy and no correlation with clinical markers of TAO severity or activity.