Magnetic Immunoassay Research Articles

Resolving ambiguities in core size determination of magnetic nanoparticles from magnetic frequency mixing data

Frequency mixing magnetic detection (FMMD) has been widely utilized as a measurement technique in magnetic immunoassays. It can also be used for the characterization and distinction (also known as “colourization”) of different types of magnetic nanoparticles (MNPs) based on their core sizes. In a previous work, it was shown that the large particles contribute most of the FMMD signal. This leads to ambiguities in core size determination from fitting since the contribution of the small-sized particles is almost undetectable among the strong responses from the large ones. In this work, we report on how this ambiguity can be overcome by modelling the signal intensity using the Langevin model in thermodynamic equilibrium including a lognormal core size distribution fL(dc,d0,σ) fitted to experimentally measured FMMD data of immobilized MNPs. For each given median diameter d0, an ambiguous amount of best-fitting pairs of parameters distribution width σ and number of particles Np with R2 > 0.99 are extracted. By determining the samples’ total iron mass, mFe, with inductively coupled plasma optical emission spectrometry (ICP-OES), we are then able to identify the one specific best-fitting pair (σ, Np) one uniquely. With this additional externally measured parameter, we resolved the ambiguity in core size distribution and determined the parameters (d0, σ, Np) directly from FMMD measurements, allowing precise MNPs sample characterization.

Application of Magnonic Crystals in Magnetic Bead Detection.

This paper aims at studying a sensor concept for possible integration in magnetic field-based lab-on-chip devices that exploit ferromagnetic resonance (FMR) phenomena in magnonic crystals. The focus is on 2D magnetic antidot arrays, i.e., magnetic thin films with periodic non-magnetic inclusions (holes), recently proposed as magnetic field sensor elements operating in the gigahertz (GHz) range. The sensing mechanism is here demonstrated for magnetic nano/microbeads adsorbed on the surface of permalloy (Ni80Fe20) antidot arrays with a rhomboid lattice structure and variable hole size. Through extensive micromagnetic modelling analysis, it is shown that the antidot arrays can be used as both bead traps and high-sensitivity detectors, with performance that can be tuned as a function of bead size and magnetic moment. A key parameter for the detection mechanism is the antidot array hole size, which affects the FMR frequency shifts associated with the interaction between the magnetization configuration in the nanostructured film and the bead stray field. Possible applications of the proposed device concept include magnetic immunoassays, using magnetic nano/microbeads as probes for biomarker detection, and biomaterial manipulation.

Comparison of Anti-Salmonella Typhi IgM Examination Results with SD Bioline and Tubex TF. Methods

Salmonella typhi is a gram-negative bacterium that is an intracellular facultative pathogen, which enters the human body and causes an acute systemic infectious disease called typhoid fever. Among the laboratory tests used to detect the presence of anti-Salmonella typhi IgM in serum are SD Bioline and Tubex TF. This study aims to determinecomparison of the results of the anti-Salmonella typhi IgM examination with the SD Bioline and Tubex TF methods. Analytical observation with cross-sectional design. This research was conducted in RSUD DR. Soedjono Selong. The time of the study was January-April 2022. The sample of this study was patients who underwent typhoid fever examination who were hospitalized at RSUD DR. Soedjono Selong as many as 60 people. This research uses the method consecutive sampling, Anti-Salmonella typhi IgM was examined with the SD Bioline kit using the immunochromatography method and the TUBEX TF kit using the Inhibition Magnetic Binding Immunoassay (IMBI) method. Data analysis was performed using SPSS, namely univariate test, and bivariate test with Chi-square. There were 26 (43.3%) male and 34 (56.7%) female patients. The youngest is 2 years old and the oldest is 64 years old with an average age of 25 years ± 19 years. Of the total 60 patients examined with SD Bioline, 5 (8.3%) were positive and 55 (91.7%) were negative. Meanwhile, examination with TUBEX TF found 3 (5%) positive people and 57 (95%) negative people. And there was a significant comparison between the results of the SD Bioline and Tubex TF examination with a value (p = 0.000) and a low level of conformity was obtained with a Kappa value of 0.000. A comparison of the results of the IgM anti-Salmonella typhi examination was obtained using the SD Bioline and Tubex TF . methodswith a very low degree of conformity.

Mechanistic insights into phenanthrene acropetal translocation via wheat xylem: Separation and identification of transfer proteins.

Polycyclic aromatic hydrocarbons (PAHs) have the potential to cause cancer, teratogenicity, and mutagenesis in humans. Long-term plant safe production relies on how PAHs are transported and coordinated across organs. However, the acropetal transfer mechanism of PAHs in staple crop stems, particularly in xylem, a critical path, is unknown. Herein, we first confirmed the presence of specific interaction between the proteins and phenanthrene by employing the magnetic phenanthrene-bound bead immunoassay and label free liquid chromatograph mass spectrometer (LC-MS/MS), suggesting that peroxidase (uniprot accession: A0A3B5XXD0) and unidentified proteins (uniprot accession: A0A3B6LUC6) may function as the carriers to load and acropetally translocate phenanthrene (a model PAH) in wheat xylem. This specified binding of protein-phenanthrene may form through hydrophobic interactions in the conservative binding region, as revealed by protein structural investigations and molecular docking. To further investigate the role of these proteins in phenanthrene solubilization, phenanthrene exposure was conducted: a substantial quantity of peroxidase was produced; an unusually high expression of uncharacterized proteins was observed, indicating their positive effects in the acropetal transfer of phenanthrene in wheat xylem. These data confirmed that the two proteins are crucial in the solubilization of phenanthrene in wheat xylem sap. Our findings provide fresh light on the molecular mechanism of PAH loading in plant xylem and techniques for ensuring the security of staple crops and improving the efficacy of phytoremediation in a PAH-contaminated environment.

Magnetic relaxation switching immunoassay for chlorpyrifos using enzyme-mediated Fe2+/Fe3+ conversion and magnetic separation

Since pesticide residues in food have attracted increasing concern worldwide, it is crucial to develop rapid and sensitive analytical methods to detect pesticide residues and ensure food safety. In this work, via the biotin-streptavidin (SA) recognition system, we constructed a magnetic relaxation switching (MRS) immunosensor for sensitive detection of chlorpyrifos (CPF). With a competitive immunoassay mode, H2O2 and Fe2+ were firstly optimized as the reaction substrates. Wherein, horseradish peroxidase (HRP) acted as enzyme label to catalyze H2O2 and mediated the conversion of Fe2+/Fe3+. By introducing Fe2+/Fe3+ interconversion as MRS signal output, CPF was detected by the immunoreaction induced variations of the transverse relaxation time (ΔT2). The proposed MRS immunosensor exhibited a detection linear range from 0.01 to 1000 ng mL−1 (R2 = 0.9916), with the limit of detection (LOD) of 6 pg mL−1 (3S/M, n = 3). As a proof-of-concept, CPF was easily detected among five different pesticides at a low concentration level (0.1 ng mL−1), as well as in real samples (apple, tea, and lettuce) with recoveries of 80.70–115.30%. Besides, the sensor can realize one step of “separation and detection” towards CPF with the aid of magnetic nanoparticles, which demonstrate its promising potential for pesticide residue detection in food samples and environment.

Deciphering the Significance of Plasma Chemokines as Prognostic Biomarkers in Pegylated IFN-Α-2a /Ribavirin-Treated Chronic Hepatitis C Genotype 4 Patients.

Hepatitis C viral (HCV) infection is a major clinical burden globally. Pegylated IFN-α-2a (PEG-IFN-α-2a) with ribavirin (RIB) therapy induces an array of cellular antiviral responses, including dsRNA kinases (PKR), chemokines, and cytokines to tackle the HCV infection. However, many HCV patients develop resistance to PEG-IFN/RIB therapy rendering the therapy ineffective. Here, we assess the significance of chemokines in response to PEG-IFN-α-2a with ribavirin (PEG-IFN/RIB) therapy. Twenty patients with HCV infection and ten healthy controls were enrolled in this study and patients were categorized into two groups 1), HCV-Responder (HCV-R), and 2) HCV-non-responder (HCV-NR). We analyzed IP-10, MIG, MCP-1, EOTAXIN, RANTES, IL-8, MIP-1a, and MIP-1b by a magnetic bead-based multiplex immunoassay approach based on Luminex X-MAP multiplex technology, using a MAGPIX instrument (Luminex Corporation, USA). A significant elevation of ALT and AST enzymes was observed in HCV-NR. Besides, the PEG-IFN/RIB therapy in both MIG and MCP-1 in HCV-NR patients was significantly induced. PEGIFN/ RIB therapy significantly increased the levels of chemokines, such as IL-8, IP-10, EOTAXIN, MIG, RANTES, and MIP-1β, in HCV-R, indicating the chemokine response to PEG-IFN/RIB therapy. Hence, MCP-1 and MIG could be the potential biomarkers in HCV-NR and might be associated with the development of liver fibrosis, liver failure, and hepatocellular carcinoma. Our study has only twenty samples of PEG-IFN/RIB treated HCV patients. This might be the reason for the lack of association between some of the inflammatory markers evaluated and the SVR, therefore, the association found between the chemokine levels observed in the plasma of HCV-R and HCV-NR and EVR cannot be extrapolated to patients infected with other HCV genotypes.

Levels of eicosanoids in nasal secretions associated with nasal polyp severity in chronic rhinosinusitis

Severe nasal polyposis and mucosal inflammation, in patients with chronic rhinosinusitis (CRS) may include a dysregulated eicosanoid profile, but a clinical role for eicosanoids in CRS with nasal polyps (NP; CRSwNP) remains to be elucidated. This study focused on assessing levels and clinical implications of inflammatory mediators in nasal secretions and urine from patients with different NP severity or Aspirin Exacerbated Respiratory Disease (AERD). Levels of leukotrienes E4 and B4, prostaglandins D2 and E2 as well as 15(S)-hydroxyeicosatetraenoic acid were measured with enzyme immunoassays and cytokines with magnetic bead immunoassays. Patients with CRSwNP were subdivided based on NP score; CRSwNP-low (NP score ≤ 4, n = 11) or CRSwNP-high (NP score ≥ 5, n = 32) and compared to CRS without polyps (CRSsNP, n = 12), CRSwNP-AERD (n = 11) and individuals without CRS (n = 25). Smell test score, fractional exhaled nitric oxide (FeNO), blood eosinophils and Sinonasal outcome test-22 were assessed as clinical markers. Leukotriene E4, prostaglandin D2 and 15(S)-hydroxyeicosatetraenoic acid in nasal secretions correlated with NP score. Nasal leukotriene E4 also correlated with FeNO and smell test score, with highest levels found in CRSwNP-AERD. Levels of prostaglandin D2 in nasal secretion as well as urinary levels of the prostaglandin D2 metabolite 11β-prostaglandin F2α differed between CRSNP-high and CRSwNP-low. Urinary 11β-prostaglandin F2α was associated with asthma comorbidity whereas a similar association with prostaglandin D2 in nasal secretions was not observed. In conclusion, subdividing patients based on NP severity in combination with analysis of eicosanoids in non-invasively collected nasal secretions, may have clinical implications when assessing CRS disease severity.

Recent Developments in Innovative Magnetic Nanoparticles-Based Immunoassays: From Improvement of Conventional Immunoassays to Diagnosis of COVID-19.

During the ongoing COVID-19 pandemic, the development of point-of-care (POC) detection with high sensitivity and rapid detection time is urgently needed to prevent transmission of infectious diseases. Magnetic nanoparticles (MNPs) have been considered attractive materials for enhancing sensitivity and reducing the detection time of conventional immunoassays due to their unique properties including magnetic behavior, high surface area, excellent stability, and easy biocompatibility. In addition, detecting target analytes through color development is necessary for user-friendly POC detection. In this review, recent advances in different types of MNPs-based immunoassays such as improvement of the conventional enzyme-linked immunosorbent assay (ELISA), immunoassays based on the peroxidase-like activity of MNPs and based on the dually labeled MNPs, filtration method, and lateral-flow immunoassay are described and we analyze the advantages and strategies of each method. Furthermore, immunoassays incorporating MNPs for COVID-19 diagnosis through color development are also introduced, demonstrating that MNPs can become common tools for on-site diagnosis.

Computer Numerical Control Micromilling of a Microfluidic Acrylic Device with a Staggered Restriction for Magnetic Nanoparticle-based Immunoassays.

Microfluidic systems have greatly improved immunoassay techniques. However, many microfabrication techniques require specialized, expensive, or complicated equipment, making fabrication costly and incompatible with mass production, which is one of the most important preconditions for point-of-care tests (POCT) to be adopted in low-resource settings. This work describes the fabrication process of an acrylic (polymethylmethacrylate, PMMA) device for nanoparticle-conjugated enzymatic immunoassay testing using the computer numerical control (CNC) micromilling technique. The functioning of the microfluidic device is shown by performing an immunoassay to detect a commercial antibody using lysozyme as a model antigen conjugated to 100 nm magnetic nanoparticles. This device integrates a physical staggered restriction of only 5 µm in height, used to capture magnetic microparticles that make up a magnetic trap by placing an external magnet. In this way, the magnetic force on the immunosupport of conjugated nanoparticles is enough to capture them and resist flow drag. This microfluidic device is particularly suitable for low-cost mass production without the loss of precision for immunoassay performance.

Computer Numerical Control Micromilling of a Microfluidic Acrylic Device with a Staggered Restriction for Magnetic Nanoparticle-Based Immunoassays

Computer Numerical Control Micromilling of a Microfluidic Acrylic Device with a Staggered Restriction for Magnetic Nanoparticle-Based Immunoassays

A Fluorescence-Based Competitive Antibody Binding Assay for Kynurenine, a Potential Biomarker of Kidney Transplant Failure.

Kynurenine is a tryptophan metabolite linked to several inflammatory processes including transplant failure, a significant challenge in transplant medicine. The detection of small molecules such as kynurenine, however, is often complex and time consuming. Herein, we report the successful synthesis of a fluorescently labelled kynurenine derivative, showing proper fluorescence and anti-kynurenine antibody binding behavior in a magnetic bead immunoassay (MIA). The fluorescent kynurenine–rhodamine B conjugate shows a KD-value of 5.9 µM as well as IC50 values of 4.0 µM in PBS and 10.2 µM in saliva. We thus introduce a rapid test for kynurenine as a potential biomarker for kidney transplant failure.

Circulating nucleosomes to identify non-smoker subjects at risk of lung cancer and triage them for low-dose CT scan.

e20558 Background: Lung cancer (LC) is the leading cause of cancer death worldwide and the most frequently occurring in men and the second most diagnosed cancer in woman after breast cancer. The primary risk factor leading to LC is tobacco smoke. Nevertheless, several studies in the US, UK and Asia reported an increasing rate of LC in non-smokers. 15-20% of LC patients worldwide are non-smokers with this percentage rising to 60% in non-smoking women in Asia. Current LC screening guidelines recommend a CT scan only for high-risk smokers. Despite there being no guidelines to recommend LC screening in non-smokers those with increased risk factors could be monitored. Therefore, a blood-test could offer a simple way to identify non-smokers at high-risk of LC and triage them to go for low-dose CT scan. Methods: We measured circulating levels of nucleosomes and CEA in 722 non-smoker subjects referred for CT scan at National Taiwan University Hospital. The patients were later confirmed to have either a LC (n = 509, including 401 patients at stage 0-1), non-malignant nodules (n = 142), or no-nodules (n = 71). Whole blood was collected in EDTA plasma tubes for analysis by six different Nu.Q chemiluminescent magnetic microparticle immunoassays (Belgian Volition SRL, Belgium) targeting H3.1-nucleosomes or different histone modifications (H3K9Me3-, H3K27Me3-, H3K36Me3-, H3K9Ac-, H3K14Ac-nucleosomes). CEA was analyzed on the Abbott ARCHITECT analyzer. We defined by logistic regression the best combination of biomarkers to identify LC cases in this non-smoking population in a rule-in approach. Results: At 95% specificity, none of the individual biomarkers exceed 24.8% of sensitivity for LC vs non-malignant nodules and no nodules. A combination of 2 nucleosome biomarkers: H3K9Me3- and H3K9Ac-nucleosomes with CEA in a logistic regression model showed improved sensitivity detecting 32.4% of LC in the non-smoker subjects at 95% specificity for LC vs non-malignant nodules and no nodules (area under the curve (AUC): 0.76, R2: 19.1%). In a non-smoking women sub-group by adding a third nucleosome biomarker: H3K36Me3-nucleosomes to the model we could detect 34.3% of the women who have lung cancer at 95% specificity (AUC: 0.75; R2: 20.2%). Conclusions: Our results indicate that a blood test combining circulating nucleosomes targeting different epigenetic modifications with CEA allow the detection of LC cases in a non-smokers population. This blood test could be part of the screening criteria for the non-smoking population at risk to develop LC and could help to triage them for low-dose CT scan.

High specificity lung cancer test to rule out cancer in non-malignant lung nodules found at LDCT.

e20533 Background: Lung Cancer (LC) is the leading cause of cancer death worldwide and smoking is the leading risk factor. Only 15% of patients with LC are still alive 5 years after diagnosis due to advanced diseases stage at diagnosis. Low-Dose Computed Tomography (LDCT) is the widely accepted standard for screening of individuals at high risk of lung cancer. However, LDCT has several limitations including the high prevalence of non-malignant pulmonary nodules detected leading to overdiagnosis, the potential harms of cumulative radiation dose and poor adherence to recommended follow-up. Therefore, novel blood-based tests could offer a simple follow confirmation approach and this test is designed to find those patients who DO NOT have cancer. Methods: We measured levels of nucleosomes, CEA and CYFRA21-1in a cohort of 912 subjects and report data relating to 184 smoker subjects referred for CT scan at National Taiwan University Hospital. The smoker patients were later confirmed to have either a LC (n = 129, including 59 patients at early stage (stage 0-I), 15 at stage II, 47 at late stage (III and IV) and 8 with unknown stage), or non-malignant nodules (n = 41), or control with no-nodules (n = 14). Whole blood was collected in EDTA plasma tubes for analysis by six different Nu.Q chemiluminescent magnetic microparticle immunoassays (Belgian Volition, Belgium) targeting H3.1-nucleosomes or different histone modifications (H3K9Me3-, H3K27Me3-, H3K36Me3-, H3K9Ac-, H3K14Ac-nucleosomes). CEA was analyzed on the Abbott ARCHITECT analyzer. CYFRA21-1 was analyzed on the Roche Cobas E411 analyzer. We evaluated each biomarker levels individually and in a combinatorial approach by logistic regression for their performance in discriminating subject with a LC vs non-malignant nodules. Results: Among the eight individual markers evaluated, the best area under the curve (AUC) in discriminating LC vs non-malignant nodule were observed for CEA, H3K9Ac-nucleosomes and CYFRA21-1 with an AUC of 0.68, 0.69 and 0.74, respectively and a specificity at 95% sensitivity of 9.5%, 7.3% and 21.4%, respectively. A logistic regression approach defined H3K9Ac-nucleosomes, CEA and CYFRA21-1 as the best panel of biomarkers tested to improve the discrimination between LC and non-malignant nodules relatives to the markers alone, achieving a specificity of 34.1% at 95% sensitivity and an AUC of 0.80. 55 out of the 59 stage 0-I, 25/26 stage III and 20/21 stage IV LC were detected by this combination of markers while 34.1 % of the patients with benign nodules are found negative and not sent to unnecessary biopsy to ascertain the nodule status. Conclusions: Results of our proof-of-concept study indicate that a blood test combining H3K9Ac-nucleosome levels with CEA and CYFRA21-1 levels could help to rule-out patients with a non-malignant nodule offering a non-invasive tool as an aid to the decision-making process of the malignancy status of nodules detected by LDCT.

Immunogenicity and safety of an inactivated SARS-CoV-2 vaccine in people living with HIV: A cross-sectional study.

We aimed to analyze the efficacy and safety of an inactivated SARS‐CoV‐2 vaccine in people living with HIV (PLWH). A total of 143 PLWH and 50 healthy individuals were included in this study. A commercially available magnetic chemiluminescence enzyme immunoassay kit was used to detect serum IgG and IgM antibodies against SARS‐CoV‐2. Serum levels of SARS‐CoV‐2‐specific IgG were significantly higher in the control group than in the PLWH group (p = 0.001). Overall, 76% of individuals in the control group were detected with seropositivity IgG against SARS‐CoV‐2 compared to 58% in the PLWH group (p = 0.024). In PLWH with IgG seropositivity, CD4+ T‐cell counts before antiretroviral therapy (ART) was higher (p = 0.015). Multivariable analysis indicated that CD4+ T cells at IgG detection (odds ratio [OR] = 1.004, p = 0.006) and time after vaccination (OR = 0.977, p = 0.014) were independently associated with seropositivity IgG against SARS‐CoV‐2 in PLWH. Neutralizing antibody (nAb) titers in PLWH against wild‐type SARS‐CoV‐2 were similar to those in the control group (p = 0.160). The proportion of seropositive nAbs against wild‐type SARS‐CoV‐2 was also similar (95% in the control group vs. 97% in the PLWH group, p = 0.665). Similar results were obtained when nAb was detected against the delta variants with similar titers (p = 0.355) and a similar proportion of seropositive nAbs were observed (p = 0.588). All the side effects observed in our study were mild and self‐limiting. The inactivated COVID‐19 vaccine appears to be safe with good immunogenicity in Chinese PLWH.

Cytokine Profile in Aqueous Humor of Patients With Ocular Toxocariasis.

PurposeOcular toxocariasis (OT) is a vision-threatening disease with a largely unknown intraocular pathogenesis. Herein, we determined the cytokine expression profile in aqueous humor (AH) of patients with OT.MethodsThis is a retrospective case-control study of cytokine levels in AH of patients with OT and uveitis and control subjects. Thirty samples from eyes with OT, 23 from eyes with non-OT uveitis, and 25 from eyes with age-related cataract were analyzed using a multiplexed magnetic bead immunoassay. Thirty-one cytokines were detected and classified into 5 categories: T-helper type 1 (Th1) -associated cytokines, Th2-associated cytokines, Th17 cytokine, proinflammatory mediators, and growth factors.ResultsIn the 31 cytokines, 9 cytokines were undetectable, including IL-1a, IL-1b, IL-2, IL-3, IL-12p70, IL-17A, TGF-a, TNF-β, and IFN-g. From the 22 cytokines, 13 exhibited significantly increased expression in the OT group than in the control group, including TNF-a, IFN-a2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, sCD40L, PDGF-AA, PDGF-AB/BB, FLT3l, and EGF. There were 5 cytokines exhibited significantly increased expression in the OT group than in non-OT group, including IL-5, IL-9, IL-10, IL-13, and PDGF-AA. There was no significantly decreased expression in any cytokines in the OT group when compared with control or non-OT groups. To the 5 cytokines that showed significant difference in OT group alone, IL-10 and IL-13 exhibited more than 13-fold increase, and IL-5 showed the most obvious as 27-fold increase in OT patients, when compared with that in control group.ConclusionThe cytokine profile expression in aqueous humor from patients with ocular toxocariasis was investigated, and our findings suggest that Th1 and Th17 cytokine responses are not enhanced, whereas the cytokine status was polarized toward a Th2 response. Our findings also suggest the involvement of IL-5, IL-10, and IL-13 in the immunopathogenesis of ocular toxocariasis.

Postnatal Cytomegalovirus Infection May Increase the Susceptibility of Tuberous Sclerosis Complex to Autism Spectrum Disorders.

ABSTRACTAutism spectrum disorder (ASD), a highly hereditary and heterogeneous neurodevelopmental disorder, is influenced by genetic and environmental factors. Tuberous sclerosis complex (TSC) is a common syndrome associated with ASD. Cytomegalovirus (CMV) infection is an environmental risk factor for ASD. The similarities in pathological and mechanistic pathways of TSC and CMV intrigued us to investigate whether CMV and TSC interacted in ASD’s occurrence. We detected CMV IgG seroprevalence of 308 TSC patients from our prospective cohort (September 2011 to March 2021) and 93 healthy children by magnetic particle indirect chemiluminescence immunoassay. A total of 206 TSC patients enrolled were divided into ASD and non-ASD groups, and the relationship between ASD and CMV seroprevalence was analyzed. Nested PCR and Western blot were used to detect CMV DNAs and proteins in cortical malformations of seven TSC patients with and without ASD. No difference was found in CMV seroprevalence between TSC patients and healthy children (74.0% versus 72.0%, P = 0.704). Univariate analysis showed the seroprevalence in TSC patients with ASD was higher than that in TSC patients without ASD (89.2% versus 75.1%, P = 0.063), and multifactorial analysis showed that CMV seroprevalence was a risk factor for ASD in TSC patients (OR = 3.976, 95% CI = 1.093 to 14.454). Moreover, CMV was more likely to be detected in the cortical malformations in TSC patients with ASD but not in those without ASD. The findings demonstrated that CMV may increase the susceptibility of TSC to ASD.IMPORTANCE CMV is an environmental risk factor for ASD, but its role in syndromic autism with known genetic etiology has been rarely studied. The pathogenesis of ASD is related to the interaction between environmental and genetic factors. This study demonstrated that CMV can contribute to the occurrence of ASD related to TSC, a common genetic syndrome associated with ASD. Our findings provided support for the theory of gene-environment interaction (G × E) in pathogenesis of ASD and a new perspective for the prevention and therapy for TSC related ASD.

A magnetic bead immunoassay to detect high affinity human IgG reactive to SARS-CoV-2 Spike S1 RBD produced in Escherichia coli.

Immunological assays to detect SARS-CoV-2 Spike Receptor Binding Domain (RBD) antigen seroconversion in humans are important tools to monitor the levels of protecting antibodies in the population in response to infection and/or immunization. Here we describe a simple, low cost, and high throughput Ni2+ magnetic bead immunoassay to detect human IgG reactive to Spike S1 RBD Receptor Binding Domain produced in Escherichia coli. A 6xHis-tagged Spike S1 RBD was expressed in E. coli and purified by affinity chromatography. The protein was mobilized on the surface of Ni2+ magnetic beads and used to investigate the presence of reactive IgG in the serum obtained from pre-pandemic and COVID-19 confirmed cases. The method was validated with a cohort of 290 samples and an area under the receiver operating characteristic curve of 0.94 was obtained. The method was operated with > 82% sensitivity at 98% specificity and was also able to track human IgG raised in response to vaccination with Comirnaty at > 85% sensitivity. The IgG signal obtained with the described method was well-correlated with the signal obtained when pre fusion Spike produced in HEK cell lines was used as antigen. This novel low-cost and high throughput immunoassay may act as an important tool to investigate protecting IgG antibodies against SARS-CoV-2 in the human population.

Covalent organic framework-gold nanoparticle heterostructures amplified dynamic light scattering immunosensor for ultrasensitive detection of NT-proBNP in whole blood

Immunoassay has shown great potential in the detection of various disease protein biomarkers because of its high specificity. However, the sensitivity of conventional immunoassay is relatively limited due to its insufficient colorimetric signal transduction. Herein, we report a novel dynamic light scattering (DLS) immunosensing strategy for ultrasensitive detection of protein markers based on the covalent organic framework-gold nanoparticle (COF@AuNP) heterostructures combined with the gold growth. By taking advantage of the unique acid response characteristics of imine-linked COF, the COF@AuNP is designed as a signal amplifier to boost the release of AuNPs, and then the released AuNPs are enlarged by gold growth to amplify the DLS signal transduction and thus remarkably improve the sensitivity. Combined with the double antibody sandwich magnetic immunoassay, the COF@AuNP-amplified DLS immunosensor successfully achieve the highly sensitive quantitative detection of N-terminal brain-type natriuretic peptide. The limit of detection reaches up to 14 fg mL−1 with the total assay time less than 2 h. The linear detection range was from 0.32 to 1000 pg mL−1, and the coefficient of variation was below 12.5%. Briefly, this immunosensor is demonstrated with high selectivity, accuracy, reproducibility, and reliability in spiked and actual whole blood samples. The COF@AuNP-amplified DLS immunosensing strategy holds high promise as an alternative for detecting disease biomarkers.

Detection of Pyrethroids in Food by Immunofluorescence Enhanced Method Based on Three-Layer Core-Shell Structure Upconversion Materials.

A novel rare earth upconversion nanomaterial with a three-layer sandwich core–shell structure was synthesized by an improved thermal decomposition method, and the morphology, fluorescence intensity and diffraction peak position of the new material were characterized by TEM (transmission electron microscope), XRD (Powder X-ray diffraction)and fluorescence spectrophotometer. The inert core/active shell/inert shell design improved the upconversion luminous efficiency of the new material several times. FTIR (Fourier transform infrared spectroscopy)characterization showed that the surface of activated upconversion nanoparticles was modified with silicon shell and amino group. Combined with the characteristics that aminoated polystyrene magnetic microspheres could be separated by the magnetic field, an upconversion magnetic separation immunoassay method for the detection of pyrethroid pesticide residues was established. The capture probe competed with the pyrethroid standard, combined the signal probe, and measured the fluorescence signal value formed by the capture probe signal probe complex at 542 nm under 980 nm excitation light. The LOD (limit of detection)of fenpropathrin was 0.01 μg/L, cypermethrin was 0.015 μg/L, and fenvalerate was 0.011 μg/L. Through the actual sample detection of apple, cabbage and other samples, the recovery rate of pyrethroids was between 83.4~97.8%. The comparison with the HPLC (high performance liquid chromatography)detection results showed that the established method had good accuracy, and could realize the quantitative analysis of pyrethroids in food.

Determination of Abrin by a Magnetic Affinity Immunoassay (MAIA) Based on the Signal Amplification of the Aptamer and Staphylococcal Protein A (SPA) Functionalized Gold Magnetic Microparticles (GMPs)

A new magnetic affinity immunoassay (MAIA) was developed for the determination of abrin based on signal amplification of staphylococcal protein A (SPA) functionalized gold magnetic microparticles (GMPs) and the aptamer. This assay consisted of a sandwich format in which SPA-coated GMPs coupled anti-abrin monoclonal antibodies (mcAb) were used as the magnetic capture probe and the enzyme-labeled abrin aptamer was used as the signal probe. Abrin was successfully determined by the proposed strategy. This method exhibited a linear response to abrin from 0.031 to 31.25 μg/L with a detection limit of 0.031 μg/L. The staphylococcal protein A, gold magnetic microparticles, and aptamer increased the sensitivity by 4 times, 2 times and 2 times, respectively The integrated amplification produced by these parameters increased the sensitivity by 16-fold compared to the traditional double-antibody sandwich enzyme linked immunosorbent assay (ELISA). This method possesses a low detection limit, acceptable reproducibility, and high specificity, which demonstrates that the MAIA shows promise in trace toxin determination.