Sandwich Electrochemiluminescence Research Articles

A novel sandwich electrochemiluminescence immunosensor for ultrasensitive detection of carbohydrate antigen 19-9 based on immobilizing luminol on Ag@BSA core/shell microspheres.

A novel sandwich-type electrochemiluminescence immunosensor based on immobilizing luminol on Ag@BSA core/shell microspheres (Ag@BSA-luminol) for ultrasensitive detection of tumor marker carbohydrate antigen 19-9 (CA19-9) has been developed. Herein, magnetic carbon nanotubes (MAGCNTs) decorated with polyethylenimine (PEI) was used to construct the base of the immunosensor. MAGCNTs with prominent electrical conductivity and high surface area could be beneficial for promoting the electron transfer and loading plenty of primary antibodies (Ab1) via glutaraldehyde (GA). Meanwhile, the magnetic property of MAGCNTs makes it easy to be attached to the surface of magnetic glass carbon electrode (MGCE) through magnetism interaction, which provides an outstanding platform for this immunosensor. Moreover, Ag@BSA microspheres with large surface area, good stability, and excellent biocompatibility were desirable candidates for effective cross-link of CA19-9 detection antibodies (Ab2). A more interesting thing was that ELISA color reaction was used as an ultrasensitive strategy for identifying Ab2 was successfully coated on Ag@BSA with the naked eye. Additionally, we immobilized the luminol on the surface of Ag@BSA to prepare the target immunosensor. Immobilization of luminol on the surface of Ag@BSA could decrease the distance between luminophores and the electrode surface, leading to great enhancement of the ECL intensity of luminol in the present of hydrogen peroxide (H2O2). Under the optimal conditions, the intensity of the ECL immunosensor increased linearly with the logarithm of CA19-9 concentration in a wide linear range from 0.0005 to 150UmL(-1) with a detection limit of 0.0002UmL(-1) (S/N=3). All the results suggested the prepared CA19-9 immunosensor displayed high sensitivity, excellent stability and good specificity. The developed method opened a new avenue to clinical bioassay.

Quenched electrochemiluminescence of Ag nanoparticles functionalized g-C3N4 by ferrocene for highly sensitive immunosensing

In this paper, a novel sandwich electrochemiluminescence (ECL) immunosensor was constructed by ferrocene for quenching Ag nanoparticles functionalized g-C3N4 (Ag@g-C3N4) emission. The prepared Ag@g-C3N4 had strong and stable ECL signals compared to pure g-C3N4 and primary antibody (Ab1) can be immobilized on Ag@g-C3N4 by adsorption of Ag nanoparticles. Ferrocene carboxylic acid (Fc-COOH) labeled secondary antibody was immobilized on Au doped mesoporous Al2O3 nanorods (Au@Al2O3–Fc-COOH@Ab2) as labels through adsorption ability of Au toward proteins. After a sandwich-type immunoreaction, a remarkable decrease of ECL signal was observed due to the ECL quenching of Ag@g-C3N4 by Au@Al2O3–Fc-COOH@Ab2. As a result, the change of ECL intensity has a direct relationship with the logarithm of CEA concentrations in the range of 1pgmL−1–100ngmL−1 with a detection limit of 0.35pgmL−1 (S/N=3). Additionally, the proposed immunosensor shows high specificity, good reproducibility, and long-term stability.

A novel sandwich electrochemiluminescence aptasensor based on molybdenum disulfide nanosheet–graphene composites and Au nanoparticles for signal amplification

In this work, we constructed a novel sandwich electrochemiluminescence aptasensor based on molybdenum disulfide nanosheet–graphene composites and Au nanoparticles.

A cost-effective sandwich electrochemiluminescence immunosensor for ultrasensitive detection of HIV-1 antibody using magnetic molecularly imprinted polymers as capture probes

In this report, a rapid and cost-effective sandwich electrochemiluminescence (ECL) immunosensor was constructed for the ultrasensitive detection of human immunodeficiency virus type 1 antibody (anti-HIV-1) using magnetic molecularly imprinted polymers (MMIPs) as capture probes by combining surface and epitope imprinting techniques and antigen conjugated with horseradish peroxidase (HRP-HIV-1) as labels. First, 3-aminobenzeneboronic acid (APBA) was used as the functional monomer and cross-linking reagent, which was polymerized on the surface of silicate-coated magnetic iron oxide nanoparticles (Fe3O4@SiO2 NPs) in the presence of human immunoglobulin G (HIgG), as the template exhibiting the same Fc region but different Fab region to anti-HIV-1 after the addition of the initiator, ammonium persulfate. This process resulted in grafting a hydrophilic molecularly imprinted polymer (MIP) film on the Fe3O4@SiO2 NPs. Thus, MMIPs, which could be reused after eluting the template, were used to recognize and enrich ultra-trace levels of anti-HIV-1. Subsequently, a novel sandwich ECL immunosensor was formed through the immunoreaction between MMIPs conjugated with varied concentrations of anti-HIV-1 and HRP-HIV-1. By the catalysis of HRP immobilized onto HRP-HIV-1 on the ECL system of Luminol-H2O2, a linear response range of the anti-HIV-1 dilution ratio (standard positive serum) was achieved from 1:20,000 to 1:50, with a detection limit of 1:60,000 (S/N=3). The developed method provides a low-cost, simple, and sensitive way for the early diagnosis of HIV infected patients.

A single antibody sandwich electrochemiluminescence immunosensor based on protein magnetic molecularly imprinted polymers mimicking capture probes

A single antibody sandwich electrochemiluminescence (ECL) immunosensor for ultratrace detection of protein was developed using magnetic molecularly imprinted polymers (MMIPs) as an alternative to the first antibody as capture probes and antibodies labeled with Ru-silica (Ru(bpy)32+-doped silica) doped Au (Ru@SiO2@Au) nanocomposites as labels. Using MMIPs as capture probes will aid mass production, greatly reduce costs and avoid the loss of bioactivity associated with the use of conventional antibodies. Moreover, MMIPs can be easily immobilized on and washed off simply by adding or removing a magnet on the electrode, which will greatly simplify the preparation and allow regeneration of the sensor. Lastly, MMIPs can enrich ultratrace levels of antigens from sample solutions to produce more immunocomplex than the conventional capture probe, thus providing an ultrasensitive assay. The logarithm of ΔECL intensity depended linearly on the logarithm of the hemoglobin (Hb) concentration in the range from 0.1 to 4×104pgmL−1 with a detection limit of 0.023pgmL−1. This approach offers obvious advantages of low cost, high sensitivity and enhanced stability compared with other immunosensors, and therefore offers significant potential for protein detection in a clinical laboratory setting.

NH2-Terminal Probrain Natriuretic Peptide Is Associated With Diabetes Complications in the EURODIAB Prospective Complications Study

OBJECTIVECirculating levels of NH2-terminal probrain natriuretic peptide (NT-proBNP), a marker of acute heart failure, are associated with increased risk of cardiovascular disease (CVD) in the general population. However, there is little information on the potential role of NT-proBNP as a biomarker of vascular complications in type 1 diabetic patients. We investigated whether serum NT-proBNP levels were associated with micro- and macrovascular disease in type 1 diabetic subjects.RESEARCH DESIGN AND METHODSA cross-sectional nested case-control study from the EURODIAB Prospective Complications Study of 507 type 1 diabetic patients was performed. Case subjects (n = 345) were defined as those with one or more complications of diabetes; control subjects (n = 162) were those with no evidence of any complication. We measured NT-proBNP levels by a two-site sandwich electrochemiluminescence immunoassay and investigated their associations with complications.RESULTSMean NT-proBNP levels were significantly higher in case than in control subjects. In logistic regression analyses, NT-proBNP values >26.46 pg/mL were independently associated with a 2.56-fold increased risk of all complications. Odds ratios of CVD (3.95 [95% CI 1.26–12.35]), nephropathy (4.38 [1.30–14.76]), and distal symmetrical polyneuropathy (4.32 [1.41–13.23]) were significantly increased in patients with NT-proBNP values in the highest quartile (>84.71 pg/mL), independently of renal function and known risk factors. These associations were no longer significant after inclusion of TNF-α into the model.CONCLUSIONSIn this large cohort of type 1 diabetic subjects, we found an association between NT-proBNP and diabetic micro- and macrovascular complications. Our results suggest that the inflammatory cytokine TNF-α may be involved in this association.