Conductometric immunoassay for interleukin-6 in human serum based on organic/inorganic hybrid membrane-functionalized interface

Abstract

Various sensor-based immunoassay methods have been extensively developed for the detection of interleukin-6 (IL6), but most often exhibit low detection signals and low detection sensitivity, and are unsuitable for routine use. The aim of this work is to develop a simple and sensitive conductometric immunoassay for IL6 in human serum by using an organic/inorganic hybrid membrane-functionalized interface. Initially, thionine-bound 3,4,9,10-perylenetetracarboxylic acid was doped into colloidal alumina, then nanogold particles were immobilized onto the thionine surface, and then horseradish peroxidase-labeled anti-IL6 antibodies were conjugated on the nanogold surface. The organic/inorganic hybrid membrane provides a good microenvironment for the immobilization of biomolecules, enhanced the surface coverage of protein, and improved the sensitivity of the immunosensor. The performance and factors influencing the performance of the immunosensor were evaluated. The detection is based on the change in local conductivity before and after the antigen-antibody interaction in 0.02 M phosphate buffer solution (pH 6.8) containing 50 microM H(2)O(2), 0.01 M KI and 0.15 M NaC1. Under optimal conditions, the proposed immunosensor exhibited a wide linear range from 25 to 400 pg/ml towards IL6 with a relatively low detection limit of 5 pg/ml (S/N = 3). The stability, reproducibility and precision of the immunosensor were acceptable. 37 serum specimens were assayed by the developed immunosensor and standard enzyme-linked immunosorbent assay, respectively, and the results obtained were almost consistent. More importantly, the detection methodology provides a promising approach for other proteins or biosecurity.

Electrochemical Methods for the Analysis of Clinically Relevant Biomolecules

“…679 The normal values of IL-6 in a healthy individual range between 10 and 75 ng L −1 . 680 A sandwich-based voltammetric sensor for IL-6 was constructed using a magnetic beads-labeled anti-IL-6 antibody captured within the wells of a microtiter plate positioned on top of a magnet. 681 Silver nanoparticle-titanium phosphate spheres (AgNP-TiP) were synthesized and used to label the secondary antibody.…”

A novel QCM immunosensor development based on gold nanoparticles functionalized sulfur-doped graphene quantum dot and h-ZnS-CdS NC for Interleukin-6 detection

“…IL-6's amount is 15.0e80.0 pg mL À1 in healthy people. Nonetheless, this ratio can increase until nanogram orders in diseases [6] and some significant diseases such as prostate [7] and breast cancer [8] start to emerge. Thus, IL-6 determination methods in plasma can be important monitoring system [9].…”

Synthesis of Silver Nanoparticle–Hollow Titanium Phosphate Sphere Hybrid as a Label for Ultrasensitive Electrochemical Detection of Human Interleukin‐6

“…Human interleukin‐6 (IL‐6), a pleiotropic cytokine that has a critical role in the inflammatory response, has been implicated in the pathogenesis of a number of inflammatory conditions, such as psoriasis, inflammatory arthritis, cardiovascular disease, and inflammatory bowel disease 25, 26. The normal level in serum is in the range of 10–75 pg mL −1 , whereas individuals with various disease states have elevations in IL‐6 levels in the ng mL −1 range 27. High levels of IL‐6 have also been correlated with prostate cancer of hormone‐independent prostate cancer patients,28 and breast cancer of AIDS patients 29.…”