Magnetic‐Core/Porous‐Shell CoFe₂O₄/SiO₂ Composite Nanoparticles as Immobilized Affinity Supports for Clinical Immunoassays

Abstract

This study demonstrates a novel approach towards the development of advanced protein assay systems based on physically functionalized, magnetic‐core/porous‐shell CoFe2O4/SiO2 composite nanoparticles. The preparation, characterization, and measurement of the relevant properties of the protein assay system is discussed, and the system is used for the detection of cancer antigen 15‐3 (CA 15‐3, used as a model here) in clinical immunoassays. The protein assay system, based on nanometer‐sized magnetic cores and silica shells, shows good adsorption properties for the selective attachment of CA 15‐3 antibodies specific to CA 15‐3. The core/shell nanostructures exhibit good magnetic properties, which enables their integration into a quartz crystal microbalance (QCM) detection cell with the help of a permanent magnet. Under optimal conditions, the resulting immunoassay system presents a good QCM response for the detection of CA 15‐3, and allows the detection of CA 15‐3 at concentrations as low as 1.5 U mL–1 (U: units). Importantly, the proposed protein assay system can be extended to the detection of other antigens and biological compounds.

Dependence of magnetic properties on crystallite size of CoFe2O4nanoparticles synthesised by auto-combustion method

“…However, it is hard to conclude that all the samples are single-phase CoFe 2 O 4 due to the similar spinel structure of CoFe 2 O 4 and -Fe 2 O 3 [18]. It is known that the Raman spectra of -Fe 2 O 3 exhibit much stronger Raman peaks at 1378 and 1576 cm À1 than that of CoFe 2 O 4 [19].…”

Electrochemical immune bioassay for the antigen–antibody interaction based on [Fe(CN)6]4-/3- and [AuCl4]- ions-derivated biomimetic interface

“…Immunosensors are miniaturized analytical devices that combine the selectivity of the immunological reaction with the sensitivity and convenience of the various detection techniques and can be effectively applied in untreated samples without requirement for separation [1][2][3][4][5][6][7][8]. Recently, many reports have been published on the use of immunosensors for a wide range of applications in food industry, environmental monitoring, biotechnology, pharmaceutical chemistry, and clinical diagnostics based on detection principle of electrochemistry, chemiluminescence, fluoroscence, impedance biochips, etc.…”

Electrochemical immune-biosensor for immunoglobulin G based bioelectrocatalytic reaction on micro-comb electrodes

“…Despite the predominance of high sensitivity, the conventional immunoassay methods such as radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISA), immunoaffinity column assay (ICA) and immunoaffinity fluorimetric biosensor (APL sensor) have some limitations such as the short shelf life of 125 I-labeled antibody, the radiation hazards, the complicated wash procedure, and the requirements for a long analysis time, expensive and cumbersome instruments and/or skillful operators. Some alternative immunoassay methods have been developed for fast determination and on-site analysis, such as piezoelectric immunosensor [3][4][5], optical immunosensors [6], surface plasmon resonance (SPR) immunosensor [7], impedimetric immunosensor [8] and quartz crystal microbalance (QCM) immunosensor [9]. Most methods, however, are of either low sensitivity, or time consuming and complicated entailing expensive instrumentation and additional labeling steps.…”