The Development and Clinical Application of Rapid Assays Using Multi-antibody-activated Magnetic Nanoparticles System in Acute Coronary Syndrome

To improve the sensitivity and specificity of immunoassay, the developing trends are to lower the detection threshold and to minimize the cross reaction. A new assay technology called immunomagnetic reduction (IMR) has been developed for rapid and on-site assay with very small volume of sample (i.e. less than 1ml whole blood). The reagent is a solution of homogeneously dispersed magnetic nanoparticles, which are coated with hydrophilic surfactants and bioprobes. Under external multiple alternating-current (ac) magnetic fields, magnetic nanoparticles oscillate with the multiple ac magnetic fields via magnetic interaction. The reagents under the external multiple ac magnetic fields show a magnetic property, called mixed-frequency ac magnetic susceptibility χac. Magnetic nanoparticles bind with the bioprobes on the outmost shell and become larger or clustered. The χac of the reagent is reduced, and the concentration of the biomolecules can be measured quantitatively. Several papers have demonstrated that IMR can be applied to assay proteins, viruses, chemicals, and nucleic acids once suitable bioprobes are immobilized onto the magnetic nanoparticles.

Rapid diagnosis of acute coronary syndrome (ACS) is a clinical and operational priority in busy emergency departments (ED). Since ACS is associated with a significant mortality and morbidity, early and correct diagnosis is of great importance. Chest pain is a frequent symptom in medical emergency departments and distinguishing patients with ACS within the chest pain group is a diagnostic challenge. Cardiac enzymes (including CPK/CK-MB, troponins, myoglobulin) and electrocardiography (ECG) in combination with the medical history and physical examination are at present the diagnostic cornerstones. Different cardiac enzymes are released after myocardial cell disintegration and are markers of cell necrosis, which might not be detected immediately after chest pain; and repeated measurements are suggested. Therefore novel biomarkers that rise earlier, have good diagnosis accuracy and have additional prognostic information are highly needed. Some publications address the potential benefit of the combination of multiple biomarker assays (markers of myocardial injury, inflammation/plaque ruptures or heart failure with different mechanism) could substantially increase clinical sensitivity and improve early risk stratification. However, this approach is rather time-consuming and not cost-effect. In the present study, a rapid IMR assay with multiple biomarkers is proposed and we will examine the performance of this new investigational IMR assays, comparison with current commercial assays.