Detection of C-Reactive Protein Utilizing Magnetic Permeability Detection Based Immunoassays

Abstract

A new sensing technology platform integrating magnetic permeability detection and a two-site heterogeneous immunoassay in a one-step analysis is described. As a platform model, measurements of C-reactive protein (CRP), a cardiac and inflammation marker, were performed in a rapid (11.5 min) high-sensitivity (hs) procedure with a low detection limit (0.2 mg/L) and accuracy (CV = 11%). The two-site heterogeneous immunoassay was performed in 1.2-mL disposable reagents vials containing solid phase (polyclonal anti-CRP conjugated silica microparticles), labeling agent (monoclonal anti-CRP conjugated superparamagnetic nanoparticles), and reaction buffer. Whole blood (20 muL) was assayed by introducing the sample into a reagent vial using a glass capillary and mixing its contents by hand for 30 s. After a 11-min sedimentation step, the vial was placed into the coil of the magnetic permeability detector, which measured the enrichment of superparamagnetic nanoparticles in the solid-phase sediment. Magnetic permeability detection and quantification is based on the principle that when paramagnetic materials are placed inside a coil, the inductance of the coil is influenced. Screening of CRP on whole blood patient samples showed good correlation with central hospital measurements for hsCRP (y = 1.018x - 0.021, R(2) = 0.980, n = 103) and normal range CRP (y = 1.02x + 2.53, R(2)= 0.991, n = 33) analyses. The mean differences of the two methods according to the Bland and Altman plots were -0.03 +/- 1.12 mg/L for hsCRP analysis and -3.4 +/- 8.64 mg/L for normal range CRP analysis.

Design and testing of a disposable microfluidic chemiluminescent immunoassay for disease biomarkers in human serum samples

“…It is classified as a characteristic acute phase reactant in human serum and a classic marker of inflammation (Christodoulides et al, 2005;Kushner and Rzewnicki, 1994;Wolf et al, 2004). Several studies have demonstrated the association between inflammation and cardiovascular disease and testing of serum CRP levels is suggested as a new way of monitoring the risk of cardiac disease (Kriz et al, 2005;Pearson et al, 2003;Ridker and Morrow, 2003). At central hospital locations, high sensitivity CRP (hsCRP) testing is currently performed utilizing turbidimetric or nephelometric homogeneous immunoassays on large clinical analyzers (Kriz et al, 2005;Roberts et al, 2001), and the techniques are very time consuming (response detection time > 12 h) and cannot be used for immediate health assessment.…”

“…Several studies have demonstrated the association between inflammation and cardiovascular disease and testing of serum CRP levels is suggested as a new way of monitoring the risk of cardiac disease (Kriz et al, 2005;Pearson et al, 2003;Ridker and Morrow, 2003). At central hospital locations, high sensitivity CRP (hsCRP) testing is currently performed utilizing turbidimetric or nephelometric homogeneous immunoassays on large clinical analyzers (Kriz et al, 2005;Roberts et al, 2001), and the techniques are very time consuming (response detection time > 12 h) and cannot be used for immediate health assessment. Moreover, the existing technology cannot be easily translated into a point-of-care device as they require high sample volumes ( > 1 mL) obtained by drawing venous blood with a syringe.…”

Use of Magnetic Nanoparticles and a Microplate Reader with Fluorescence Detection to Detect C‐reactive Protein

“…The detection limit for CRP was 0.2 mg/L, and the linear dynamic range was 5-160 mg/L. [13][14] MNPs are composed of Fe 3 O 4 , and thus have lower toxicity and are more biocompatible compared to other NPs. MNPs have also been used as contrast agents for magnetic resonance imaging (MRI) to locate targeted tissues for patients.…”

A novel interdigitated capacitor based biosensor for detection of cardiovascular risk marker

“…Recently, there are several advancements for measuring CRP has been reported. For example, a CRP assay by using a magnetic permeability detector has been reported with a detection limit of 0.2 mg/l (Kriz et al, 2005). A label-free assay using surface plasmon resonance (SPR)-based technology was demonstrated with a detection limit of 2-5 mg/l (Meyer et al, 2006).…”