Dynamic Range Expansion of the C-Reactive Protein Quantification with a Tandem Giant Magnetoresistance Biosensor

Abstract

In this study, we report a convenient analytical method for a full-range quantification of the C-reactive protein (CRP), a blood biomarker of infection and cardiovascular events. We determine CRP over the entire diagnostically relevant concentration range in undiluted human blood serum in a single test, using a tandem giant magnetoresistance (GMR) sensor. The tandem principle combines a sandwich assay and a competitive assay, which allows for the discrimination of the concentration values resulting from the multivalued dose–response curve (“Hook” effect), which characterizes the one-step sandwich assay at high CRP concentrations. The sensor covers a linear detection range for CRP concentration from 3 ng/mL to 350 μg/mL, the detection limit (s/n = 3) is 1 ng/mL. The prominent features of the chip-based method are its expanded dynamic range and low sample volume (50 μL), and the need for a short measurement time of 15 min. These figures of merit, in addition to the low detection limit equal to the established assay instrumentation, make it a viable candidate for use in point-of-care diagnostics.

Giant Magnetoresistance Biosensors in Biomedical Applications

“…Other bioassay schemes such as the competitive bioassay, although less sensitive to experimental errors as it only requires one binding site on the target analyte, have also been reported for detecting small molecules that usually lack two binding sites/epitopes required for the sandwich assay. − As shown in Figure D, the detection probes are at first incubated with a biological sample containing target analytes to allow the specific binding to saturate. The mixture is then added to GMR biosensors that are densely covered with target analytes, where the unoccupied detection probes can bind to GMR biosensors.…”

Giant Magnetoresistance Biosensors for Food Safety Applications

“…By establishing different biosensors, the portable sensing platform was proven to be able to detect 12 different tumor biomarkers simultaneously. Using the same sensing platform, Meng et al realized the detection of N-terminal pro-B-type natriuretic with a LOD of 5 pg/mL and C-reactive protein with a LOD of 1 ng/mL, which shows the universal applicability of this platform [ 97 , 98 ].…”

Current Progress of Magnetoresistance Sensors

“…The MR sensor-based biological sensing platforms have attracted the interest of researchers since the first GMR biosensor array was developed in 1998 [168]. Currently, MR biosensors are applied in three major categories of biomedical applications: biomedical diagnosis, food safety, and environmental monitoring [127,[169][170][171][172][173][174][175][176].…”