Abstract
In this work, we describe an approach of detecting biomarkers by Surface Plasmon Resonance imaging (SPRi) technique in real samples. Two C-Reactive Protein (CRP)-antibody immobilization methods were used: The first method was based on direct physisorption of CRP-antibody onto gold surface; the second one was based on oriented CRP-antibody with protein G intermediate layer. The two developed immunosensors were tested against CRP antigen in phosphate buffer saline solution with the SPRi technique. The response of the developed immunosensors was reproducible and stable. The detection limit of 10 pg·mLǃ and 50 pg·mLǃ CRP-antigen was observed with and without protein G respectively with this technique. Moreover, the developed SPRi immunosensor was used for CRP-antigen detection in human plasma. A detection limit of 5 ng·mLǃ and 10 ng·mLǃ was obtained with and without protein G respectively. These obtained results were compared to those obtained with QCM (Quartz Crystal Microbalance) and Enzyme-Linked Immunosorbent Assay (ELISA) techniques.
Highlights
C-reactive protein (CRP) is a protein present in plasma and is one of the most expressed proteins in acute phase inflammation cases, being a known biomarker of inflammatory states [1]
These results show that the biosensor based on oriented CRP-antibody with protein G allows SPR signal amplification and a better limit detection in comparison with the results obtained without protein G
We describe an approach of detecting biomarkers by surface plasmon resonance imaging technique
Summary
C-reactive protein (CRP) is a protein present in plasma and is one of the most expressed proteins in acute phase inflammation cases, being a known biomarker of inflammatory states [1]. Detection and quantification of CRP in an easy, cheap, and fast way can improve clinical diagnostics in order to prevent serious inflammatory states [2]. The detection of this protein has been studied by various traditionals techniques such as radial immunodiffusion (RID), Radio-Immuno-Assay (RIA), Immuno-Nephelometry (IN), Immuno-Turbidimetry (IT), ImmunoFluorescence (IF), Immuno-Chemiluminescence (IC) and Standard Enzyme Immunoassay (SEI) [3]. In order to improve the CRP detection limit for clinical use, a new approach was employed based on the excitation of surface plasmon resonance on functionalized electrode with 16 gold spots. More details on SPR phenomenon can be found in reference [9]
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