Analysis of C-Reactive Protein on Amide-Linked N-Hydroxysuccinimide−Dextran Arrays with a Spectral Surface Plasmon Resonance Biosensor for Serodiagnosis

Abstract

A new label-free array system using amide-linked (AL) NHS-dextran and a spectral SPR biosensor are presented for the high-throughput analysis of C-reactive protein (CRP) in human sera. The AL NHS-dextran layer on the surface of gold arrays was composed of an amide linkage between NHS-modified carboxymethyl-dextran and amine-modified 11-mercaptoundecanoic acid. The topology of the AL NHS-dextran layer was analyzed by atomic force microscopy, and it was found to be superior to the previously used epoxide-linked carboxymethyl-dextran layer in its immobilization of proteins. Specific immunoreactions and a dose-dependent increase of SPR signals were demonstrated on the AL NHS-dextran layer. Then, the label-free array system was successfully applied to the rapid analysis of CRP in 120 human sera. CRP levels in human sera determined by the array-based spectral SPR biosensor showed a good correlation with those determined by the latex-enhanced turbidimetry immunoassay (n = 120, r = 0.945, p < 0.0001). Thus, the array-based spectral SPR biosensor based on the AL NHS-dextran surface is a potential system for rapid and label-free serodiagnosis of human diseases.

Surface plasmon resonance applications in clinical analysis

“…After AFM studies, they found this surface [47] more suitable for proteins immobilization than a normal epoxide-linked carboxymethyl-dextran layer. Monoclonal anti-CRP antibodies were immobilized onto the surface and rapid analysis of CRP was performed down to 20 μg/L (∼0.8 nM) concentration in 120 human sera diluted (1:10 in PBS, pH 7.4); results showed a good correlation with the turbidimetry reference immunoassay [55].…”

Trends and Perspectives in Immunosensors

“…However, the equipment required can be bulky and expensive, but emerging technologies will lead to significant reductions in size. SPR assays have found many applications in different fields such as biomedical diagnostics [88,89], and drug discovery [90,91]. …”

Combining Electrochemical Impedance Spectroscopy and Surface Plasmon Resonance into one Simultaneous Read-Out System for the Detection of Surface Interactions

“…Within biosensor technology surface plasmon resonance (SPR) is considered to be a real-time and label-free tool [2]. Over the past two decades SPR has found its way into medical diagnostics [3–5], environmental analysis [6–9] and food control [9–12]. The working principle is based on changes in the refractive index at interfaces.…”