Plasmonic Optical Biosensors for Detecting C-Reactive Protein: A Review.

Joo Seon Seok,Heongkyu Ju

doi:10.3390/mi11100895

Abstract

C-reactive protein (CRP), a potent acute-phase reactant that increases rapidly in response to inflammation, tissue damage or infections, is also considered an indicator of the risk of cardiovascular diseases and neurological disorders. Recent advances in nanofabrication and nanophotonic technologies have prompted the optical plasmonic phenomena to be tailored for specific detection of human serum CRP into label-free devices. We review the CRP-specific detection platforms with high sensitivity, which feature the thin metal films for surface plasmon resonance, nano-enhancers of zero dimensional nanostructures, and metal nanoparticles for localized surface plasmon resonance. The protocols used for various types of assay reported in literature are also outlines with surface chemical pretreatment required for specific detection of CRPs on a plasmonic surface. Properties including sensitivity and detection range are described for each sensor device reviewed, while challenges faced by plasmonic CRP sensors are discussed in the conclusion, with future directions towards which research efforts need to be made.

Highlights

In 1930, Tillett and Francis discovered the protein that responded to the encapsulated (c)-polysaccharide of pneumococcus in patients with acute pneumococcal infections [1], later named the C-reactive protein (CRP)
Plasmonic optical biosensors are reviewed with a focus on those developed for highly sensitive and specific detection of CRPs, the important biomarkers for general inflammatory responses, and for cardiovascular diseases and neurological disorders
This review categorizes the plasmonic biosensors into two kinds, i.e., those on surface plasmon resonance (SPR) occurring between a flat metal film and dielectric analyte media, and those using localized surface plasmon resonance (LSPR) occurring on metal nanostructures with their size much smaller than incident light wavelength

Summary

Introduction

In 1930, Tillett and Francis discovered the protein that responded to the encapsulated (c)-polysaccharide of pneumococcus in patients with acute pneumococcal infections [1], later named the C-reactive protein (CRP). With the antibody C8, the sensor could detect both types of CRPs. while the SPR angle shift by pCRP remained unchanged after surface washing, while those by mCRP decreased noticeably. For 8D8 or 9C9 antibodies, only one of both types of CRPs produced a significantly detectable signal, its sensitivity substantially lower than that for C8 This encouraged the use of the C8–pCRP immunoreaction pair for detecting the CRP level ranging from 1 μg/mL to 26 μg/mL with a LOD of 1 μg/mL [29]. Choi et al [45] immobilized antibodies using an oxygen plasma-treated parylene N film, and enhanced the sensitivity of the SPR-based sensor. The red shift of the absorption peak wavelength occurred with increasing the concentration, producing the LOD of 9 ng/mL

Sandwich Immunoassay

Discussion