A localized surface plasmon resonance (LSPR) immunosensor for CRP detection using 4-chloro-1-naphtol (4-CN) precipitation

Abstract

In this study, C-reactive protein (CRP) was detected by monitoring of LSPR shift promoted by precipitation of 4-chloro-1-naphthol (4-CN). The precipitation occurred by horseradish peroxide (HRP) catalyst which is modified at CRP-detection antibody utilized in sandwich enzyme-linked immunosorbent assay (ELISA) on gold nano bipyramid (GNBP) substrate. Due to 4-CN precipitates which are located nearby the surface of GNBP, local refractive index (RI) and molecular density were greatly increased. This phenomenon eventually induced strong spectral red-shift of absorption band of GNBP. An excellent linear relationship (R 2 =0.9895) between the LSPR shift and CRP concentration was obtained in the range from 100 pg/mL to 100 ng/mL and limit of detection (LOD) was reached to 87 pg/mL.

CRP Detection Using Gold Nanosensors – Effect of Layer Thickness and Immobilization Chemistry

“…The utilized solution seems to have lower refractive index as the standard buffer in 10, so the initial steep decrease in 11 can be attributed to this difference. However, afterwards the buffer from 10 is used again (12), allowing for a reproducible measurement: about 0.3 nm decrease between 10 and 12. Comparing 12 with 6 shows that some of the attached biotinylated antibodies ( 7) are still on the substrate.…”

“…Several plasmonic nanoparticle-based methods are established in enzyme-linked immunosorbent assay (ELISA) platforms. These assays use labeled secondary antibodies in sandwich assays [12][13][14][15][16] or metal-enhanced optical signals by enzymatic deposition 15 or metal-enhanced uorescence 17 for the signal enhancement.…”

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

“…The sandwich immunoassay with horseradish peroxide (HRP) found in the ELISA could be utilized to detect CRP in a LSPR-based sensing system as shown in Figure 6 c, gold nano-bipyramid (GNBP) was used as a substrate on which CRP capture antibody was immobilized by physisorption. CRP was injected to bind the capture antibody [ 51 ]. The HRP-labeled detection antibody was then injected to bind CRP, followed by reduction of 4-chloro-1-naphthol (4-CN) by the HRP catalyst with hydrogen peroxide.…”

“…( c ) Illustration of the LSPR immunosensor for CRP detection using 4-CN precipitation on GNBP substrate. Reproduced with permission from [ 51 ]; published by SPIE, 2017.…”

“…Highly sensitive CRP detection performed mostly in vitro exploits the immunoreaction-based methodologies such as the turbidoimmunometric assays [ 30 , 31 , 32 ], immunonephelometric assays [ 33 , 34 , 35 , 36 ], the enzyme-linked immunosorbent assay (ELISA) [ 37 , 38 ], the fluorescence assay with immunoreaction [ 39 , 40 , 41 ], and the optical plasmonic immunoassays [ 19 , 29 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ].…”