One-step synthesis of biotinylated gold nanoparticles for application in immunoassay

Abstract

Biomarkers are the biological indicators with characteristic concentration depending on the disease state. They can be detected and measured in biological fluids such as plasma, serum, cerebrospinal fluid, or body tissues. Nowadays, the most of attention among inflammatory biomarkers engrossed by C-reactive protein (CRP). CRP is synthesized by the liver and has five non-covalently linked and non-glycosylated identical subunits of 206 amino acids each, forming a disk-shaped pentagon or pentameric shape. The CRP level rapidly increases in response to trauma, inflammation, and infection. The physiological level of CRP is around 5 mg/L, but it can rise significantly in the case of the disease up to 500 mg/L after 48 hours.
The development of sensitive, rapid, selective analytical methods for the detection of CRP is an important task for medicine. To achieve this, it is important to develop new strategies for the sensitive detection of CRP in the biological fluids. Thus, in this work, we proposed a one-step method for the facile synthesis of biotin modified gold nanoparticles (GNPs) for application as effective labels of CRP detection in immunoassay. GNPs were synthesized in thermal synthesis at 100ºC for 15 minutes. The average size of GNPs was ~6 nm. The specific surface plasmonic resonance maximum was at the area of 520 nm. We used the biotin-streptavidin “click- chemistry” for the obtainment of a specific marker for CRP. The crucial advantage of this technique is the presence of four biotin-binding sites at one streptavidin molecule interacted with one antibody. Thus, the one streptavidin can interact with three biotin molecules at the surface of GNPs and one specific anti-CRP antibody. We demonstrated the application of the development labels in a microplate and presented the strong dependence of GNPs’ absorbance maxima from the anti-CRP antibodies.
Therefore, the proposed method can be used for the development of sensitive immunoassay of CRP concentration in human biological fluids.
The reported study was funded by RFBR, project number 19-33-90159.

Speaker

Alina Kokorina
Saratov State University
Russia

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