Scientists invent new probes for immunochromatography strips

Schematic diagram of three-dimensional multibranched gold nanoparticles for immunochromatography strips. Photo courtesy of the research team

Recently, the team of academician Wu Qingping of the Microbial Safety and Health Research Center of the Institute of Microbiology of Guangdong Academy of Sciences has invented a new gold nanoparticle (AuNP) detection probe for the detection of E. coli O157:H7. The study was published in the Chemical Engineering Journal. Dr. Yanna Shao is the first author of the paper, and Professor Ding Yu is the corresponding author.

Immunochromatography test strip is a rapid detection tool commonly used in medicine, such as early pregnancy test strip and new crown antigen test strip. Large particle size AuNP replaces the traditional 30-40 nm AuNP, which can only improve the signal intensity of immunochromatography strips to a certain extent, mainly because the lamellar growth caused by perfect matching of the crystal lattice can only prepare large particle size AuNP with low absorption and high scattering.

In this work, the researchers innovatively introduced dopamine to replace the traditional trisodium citrate as a reducing agent and stabilizer, and prepared a 3D dendritic AuNP (PDA-AuNP) with high absorption and low scattering, which is essential for the application of this new probe to immunochromatography strips. PDA-AuNP shows excellent water solubility while creating a black appearance that contrasts strongly with nitrocellulose membranes (white).

By regulating the concentration of dopamine and seed gold, the researchers accurately synthesized dendritic gold nanoparticles with wide absorption at 40, 80, 110, 140 and 170 nm, and resolved the differences in the sensitivity of PDA-AuNP particle size, optical intensity and binding efficiency for the detection of E. coli O157:H7. The 170 nm PDA-AuNP-based immunochromatography strip has a minimum detection limit of 200 CFU/mL, which is more than 20 times lower than the traditional 40 nm trisodium citrate reduced AuNP (SC-AuNP).

According to reports, PDA-AuNP, as a simple labeling material with high optical performance, shows great application prospects in low-cost, high-performance immunochromatography platforms. (Source: China Science News, Zhu Hanbin, Li Chengbin)

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