Sharp Branched Gold Nanostar-Based Lateral-Flow Immunoassay for Detection of Yersinia pestis

Abstract

Over the past few decades, colorimetric paper-based lateral flow immunoassay (LFIA) has emerged as a versatile analytical tool for rapid point-of-care detection of infectious diseases with high simplicity and flexibility. The LFIA sensitivity is based on color visualization of the antibody-labeled nanoparticles bound with the target analytes at the test line. Therefore, the nanoparticle design is crucial for LFIA sensitivity. The traditional LFIA is based on spherical gold nanoparticles, which usually suffer from poor sensitivity because of very low optical contrast at the test line. To improve the LFIA sensitivity, we have developed an LFIA based on gold nanostars (GNSs) with different branch lengths and sharpness (GNS-1, GNS-2, and GNS-3), which possess higher optical contrast than conventional gold nanospheres (GNSPs). We have selected the bacterium Yersinia pestis as a model analyte system. The effective affinity of GNSPs and GNSs with the Y. pestis fraction 1 (F1) protein was quantitively investigated by colorimetric and optical density measurements of the test line. The results show that GNS-3, which has maximum spike length and branch sharpness, exhibits the highest analytical sensitivity based on the limit of detection of the LFIA readout compared to other GNSs and GNSPs. The detection limit of the Y. pestis F1 antigen was achieved up to 0.1 ng/mL for GNS-3, which is 100 times lower than that for the GNSP at a 1 pmol/L concentration and 10 times lower than that for the reported procedure based on traditional gold nanoparticles. Overall, our prototype LFIA platform based on a highly spiked GNS (GNS-3) exhibits high analytical sensitivity, indicating it to be a promising candidate for routine LFIA application to detect infectious diseases.

Dual-Modal Colorimetric and Surface-Enhanced Raman Scattering (SERS)-Based Lateral Flow Immunoassay for Ultrasensitive Detection of SARS-CoV-2 Using a Plasmonic Gold Nanocrown

“…The red-shifting of the plasmon peak is consistent with our previous studies for antibody conjugation of gold nanostars. 12 Figure 4a shows the schematic representation of the colorimetric LFIA platform. Figure 4b shows the color brightness of GNC-2 and 35 nm GNSP at the same concentration (60 pM), indicating that GNC-2 has the highest color brightness than GNSP.…”

“…12−16 For instance, we have recently shown that high aspect-ratio, sharp-branched gold nanostars possess higher optical contrast over conventional gold nanospheres, which improved the colorimetric LFIA sensitivity. 12 Therefore, further nanoparticle optimization can improve the visual color brightness and increase the sensitivity of the LFIA.…”

“…The synthesis of SARS-CoV-2 antibody conjugation of GNSP and GNC-2 was followed by our previously reported procedure. 12 Briefly, 1 mL of solution of as-synthesized GNSP or GNC-2 nanoparticles was centrifuged and resuspended in 1 mL of 5 mM SH-PEG-NHS (Mw-5k). The solution was stirred for 1 h at room temperature and then centrifuged and resuspended in 1 mL of PBS (10×, pH 7.4) buffer solution.…”

“…The traditional LFIA is based on color visualization on the test line (T line), where an intense red color of the gold nanoparticles appeared on the T line of the strip in the presence of the target antigen. However, colorimetric LFIA suffers from poor sensitivity and quantitative ability, mainly due to the poor optical brightness of the gold nanospheres. − For instance, we have recently shown that high aspect-ratio, sharp-branched gold nanostars possess higher optical contrast over conventional gold nanospheres, which improved the colorimetric LFIA sensitivity . Therefore, further nanoparticle optimization can improve the visual color brightness and increase the sensitivity of the LFIA.…”

Multiplex SERS detection of polycyclic aromatic hydrocarbon (PAH) pollutants in water samples using gold nanostars and machine learning analysis

“…The final concentration of the CTAB-capped GNSs was calculated to be 2 pmol L −1 by following our previously reported procedure. 58 As the GNSs were centrifuged and dis-persed in water, we believe that the amount of CTAB in the GNS solution was negligible.…”