Gold Nanostars: Sensitive, Highly Capturable Reporters Improving Visual Lateral Flow Assay Limit of Detection

Lateral flow assay (LFA) is a point-of-care (POC) diagnostic testing method. LFA is advantageous over many other POC tests for its diverse applications, simplicity, convenience of use, quick time-to-result, low cost, and independence of elaborate equipment or trained labor. However, the lack of desired sensitivity of the so-far-reported reporters limits LFA applications. This thesis reports the use in LFA of gold nanostars (AuNSs) synthesized by applying a seed growth method, systematically functionalized with antibodies without any aggregation, and fully characterized. The influence of the morphology of the particles on the sensitivity and limit of detection (LOD) of the LFA for human chorionic gonadotropin (hCG) hormone was studied. The results were compared to those with standard commercial 40 nm gold nanospheres (AuNPs). The gold nanostars used in this study produce low LODs owing to their high capturability and high optical detectability related to their localized surface Plasmon resonance (LSPR). Preliminary experiments on engineering and evaluation of hCG-targeted LFA using AuNSs colloid gave a visual LOD of 2 pg/mL, about 50 fold magnitude more sensitive than colloidal gold LFA (~100 pg/mL) at the same conditions.