Stability matters: evaluating the long-term performance of AuNP-DNA conjugates in lateral flow assays through varied conjugation methods and storage buffers

Identifier:  imarina:9462717

Handle: https://hdl.handle.net/20.500.11797/imarina9462717

Authors:  Fuentes-Chust, C; Parolo, C; Piper, A; Merkoçi, A

Abstract:
This study evaluates five distinct conjugation techniques for attaching DNA to gold nanoparticles (AuNPs), focusing on their applicability in lateral flow assays (LFA). The selected methods include three salt-aging techniques, one polyT-adsorption method, and a rapid butanol dehydration (INDEBT) approach. These methods were chosen based on factors such as popularity, protocol duration, and ionic strength. Additionally, the study investigates the storage stability of DNA-AuNP conjugates in four different buffers: 100 mM Tris-MgCl2, 10 mM PBS-MgCl2, PBS, and deionized water. These buffers were selected to evaluate the effects of ionic strength and their compatibility with LFA materials on conjugate stability and performance. Results indicate that salt-aging methods, particularly with water or PBS, maintained LFA functionality up to 21 days. Adsorbed DNA and all samples stored in PBS-MgCl2 were not functional from the start and aggregated over time. INDEBT and Tris-MgCl2 conjugates demonstrated initial functionality but degraded due to butanol residues and aggregation. A complementary analysis using electrophoretic mobility shift assays (EMSAs), UV-Vis spectroscopy, and dynamic light scattering (DLS) provided essential insights into conjugate behavior. These results emphasize the importance of buffer selection and conjugation techniques for optimizing DNA-AuNP conjugates in LFAs, ensuring their reliability and effectiveness in diagnostic applications.