pH and NaCl Optimisation to Improve the Stability of Gold and Silver Nanoparticles' Anti-Zearalenone Antibody Conjugates for Immunochromatographic Assay

Thasmin Shahjahan; Bilal Javed; Vinayak Sharma; Furong Tian

doi:10.3390/mps6050093

pH and NaCl Optimisation to Improve the Stability of Gold and Silver Nanoparticles' Anti-Zearalenone Antibody Conjugates for Immunochromatographic Assay

Methods Protoc. 2023 Oct 3;6(5):93. doi: 10.3390/mps6050093.

Authors

Thasmin Shahjahan¹, Bilal Javed^{1

2

3}, Vinayak Sharma², Furong Tian^{1

2}

Affiliations

¹ School of Food Science and Environmental Health, College of Sciences and Health, Technological University Dublin, D07 H6K8 Dublin, Ireland.
² Nano Lab, FOCAS Research Institute, Technological University Dublin, D08 CKP1 Dublin, Ireland.
³ RELX Elsevier, D18 X6N2 Dublin, Ireland.

Abstract

The aim of this research is to define optimal conditions to improve the stability of gold and silver nanoparticles' anti-zearalenone antibody conjugates for their utilisation in lateral flow immunochromatographic assay (LFIA). The Turkevich-Frens method was used to synthesise gold nanoparticles (AuNPs), which were between 10 and 110 nm in diameter. Silver nanoparticles (AgNPs) with a size distribution of 2.5 to 100 nm were synthesised using sodium borohydride as a reducing agent. The onset of AuNP and AgNP aggregation occurred at 150 mM and 80 mM NaCl concentrations, respectively. Stable Au and Ag nanoparticle-antibody conjugates were achieved at 1.2 mM of K₂CO₃ concentration, which corresponds to the pH value of ≈7. Lastly, the highest degree of conjugation between Au and Ag nanoparticles and anti-zearalenone antibodies was at 4 and 6 µg/mL of antibody concentrations. The optimisation of the conjugation conditions can contribute to better stability of nanoparticles and their antibody conjugate and can improve the reproducibility of results of bioreporter molecules in biosensing lateral flow devices.

Keywords: antibody conjugates; bioreporter; biosensing; lateral flow devices; nanoparticles aggregation; pH.

Grants and funding

This research was funded by the Government of Ireland’s postgraduate scholarship programme and from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 847402.