Mycosome-Coated Gold Nanoparticles for Plasmonic Detection of Tuberculosis-Associated Antibodies

Abstract

Considering that more than 10 million people develop tuberculosis disease (TB) each year and that nearly 3 million of them are never diagnosed, label-free screening methods constitute one of the top public health priorities worldwide. Herein we report the fabrication of a plasmonic system for the detection of TB-associated antibodies. Gold nanoparticles (AuNPs) were synthesized at controlled sizes and modified to display antigen lipid glycans from mycobacteria, the group of organisms comprising the TB causal agent. Facile self-assembly procedures were employed to form mycobacterial phosphatidylinositol mannoside (PIM)containing unilamellar liposomes (mycosomes) and to attach them onto gold surfaces using thiol chemistry. Using enzyme-linked immunoassays with rabbit hyperimmune sera, the constructs were found to specifically capture antilipid antibodies, presenting a dose-dependent response. Also, the functional hybrid nanoparticles showed localized surface plasmon resonance (LSPR) shifts of up to 2 nm upon their interaction with specific antibodies, indicating their suitability for the optical transduction of antigen−antibody reactions. Finally, the applicability of the system for real-world detection of TB-associated antibodies was demonstrated through analysis of 12 samples of human individuals, including 7 cases with pulmonary TB. To the best of our knowledge, this is the first biomimetic nanogold−lipid system for the implementation of lipids as immunosensing reagents for the plasmonic detection and diagnosis of TB.