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

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.