Metal-Organic Frameworks for Preserving Structure and Functionality of Bionanoconjugates

Abstract

Nanophotonic biosensors based on plasmonic nanostructures has emerged as a promising platform for molecular diagnostics at the point-of-care. However, poor thermal stability of antibodies and numerous plasmonic nanostructures limit the application of plasmonic biosensors in resource limited settings due to the requirement of cold chain transport. Here, we report the usage of a class of metal-organic framework, zeolitic imidazolate framework-8 (ZIF-8), as a protective coating for the preservation of plasmonic transducers and biorecognition elements. Gold nanobipyramids (AuNBPs) serve as a model plasmonic transducer where sharp geometric features provide improved sensitivity but are prone to reshaping due to its high surface energy. AuNBPs stored at elevated temperatures reveal a rounded tip geometry and reduced sensitivity as plasmonic nanotransducers for localized surface plasmon resonance spectroscopy and surface enhanced Raman spectroscopy. ZIF-8 coating provides AuNBPs and immobilized antibodies with excellent thermal stability with facile synthesis and removal on various substrates. The efficacy, versatility, and facile implementation of ZIF-8 coating offer great promise for the extension of molecular diagnostic serve to resource-limited settings.