A Generic Covalent Functionalization Concept for Near-Infrared Fluorescent Carbon Nanotube Biosensors

Abstract

Biosensors are powerful tools with wide applications in basic research and biomedical diagnostics. In the last decades, the use of nanomaterials decorated with biological recognition units have attracted significant attention and reformed the field. However, this development requires substantial input from the chemical sciences.In this context, semiconducting single-walled carbon nanotubes (SWCNTs) are versatile near infrared (NIR, 870 – 2400 nm) emitting fluorophores. They have been non-covalently modified to create sensors that change their fluorescence when interacting with biomolecules. However, non-covalent chemistry has several disadvantages and prevents a consistent way to signal transduction and rational design. Here, we introduce a widely applicable covalent approach to create molecular sensors without destroying the fluorescence in the NIR. For this purpose, a new class of quantum defects in the SWCNT lattice is used to bind biomolecules and to guarantee colloidal stability. To showcase the potential of this approach we demonstrate sensing for different classes of biomolecular analytes (nucleic acids, proteins as well as macromolecular complexes). We analyze sensitivity and selectivity of this recognition approach and present a straightforward way for the generation of novel sensors. In summary, we introduce a novel quantum defect-based covalent functionalization approach of fluorescent SWCNTs with great potential for biosensing.