A Low Energy Route to DNA-Wrapped Carbon Nanotubes via Replacement of Bile Salt Surfactants

Abstract

DNA-wrapped carbon nanotubes are a class of bionano hybrid molecules that have enabled carbon nanotube sorting, controlled assembly, and biosensing and bioimaging applications. The current method of synthesizing these hybrids via direct sonication of DNA/nanotube mixtures is time-consuming and not suitable for high-throughput synthesis and combinatorial sequence screening. Additionally, the direct sonication method does not make use of nanotubes presorted by extensively developed surfactant-based methods, is not effective for large diameter (>1 nm) tubes, and cannot maintain secondary and tertiary structural and functional domains present in certain DNA sequences. Here, we report a simple, quick, and robust process to produce DNA-wrapped carbon nanotube hybrids with nanotubes of broad diameter range and DNA of arbitrary sequence. This is accomplished by exchanging strong binding bile salt surfactant coating with DNA in methanol/water mixed solvent and subsequent precipitation with isopropyl alcohol. The exchange process can be completed within 10 min and converts over 90% nanotubes into the DNA wrapped form. Applying the exchange process to nanotubes presorted by surfactant-based methods, we show that the resulting DNA-wrapped carbon nanotubes can be further sorted to produce nanotubes with defined handedness, helicity, and endohedral filling. The exchange method greatly expands the structural and functional variety of DNA-wrapped carbon nanotubes and opens possibilities for DNA-directed assembly of structurally sorted nanotubes and high-throughput screening of properties that are controlled by the wrapping DNA sequences.