Single-wall carbon nanotubes (SWCNTs) have emerged to be useful tools in molecular recognition in recent years. Due to their well-defined electronic and optical properties, SWCNTs offer unique properties that most small-molecule sensors lack, such as a near-IR (NIR) photoluminescence which makes them great candidates for sensing simple and complex molecules. Typically, the synthesis of SWCNTs yields over 30 distinct tube chiralities, with two-thirds of the mixture comprising semiconducting and the remaining third consisting of quasi-metallic or true-metallic tubes. To add to the mixture's structural complexity, each chirality with the same helicity could also have different handedness – species that are enantiomeric in nature. In our lab at NIST, we have recently developed techniques based on aqueous two-phase extraction (ATPE) to separate enantiomers of SWCNTs wrapped with specific ssDNA sequences. Most of the sensing assays that use SWCNTs, whether they are coated and dispersed by surfactants or DNA, take advantage of the mixture of various SWCNT helicities to elicit an optical response from interactions with small molecules. However, the responses obtained from each enantiomeric species of SWCNTs are largely ignored, or at best, assumed to be similar. This presentation discusses the differences in photoluminescence response observed when diastereopure and mixtures of SWCNTs wrapped with various DNA sequences interact with enantiopure small molecules. With this study, we give proof that specific DNA sequences allow for stereoselective optical responses between the mixtures of diastereomeric DNA-SWCNT nanohybrids and single-chirality enriched DNA-SWCNTs, and enantiomeric amino acids. This study is the first proof-of-concept that small chiral molecules interact with chirality enriched DNA-SWCNTs to different extents and give rise to specific optical signatures that could be exploited for future developments of sensing arrays for complex biological mixtures.

Stereoselective photoluminescent properties of DNA single walled carbon nanotubes: A primer for molecular perceptron

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.