(559a) Chirality-Resolved Optical Spectroscopy for Recognition Sequence Identification and Sensor Construction in DNA-Carbon Nanotube Hybrids

Short single-stranded DNA (ssDNA) has emerged as the natural polymer of choice for non-covalently functionalizing photoluminescent single-walled carbon nanotubes. In addition, specific empirically identified DNA sequences can be used to separate single species (chiralities) of nanotubes with exceptionally high purity. Currently, there are no general principles for identifying or designing DNA-nanotube hybrids, due in part to an incomplete understanding of the fundamental interactions between a DNA sequence and a specific nanotube structure. We therefore developed a combined experimental and analysis platform, based on time-resolved near-infrared fluorescence spectroscopy, to extract the complete set of photoluminescence parameters that characterize DNA-nanotube hybrids. Here, we systematically investigated the d(GT)_n oligonucleotide family for their resistance to displacement by sodium deoxycholate, and the subsequent photoluminescence response, for six nanotube chiralities. The kinetics of intensity modulation are essentially single exponentials, and the time constants obtained, which quantify the stability of DNA binding, range from 5 to 80 seconds. Surprisingly, these time constants do not depend on the intrinsic optical parameters within the hybrids, suggesting that DNA stability is not due to increased surface nanotube surface coverage by DNA. Further, a principal component analysis of the excitation and emission shifts, along with intensity enhancement at equilibrium accurately identified the (8,6) nanotube as the partner chirality to (GT)₆ ssDNA. Combined, the chirality-resolved equilibrium and kinetics data can guide the development of DNA-nanotube pairs with tunable stability and optical modulation. Additionally, this high-throughput optical platform could function as a primary screen for mapping the DNA-chirality recognition phase space.