New structural characteristics emerge when solid-state crystals are constructed in lower dimensions. This is exemplified by single-wall carbon nanotubes, which exhibit a degree of freedom in handedness and a multitude of helicities that give rise to three distinct types of electronic structures: metals, quasi-metals, and semiconductors. Here we report the use of intrinsically chiral single-stranded DNA to achieve simultaneous handedness and helicity control for all three types of nanotubes. We apply polymer aqueous two-phase systems to select special DNA-wrapped carbon nanotubes, each of which we argue must have an ordered DNA structure that binds to a nanotube of defined handedness and helicity and resembles a well-folded biomacromolecule with innate stereoselectivity. We have screened over 300 short single-stranded DNA sequences with palindrome symmetry, leading to the selection of more than 20 distinct carbon nanotube structures that have defined helicity and handedness and cover the entire chiral angle range and all three electronic types. The mechanism of handedness selection is illustrated by a DNA sequence that adopts two distinct folds on a pair of (6,5) nanotube enantiomers, rendering them large differences in fluorescence intensity and chemical reactivity. This result establishes a first example of functionally distinguishable left- and right-handed carbon nanotubes. Taken together, our work demonstrates highly efficient enantiomer differentiation by DNA and offers a first comprehensive solution to achieve simultaneous handedness and helicity control for all three electronic types of carbon nanotubes.

The dispersion microstructure and rheological properties of aqueous sulfonated cellulose nanocrystal (CNC) suspensions have been investigated. Between 3.07 and 10.4 vol % the suspensions phase separated into liquid crystalline and isotropic domains. At 12.1 vol %, no isotropic phase was visible, and the samples had the fingerprint texture characteristic of a cholesteric liquid crystal. Below 35 °C, temperature had little influence on rheology and phase behavior. However, between 35 and 40 °C there was a significant change in both the fraction of isotropic phase and the rheological properties. In contrast to many lyotropic suspensions, the steady shear viscosity did not go through a maximum with increasing concentration. Maxima were observed for complex viscosity, storage modulus, and loss modulus at concentrations that appeared fully liquid crystalline. Time–concentration superposition was successful for the loss modulus but not the storage modulus. This suggests that the interface in biphasic samples affects the elastic relaxation but not the viscous response. At still higher concentrations, the fingerprint texture of the liquid crystal phase was absent, and the dispersions behaved as rheological gels.

Sorting single-wall carbon nanotubes (SWCNTs) of different chiralities is both scientifically interesting and technologically important. Recent studies have shown that polymer aqueous two-phase extraction is a very effective way to achieve nanotube sorting. However, works published to date have demonstrated only separation of surfactant-dispersed SWCNTs, and the mechanism of chirality-dependent SWCNT partition is not well understood. Here we report a systematic study of spontaneous partition of DNA-wrapped SWCNTs in several polymer aqueous two-phase systems. We show that partition of DNA-SWCNT hybrids in a given polymer two-phase system is strongly sequence-dependent and can be further modulated by salt and polymer additives. With the proper combination of DNA sequence, polymer two-phase system, and partition modulators, as many as 15 single-chirality nanotube species have been effectively purified from a synthetic mixture. As an attempt to provide a unified partition mechanism of SWCNTs dispersed by surfactants and by DNA, we present a qualitative analysis of solvation energy for SWCNT colloids in a polymer-modified aqueous phase. Our observation and analysis highlight the sensitive dependence of the hydration energy on the spatial distribution of hydrophilic functionalities.

The introduction of sp defects into single-walled carbon nanotubes through covalent functionalization can generate new light-emitting states and thus dramatically expand their optical functionality. This may open up routes to enhanced imaging, photon upconversion, and room-temperature single-photon emission at telecom wavelengths. However, a significant challenge in harnessing this potential is that the nominally simple reaction chemistry of nanotube functionalization introduces a broad diversity of emitting states. Precisely defining a narrow band of emission energies necessitates constraining these states, which requires extreme selectivity in molecular binding configuration on the nanotube surface. We show here that such selectivity can be obtained through aryl functionalization of so-called 'zigzag' nanotube structures to achieve a threefold narrowing in emission bandwidth. Accompanying density functional theory modelling reveals that, because of the associated structural symmetry, the defect states become degenerate, thus limiting emission energies to a single narrow band. We show that this behaviour can only result from a predominant selectivity for ortho binding configurations of the aryl groups on the nanotube lattice.

The abnormal accumulation of lipids within the endolysosomal lumen occurs in many conditions, including lysosomal storage disorders, atherosclerosis, non-alcoholic fatty liver disease (NAFLD), and drug induced phospholipidosis. Current methods cannot monitor endolysosomal lipid content in vivo, hindering preclinical drug development and research into the mechanisms linking endolysosomal lipid accumulation to disease progression. We developed a single-walled carbon nanotube-based optical reporter that non-invasively measures endolysosomal lipid accumulation via bandgap modulation of its intrinsic near-infrared emission. The reporter detected lipid accumulation in Niemann-Pick disease, atherosclerosis, and NAFLD models in vivo. By applying the reporter to the study of NAFLD, we found that elevated lipid quantities in hepatic macrophages caused by a high fat diet persist long after reverting to a normal diet. The reporter dynamically monitored endolysosomal lipid accumulation in vivo over time scales ranging from minutes to weeks, indicating its potential to accelerate preclinical research and drug development processes.

Molecularly functionalized single-walled carbon nanotubes (SWCNTs) are potentially useful for fiber optical applications due to their room temperature single-photon emission capacity at telecommunication wavelengths. Several distinct defect geometries are generated upon covalent functionalization. While it has been shown that the defect geometry controls electron localization around the defect site, thereby changing the electronic structure and generating new optically bright red-shifted emission bands, the reasons for such localization remain unexplained. Our joint experimental and computational studies of functionalized SWCNTs with various chiralities show that the value of mod­(n-m,3) in an (n,m) chiral nanotube plays a key role in the relative ordering of defect-dependent emission energies. This dependence is linked to the complex nodal characteristics of electronic wave function extending along specific bonds in the tube, which justifies the defect-geometry dependent exciton localization. This insight helps to uncover the essential structural motifs allowing tuning the redshifts of emission energies in functionalized SWCNTs.

SUMMARY Organic color centers are an emergent class of quantum emitters that hold vast potential for applications in bioimaging, chemical sensing, and quantum information processing. Here, we show that these synthetic color centers follow interesting structure-property relationships through comparative spectral studies of 14 purified single-walled carbon nanotube chiralities and 30 different functional groups that vary in electron-withdrawing capability and bonding configurations. The defect emission is tunable by as much as 400 meV in the near-infrared as a function of host structure and the chemical nature of the color centers. However, the emission energy is nearly free from chiral angle and family patterns of the nanotube host (although this strongly depends on the nanotube diameter), suggesting that a trapped exciton at the organic color centers to some degree electronically decouples from the one-dimensional semiconductor host. Our findings provide important insights for designing and controlling this new family of synthetic color centers.

The first lyotropic cholesteric single-walled carbon nanotube (SWNT) liquid crystal phase was obtained by dispersing SWNTs in an aqueous solution of double-stranded DNA (dsDNA). Depending on the dispersion methodology, the polydomain nematic phase previously reported for other lyotropic carbon nanotube dispersions could also be obtained. The phase behavior and dispersion microstructure were affected by the relative concentrations of dsDNA and SWNT and whether small bundles were removed prior to concentrating the dispersions. This readily controlled phase behavior opens new routes for producing SWNT films with controlled morphology.