Highly-Selective Harvesting of (6,4) SWCNTs Using the Aqueous Two-Phase Extraction Method and Nonionic Surfactants

Surfactant Micelle-Driven High-Efficiency and High-Resolution Length Separation of Carbon Nanotubes for Electronic Applications

High-efficiency extraction of long single-wall carbon nanotubes (SWCNTs) with excellent optoelectronic properties from SWCNT solution is critical for enabling their application in high-performance optoelectronic devices. Here, a straightforward and high-efficiency method is reported for length separation of SWCNTs by modulating the concentrations of binary surfactants. The results demonstrate that long SWCNTs can spontaneously precipitate for binary-surfactant but not for single-surfactant systems. This effect is attributed to the formation of compound micelles by binary surfactants that squeeze the free space of long SWCNTs due to their large excluded volumes. With this technique, it can readily separate near-pure long (≥500 nm in length, 99% in content) and short (≤500 nm in length, 98% in content) SWCNTs with separation efficiencies of 26% and 64%, respectively, exhibiting markedly greater length resolution and separation efficiency than those of previously reported methods. Thin-film transistors fabricated from extracted semiconducting SWCNTs with lengths >500 nm exhibit significantly improved electrical properties, including a 10.5-fold on-state current and 14.7-fold mobility, compared with those with lengths <500 nm. The present length separation technique is perfectly compatible with various surfactant-based methods for structure separations of SWCNTs and is significant for fabrication of high-performance electronic and optoelectronic devices.

Monitoring Enzyme Activity Using Near-Infrared Fluorescent Single-Walled Carbon Nanotubes

Enzymes serve as pivotal biological catalysts that accelerate essential chemical reactions, thereby influencing a variety of physiological processes. Consequently, the monitoring of enzyme activity and inhibition not only yields crucial insights into health and disease conditions but also forms the basis of research in drug discovery, toxicology, and the understanding of disease mechanisms. In this context, near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) have emerged as effective tools for tracking enzyme activity and inhibition through diverse strategies. This perspective explores the physicochemical attributes of SWCNTs that render them well-suited for such monitoring. Additionally, we delve into the various strategies developed so far for successfully monitoring enzyme activity and inhibition, emphasizing the distinctive features of each principle. Furthermore, we contrast the benefits of SWCNT-based NIR probes with conventional gold standards in monitoring enzyme activity. Lastly, we highlight the current challenges faced in this field and suggest potential solutions to propel it forward. This perspective aims to contribute to the ongoing progress in biodiagnostics and seeks to engage the wider community in developing and applying enzymatic assays using SWCNTs.

Size Matters in Conjugated Polymer Chirality-Selective SWCNT Extraction

Carbon-based nanomaterials have catalyzed breakthroughs across various scientific and engineering disciplines. The key to unlocking a new generation of tailor-made nanomaterials based on single-walled carbon nanotubes (SWCNTs) lies in the precise sorting of raw material into individual chiralities, each possessing unique properties. This can be achieved using conjugated polymer extraction (CPE), but to a very limited extent since the process generates only a few chirality-enriched suspensions. Therefore, it is imperative to comprehend the mechanism of the wrapping of SWCNTs by polymers to unleash CPE's full potential. However, the lack of a diverse palette of chirality-selective polymers with varying macromolecular parameters has hindered a comprehensive understanding of how the nature of the polymer affects the performance and selectivity of SWCNT isolation. To address this gap, multiple batches of such polymers are synthesized to elucidate the impact of molecular weight and dispersity on the purity and concentrations of the generated SWCNT suspensions. The obtained results explain the inconsistent outcomes reported in the literature, greatly improving the application potential of this promising SWCNT sorting approach. Concomitantly, the discovered significant influence of the macromolecular characteristics of conjugated polymers on the SWCNT isolation efficacy sheds considerable insight into the unresolved mechanism of this sorting technique.

Effects of excipients on the interactions of self-emulsifying drug delivery systems with human blood plasma and plasma membranes

Due to its versatility in formulation and manufacturing, self-emulsifying drug delivery systems (SEDDS) can be used to design parenteral formulations. Therefore, it is necessary to understand the effects of excipients on the behavior of SEDDS formulations upon parenteral administration, particularly their interactions with blood plasma and cell membranes. In this study, we prepared three neutrally charged SEDDS formulations composed of medium-chain triglycerides as the oil phase, polyoxyl-35 castor oil (EL35) and polyethylene glycol (15)-hydroxystearate (HS15) as the nonionic surfactants, medium-chain mono- and diglycerides as the co-surfactant, and propylene glycol as the co-solvent. The cationic surfactant, didodecyldimethylammonium bromide (DDA), and the anionic surfactant, sodium deoxycholate (DEO), were added to the neutral SEDDS preconcentrates to obtain cationic and anionic SEDDS, respectively. SEDDS were incubated with human blood plasma and recovered by size exclusion chromatography. Data showed that SEDDS emulsion droplets can bind plasma protein to different extents depending on their surface charge and surfactant used. At pH 7.4, the least protein binding was observed with anionic SEDDS. Positive charges increased protein binding. SEDDS stabilized by HS15 can adsorb more plasma protein and induce more plasma membrane disruption activity than SEDDS stabilized by EL35. These effects were more pronounced with the HS15 + DDA combination. The addition of DDA and DEO to SEDDS increased plasma membrane disruption (PMD) activities, and DDA (1% w/w) was more active than DEO (2% w/w). PMD activities of SEDDS were concentration-dependent and vanished at appropriate dilution ratios.

An Automated Gradient Titration Fluorescence Methodology for High-Resolution Identification of Aqueous Two-Polymer Phase Extraction Conditions for Single-Wall Carbon Nanotubes

A significant advance in rate and precision of identifying the co-surfactant concentrations leading to differential extraction of specific single-wall carbon nanotube (SWCNT) species in aqueous two-polymer phase extraction experiments is reported. These gains are achieved through continuous titration of co-surfactant and other solution components during automated fluorescence measurements on SWCNT dispersions. The resulting fluorescence versus concentration curves display intensity and wavelength shift transitions traceable to the nature of the adsorbed surfactant layer on specific SWCNT structures at the (n,m) species and enantiomer level at high resolution. The increased precision and speed of the titration method resolve previously invisible complexity in the SWCNT fluorescence during the transition from one surfactant dominating the SWCNT interface to the other, offering insight into the fine details of the competitive exchange process. For the first time, we additionally demonstrate that the competitive process of the surfactant switch is direction independent (reversible) and hysteresis-free; the latter data effectively specifies an upper bound for the time scale of the exchange process. Titration curves are compared to literature results and initial advanced parameter variation is conducted for previously unreasonable to investigate solution conditions.

Enhancing Intracellular Optical Performance and Stability of Engineered Nanomaterials via Aqueous Two-Phase Purification

Supramolecular hybrids of DNA and single-walled carbon nanotubes (SWCNTs) have been introduced in numerous biosensing applications due to their unique optical properties. Recent aqueous two-phase (ATP) purification methods for SWCNTs have gained popularity by introducing specificity and homogeneity into the sensor design process. Using murine macrophages probed by near-infrared and Raman microscopies, we show that ATP purification increases the retention time of DNA-SWCNTs within cells while simultaneously enhancing the optical performance and stability of the engineered nanomaterial. Over a period of 6 h, we observe 45% brighter fluorescence intensity and no significant change in emission wavelength of ATP-purified DNA-SWCNTs relative to as-dispersed SWCNTs. These findings provide strong evidence of how cells differentially process engineered nanomaterials depending on their state of purification, lending to the future development of more robust and sensitive biosensors with desirable in vivo optical parameters using surfactant-based ATP systems with a subsequent exchange to biocompatible functionalization.

Adsorption characteristics of sulfonamide antibiotic molecules on carbon nanotube and the effects of environment

CONTEXT

In this paper, the adsorption characteristics of five sulfonamide antibiotic molecules on carbon nanotubes were investigated using density functional theory (DFT) calculations. The adsorption configurations of different adsorption sites were optimized, and the most stable adsorption configuration of each sulfonamide molecule was determined by adsorption energy comparison, and the relative adsorption stability of five sulfonamide molecules on carbon nanotubes was determined by comparing their adsorption energies, i.e., sulfamethazine > sulfadiazine > sulfamerazine > sulfamethoxazole > sulfanilamide. The electron densities of the adsorption configurations were then calculated to confirm that the adsorption of five sulfonamide drug molecules on carbon nanotubes should be physical adsorption. Moreover, the adsorption energy of five sulfonamide molecules on carbon nanotubes in the aqueous environment was larger than that in the vacuum even though the adsorption process remain to be physical adsorption. The adsorption characteristics of the five sulfonamide molecules in various acid-base environments were finally investigated. In contrast, the adsorption energies of the five drug molecules in acid-base environments were significantly reduced, indicating that carbon nanotubes may need to have a suitable pH range to achieve the optimal adsorption effect when they are used for the treatment of sulfonamide antibiotics.

METHODS

In this paper, we use density functional theory (DFT) with PBE functional to study the adsorption properties of five sulfonamides on carbon nanotubes. The structural optimization and the calculation of electronic structural properties are carried out by CP2K package (version 7.1), adopting the DZVP-MOLOPT-SR-GTH basis set and Goedeck-Teter-Hutter (GTH) pseudo potential. Grimme's D3 correction is used to during all the calculations to correctly capture the influence of the van der Waals interactions.