We characterized the microwave-frequency (0.5-6 GHz) dielectric properties of aqueous dispersions of pristine and purified single-walled carbon nanotubes (SWCNTs). SWCNTs were synthesized by two CVD-based methods and purified using two acid-based purification methods. We characterized the structural and chemical differences across SWCNT samples using Raman analysis, UV-Vis spectroscopy, atomic force microscopy, and thermogravimetric analysis. We found that the dielectric properties of the pristine SWCNT dispersions did not vary with synthesis method, but the dielectric properties of purified SWCNT dispersions were variably impacted by acid purification due to different degrees of morphological and chemical changes in the SWCNTs.

Cell-specific uptake of drug delivery systems (DDSs) are crucial to achieve optimal efficacy of many drugs. Widely employed strategies to facilitate targeted intracellular drug delivery involves attachment of targeting ligands (peptides or antibodies) to DDSs. Target receptors mutations can limit the effectiveness of this approach. Herein, we demonstrate, through in vitro inhibitory and drug delivery studies, that graphene nanoribbons (GNRs), water dispersed with the amphiphilic polymer called PEG-DSPE ((1, 2-distearoyl-sn-glycero-3phosphoethanolamine-N [amino (polyethylene glycol)]) (induce membrane depolarization-mediated epidermal growth factor receptor (EGFR) activation. This phenomenon is ligand-independent and EGFR activation occurs via influx of Ca 2+ ions from the extracellular space. We further provide evidence, through in vivo studies, that this mechanism could be exploited to facilitate efficacious drug delivery into tumors that overexpress EGFR. The results suggest that transient membrane depolarization-facilitated cell receptor activation can be employed as an alternate strategy for enhanced intracellular drug delivery.

In this paper, we present an experimental study of the microwave-frequency dielectric properties and heating response of aqueous dispersions of single-and double-walled carbon nanotubes (CNTs). The CNTs were chemically treated using a method that enables the creation of stable dispersions of isolated tubes at very high concentrations. The CNT dispersions show significantly enhanced dielectric properties and heating response compared to the control (an aqueous sample without CNTs). The observed enhancement with this specific CNT dispersion formulation is far greater than any previously reported. The results suggest that these modified CNTs are promising candidates as contrast agents for microwave diagnostic imaging and heating agents for nanoparticle-mediated microwave thermal therapy for cancer.Index Terms-microwave dielctric spectroscopy, microwave heating, carbon nanotubes, contrast agents, heating agents, cancer imaging, cancer treatment.

We present a formulation for achieving stable high-concentration (up to 20 mg/ml) aqueous dispersions of carbon nanotubes (CNTs) with exceptionally high microwave-frequency (0.5-6 GHz) dielectric properties. The formulation involves functionalizing CVD-synthesized CNTs via sonication in nitric and sulfuric acid. The overall chemical integrity of the CNTs is largely preserved, as demonstrated via physical and chemical characterizations, despite significant shortening and functionalization with oxygen-containing groups. This is attributed to the protected inner walls of double-walled CNTs in the samples. The resulting CNT dispersions show greatly enhanced dielectric properties compared to a CNT-free control. For example, at 3 GHz, the average relative permittivity and effective conductivity across several 20 mg/ml CNT samples were increased by ∼ 70% and ∼ 400%, respectively, compared to the control. These CNT dispersions exhibit the stability and extraordinary microwave properties desired in systemically administered theranostic agents for microwave diagnostic imaging and/or thermal therapy.

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