Semiconducting nanoelectronic materials, including single-walled carbon nanotubes (SWCNT) and transition metal dichalcogenides (TMDs) possess interesting optoelectronic properties that could enable next-generation electronics, sensing technologies, and biomedicine. In this thesis, biomolecule-assisted dispersion and assembly of these nanomaterials are explored for human toxicity, environmental hazard potential, and applications in supramolecular hydrogels. Liquid-based exfoliation of hydrophobic nanomaterials requires the presence of a surfactant in aqueous solution. Surfactant-assisted exfoliation of nanomaterials is a highly scalable and applicable processing method, but often results in dispersions of poor quality or yield. Here, we survey a library of nonionic, biocompatible block copolymers, known commercially as Pluronics and Tetronics, that are capable of stabilizing MoS2 in aqueous solution. We determine that Pluronic F87 results in the highest concentration MoS2 dispersion. This poloxamer is applied to the dispersion of a range of emerging 2D materials, establishing a facile aqueous exfoliation method for further studies. Using the same biocompatible block copolymer found in the previous study, we establish a library of MoS2 nanomaterials with highly refined physicochemical properties. The library of MoS2 nanomaterials is comprised of Pluronic-dispersed MoS2, aggregated MoS2, and lithiated MoS2. In a study of their inhalation risk in humans, it is found that aggregated MoS2 induces an inflammatory response after acute exposure. None of the MoS2 nanomaterials are found to induce fibrosis of the lung after subchronic exposure. In the natural aquatic environment, Pluronic-dispersed MoS2 nanomaterials are comparatively more stable and more likely to interact with surface media than lithiated-MoS2. Furthermore, the hazard potential of SWCNT is investigated. Specifically, we demonstrate that electronic type has little bearing on the lung inflammatory response of SWCNT. These results are essential to the establishment of safe handling practices for nanomaterials and are of interest from a regulatory perspective. Finally, biomolecule-assisted assembly is studied in the form of an optothermally responsive SWCNT–DNA supramolecular hydrogel (SMH). In this SMH, SWCNT are dispersed in aqueous solution by helical wrapping of single-stranded DNA. DNA base pairing is employed to form a SWCNT network, thereby providing the cross-linking force necessary for gelation. The mechanical strength of this SMH is proportional to the SWCNT concentration, and can be tuned accordingly. The SMH is fully thermo- and NIR- reversible and therefore has potential for applications in sensing and responsive materials

Last modified

• 01/28/2019

Creator

• Nikita Mansukhani

DOI

• https://doi.org/10.21985/N2T109

Subject

• Material Science and Engineering

Keyword

• Carbon Nanomaterials
• Toxicity
• Biofunctionalization
• Supramolecular Hydrogel
• Two-Dimensional Nanomaterials

Date created

• 2017-01-01

Resource type

• Dissertation

Rights statement

• In Copyright