Characterizing the Cellular Response to Nitrogen-Doped Carbon Nanocups

Nitrogen-Doped Carbon Nanotube Cups for Cancer Therapy

Carbon nanomaterials have attracted significant attention for a variety of biomedical applications including sensing and detection, photothermal therapy, and delivery of therapeutic cargo. The ease of chemical functionalization, tunable length scales and morphologies, and ability to undergo complete enzymatic degradation make carbon nanomaterials an ideal drug delivery system. Much work has been done to synthesize carbon nanomaterials ranging from carbon dots, graphene, and carbon nanotubes to carbon nanocapsules, specifically carbon nanohorns or nitrogen-doped carbon nanocups. Here, we analyze specific properties of nitrogen-doped carbon nanotube cups which have been designed and utilized as drug delivery systems with the focus on the loading of these nanocapsules with specific therapeutic cargo and the targeted delivery for cancer therapy. We also summarize our targeted synthesis of gold nanoparticles on the open edge of nitrogen-doped carbon nanotube cups to create loaded and sealed nanocarriers for the delivery of chemotherapeutic agents to myeloid regulatory cells responsible for the immunosuppressive properties of the tumor microenvironment and thus tumor immune escape.

Do Carbon Nanotubes and Asbestos Fibers Exhibit Common Toxicity Mechanisms?

During the last two decades several nanoscale materials were engineered for industrial and medical applications. Among them carbon nanotubes (CNTs) are the most exploited nanomaterials with global production of around 1000 tons/year. Besides several commercial benefits of CNTs, the fiber-like structures and their bio-persistency in lung tissues raise serious concerns about the possible adverse human health effects resembling those of asbestos fibers. In this review, we present a comparative analysis between CNTs and asbestos fibers using the following four parameters: (1) fibrous needle-like shape, (2) bio-persistent nature, (3) high surface to volume ratio and (4) capacity to adsorb toxicants/pollutants on the surface. We also compare mechanisms underlying the toxicity caused by certain diameters and lengths of CNTs and asbestos fibers using downstream pathways associated with altered gene expression data from both asbestos and CNT exposure. Our results suggest that indeed certain types of CNTs are emulating asbestos fiber as far as associated toxicity is concerned.

Design and Testing of Bistable Lattices with Tensegrity Architecture and Nanoscale Features Fabricated by Multiphoton Lithography

A bistable response is an innate feature of tensegrity metamaterials, which is a conundrum to attain in other metamaterials, since it ushers unconventional static and dynamical mechanical behaviors. This paper investigates the design, modeling, fabrication and testing of bistable lattices with tensegrity architecture and nanoscale features. First, a method to design bistable lattices tessellating tensegrity units is formulated. The additive manufacturing of these structures is performed through multiphoton lithography, which enables the fabrication of microscale structures with nanoscale features and extremely high resolution. Different modular lattices, comprised of struts with 250 nm minimum radius, are tested under loading-unloading uniaxial compression nanoindentation tests. The compression tests confirmed the activation of the designed bistable twisting mechanism in the examined lattices, combined with a moderate viscoelastic response. The force-displacement plots of the 3D assemblies of bistable tensegrity prisms reveal a softening behavior during the loading from the primary stable configuration and a subsequent snapping event that drives the structure into a secondary stable configuration. The twisting mechanism that characterizes such a transition is preserved after unloading and during repeated loading-unloading cycles. The results of the present study elucidate that fabrication of multistable tensegrity lattices is highly feasible via multiphoton lithography and promulgates the fabrication of multi-cell tensegrity metamaterials with unprecedented static and dynamic responses.