Assumption-free morphological quantification of single anisotropic nanoparticles and aggregates

Characterizing the morphometric parameters of noble metal nanoparticles for sensing and catalysis is a persistent challenge due to their small size and complex shape. Herein, we present an approach to determine the volume, surface area, and curvature of non-symmetric anisotropic nanoparticles using electron tomography and design- based stereology without the use of segmentation tools or modeling of the particles. Finally, we apply these tools to aggregates to estimate their fractal dimension

A new angle on dynamic depolarized light scattering: number-averaged size distribution of nanoparticles in focus

Size polydispersity is a common phenomenon that strongly influences the physicochemical properties of nanoparticles (NPs). We present an analytical approach that is universally applicable to characterizing optically anisotropic round NPs and determines directly the number-averaged size distribution and polydispersity via depolarized dynamic light scattering (DDLS). To demonstrate, we use aqueous suspensions of Au NPs of different sizes and surface functionalization

Plasmonic nanoparticles and their characterization in physiological fluids

Nanoparticles possess unique properties beyond that of classical materials, and while these properties can be used for designing a dedicated functionality, they may also pose a problem to living organisms, to human health and the environment. The specific primary routes by which nanoparticles may interact with the human body include inhalation, injection, ingestion and application to the skin. Independent of the entry route, the particles inevitably encounter a complex physiological fluid populated with e.g. proteins, vitamins, lipids and salts/ions. Different consequences of such an encounter may include formation of a surface-bound protein layer, particle dissolution or aggregation, which are expected to have a crucial impact on cellular interaction. Understanding cellular responses to nanoparticle interactions starts with understanding particle behavior in physiological fluids. Nanoparticles are now available in practically any size, shape and functionalization, to promote distinct optical, magnetic, and physico-chemical properties, making the prediction of their behavior, in physiological fluids, not a trivial task. Characterization has therefore become of paramount importance. In this review, we give an overview about the diversity of physiological fluids as well as present an inventory of the most relevant experimental techniques used to study plasmonic nanoparticles

Thermally reversible self-assembly of nanoparticles via polymer crystallization

The directed self-assembly of gold nanoparticles through the crystallization of surface-grafted polyethylene oxide (PEO) in ethanol–water mixtures is described. This process is fully reversible and tunable through either the size of the core or the polymeric coating. Characterization by X-ray scattering and electron microscopy of the self-assembled structures reveals order at the nanoscale, typically not the case for thermoresponsive gold nanoparticles coated with lower or upper critical solution temperature polymers. A further novelty is the result of selective binding of calcium ions to the PEO in the fluid state: a reversible thermoresponsive transition become irreversible

Surface charge of polymer coated SPIONs influences the serum protein adsorption, colloidal stability and subsequent cell interaction in vitro

It is known that the nanoparticle–cell interaction strongly depends on the physicochemical properties of the investigated particles. In addition, medium density and viscosity influence the colloidal behaviour of nanoparticles. Here, we show how nanoparticle–protein interactions are related to the particular physicochemical characteristics of the particles, such as their colloidal stability, and how this significantly influences the subsequent nanoparticle–cell interaction in vitro. Therefore, different surface charged superparamagnetic iron oxide nanoparticles were synthesized and characterized. Similar adsorbed protein profiles were identified following incubation in supplemented cell culture media, although cellular uptake varied significantly between the different particles. However, positively charged nanoparticles displayed a significantly lower colloidal stability than neutral and negatively charged particles while showing higher non-sedimentation driven cell-internalization in vitro without any significant cytotoxic effects. The results of this study strongly indicate therefore that an understanding of the aggregation state of NPs in biological fluids is crucial in regards to their biological interaction(s)

Ultrathin ceramic membranes as scaffolds for functional cell coculture models on a biomimetic scale

Epithelial tissue serves as an interface between biological compartments. Many in vitro epithelial cell models have been developed as an alternative to animal experiments to answer a range of research questions. These in vitro models are grown on permeable two-chamber systems; however, commercially available, polymer-based cell culture inserts are around 10 μm thick. Since the basement membrane found in biological systems is usually less than 1 μm thick, the 10-fold thickness of cell culture inserts is a major limitation in the establishment of realistic models. In this work, an alternative insert, accommodating an ultrathin ceramic membrane with a thickness of only 500 nm (i.e., the Silicon nitride Microporous Permeable Insert [SIMPLI]-well), was produced and used to refine an established human alveolar barrier coculture model by both replacing the conventional inserts with the SIMPLI-well and completing it with endothelial cells. The structural–functional relationship of the model was evaluated, including the translocation of gold nanoparticles across the barrier, revealing a higher translocation if compared to corresponding polyethylene terephthalate (PET) membranes. This study demonstrates the power of the SIMPLI-well system as a scaffold for epithelial tissue cell models on a truly biomimetic scale, allowing construction of more functionally accurate models of human biological barriers

Decoupling the shape parameter to assess gold nanorod uptake by mammalian cells

The impact of nanoparticles (NPs) upon biological systems can be fundamentally associated with their physicochemical parameters. A further often-stated tenet is the importance of NP shape on rates of endocytosis. However, given the convoluted parameters concerning the NP–cell interaction, it is experimentally challenging to attribute any findings to shape alone. Herein we demonstrate that shape, below a certain limit, which is specific to nanomedicine, is not important for the endocytosis of spherocylinders by either epithelial or macrophage cells in vitro. Through a systematic approach, we reshaped a single batch of gold nanorods into different aspect ratios resulting in near-spheres and studied their cytotoxicity, (pro-)inflammatory status, and endocytosis/exocytosis. It was found that on a length scale of ∼10–90 nm and at aspect ratios less than 5, NP shape has little impact upon their entry into either macrophages or epithelial cells. Conversely, nanorods with an aspect ratio above 5 were preferentially endocytosed by epithelial cells, whereas there was a lack of shape dependent uptake following exposure to macrophages in vitro. These findings have implications both in the understanding of nanoparticle reshaping mechanisms, as well as in the future rational design of nanomaterials for biomedical applications

Beyond global charge: role of amine bulkiness and protein fingerprint on nanoparticle–cell interaction

Amino groups presented on the surface of nanoparticles are well‐known to be a predominant factor in the formation of the protein corona and subsequent cellular uptake. However, the molecular mechanism underpinning this relationship is poorly defined. This study investigates how amine type and density affect the protein corona and cellular association of gold nanoparticles with cells in vitro. Four specific poly(vinyl alcohol‐co‐N‐vinylamine) copolymers are synthesized containing primary, secondary, or tertiary amines. Particle cellular association (i.e., cellular uptake and surface adsorption), as well as protein corona composition, are then investigated. It is found that the protein corona (as a consequence of “amine bulkiness”) and amine density are both important in dictating cellular association. By evaluating the nanoparticle surface chemistry and the protein fingerprint, proteins that are significant in mediating particle–cell association are identified. In particular, primary amines, when exposed on the polymer side chain, are strongly correlated with the presence of alpha‐2‐HS‐ glycoprotein, and promote nanoparticle cellular association

"It‘s Hard to Keep Track": Mapping a Shifting Nation in Dylan Horrocks‘s Hicksville

Using an art form that justifiably lays claim to both visual and literary genealogies—the graphic novel—Dylan Horrocks's Hicksville advances, rather than strictly challenges, many of the discussions which have informed the local manufacture of art and literature. My purpose in this thesis is to explore Horrocks's deployment of the critical perspectives of both art historical and literary discourse as they have developed from the pre-colonial to the twenty-first century in New Zealand, especially those associated with cultural nationalism. Hicksville claims a particular relation to the existing traditions within both art-historical and literary lines wherein they are conjoined in practice; integrated into the formal properties of Horrocks's work, the traditional concerns of local art and literature are not only subject matter but guide Horrocks‘s approach to narrative. The tension between art and place—the responsibility of the artist to the nation and its referents—appears in Hicksville as a structuring device rather than polemic via its concern with the economisation of art—or global capitalism—as it bears upon particular places and art practices. Yet Horrocks‘s handling of this theme upholds neither aestheticism nor populism. Rather, he invites the reader to make sense of extensive references to a range of artistic figures, from Heaphy to Hergé to Hotere, in a way that accounts for their equal force. Hicksville thus deliberately destabilises the joint histories of art and literary history to pointed effect, valuing its range of artistic and cultural inheritances—whether the visual or literary, the highbrow or lowbrow—for how they can remind us that contemporary artistic accounts of New Zealand must also consider the various ways the country has been constructed throughout its wide