Surface modification and cellular uptake evaluation of Au-coated Ni80Fe20 nanodiscs for biomedical applications

Playing with sizes and shapes of colloidal particles via dry etching methods

Monolayers of self-assembled quasi-spherical colloidal particles are essential building blocks in the field of materials science and engineering. More typically, they are used as a template for the fabrication of nanostructures if they serve, for instance, as a mask for deposition of new material on the surface on which particles are assembled or for etching of the material underneath; in this case, they are removed afterwards. This is what occurs in colloidal or nanosphere lithography. In some other cases, they are not used as a sacrificial material but they are incorporated in the final structure because they are inherently interesting for their properties. Independently of their specific use and application, different strategies have been devised in order to modify size and shape of colloidal particles, so as to enrich the variety of attainable patterns and to tailor the properties of the final structures and materials. In this review, we will focus on one of the most widespread methods to shape spherical colloidal particles, i.e. dry etching techniques. We will follow the development of such approaches until recent days, so as to trace an extensive panorama of the diverse parameters that can be harnessed to achieve specific morphological changes and highlight the characteristic features of the variants of this method. We will finally discuss how particles modified via dry etching can be used for patterning or can be resuspended in solvents for very diverse applications.

Influence of shape, size and magnetostatic interactions on the hyperthermia properties of permalloy nanostructures

We present a detailed study of permalloy (Ni₈₀Fe₂₀) nanostructures with variable shape (disk, cylinder and sphere) for magnetic hyperthermia application, exploiting hysteresis losses for heat release. The study is performed modifying nanostructure aspect ratio and size (up to some hundreds of nanometres), to find the optimal conditions for the maximization of specific heating capabilities. The parameters are also tuned to guarantee negligible magnetic remanence and fulfilment of biophysical limits on applied field amplitude and frequency product, to avoid aggregation phenomena and intolerable resistive heating, respectively. The attention is first focused on disk-shaped nanostructures, with a comparison between micromagnetic simulations and experimental results, obtained on nanodisks still attached on the lithography substrate (2D array form) as well as dispersed in ethanol solution (free-standing). This analysis enables us to investigate the role of magnetostatic interactions between nanodisks and to individuate an optimal concentration for the maximization of heating capabilities. Finally, we study magnetization reversal process and hysteresis properties of nanocylinders (diameter between 150 nm and 600 nm, thickness from 30 nm up to 150 nm) and nanospheres (size between 100 nm and 300 nm), to give instructions on the best combination of geometrical parameters for the design of novel hyperthermia mediators.

Enabling technologies for the preparation of multifunctional “bullets” for nanomedicine

Recent advances in nanotechnology, including modern enabling techniques that can improve synthetic preparation and drug formulations, have opened up new frontiers in nanomedicine with the development of nanoscale carriers and assemblies. The use of delivery platforms has attracted attention over the past decade as researchers shift their focus away from the development of new drug candidates, and toward new means with which to deliver therapeutic and/or diagnostic agents. This work will explore a transdisciplinary approach for the production of a number of nanomaterials, nanocomplexes and nanobubbles and their application in a variety of potential biological and theranostic protocols. Particular attention will be paid to nanobubbles, stimuli responsive nanoparticles and cyclodextrin grafted nanosystems produced under non-conventional conditions, such as microwave and ultrasound irradiation. Besides nanoparticles preparation, ultrasound can also act as an enabling technology when activating sensitive nanobubbles and nanoparticles.