Magnetic Domains and Surface Effects in Hollow Maghemite Nanoparticles

In the present work, we investigate the magnetic properties of ferrimagnetic and noninteracting maghemite (g-Fe2O3) hollow nanoparticles obtained by the Kirkendall effect. From the experimental characterization of their magnetic behavior, we find that polycrystalline hollow maghemite nanoparticles are characterized by low superparamagnetic-to-ferromagnetic transition temperatures, small magnetic moments, significant coercivities and irreversibility fields, and no magnetic saturation on external magnetic fields up to 5 T. These results are interpreted in terms of the microstructural parameters characterizing the maghemite shells by means of an atomistic Monte Carlo simulation of an individual spherical shell model. The model comprises strongly interacting crystallographic domains arranged in a spherical shell with random orientations and anisotropy axis. The Monte Carlo simulation allows discernment between the influence of the structure polycrystalline and its hollow geometry, while revealing the magnetic domain arrangement in the different temperature regimes.Comment: 26 pages, 8 figures. In press in Phys. Rev.

Impact of engineered nanoparticles in initiating or modulating pathology-related Inflammation

The possibility that nanomaterials could perturb the normal course of an inflammatory response is a key issue when assessing nano-immunosafety. The alteration of the normal progress of an inflammatory response may have pathological consequences, since inflammation is a major defensive mechanism and its efficiency maintains the body’s health. We can thus consider as pathology-related inflammation those inflammatory reactions that, instead of eliminating foreign agents, lack down-regulation and cause tissue damage. To assess the ability of nanoparticles to initiate and modulate inflammatory reactions, an in vitro model was used that recapitulates all the stages of infection-induced inflammation, from initiation to resolution, based on human primary blood monoytes. A parallel model reproducing pathological chronic inflammation shows that the differences between resolving and persistent inflammation are subtle and evident only upon kinetic analysis of gene expression profiles and production of inflammatory factors. Rigorously endotoxin-free Au and Ag nanoparticles have been assessed for their ability to directly initiate in vitro inflammation and for their capacity to modulate the course both physiological resolving inflammation and pathological persistent inflammation. In no case significant effects were observed, with the exception of a transient increase of the inflammatory response in the presence of Ag nanoparticles. An important issue in the regulation of monocyte/macrophage inflammatory functions is the capacity of innate “memory”, i.e., the ability of respond differently to a challenge if previously primed with the same or a different agent. How nanoparticles can impact innate memory was assessed by using Au nanoparticles as priming and challenge agent with and without LPS and zymosan. Priming with LPS and zymosan could drastically decrease the response of monocytes (production of TNFa) to a challenge with any stimulus, given 7 days after the first. The presence of Au nanoparticles did not influence such behaviour. Likewise, Au nanoparticles did not directly induce memory, i.e., did not influence the response of monocytes to subsequent stimuli. We conclude that Au and Ag nanoparticles, at the size and concentrations used, are taken up by monocytes without this causing any notable interference with their capacity to mount an adequate defensive responses to microbial challenges, either immediate or after some time from exposure. This work was supported by per EU FP7 projects HUMUNITY and BioCog, the H2020 project PANDORA, the CNR Flagship Project InterOmics, and the cluster project Medintech of the Italian Ministry of Education, University and Research

Addressing nanomaterial immunosafety by evaluating innate immunity across living species

The interaction of a living organism with external foreign agents is a central issue for its survival and adaptation to the environment. Nanosafety should be considered within this perspective, and it should be examined that how different organisms interact with engineered nanomaterials (NM) by either mounting a defensive response or by physiologically adapting to them. Herein, the interaction of NM with one of the major biological systems deputed to recognition of and response to foreign challenges, i.e., the immune system, is specifically addressed. The main focus is innate immunity, the only type of immunity in plants, invertebrates, and lower vertebrates, and that coexists with adaptive immunity in higher vertebrates. Because of their presence in the majority of eukaryotic living organisms, innate immune responses can be viewed in a comparative context. In the majority of cases, the interaction of NM with living organisms results in innate immune reactions that eliminate the possible danger with mechanisms that do not lead to damage. While in some cases such interaction may lead to pathological consequences, in some other cases beneficial effects can be identified

Probing the immune responses to nanoparticles across environmental species. A perspective of the EU Horizon 2020 project PANDORA

Understanding how engineered nanomaterials affect immune responses of living organisms requires a strong collaborative effort between immunologists, toxicologists, ecologists, physiologists, inorganic chemists, nanomaterial scientists and experts in law and risk management. This perspective aims to provide a new viewpoint on the interaction between engineered nanomaterials and the immune defensive systems across living species, gained within the EU Horizon 2020 project PANDORA. We consider the effects of nanoparticle exposure on immune functions in plants, marine and terrestrial invertebrates and their relation to the current state of knowledge for vertebrates (in particular humans). These studies can shed light on the broader perspective of defensive and homeostatic mechanisms (immunity, inflammation, stress responses, microbiota, stem cell differentiation) suggesting ways to: i) perform a comparative analysis of the nanoparticle impact on immunity across model organisms; ii) inspire best practices in experimental methodologies for nanosafety/nanotoxicity studies; iii) regroup and harmonise fragmented research activities; iv) improve knowledge transfer strategies and nano-security; v) propose innovative tools and realistic solutions, thereby helping in identifying future research needs and tackling their challenges

Diverse Applications of Nanomedicine

The design and use of materials in the nanoscale size range for addressing medical and health-related issues continues to receive increasing interest. Research in nanomedicine spans a multitude of areas, including drug delivery, vaccine development, antibacterial, diagnosis and imaging tools, wearable devices, implants, high-throughput screening platforms, etc. using biological, nonbiological, biomimetic, or hybrid materials. Many of these developments are starting to be translated into viable clinical products. Here, we provide an overview of recent developments in nanomedicine and highlight the current challenges and upcoming opportunities for the field and translation to the clinic. \ua9 2017 American Chemical Society