The successful sunlight-photolyzed reversible addition− fragmentation chain transfer (RAFT) photopolymerization can be reversibly activated and deactivated by irradiation with sunlight in the absence of photocatalyst and photoinitiator. In the present work, the thiocarbonylthio compounds (dithiobenzoate, trithiocarbonate, and xanthate) can all be employed to carry out the polymerization under sunlight irradiation acting as an initiator, chain transfer agent, and termination agent. Moreover, it was demonstrated that the recyclablecatalyst-aided, opened-to-air, and sunlight-photolyzed RAFT (ROS-RAFT) polymerizations can be successfully carried out to fabricate precise and predictable polymers in the presence of the recyclable magnetic semiconductor nanoparticles (NPs). The oxygen tolerance is likely attributed to a specific interaction between NPs and oxygen.

A series of ferrite nanoparticles with different Zn content were synthesized following a single-step electrochemical method in aqueous medium.

Zn-doped Fe3O4 magnetic nanoparticles have been proposed as the ideal ferrite for some biomedical applications like magnetic hyperthermia or photothermal therapy because of the possibility to adjust their size and chemical composition in order to design tailored treatments. However, reliable approaches are needed to risk assess Zn ferrite nanoparticles before clinical development. In this work, the in vitro toxicity of the nanoparticles was evaluated in five cellular models (Caco-2, HepG2, MDCK, Calu-3 and Raw 264.7) representing different target organs/systems (gastrointestinal system, liver, kidney, respiratory system and immune system). For the first time, these nanoparticles were evaluated in an in vivo Xenopus laevis model to study whole organism toxicity and their impact on iron and zinc metabolic pathways. Short and long-term in vivo exposure studies provided insights into the contrasting adverse effects between acute and chronic exposure. Quantitative PCR combined with elemental analysis and AC magnetic susceptibility measurements revealed that at short-term exposure (72 h) the nanoparticles' absorption process is predominant, with the consequent over-expression of metal transporters and metal response proteins. At long-term exposure (120 h), there is an up-regulation of 2 metal accumulation involved genes and the return to basal levels of both iron and zinc transporters, involved in the uptake of metals. This suggests that at this stage the nanoparticles' absorption process is residual compared with the following steps in metabolism, distribution and/or excretion processes, indicated by the increase of iron accumulation proteins at both transcriptional and translational level. This testing approach based on a battery of cellular systems and the use of the Xenopus laevis model could be a viable strategy for studying the toxicity, degradability and ultimately the long-term fate of zinc ferrites in the organism.

Superparamagnetic iron oxide nanoparticles have played a fundamental role in the recent development on nanomedicine, being one of the most popular imaging and therapeutic agents. Recently, the ability of iron magnetic nanoparticles for efficient heat generation under infrared optical excitation has even boosted the interest of scientific community in this family of nanomaterials. Combination of magnetic and optical heating into a single nanostructure makes possible the development of advanced therapy treatments based on synergetic effects between these two heat sources that, in addition, could be combined with high penetration magnetic imaging. Despite of its potential, the application of iron oxide nanoparticles in photothermal treatments is limited because the lack of knowledge about the physical mechanisms behind their light-to-heat conversion capacity. In this work we have systematically investigated the photothermal efficiency of iron oxide nanoparticles with a variable composition achieved by partial replacement of iron by zinc atoms. We have experimentally found that the light-to-heat conversion efficiency gradually increases with the iron content, suggesting a dominant role of iron related transitions in the heating processes. Experimental data included in this work reveal a simple route to tailor the light activated heating processes in iron oxide nanoparticles towards fully controllable treatments.

No abstract