Accumulation and cellular toxicity of engineered metallic nanoparticle in freshwater microalgae: Current status and future challenges

Metal nanoparticles (MNPs) are employed in a variety of medical and non-medical applications. Over the past two decades, there has been substantial research on the impact of metallic nanoparticles on algae and cyanobacteria, which are at the base of aquatic food webs. In this review, the current status of our understanding of mechanisms of uptake and toxicity of MNPs and metal ions released from MNPs after dissolution in the surrounding environment were discussed. Also, the trophic transfer of MNPs in aquatic food webs was analyzed in this review. Approximately all metallic nanoparticles cause toxicity in algae. Predominantly, MNPs are less toxic compared to their corresponding metal ions. There is a sufficient evidence for the trophic transfer of MNPs in aquatic food webs. Internalization of MNPs is indisputable in algae, however, mechanisms of their transmembrane transport are inadequately known. Most of the toxicity studies are carried out with solitary species of MNPs under laboratory conditions rarely found in natural ecosystems. Oxidative stress is the primary toxicity mechanism of MNPs, however, oxidative stress seems a general response predictable to other abiotic stresses. MNP-specific toxicity in an algal cell is yet unknown. Lastly, the mechanism of MNP internalization, toxicity, and excretion in algae needs to be understood carefully for the risk assessment of MNPs to aquatic biota.

Intermatrix synthesis: easy technique permitting preparation of polymer-stabilized nanoparticles with desired composition and structure

The synthesis of polymer-stabilized nanoparticles (PSNPs) can be successfully carried out using intermatrix synthesis (IMS) technique, which consists in sequential loading of the functional groups of a polymer with the desired metal ions followed by nanoparticles (NPs) formation stage. After each metal-loading-NPs-formation cycle, the functional groups of the polymer appear to be regenerated. This allows for repeating the cycles to increase the NPs content or to obtain NPs with different structures and compositions (e.g. core-shell or core-sandwich). This article reports the results on the further development of the IMS technique. The formation of NPs has been shown to proceed by not only the metal reduction reaction (e.g. Cu0-NPs) but also by the precipitation reaction resulting in the IMS of PSNPs of metal salts (e.g. CuS-NPs).

Novel strategies for preparation and characterization of functional polymer-metal nanocomposites for electrochemical applications

Stabilization of metal nanoparticles (MNPs) in polymeric matrices of different types has proven to be one of the most promising strategies to prevent their aggregation and to retain their properties. Polymer-stabilized MNPs (PSMNPs) and those based on polymer-metal nanocomposite materials are starting to find wide application in various fields of science and technology. In this paper, we demonstrate that metal-polymer nanocomposite membranes (MPNCMs) containing MNPs can easily be prepared in an ion-exchange such as, for example, sulfonated polyetherether ketone (SPEEK) matrix by using the polymeric membranes as nanoreactors for synthesis and to characterize the composition and structure of the formed MNPs. Metal ions (or metal ion complexes) are first incorporated into the polymeric matrix where they undergo reduction, leading to formation of corresponding MPNCMs. Since this technique allows successive metal loading-reduction cycles to be carried out, it enables synthesis of both monometallic and bimetallic (e.g., core-shell) MNPs. The proposed approach is illustrated by synthesis and characterization of MPNCMs containing both monometallic and bimetallic core-shell MNPs, formed by combinations of Pd, Pt, Co, Ni, and Cu, along with their application in electrochemical sensor and biosensor constructions.

The solid-state synthesis of metal nanoparticles from organometallic precursors

Nanoparticles (NPs), average size of 2-5 nm, of ruthenium, cobalt, and rhodium have been prepared by an original method, namely the solid-state decomposition under dihydrogen of an organometallic precursor either dispersed in polymer films or directly as nanocrystals. The NPs dispersion, size, and morphology are investigated by transmission electron microscopy, and their structure by wide angle X-ray scattering. Infrared spectroscopy, after adsorption of carbon monoxide on the metal NPs surfaces, evidences a nonoxidized surface of high reactivity.