Toxicity of different-sized cobalt ferrite (CoFe2O4) nanoparticles to Oncorhynchus mykiss at early development stages.

As innovative and versatile agents with potential applications in a wide range of fields including medicine, electronics, wastewater treatment, cosmetics, and energy storage devices, magnetic nanoparticles (NPs) are significant attention. However, our knowledge of the harmful effects of different-sized NPs, particularly of their effects on aquatic animals, is limited. In this study, we evaluated the impact of different-sized (sub-2, 5, and 15 nm) cobalt ferrite (CoFe2O4) NPs on the biological parameters of rainbow trout (Oncorhynchus mykiss) embryos and larvae. The NPs were characterized using techniques such as high-resolution transmission electron microscopy (HRTEM) for imaging, X-ray diffraction (XRD) for crystallographic analysis, and energy-dispersive X-ray spectroscopy (EDX) for elemental analysis, and were tested for impact through a series of toxicity, genotoxicity, and biochemical assays at a concentration of 100 mg/L. The obtained results showed that toxicity of CoFe2O4 NPs depended on the size of NPs and the developmental stage of the fish. Our results, which revealed significant changes in biological parameters of O. mykiss under exposure to CoFe2O4 NPs, imply that these NPs may be not environmentally safe. The hierarchical cluster analysis showed that embryos of the control group were clearly separated from those exposed to NPs of various sizes. However, in the exposed larvae, the effects of control and the smallest-sized NPs (sub-2 nm) differed from those induced by larger NPs (5 nm and 15 nm). Additional research is necessary to comprehend the mechanisms underlying the observed variations, which would be advantageous for both managing the risk of NPs to humans and advancing the field of aquatic nanotoxicology.

Designing red-fluorescent superparamagnetic nanoparticles by conjugation with gold clusters.

Photoluminescent (PL) metal and metal oxide nanoclusters (NCs), with a size of just several nanometers, are a separate class of nanomaterials abundant with new attractive optical, physical, and chemical properties and biocompatibility. However, the synthesis of PL magnetic NCs via attachment of PL NCs to iron oxide-based nanoparticles (NPs) is still problematic. Motivated by this, herein, we report the development of a microwave-driven conjugation approach of red-fluorescent gold nanoclusters (BSA@AuNCs) to superparamagnetic NPs. Synthesized CoFe2O4@AuNCs possess strong photoluminescence in water and ethanol media as well as good colloidal and optical stability, and magnetization response. High-resolution transmission electron microscopy (HRTEM), steady-state and time-resolved photoluminescence spectroscopy, X-ray powder diffraction (XRD), and magnetic measurements from ambient to cryogenic temperatures were applied for structural characterization and evaluation of optical and magnetic properties of the synthesized species.

Ultra-small methionine-capped Au0/Au+ nanoparticles as efficient drug against the antibiotic-resistant bacteria.

In this study we examined the influence of ultra-small gold and magnetite­gold nanoparticles (NPs) stabilized with d,l-methionine, Fe3O4@Au@Met, on their antibacterial efficacy against three of twelve the worst bacterial family members included in the World Health Organization (WHO) list. In particular, gram-negative Acinetobacter baumannii, Salmonella enterica and gram-positive methicillin-resistant Staphylococcus aureus and Micrococcus luteus were tested. Apart from the synthesis, gold species reduction and NP stabilization, an excess of methionine has been used herein to detach ultra-small gold NPs from the Fe3O4@Au@Met surface, collect them and investigate. The antimicrobial efficiency of the ultra-small (Ø ~ 1.8 nm) Au@Met NPs and Fe3O4@Au@Met NPs was evaluated through the quantitative analysis by comparing with that of naked magnetite NPs, d,l-Met and BSA. It has been determined that compared with the control sample, 70 mg L-1 probe of Au@Met NPs exhibited the killing efficiency of 84.4-58.5% against gram-negative bacteria and 89.1-75.7% against gram-positive bacteria. The composition, structure, and morphology of the synthesized and tested herein NPs were investigated by inductively coupled plasma optical emission spectrometry, magnetic measurements, FTIR, XRD, XPS, AFM and HRTEM.

Methionine-mediated synthesis of magnetic nanoparticles and functionalization with gold quantum dots for theranostic applications.

Biocompatible superparamagnetic iron oxide nanoparticles (NPs) through smart chemical functionalization of their surface with fluorescent species, therapeutic proteins, antibiotics, and aptamers offer remarkable potential for diagnosis and therapy of disease sites at their initial stage of growth. Such NPs can be obtained by the creation of proper linkers between magnetic NP and fluorescent or drug probes. One of these linkers is gold, because it is chemically stable, nontoxic and capable to link various biomolecules. In this study, we present a way for a simple and reliable decoration the surface of magnetic NPs with gold quantum dots (QDs) containing more than 13.5% of Au+. Emphasis is put on the synthesis of magnetic NPs by co-precipitation using the amino acid methionine as NP growth-stabilizing agent capable to later reduce and attach gold species. The surface of these NPs can be further conjugated with targeting and chemotherapy agents, such as cancer stem cell-related antibodies and the anticancer drug doxorubicin, for early detection and improved treatment. In order to verify our findings, high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), FTIR spectroscopy, inductively coupled plasma mass spectroscopy (ICP-MS), and X-ray photoelectron spectroscopy (XPS) of as-formed CoFe2O4 NPs before and after decoration with gold QDs were applied.