Anisotropic bimetallic nanoparticles are promising candidates for plasmonic and catalytic applications. Their catalytic performance and plasmonic properties are closely linked to the distribution of the two metals, which can change during applications in which the particles are exposed to heat. Due to this fact, correlating the thermal stability of complex heterogeneous nanoparticles to their microstructural properties is of high interest for the practical applications of such materials. Here, we employ quantitative electron tomography in high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM) mode to measure the 3D elemental diffusion dynamics in individual anisotropic Au-Ag nanoparticles upon heating in situ.This approach allows us to study the elemental redistribution in complex, asymmetric nanoparticles on a single particle level, which was inaccessible to other techniques so far. In this work, we apply the proposed method to compare the alloying dynamics of Au-Ag nanoparticles with different shapes and compositions and find that the shape of the nanoparticle does not exhibit a significant effect on the alloying speed whereas the composition does. Finally, comparing the experimental results to diffusion simulations allows us to estimate the diffusion coefficients of the metals for individual nanoparticles.
Toxicological research of novel nanomaterials is a major developmental step of their clinical approval. Since iron oxide magnetic nanoparticles have a great potential in cancer treatment and diagnostics, the investigation of their toxic properties is very topical. In this paper we synthesized bovine serum albumin‐coated iron oxide nanoparticles with different sizes and their polyethylene glycol derivative. To prove high biocompatibility of obtained nanoparticles the number of in vitro toxicological tests on human fibroblasts and U251 glioblastoma cells was performed. It was shown that albumin nanoparticles’ coating provides a stable and biocompatible shell and prevents cytotoxicity of magnetite core. On long exposure times (48 hours), cytotoxicity of iron oxide nanoparticles takes place due to free radical production, but this toxic effect may be neutralized by using polyethylene glycol modification.
The combination of energy-dispersive X-ray spectroscopy (EDX) and electron tomography is a powerful approach to retrieve the 3D elemental distribution in nanomaterials, providing an unprecedented level of information for complex,...
Raman-encoded
gold nanoparticles (NPs) have been widely employed
as photostable multifunctional probes for sensing, bioimaging, multiplex
diagnostics, and surface-enhanced Raman scattering (SERS)-guided tumor
therapy. We report a strategy toward obtaining a particularly large
library of Au nanocapsules encoded with Raman codes defined by the
combination of different thiol-free Raman reporters, encapsulated
at defined molar ratios. The fabrication of SERS tags with tailored
size and predefined codes is based on the in situ incorporation of Raman reporter molecules inside Au nanocapsules
during their formation via galvanic replacement coupled
to seeded growth on Ag NPs. The hole-free closed-shell structure of
the nanocapsules is confirmed by electron tomography. The unusually
wide encoding possibilities of the obtained SERS tags are investigated
by means of either wavenumber-based encoding or Raman frequency combined
with signal intensity, leading to an outstanding performance as exemplified
by 26 and 54 different codes, respectively. We additionally demonstrate
that encoded nanocapsules can be readily bioconjugated with antibodies
for applications such as SERS-based targeted cell imaging and phenotyping.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.