Dynamic light scattering on bioconjugated laser generated gold nanoparticles.

Gold nanoparticles (AuNPs) conjugated to DNA are widely used for biomedical targeting and sensing applications. DNA functionalization is easily reached on laser generated gold nanoparticles because of their unique surface chemistry, not reproducible by other methods. In this context, we present an extensive investigation concerning the attachment of DNA to the surface of laser generated nanoparticles using Dynamic Light Scattering and UV-Vis spectroscopy. The DNA conjugation is highlighted by the increase of the hydrodynamic radius and by the UV-Vis spectra behavior. Our investigation indicates that Dynamic Light Scattering is a suitable analytical tool to evidence, directly and qualitatively, the binding between a DNA molecule and a gold nanoparticle, therefore it is ideal to monitor changes in the conjugation process when experimental conditions are varied

In Situ Labeling of the Aqueous Compartment of Extracellular Vesicles with Luminescent Gold Nanoclusters

International audienceExtracellular vesicles (EVs) are well-known membrane-limited particles secreted by both healthy and cancerous cells. They are considered as biomarkers for early cancer diagnosis and are involved in many pathologies and physiological pathways. They could serve as diagnostic tools in liquid biopsies, as therapeutics in regenerative medicine, or as drug delivery vehicles. Our aim is here to encapsulate luminescent nanoprobes in the aqueous compartment of human EVs extracted from reproductive fluids. The analysis and labeling of the EVs content with easily detectable luminescent nanoparticles could enable a powerful tool for early diagnosis of specific diseases and also for the design of new therapeutics. In this view, gold nanoclusters (AuNCs) appear as an attractive alternative as nontoxic fluorophore probes because of their luminescence properties, large window of fluorescence lifetimes (1 ns-1 μs), ultrasmall size (<2 nm), good biocompatibility, and specific ability as X-ray photosensitizers. Here, we investigated an attractive method that uses fusogenic liposomes to deliver gold nanoclusters into EVs. This approach guarantees the preservation of the EVs membrane without any breakage, thus maintaining compartmental integrity. Different lipid compositions of liposomes preloaded with AuNCs were selected to interact electrostatically with human EVs and compared in terms of fusion efficiency. The mixture of liposomes and EVs results in membrane mixing as demonstrated by FRET experiments and fusion revealed by flux cytometry and cryo-TEM. The resulting fused EVs exhibit typical fluorescence of the AuNCs together with an increased size in agreement with fusion. Moreover, the fusion events in mixtures of EVs and AuNCs preloaded liposomes were analyzed by using cryo-electron microscopy. Finally, the ratio of released AuNCs during the fusion between the fusogenic liposomes and the EVs was estimated to be less than 20 mol % by Au titration using ICP spectroscopy

Figure 1

<p>UV-Vis spectra of AuNPs aggregated with different NaCl concentrations (a). Hydrodynamic radius difference between aggregated and as-prepared nanoparticles measured with DLS as a function of NaCl concentration (b).</p

Hydrodynamic radius difference (ΔR_H) versus the NaCl salt solution for different DNA concentrations, measured with “no salt aging” (a) and “salt aging” (b) procedure.

<p>Hydrodynamic radius difference (ΔR_H) versus the NaCl salt solution for different DNA concentrations, measured with “no salt aging” (a) and “salt aging” (b) procedure.</p

Figure 3

<p>Autocorrelation functions g₂ (t) of as-prepared AuNPs solution and of DNA/AuNPs solution at 100 mM NaCl, for “salt aging” and “no salt aging” procedure (a). Hydrodynamic radius difference (ΔR_H) versus the NaCl concentration for “salt aging” and “no salt aging” procedure (b). The DNA concentration was 0.1 μM.</p

UV-vis spectra of AuNPs/DNA solution for different NaCl concentrations obtained with “no salt aging” (a) and “salt aging” (b) procedure.

<p>The DNA concentration was 0.1 μM.</p

Internalization of Pegylated Er:Y2O3 Nanoparticles inside HCT-116 Cancer Cells: Implications for Imaging and Drug Delivery

International audienceLanthanide-doped nanoparticles, featuring sharp emission peaks with narrow bandwidth, exhibit high downconversion luminescence intensity, making them highly valuable in the fields of bioimaging and drug delivery. High-crystallinity Y2O3 nanoparticles (NPs) doped Er3+ ions were functionalized by using a pegylation procedure to confer water solubility biocompatibility. The NPs thoroughly characterized transmission electron microscopy (TEM), inductively coupled plasma mass spectrometry (ICP-MS), photoluminescence measurements. pegylated studied both from toxicological perspective demonstrate their internalization within HCT-116 cancer cells. Cell viability tests allowed for identification “optimal” concentration, which yields detectable fluorescence signal without being toxic process was investigated combined approach involving confocal ICP-MS. obtained data clearly indicate efficient into cells intensity showing strong correlation concentrations delivered Overall, this research contributes significantly nanotechnology biomedical research, noteworthy implications imaging delivery applications

Er:Y₂O₃ and Nd:Y₂O₃ Nanoparticles: Synthesis, Pegylation, Characterization and Study of Their Luminescence Properties

Lanthanide-doped yttrium oxide nanoparticles can display selective upconversion properties, rendering them invaluable in the field of nanomedicine for both sensing and diagnostics. Different syntheses of Er:Y2O3 and Nd:Y2O3 nanoparticles (NPs) were studied and optimized to obtain small particles of regular shape and good crystallinity. The morphological and compositional characterizations of the nanoparticles were obtained with different techniques and showed that both Er:Y2O3 and Nd:Y2O3 NPs were well dispersed, with dimensions of the order of a few tens of nanometers. The photoluminescence and cathodoluminescence measurements showed that both Er:Y2O3 and Nd:Y2O3 NPs had good emission as well as upconversion. The nanophosphors were functionalized by a pegylation procedure to suppress unwanted reactions of the NPs with other biological components, making the NP systems biocompatible and the NPs soluble in water and well dispersed. The pegylated core/shell nanoparticles showed the same morphological and optical characteristics as the core, promoting their strategic role as photoactive material for theragnostics and biosensing