The direct permeation of nanoparticles through the plasma membrane transiently modifies its properties

Insights into Tissue-Specific Bioaccumulation of Nanoplastics in Marine Medaka as Revealed by a Stable Carbon Isotopic Approach

“…In contrast to digestive or respiratory organs, the ovary is separated by the body cavity and is unlikely to remain in direct contact with the nanoplastics, suggesting an intrinsic uptake route for nanoplastic into the ovary. Previously, it has been shown that nanoparticles with a hydrodynamic size of less than 200 nm are capable of membrane penetration, although this can be influenced by shape and/or surface functional groups of the nanoparticles, , as verified in various organisms at the cellular and individual levels. , Indeed, size-selective bioaccumulation of nanoparticles (<100 nm) in the reproductive organs of the mouse is reportedly associated with increased blood-vessel density during ovulation due to the blood-vessel membrane permeability of nanoplastics . Moreover, the fact that lipids constitute a major proportion of fish egg yolk (in the form of lipid droplets) supports the bioaccumulation of hydrophobic nanoplastics. − Given that Oryzias spp.…”

Characterization of Transport Activity of SLC11 Transporters in Xenopus laevis Oocytes by Fluorophore Quenching

“…As expected, these values are slightly higher than those previously recorded by spectrofluorimetric measurement in saline solution, 16 but in agreement with those calculated for other divalent cations in the same conditions. 14–16…”

“…In our laboratory, a similar approach, using calcein and conventional fluorescence microscopy, was also applied to investigate the crossing of the plasma membrane by the metal nanoparticles. 14–16 In all these works, a single cell was studied, at times greatly limiting the number of samples collectable for each batch of oocytes. Only in Kottra et al 18 was a plate reader approach applied to measure the transport of a fluorescent compound, but in this case, the protein studied could move across the membrane large fluorescent molecules.…”

“…In recent years, many institutions have chosen to support radioactive-free experiments because working with radiolabeled compounds, when available, has high costs, has high risks for the workers and the environment, and requires a specifically controlled and isolated working area. In the literature, there are only a few papers that suggest alternative approaches to study transporter proteins, such as the use of fluorescence probes in transporter assays for investigating DMT1 transport using Phen Green SK 12 or exploring the function of c-Nramp1, c-NrampB, and rDMT1 using calcein 13 and, similarly, membrane–metal nanoparticle interaction, 14–16 or using fluorimetry and ion-sensitive microelectrodes. 17 In all these examples, the fluorophore quenching was studied with confocal or classical microscopy, one oocyte at a time, limiting the number of samples collected for each batch.…”

The “www” of Xenopus laevis Oocytes: The Why, When, What of Xenopus laevis Oocytes in Membrane Transporters Research

“…For the characterization of the dictyostelium discoideum orthologs of DMT1, NRAMP1, and 2, calcein, a more common (and cheaper) fluorescence indicator, was used both in the cells of the amoeba and in Xenopus laevis oocytes [ 64 ]. In this work, the quenching of calcein was monitored by confocal microscopy on a single oocyte, but the technique also works with basic LED-based fluorescence microscopy with equal detection capacity, as reported in [ 132 ] and as shown in the various experiments carried out to validate the method and in the subsequent peculiar oocytes applications [ 133 , 134 ]. The method proposed by Illing and modified by our group works well, but it has two disadvantages.…”