Biology subjects

Sandre, O.

Publications and source records attributed to Sandre, O..

3 recordsLinked to original sources

bioRxiv2026

Origin of Fe ions in ROS production induced in magnetic hyperthermia anti-cancer nanotherapy: release from iron oxide nanoparticles or not?

The first and critical reaction in magnetic hyperthermia to induce the death of cancer cells is the production of ROS (reactive oxygen species). We previously showed that it is possible to specifically deliver iron oxide magnetic nanoparticles (IONPs) in the lysosomes of cancer cells and eradicate them by targeted magnetic intra-lysosomal hyperthermia (MILH) via the application of a high frequency alternating magnetic field (AMF) without macroscopic temperature elevation. The mechanism involves a local temperature elevation at the IONPs surface which enhances the ROS production through the Fenton reaction; ROS then peroxide the proteins and lipids of the lysosomal membrane, inducing its permeabilization and leading to lysosomal enzymes release and cell death. Fe ions, critical to produce ROS in MILH, were assumed to be released by IONPs. We thus developed PEGylated multi-cores IONPs called NanoFlowers (NF@PEG) presenting or not a SiO2 shell (NF@SiO2 @PEG), the later preventing the Fe3+ release from IONPs. NF@PEG released Fe ions and produced ROS production in vitro, in acidic medium mimicking lysosome upon AMF exposure, whereas NF@SiO2@PEG did not. Surprisingly, both nanoparticles increased the ROS production in cells, induced lysosome permeabilization and cell death, and slowed down the proliferation of cancer cells with the same efficacy, upon AMF application, indicating that MILH was efficient in absence of Fe3+ release from IONPs. In contrast, Ferristatin-II, an iron uptake inhibitor, prevented the ROS production and cell death in MILH induced by both IONPs, elucidating the role of endogenous iron cations responsible for the ROS production ROS in MILH to kill cancer cells.

cancer biology↗

bioRxiv2026

Are bio-sourced nanoplastics inert for aquatic species? A toxicity study on three micro-algae species and a freshwater bivalve

Concerns raised by ubiquitate plastic contamination are urging to develop alternative materials. In the recent years, bio-sourced polymers also coined as bioplastics have been proposed to mitigate plastic pollution while meeting industrial and commercial expectations. Like petro-sourced plastics, they are expected to break-down in the environment into fragments down to sub-micron size. However, only scarce data are available on the impacts of such biosourced nanoplastics once released into the environment. This study examines the effects on aquatic species of model nanoplastics made from several bio-sourced polymers (Bio-NPs) that are either already on market (PHA, PLA, PA11) or still under development (NIPU, PCAR). We exposed three species of micro-algae (at 10, 100, and 1000 g/L, for 24 and 48 hours, and one week) to test the effects of Bio-NPs on algal growth. We also exposed freshwater bivalves C. fluminea (at 1, 10 and 100 g/L, for one week) to test the filtration activity and gene expressions in response to Bio-NPs exposure. All five Bio-NPs tested generated growth inhibitions in at least one of the three algae tested. PLA and PA11 were the most deleterious ones for algal growth among the five tested Bio-NPs. The highest growth inhibitions were observed on the fresh water species D. subspicatus. Each Bio-NP tested resulted in significant decreases of the filtration rates of C. fluminea. PHA impaired filtration at the lowest concentrations tested (1 g/L), whereas PCAR, PA11 and NIPU led to significant effects only at higher concentrations (10 and 100 g/L). The results from gene expressions in C. fluminea showed strong inductions of all gene functions tested for all the five bio-NPs tested. These Bio-NPs triggered endocytosis and detoxification mechanisms. They impaired the mitochondrial metabolism and triggered oxidative stress and immune responses. PA11, NIPU and PHA exposures resulted in the strongest gene regulations. The present study brings brand new findings about a kind of nanoplastics that may be released into the environment in a near future as the use of bioplastics is growing fast. It will help better understanding the impacts of such fragmented bioplastic NPs on aquatic species.

ecology↗

bioRxiv2022

Origin, exposure routes and xenobiotics impart nanoplastics with toxicity on freshwater bivalves

Various environmental aged plastic wastes were collected in the environment and crushed to the nanometric scale to get a mix of nanoplastics (NPs) of different natures - mostly polyolefins (PE, PP), polyesters (PET) and polyvinylics (PS and PVC) - and undefined shapes (noted NP-L, mean hydrodynamic diameter at 285 nm). We aimed to test the toxicity of NPs of environmentally relevance on freshwater bivalves and compare results to commonly used styrenic NP-PS (206 nm). Corbicula fluminea were exposed to four different conditions with NPs (0.008 to 10 g/L), for 21 days and kept under depuration conditions for 21 additional days: 1) waterborne exposure to NP-L, 2) diet borne exposure to NP-L, 3) synergic waterborne exposure to NP-L and AlCl3 salt (1 mg/L), 4) waterborne exposure to NP-PS. Enzyme activities, gene expressions and behavioural tests were assessed. Trophic and synergic exposures with Al triggered more gene modulations than direct exposure to NP-L (namely on 12s, atg12, gal, segpx, p53 and ache). NP-PS were also more harmful than NP-L, but only at high concentrations (10 g/L). The effects of each treatment lasted until 7 days of depuration and no more gene inductions were observed after 21 days in clean water. Very few effects were shown on phenol-oxidase (PO), and glutathione S-transferase (GST). However, the inhibition of acetylcholinesterase (AchE) was concomitant with an increase of the filtration activity of bivalves exposed to NP-L (trophic route) and NP-PS, suggesting neurotoxic effects. By disturbing the ventilatory activity, NPs could have direct effects on xenobiotic accumulation and excretion capacities. The results point out how the structure, aging, exposure routes and additional xenobiotics can interact with adverse outcomes of NPs in bivalves. These findings underline the importance to consider naturally aged environmental NPs in ecotoxicological studies rather than synthetic latexes, i.e. crosslinked nanospheres prepared from virgin polymers. This manuscript presents the first data of toxicity on freshwater organisms exposed to nanoplastics coming from natural sources. Whereas the majority of papers are dealing with non-environmentally representative plastics (mainly commercially-available polystyrene latexes) to evaluate nanoplastic effects on organisms, this study develops methods to prepare model nanoplastics from plastic wastes collected in rivers, and to assess their real adverse effects on aquatic organisms. Our results show significant differences between the inflammatory effects triggered by nanoplastics coming from natural sources and polystyrene nanobeads. This work suggests that the data published so far in the literature may underestimate the toxicity of nanoplastics spread into the environment on the aquatic organisms at the bottom of the food chain, which might consequently impart halieutic resources on the long term.

pharmacology and toxicology↗