Effects of polystyrene nanoplastic size on zebrafish embryo development

Polystyrene nanoplastics (PS) require a comprehensive evaluation of their toxicity and potential risks to humans and the environment. The zebrafish model, a well-established animal model increasingly utilized for nanotoxicity assessments, was employed in this study. Our research aimed to explore the toxic effects of PS with sizes of 30, 100, 200, and 450 nm on zebrafish embryos. Exposure experiments were conducted on embryos at 4 h post-fertilization (hpf) using various concentrations of nanoparticles (20, 40, 60, 80, and 100 mg/L) until 96 hpf. Notably, PS ranging from 100 to 450 nm did not adversely affect zebrafish embryo development. However, PS with a size of 30 nm at a concentration of 100 mg/L resulted in embryo mortality but not embryonic malformations. Furthermore, our investigation confirmed the uptake of these nanoparticles by zebrafish larvae following the opening of their mouths, with the particles being found predominantly in the digestive system of the larvae. Additionally, 30 nm PS were found to significantly modulate the expression levels of genes associated with oxidative stress and apoptosis. These findings highlight the developmental impacts of 30 nm PS on zebrafish embryos, raising concerns about potential similar consequences in humans. Considering our findings, it is essential to encourage further research into the management and regulation of PS to mitigate their potential environmental and health impacts.

The Synthesis of Narrowly Dispersed Poly(ε-caprolactone) Microspheres by Dispersion Polymerization Using a Homopolymer Poly(dodecyl acrylate) as the Stabilizer

Using dodecyl acrylate as a raw material and 2-Cyanoprop-2-yl-dithiobenzoate as a chain transfer agent, poly(dodecyl acrylate) is synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Using poly(dodecyl acrylate) as stabilizers, narrowly dispersed poly(ε-caprolactone) microspheres with particle sizes ranging from 0.5 to 1.5 μm are successfully synthesized by ring-opening dispersion polymerization. The effects of the molecular weight of poly(dodecyl acrylate), the volume proportion of mixed solvent (i.e., 1,4-dioxane/heptane), and the reaction temperature on the particle size and its distribution are investigated. With careful control of the synthesis condition, microspheres can be obtained with a particle size distribution of 1.09 (Dw/Dn). The average particle size of poly(ε-caprolactone) microspheres decreased with the increase in the molecular weight of poly(dodecyl acrylate) and increased with the increase in the relative content of 1,4-dioxane. The uniformity of microspheres decreased with the increase in the polymerization temperature.

Light-Scattering Analysis of Drying Behavior in Suspension Droplets with Silica and Polystyrene Particles and a Hydrosoluble Polymer

The coffee-ring structure, which is the final drying pattern of a sessile suspension droplet, is a key factor in controlling the uniformity of the particulate deposits in various coatings. Two light-scattering methods, diffusing wave spectroscopy (DWS) and multispeckle DWS (MSDWS), were used to quantitatively distinguish temporal changes in particle mobility in evaporating suspension droplets containing micrometer-sized silica and polystyrene (PS) particles. The characteristic particle mobility was measured in terms of the mean square displacement in the early stage of drying, and the local particle dynamics around the edge and center regimes of the droplets during drying were analyzed using MSDWS. Hydroxyethyl cellulose (HEC), a hydrosoluble polymer, was added to the silica and PS suspensions to further investigate its role in suppressing or enhancing coffee-ring patterns based on particle-polymer interactions. Consequently, dried microstructures can be directly correlated with real-time drying dynamics, as well as the interactions between solutes by comprehensive light-scattering methods.

Impact of a real food matrix and in vitro digestion on properties and acute toxicity of polystyrene microparticles

Although it is proved that humans ingest microplastics via food, and microplastics were found in human tissues, blood and feces, there needs to be more data on the properties and health-related effects of plastic particles that interact with food and undergo digestion. This study aimed to examine the impact of a real food matrix, milk, on the behavior and gastrointestinal fate of polystyrene microparticles (PSMP). In the presence of the food matrix, the net negative ζ-potential values of PSMP (diameter size of 1.823 μm) decreased significantly due to the formation of the corona, mostly consisting of α and β-casein fragments. Protein corona profiles and morphologies of particles incubated with whole and skim milk were found to be similar, and the protein profiles were completely altered after in vitro digestion simulation. In vitro and in vivo toxicity studies showed that neither bare PSMP nor food-interacted PSMP pose acute toxicity on the Caco-2 cell line and zebrafish embryos under the chosen experimental conditions. In summary, these results may contribute to a better understanding of changes that microplastics undergo in foods. Further studies on repeated exposure or chronic toxicity are needed to fully reveal the effect of food matrix on microplastic toxicity.

Calcium-channel-blockers exhibit divergent regulation of cancer extravasation through the mechanical properties of cancer cells and underlying vascular endothelial cells

Cardiovascular and cancer illnesses often co-exist, share pathological pathways, and complicate therapy. In the context of the potential oncological role of cardiovascular-antihypertensive drugs (AHD), here we examine the role of calcium-channel blocking drugs on mechanics of extravasating cancer cells, choosing two clinically-approved calcium-channel blockers (CCB): Verapamil-hydrochloride and Nifedipine, as model AHD to simultaneously target cancer cells (MCF7 and or MDA231) and an underlying monolayer of endothelial cells (HUVEC). First, live-cell microscopy shows that exposure to Nifedipine increases the spreading-area, migration-distance, and frequency of transmigration of MCF-7 cells through the HUVEC monolayer, whereas Verapamil has the opposite effect. Next, impedance-spectroscopy shows that for monolayers of either endothelial or cancer cells, Nifedipine-treatment alone decreases the impedance of both cases, suggesting compromised cell-cell integrity. Furthermore, upon co-culturing MCF-7 on the HUVEC monolayers, Nifedipine-treated MCF-7 cells exhibit weaker impedance than Verapamil-treated MCF-7 cells. Following, fluorescent staining of CCB-treated cytoskeleton, focal adhesions, and cell-cell junction also indicated that Nifedipine treatment diminished the cell-cell integrity, whereas verapamil treatment preserved the integrity. Since CCBs regulate intracellular Ca²⁺, we next investigated if cancer cell's exposure to CCBs regulates calcium-dependent processes critical to extravasation, specifically traction and mechanics of plasma membrane. Towards this end, first, we quantified the 2D-cellular traction of cells in response to CCBs. Results show that exposure to F-actin depolymerizing drug decreases traction stress significantly only for Nifedipine-treated cells, suggesting an actin-independent mechanism of Verapamil activity. Next, using an optical tweezer to quantify the mechanics of plasma membrane (PM), we observe that under constant, externally-applied tensile strain, PM of Nifedipine-treated cells exhibits smaller relaxation-time than Verapamil and untreated cells. Finally, actin depolymerization significantly decreases MSD only for Verapamil treated cancer-cells and endothelial cells and not for Nifedipine-treated cells. Together, our results show that CCBs can have varied, mechanics-regulating effects on cancer-cell transmigration across endothelial monolayers. A judicious choice of CCBs is critical to minimizing the pro-metastatic effects of antihypertension therapy.

Targeted Drug Delivery for Sustainable Crop Protection: Transport and Stability of Polymeric Nanocarriers in Plants

Spraying of agrochemicals (pesticides, fertilizers) causes environmental pollution on a million-ton scale. A sustainable alternative is target-specific, on-demand drug delivery by polymeric nanocarriers. Trunk injections of aqueous nanocarrier dispersions can overcome the biological size barriers of roots and leaves and allow distributing the nanocarriers through the plant. To date, the fate of polymeric nanocarriers inside a plant is widely unknown. Here, the in planta conditions in grapevine plants are simulated and the colloidal stability of a systematic series of nanocarriers composed of polystyrene (well-defined model) and biodegradable lignin and polylactic-co-glycolic acid by a combination of different techniques is studied. Despite the adsorption of carbohydrates and other biomolecules onto the nanocarriers' surface, they remain colloidally stable after incubation in biological fluids (wood sap), suggesting a potential transport via the xylem. The transport is tracked by fluorine- and ruthenium-labeled nanocarriers inside of grapevines by 19 F-magnetic resonance imaging or induced coupled plasma - optical emission spectroscopy. Both methods show that the nanocarriers are transported inside of the plant and proved to be powerful tools to localize nanomaterials in plants. This study provides essential information to design nanocarriers for agrochemical delivery in plants to sustainable crop protection.

Effect of surface morphology change of polystyrene microspheres through etching on protein corona and phagocytic uptake

Surface physicochemistry properties of polymer particles are crucial for protein corona formation and macrophage phagocytosis when they contact with living body. In this work, polystyrene microspheres (PS-MSs) were selected as a model of polymer microparticles and fabricated by chromic acid etching through controlling conditions to obtain different surface morphology structures and to investigate their effect on the protein adsorption and phagocytic uptake of PS-MSs. The adsorption of bovine serum albumin (BSA) and fibrinogen (FIB) on PS-MSs showed almost the same tendency, i.e. the etched PS-MSs presented lower protein adsorption compared with original microspheres. The adsorption of BSA and FIB was the lowest when the protuberances on the etched surfaces were maximum and the size of the protuberances was minimum. Furthermore, the surface morphologies of PS-MSs were influenced in return not only by the amounts of proteins but also by protein types. Meanwhile, the macrophages phagocytosis of PS-MSs depended on the amounts and kinds of adsorbed proteins, especially the albumin content. In a word, phagocytosis and protein adsorption can be regulated by microsphere morphologies through etching, which provides a promising strategy to avoid invalid uptake for polymer particles such as drug delivery carriers.

Multiplexed microarrays based on optically encoded microbeads

In recent years, there has been growing interest in optically-encoded or tagged functionalized microbeads as a solid support platform to capture proteins or nucleotides which may serve as biomarkers of various diseases. Multiplexing technologies (suspension array or planar array) based on optically encoded microspheres have made possible the observation of relatively minor changes in biomarkers related to specific diseases. The ability to identify these changes at an early stage may allow the diagnosis of serious diseases (e.g. cancer) at a time-point when curative treatment may still be possible. As the overall accuracy of current diagnostic methods for some diseases is often disappointing, multiplexed assays based on optically encoded microbeads could play an important role to detect biomarkers of diseases in a non-invasive and accurate manner. However, detection systems based on functionalized encoded microbeads are still an emerging technology, and more research needs to be done in the future. This review paper is a preliminary attempt to summarize the state-of-the-art concerning diagnostic microbeads; including microsphere composition, synthesis, encoding technology, detection systems, and applications.