Amine-modified Polystyrene Nanoparticles Research Articles

How do the Growth and Metabolic Activity of Aquatic fungi Geotrichum Candidum and Aspergillus Niger Respond to Nanoplastics?

In this study, exposure experiments were conducted to assess the effects of polystyrene nanoparticles (PS) and amine-modified polystyrene nanoparticles (APS) at environmental concentrations (1, 10, and 100µg L- 1) on two fungal species (Geotrichum candidum and Aspergillus niger), isolated from leaf litter in streams, concerning their growth and metabolic activity. Results showed that PS at 1 and 10µg L- 1 have hormesis effects on G. candidum growth. Compared with G. candidum, A. niger had higher sensitivity to nanoplastic exposure. Besides, the peroxidase and cellobiohydrolase activities of A. niger were significantly inhibited by nanoplastics (except 1µg L- 1 PS), which would weaken its metabolic activity in carbon cycling. These results provided a new thought on how the growth and functions of aquatic fungi cope with the stress induced by nanoplastics. Overall, the study provided evidence for the different responses of aquatic fungi to nanoplastics in streams.

Investigations of acute effects of polystyrene and polyvinyl chloride micro- and nanoplastics in an advanced in vitro triple culture model of the healthy and inflamed intestine

The continuous degradation of plastic waste in the environment leads to the generation of micro- and nanoplastic fragments and particles. Due to the ubiquitous presence of plastic particles in natural habitats as well as in food, beverages and tap water, oral exposure of the human population with plastic particles occurs worldwide. We investigated acute toxicological effects of polystyrene (PS) and polyvinyl chloride (PVC) micro- and nanoparticles in an advanced in vitro triple culture model (Caco-2/HT29-MTX-E12/THP-1) mimicking the healthy and inflamed human intestine to study the effect of inflammatory processes on plastic particle toxicity. We monitored barrier integrity, cytotoxicity, cell layer integrity, DNA damage, the release of pro-inflammatory cytokines (IL-1β, IL-6, IL-8 and TNF-α) and mucus distribution after 24 h of particle exposure. In addition, we investigated cytotoxicity, DNA damage and IL-1β release in monocultures of the three cell lines. Amine-modified polystyrene nanoparticles (PS–NH2) served as a positive control for particle-induced toxicity. No acute effects in the investigated endpoints were observed in the model of the healthy intestine after PS or PVC exposure. However, during active inflammatory processes, exposure to PVC particles was found to augment the release of IL-1β and to cause a loss of epithelial cells. Our results suggest that prevalent intestinal inflammation might be an important factor to consider when assessing the hazard of ingested micro- and nanoplastic particles.

Lysosome-dependent cell death and deregulated autophagy induced by amine-modified polystyrene nanoparticles.

Nanoparticles (NPs) typically accumulate in lysosomes. However, their impact on lysosomal function, as well as autophagy, a lysosomal degradative pathway, is still not well known. We have previously reported in the 1321N1 cell line that amine-modified polystyrene (NH2-PS) NPs induce apoptosis through damage initiated in the lysosomes leading ultimately to release of lysosomal content in the cytosol, followed by apoptosis. Here, by using a combination of biochemical and cell biological approaches, we have characterized in a mouse embryonic fibroblast cell line that the lysosomal alterations induced by NH2-PS NPs is progressive, initiating from mild lysosomal membrane permeabilization (LMP), to expansion of lysosomal volume and intensive LMP before the summit of cell death. Though the cells initially seem to induce autophagy as a surviving mechanism, the damage of NH2-PS NPs to lysosomes probably results in lysosomal dysfunctions, leading to blockage of autophagic flux at the level of lysosomes and the eventual cell death.

RNAi-Mediated Inhibition of Apoptosis Fails to Prevent Cationic Nanoparticle-Induced Cell Death in Cultured Cells

Nanoparticles are increasingly being considered as a novel and potent tool for drug delivery, and, therefore, concerns regarding the safety of their use in humans are pertinent. It has been shown that nanoparticles displaying unsaturated amines at their surface are toxic to cells, but the molecular and cellular mechanisms elicited in this response have yet to be described. In this work we identify key proteins involved in the cytotoxicity of amine-modified polystyrene nanoparticles. We also demonstrate the suitability of RNAi to provide a molecular description of how nanoparticles and cells interact. We have used a focused RNAi strategy in 1321N1 cells to identify key proteins involved in the cytotoxicity induced by amine-modified polystyrene nanoparticles. We show that the apoptosome is central to the observed mechanism of toxicity and that, although the proapoptotic proteins BAX, BAK, BID, BIM and PUMA are critical modulators of the process, their cellular depletion is insufficient to protect cells from nanoparticle-induced cell death. We conclude that the apoptosome, together with proapoptotic proteins of the Bcl-2 family of proteins, is central to amine-modified polystyrene nanoparticle-induced cell death. We further demonstrate that RNAi is a powerful and suitable tool to study the effects of nanoparticles on cellular processes, in particular apoptosis.

Time resolved study of cell death mechanisms induced by amine-modified polystyrene nanoparticles

Positively charged polymers and nanoparticles (NPs) can be toxic to cells in various systems. Using human astrocytoma cells, we have previously shown that 50 nm amine-modified polystyrene NPs damage mitochondria and induce cell death by apoptosis. Here we provide comprehensive details of the cellular events occurring after exposure to the NPs in a time-resolved manner. We demonstrate that the accumulation of NPs in lysosomes plays a central role in the observed cell death, leading to swelling of the lysosomes and release of cathepsins into the cytosol, which ultimately propagates the damage to the mitochondria with subsequent activation of apoptosis. This is accompanied and sustained by other events, such as increasing ROS levels and autophagy. Using various inhibitors, we also show the interplay between apoptosis and autophagy as a response to NP accumulation in lysosomes.

Nanoparticle Surface Charge Directs the Cellular Binding of Nanoparticle-Protein Complexes

Nanoparticles are commonly utilized in biological systems as imaging probes, drug delivery agents and in vivo sensors. In most biological applications, the nanoparticle is exposed to a complex mixture of extracellular proteins that adsorb non-specifically to the nanoparticle surface. The resulting “protein corona” can dominate the interactions of the nanoparticle with the cellular membrane. We have focused on the role of nanoparticle surface charge in the cellular binding of nanoparticles in the presence of extracellular proteins. Cationic, amine-modified polystyrene nanoparticles and anionic, carboxylate-modified polystyrene nanoparticles were studied as a model system. The cellular binding of cationic and anionic nanoparticles is distinctly different, determined from fluorescence microscopy experiments. For cationic nanoparticles, the cellular binding is increased in the presence of serum proteins. In comparison, anionic nanoparticle binding is inhibited by the presence of serum proteins. Competition assays performed with flow cytometry allowed us to quantify differences in binding and to identify the cellular receptors used by the nanoparticle-protein complexes. We have determined that complexes formed with anionic nanoparticles bind to native protein receptors, while those formed with cationic nanoparticles bind to scavenger receptors. These results indicate that for nanoparticles used in biological applications, the initial surface charge of the nanoparticle mediates cellular binding. Currently, we are extending our studies to nanoparticles used for drug and gene delivery.

Biocompatibility, endocytosis, and intracellular trafficking of mesoporous silica and polystyrene nanoparticles in ovarian cancer cells: effects of size and surface charge groups

Background and methodsNanoparticles engineered to carry both a chemotherapeutic drug and a sensitive imaging probe are valid tools for early detection of cancer cells and to monitor the cytotoxic effects of anticancer treatment simultaneously. Here we report on the effect of size (10–30 nm versus 50 nm), type of material (mesoporous silica versus polystyrene), and surface charge functionalization (none, amine groups, or carboxyl groups) on biocompatibility, uptake, compartmentalization, and intracellular retention of fluorescently labeled nanoparticles in cultured human ovarian cancer cells. We also investigated the involvement of caveolae in the mechanism of uptake of nanoparticles.ResultsWe found that mesoporous silica nanoparticles entered via caveolae-mediated endocytosis and reached the lysosomes; however, while the 50 nm nanoparticles permanently resided within these organelles, the 10 nm nanoparticles soon relocated in the cytoplasm. Naked 10 nm mesoporous silica nanoparticles showed the highest and 50 nm carboxyl-modified mesoporous silica nanoparticles the lowest uptake rates, respectively. Polystyrene nanoparticle uptake also occurred via a caveolae-independent pathway, and was negatively affected by serum. The 30 nm carboxyl-modified polystyrene nanoparticles did not localize in lysosomes and were not toxic, while the 50 nm amine-modified polystyrene nanoparticles accumulated within lysosomes and eventually caused cell death. Ovarian cancer cells expressing caveolin-1 were more likely to endocytose these nanoparticles.ConclusionThese data highlight the importance of considering both the physicochemical characteristics (ie, material, size and surface charge on chemical groups) of nanoparticles and the biochemical composition of the cell membrane when choosing the most suitable nanotheranostics for targeting cancer cells.

Cationic nanoparticles induce caspase 3-, 7- and 9-mediated cytotoxicity in a human astrocytoma cell line

On a daily basis we are exposed to cationic nanoparticulates in many different ways. They are known to distribute to many organs of the body, and while some evidence suggests that these nanoparticles are toxic to cells, the mechanism of their toxicity is not clear. Here we apply a combination of biochemical and imaging techniques to study the mechanism by which amine-modified polystyrene nanoparticles induce cell death in a human brain astrocytoma cell line. Flow cytometry analysis of cells exposed to cationic nanoparticles revealed an increase in cell membrane permeability of the dyes YoPro-1 and propidium iodide, indicating onset of an apoptotic followed by a secondary necrotic response. Activation of caspases 3/7 and 9 and cleavage of poly(ADP-ribose) polymerase (PARP)-1 was also detected, providing clear molecular evidence of the apoptotic pathway induced by the nanoparticles. Transmission electron microscopy also revealed that these nanoparticles induce morphological changes in lysosomes and mitochondria, consistent with our observation of a rapid increase in the formation of reactive oxygen species in these cells. Together these results suggest that amine-modified polystyrene nanoparticles can mediate cell death through an apoptotic mechanism mediated by damage to the mitochondria.