Experimental and theoretical comparison of intracellular import of polymeric nanoparticles and small molecules: toward models of uptake kinetics

Size-dependent internalization of polystyrene microplastics as a key factor in macrophages and systemic toxicity

Microplastics are emerging pollutants with a wide range of ecological and biological effects, including the ability to accumulate in organisms and induce toxicity. Although numerous studies have investigated the distribution and toxicity of microplastics in murine models and cell lines, the conclusions are inconsistent owing to variations in experimental designs, particle sizes, exposure methods, and dose quantifications. To address these gaps, we systematically evaluated the size-dependent internalization and toxicity of polystyrene microplastics (PS-MPs) using in vitro and in vivo models. Fluorescently labeled PS-MPs were used to confirm the negligible toxicity of fluorophores on macrophages, demonstrating their suitability for tracking particle accumulation. In vitro experiments using RAW 264.7 cell lines and primary peritoneal macrophages revealed size-dependent phagocytosis and cytotoxicity, with smaller particles (0.5 µm) demonstrating higher internalization and causing greater mitochondrial depolarization, reactive oxygen species generation, and apoptosis compared to that with larger particles (5 µm). Acute in vivo experiments comparing oral administration and tail-vein injection revealed that the absorbed dose and toxicity were significantly influenced by particle size, with smaller PS-MPs showing higher organ retention and alterations in hematological and metabolic parameters. Additionally, a 28-day subacute oral exposure study highlighted systemic toxicity, including weight loss, disrupted food intake, elevated oxidative stress markers, and reduced antioxidant enzyme activity. By integrating multiple exposure routes, macrophage models, and fluorescence toxicity evaluations, this study provided a comprehensive and realistic assessment of microplastic toxicity, offering valuable insights for advancing toxicological evaluations and regulatory frameworks. However, this study did not address the influence of other plastic types, shapes, or environmental factors on toxicity. Future studies are thus needed to explore these variables and the long-term implications of real-world microplastic exposure.

Exploring the influence of polystyrene-nanoplastics on two distinct in vitro systems in farm animals: A pilot study

The harmful effects of micro- and nanoplastics (MNPs) on the aquatic ecosystem are already well established, and several studies have demonstrated that MNPs can contaminate the soil. However, the impact of MNPs on farm animals, whose products are intended for human consumption, as well as the accumulation and translocation of these particles in their bodies, is less investigated and not well understood. To address this issue, we evaluated the cellular uptake and the effects of three different concentrations (5, 25, and 75 μg/mL) of 100 nm polystyrene nanoplastics (PS-NPs) on ovarian bovine granulosa cells (GCs) and porcine myoblasts derived from skeletal muscle satellite cells as in vitro primary cell culture models. The uptake of PS-NPs was shown for all the concentrations tested, both for GCs and for myoblasts. The results for GCs reported a significant decrease in cell viability (P < 0.05) for all concentrations of nanoplastics tested compared to the control. However, steroid hormone production and the mRNA expression of GC physiology marker genes were not affected. The results for myoblasts showed a significant decrease in the mean confluence (P < 0.05) after exposure to a concentration of 75 μg/mL of nanoplastics compared to the control. This may be indicative of an initial inhibition of muscle fibre formation. However, cell viability, proliferative capacity, and the mRNA expression of myogenesis-associated genes were not affected. As there is currently no standard method for assessing the quantity of particles that overcome the anatomical barriers and accumulate in various parts of the body, recognizing the implications of exposure to MNPs in farm animals can help us to better comprehend the potential risks to human health. This knowledge is critical for developing informed treatment and avoidance strategies, ensuring the safety of both the food we consume and the environment in which it is produced.

Mapping Selenium Nanoparticles Distribution Inside Cells through Confocal Raman Microspectroscopy

Selenium nanoparticles (SeNPs) exhibit significant potential in biomedical applications due to their antimicrobial, anticancer, and anti-inflammatory properties. In this study, we synthesized biocompatible SeNPs and employed confocal Raman microspectroscopy to map their distribution within human dermal fibroblast (HDF) cells. SeNPs possess a distinctive Raman band placed outside the cellular fingerprint region, which facilitates its detection and precise Raman imaging. Viability assays revealed that SeNPs exhibit cytotoxic effects only at the highest concentrations and for long exposure times while resulting in no harmful effects during all of the other treatments. For the first time, we achieved three-dimensional (3D) Raman mapping of SeNPs within cells, providing insights into their cellular penetration. Additionally, two-dimensional (2D) Raman mapping performed at different times and at sublethal concentrations demonstrated dynamic uptake and confirmed internalization. These findings highlight the effectiveness of SeNPs for biomedical imaging and therapeutic applications, offering an additional approach to studying nanoparticle-cell interactions.

Uncovering layer by layer the risk of nanoplastics to the environment and human health

Nanoplastics (NPs), defined as plastic particles with dimensions less than 100 nm, have emerged as a persistent environmental contaminant with potential risk to both environment and human health. Nanoplastics might translocate across biological barriers and accumulate in vital organs, leading to inflammatory responses, oxidative stress, and genotoxicity, already reported in several organisms. Disruptions to cellular functions, hormonal balance, and immune responses were also linked to NPs exposure in in vitro assays. Further, NPs have been found to adsorb other pollutants, such as persistent organic pollutants (POPs), and leach additives potentially amplifying their advere impacts, increasing the threat to organisms greater than NPs alone. However, NPs toxic effects remain largely unexplored, requiring further research to elucidate potential risks to human health, especially their accumulation, degradation, migration, interactions with the biological systems and long-term consequences of chronic exposure to these compounds. This review provides an overview of the current state-of-art regarding NPs interactions with environmental pollutants and with biological mechanisms and toxicity within cells.

Environmental release behavior, cell toxicity and intracellular distribution of novel biodegradable plastic materials

In response to the increasingly severe issue of plastic waste, biodegradable plastics have garnered extensive attention as a potential alternative to traditional plastics. Among these materials, biodegradable plastics hold a dominant position. The objective of this study was to assess the environmental risks of five commercially available biodegradable plastics: polyglycolic acid (PGA), polylactic acid (PLA), poly(butylene succinate) (PBS), poly(butylene carbonate) (PBC), and poly(butylene adipate-co-terephthalate) (PBAT). The evaluation included their physical properties, microplastic release behavior, and cytotoxicity. In addition, the effect of age process on the environmental behavior of biodegradable plastic materials was further investigated. The results revealed that PGA and PBS exhibited lower risks in terms of microplastic release, whereas PLA demonstrated higher environmental mobility. Further cytotoxicity experiments indicated that PLA and PBS exerted significant toxic effects on human cell lines, including human normal liver cells (LO2), human monocytic leukemia cells (THP-1), human umbilical vein endothelial cells (HUVECs), and human colon carcinoma cells (Caco-2). Additionally, this study utilized Nile Red labeling to observe the co-culture system of PGA with THP-1 cells, uncovering that THP-1 cells gradually engulfed and internalized PGA microplastics over time. This finding provides new insights into the potential mechanism by which microplastics promote cell proliferation. Moreover, we also found that the aging process partially reduced the cytotoxicity of PGA, but had little effect on environmental mobility. Considering the comprehensive research findings, PGA is considered an ideal material for large-scale applications due to its low cytotoxicity and environmental risks. In contrast, the environmental safety of other types of plastics requires more comprehensive risk assessment to determine their suitability. This study provides significant scientific evidence for the environmental impact assessment of biodegradable plastics and plays a crucial role in promoting the development of sustainable plastic alternatives.

High-throughput approach to measure number of nanoparticles associated with cells: size dependence and kinetic parameters

Understanding how nanoparticle properties influence uptake by cells is highly important for developing nanomedicine design principles. For this, quantitative studies where actual numbers of cell-associated particles are determined are highly relevant. However, many techniques able to measure particle numbers suffer from low-throughput or place requirements on the types of nanoparticles that can be measured. Here we show the usage of flow cytometry to measure numbers of cell-associated nanoparticles for particles ranging in size from 100-500 nm, and extend this range to 40-500 nm by separate calibration. For the 100 nm particles, we corroborate the numbers by direct, low-throughput, counting using fluorescence microscopy. Applying flow cytometry we subsequently investigated the effect of particle size on the number of cell-associated particles for various timespans up to 5 h and found only a minor effect of size between 40, 100, and 200 nm particles. Next, we measured the kinetic rate constants describing the adsorption, desorption, and internalization for the 100 nm particles specifically. In general, we found values in accordance with previous literature. We foresee the future usage of the methodology applied here to investigate the kinetics of nanoparticle cellular uptake for a variety of particle types.

Elucidating siRNA Cellular Delivery Mechanism Mediated by Quaternized Starch Nanoparticles

Starch-based nanoparticles are highly utilized in the realm of drug delivery taking advantage of their biocompatibility and biodegradability. Studies have utilized Quaternized starch (Q-starch) for small interfering RNA (siRNA) delivery, in which quaternary amines enable interaction with negatively charged siRNA, resulting in self-assembly complexation. Although reports present numerous applications, the demonstrated efficacy is nonetheless limited due to undiscovered cellular mechanistic delivery. In this study, a deep dive into Q-starch/siRNA complexes' cellular mechanism and kinetics at the cellular level is revealed using single-particle tracking and cell population level using imaging flow cytometry. Uptake studies depict the efficient cellular internalization via endocytosis while a significant fraction of complexes' intracellular fate is lysosome. Utilizing single-particle tracking, it is found that an average of 15% of cellular detected complexes escape the endosome which holds the potential for the integration in the cytoplasmatic gene silencing mechanism. Additional experimental manipulations (overcoming endosomal escape) demonstrate that the complex's disassembly is the rate-limiting step, correlating Q-starch's structure-function properties as siRNA carrier. Structure-function properties accentuating the high affinity of the interaction between Q-starch's quaternary groups and siRNA's phosphate groups that results in low release efficiency. However, low-frequency ultrasound (20 kHz) application may have induced siRNA release resulting in faster gene silencing kinetics.

Granulated rubber in playgrounds and sports fields: A potential source of atmospheric plastic-related contaminants and plastic additives after runoff events

The use of "crumb rubber" coming from recycling materials in outdoor floors like playgrounds has been a frequent practice during the last years. However, these surfaces are object of abrasion and weathering being a potential source of micro and nanoplastics (MNPLs) to the atmosphere and a potential source of human exposure to them. Our main goal has been to expose different crumb rubber materials to summer weathering effects. The released inhalable fractions were sampled for two months with passive samplers and the composition of MNPLs and plastic additives (organic and inorganic) were evaluated. The ecotoxicological effects of leached materials emulating runoff events was evaluated in freshwater micro crustacean Daphnia magna and the green algae Chlorella vulgaris. The analysis of MNPLs showed the presence of polyethylene, polypropylene, polybutadiene, polysiloxanes and polybutylene at concentrations up to 30,426 ng/m3. In the same fraction, we also identified up to 56 plastic additives, including antioxidants, pigments, copolymers, flame retardants, fungicides, lubricants, plasticizers, UV filters and metal ions. Finally, runoff ecotoxicological effects on D. magna and C. vulgaris showed that leached compounds, either from virgin or aged material, would be toxicants for exposed organisms although at concentrations much higher than those expected to be released to the media.

Differential sensitivity of hemocyte subpopulations (Mytilus edulis) to aged polyethylene terephthalate micro- and nanoplastic particles

Bivalve hemocytes, particularly granulocytes and hyalinocytes, play a crucial role in cell-mediated immunity. However, their interactions with aged plastic particles, exhibiting altered properties that more closely resemble those in natural environments, remain largely underexplored. This study assesses the differential responses of hemocyte subpopulations (Mytilus edulis) to chemically aged polyethylene terephthalate (PET) microplastic (MPs) and nanoplastic (NPs) particles across multiple cellular effect endpoints. Particle characteristics were analyzed using Single Particle Extinction and Scattering, Raman Spectroscopy, Scanning Electron Microscopy, and Dynamic Light Scattering. In vitro experiments with aged PET MPs (1.9 µm) and NPs (0.68 µm) were conducted at three internally relevant concentrations: 10 (C1), 10³ (C2), and 10⁵ particles/mL (C3). Cellular responses were assessed by measuring lysosomal content stability, reactive oxygen species (ROS) production, cellular mortality, and morphological parameters using flow cytometry at 6, 12, 24, and 48 hours. Our findings provide mechanistic insights into the differential sensitivities of granulocytes and hyalinocytes to aged PET, influenced by particle size and concentration. Specifically, aged PET MPs and NPs induce distinct size and concentration-dependent patterns of lysosomal destabilization, coinciding with the loss of functional integrity. Elevated ROS levels were observed only in granulocytes and hyalinocytes exposed to high concentrations of aged PET NPs, underscoring the effects on oxidative stress. Both aged PET MPs and NPs induce significant increases in cellular mortality, particularly after 24 h of exposure at high concentrations. These findings reveal the complex cellular mechanisms underlying hemocyte functional impairment following exposure to aged PET particles under environmentally and biologically relevant conditions.

Current status of mannose receptor-targeted drug delivery for improved anti-HIV therapy

In the pursuit of achieving better therapeutic outcomes in the treatment of HIV, innovative drug delivery strategies have been extensively explored. Mannose receptors, which are primarily found on macrophages and dendritic cells, offer promising targets for drug delivery due to their involvement in HIV pathogenesis. This review article comprehensively evaluates recent drug delivery system advancements targeting the mannose receptor. We have systematically described recent developments in creating and utilizing drug delivery platforms, including nanoparticles, liposomes, micelles, noisomes, dendrimers, and other nanocarrier systems targeted at the mannose receptor. These strategies aim to enhance drug delivery specificity, bioavailability, and therapeutic efficacy while decreasing off-target effects and systemic toxicity. Furthermore, the article delves into how mannose receptors and HIV interact, highlighting the potential for exploiting this interaction to enhance drug delivery to infected cells. The review covers essential topics, such as the rational design of nanocarriers for mannose receptor recognition, the impact of physicochemical properties on drug delivery performance, and how targeted delivery affects the pharmacokinetics and pharmacodynamics of anti-HIV agents. The challenges of these novel strategies, including immunogenicity, stability, and scalability, and future research directions in this rapidly growing area are discussed. The knowledge synthesis presented in this review underscores the potential of mannose receptor-based targeted drug delivery as a promising avenue for advancing HIV treatment. By leveraging the unique properties of mannose receptors, researchers can design drug delivery systems that cater to individual needs, overcome existing limitations, and create more effective and patient-friendly treatments in the ongoing fight against HIV/AIDS.

The anticancer impact of folate-linked ZnO-decorated bovine serum albumin/silibinin nanoparticles on human pancreatic, breast, lung, and colon cancers

In the current study, we aimed to design an individual hybrid silibinin nano-delivery system consisting of ZnO and BSA components to study its antioxidant activity and apoptotic potential on human pancreatic, breast, lung, and colon cancer cell lines. The folate-linked ZnO-decorated bovine serum albumin/silibinin nanoparticles (FZBS-NP) were synthesized and characterized by FTIR, FESEM, DLS, and zeta potential analysis. The FZBS-NP's cytotoxicity was evaluated by measuring the cancer cells' (MCF-7, A549, HT-29, and Panc) viability. Moreover, the apoptotic potential of the nanoparticles was studied by conducting several analyses including AO/PI and DAPI cell staining analysis, apoptotic gene expression profile (BAX, BCL2, and Caspase-8) preparation, and FITC Annexin V/PI flow cytometry. Finally, both antioxidant assays (ABTS and DPPH) were utilized to analyze the FZBS-NPs' antioxidant activities. The 152-nm FZBS-NP significantly induced the selective apoptotic death on the MCF-7, A549, HT-29, Panc, and Huvec cancer cells by increasing the SubG1 cell population following the increased treatment concentrations of FZBS-NP. Moreover, the FZBS-NPs exhibited powerful antioxidant activity. The BSA component of the FZBS-NPs delivery system improves the ability of the nanoparticles to gradually release silibinin and ZnO near the cancer cells. On the other hand, considering the powerful antioxidant activity of FZBS-NP, they have the potential to selectively induce apoptosis in human colon and breast cancer cells and protect normal types, which makes it an efficient safe anticancer compound. However, to verify the FZBS-NP anti-cancer efficiency further cancer and normal cell lines are required to measure several types of apoptotic gene expression.

The combined toxicity of polystyrene nano/micro-plastics and triphenyl phosphate (TPHP) on HepG2 cells

Combined toxicity is a critical concern during the risk assessment of environmental pollutants. Due to the characteristics of strong hydrophobicity and large specific surface area, microplastics (MPs) and nanoplastics (NPs) have become potential carriers of organic pollutants that may pose a health risk to humans. The co-occurrence of organic pollutants and MPs would cause adverse effects on aquatic organism, while the information about combined toxicity induced by organophosphorus flame retardants and MPs on human cells was limited. This study aimed to reveal the toxicity effects of co-exposure to triphenyl phosphate (TPHP) and polystyrene (PS) particles with micron-size/nano-size on HepG2 cell line. The adsorption behaviors of TPHP on PS particles was observed, with the PS-NP exhibiting a higher adsorption capacity. The reactive oxygen species generation, mitochondrial membrane potential depolarization, lactate dehydrogenase release and cell apoptosis proved that PS-NPs/MPs exacerbated TPHP-induced cytotoxicity. The particle size of PS would affect the toxicity to HepG2 cells that PS-NP (0.07 μm) exhibited more pronounced combined toxicity than PS-MP (1 μm) with equivalent concentrations of TPHP. This study provides fundamental insights into the co-toxicity of TPHP and PS micro/nanoplastics in HepG2 cells, which is crucial for validating the potential risk of combined toxicity in humans.

Corn Silk Polysaccharide Reduces the Risk of Kidney Stone Formation by Reducing Oxidative Stress and Inhibiting COM Crystal Adhesion and Aggregation

The aim of this study is to explore the inhibition of nanocalcium oxalate monohydrate (nano-COM) crystal adhesion and aggregation on the HK-2 cell surface after the protection of corn silk polysaccharides (CSPs) and the effect of carboxyl group (-COOH) content and polysaccharide concentration.

METHOD

HK-2 cells were damaged by 100 nm COM crystals to build an injury model. The cells were protected by CSPs with -COOH contents of 3.92% (CSP0) and 16.38% (CCSP3), respectively. The changes in the biochemical indexes of HK-2 cells and the difference in adhesion amount and aggregation degree of nano-COM on the cell surface before and after CSP protection were detected.

RESULTS

CSP0 and CCSP3 protection can obviously inhibit HK-2 cell damage caused by nano-COM crystals, restore cytoskeleton morphology, reduce intracellular ROS level, inhibit phosphoserine eversion, restore the polarity of the mitochondrial membrane potential, normalize the cell cycle process, and reduce the expression of adhesion molecules, OPN, Annexin A1, HSP90, HAS3, and CD44 on the cell surface. Finally, the adhesion and aggregation of nano-COM crystals on the cell surface were effectively inhibited. The carboxymethylated CSP3 exhibited a higher protective effect on cells than the original CSP0, and cell viability was further improved with the increase in polysaccharide concentration.

CONCLUSIONS

CSPs can protect HK-2 cells from calcium oxalate crystal damage and effectively reduce the adhesion and aggregation of nano-COM crystals on the cell surface, which is conducive to inhibiting the formation of calcium oxalate kidney stones.

Nano-scale and micron-scale plastics amplify the bioaccumulation of benzophenone-3 and ciprofloxacin, as well as their co-exposure effect on disturbing the antioxidant defense system in mussels, Perna viridis

Plastics ranging from nano-scale to micron-scale are frequently ingested by many marine animals. These particles exhibit biotoxicity and additionally perform as vectors that convey and amass adsorbed chemicals within organisms. Meanwhile, the frequency of detection of the benzophenone-3 and ciprofloxacin can be adsorbed on plastic particles, then accumulated in bivalves, causing biotoxicity. To understand their unknown accumulative kinetics in vivo affected by different plastic sizes and toxic effect from co-exposure, several scenarios were set up in which the mode organism were exposed to 0.6 mg/L of polystyrene carrying benzophenone-3 and ciprofloxacin in three sizes (300 nm, 38 μm, and 0.6 mm). The live Asian green mussels were chosen as mode organism for exposure experiments, in which they were exposed to environments with plastics of different sizes laden with benzophenone-3 and ciprofloxacin, then depurated for 7 days. The bioaccumulation and depuration kinetics of benzophenone-3 and ciprofloxacin were measured using HPLC-MS/MS after one week of exposure and depuration. Meanwhile, their toxic effect were investigated by measuring the changes in six biomarkers (condition index, reactive oxygen species, catalase, glutathione, lipid peroxidation, cytochrome P450 and DNA damage). The bioconcentration factors in mussels under different exposure conditions were 41.48-111.75 for benzophenone-3 and 6.45 to 12.35 for ciprofloxacin. The results suggested that microplastics and nanoplastics can act as carriers to increase bioaccumulation and toxicity of adsorbates in mussels in a size-dependent manner. Overproduction of reactive oxygen species caused by microplastics and nanoplastics led to increased DNA damage, lipid peroxidation, and changes in antioxidant enzymes and non-enzymatic antioxidants during exposure. Marked disruption of antioxidant defenses and genotoxic effects in mussels during depuration indicated impaired recovery. Compared to micron-scale plastic with sizes over a hundred micrometers that had little effect on bivalve bioaccumulation and toxicity, nano-scale plastic greatly enhanced the biotoxicity effect.

Polystyrene nanoparticle exposure accelerates ovarian cancer development in mice by altering the tumor microenvironment

Microplastics and nanoplastics are ubiquitous pollutants, widely spread in the living and natural environment. Although their potential impact on human health has been investigated, many doubts remain about their effects in carcinogenic processes. We investigated the potential effects and its molecular mechanisms of polystyrene nanoplastics (PS-NPs) on epithelial ovarian cancer (EOC) using the human EOC cell line HEY as an in vitro cell model and mice as a mammalian model. In vivo exposure to PS-NPs (100 nm; 10 mg/L) via drinking water significantly accelerated EOC tumor growth in mice. In in vitro tests the PS-NPs reduced the relative viability of EOC cells in a dose-dependent manner. Histological analysis showed increased mitotic counts in EOC tumor tissues of PS-NP exposed mice. PS-NP exposure significantly affected gene expression and disturbed many metabolic pathways in both cultured EOC cells and EOC tumor tissue in mice. Gene functional and pathway analysis indicated that immune-related responses and the tumor microenvironment pathway were significantly enriched, which may be attributed to disturbed expression of thrombomodulin (THBD) and its regulators. It may be concluded that PS-NP exposure caused a significant acceleration of EOC tumor growth in mice and a dose-dependent decrease in the relative viability of EOC cells by altering the tumor growth microenvironment. This offers new insights into the mechanisms underlying PS-NP effects on EOC.

Evaluation of the pulmonary toxicity of PSNPs using a Transwell-based normal human bronchial epithelial cell culture system

To reduce the nanoplastics (NPs) toxicity assessment error, we established a Transwell-based bronchial epithelial cell exposure system to assess the pulmonary toxicity of polystyrene NPs (PSNPs). Transwell exposure system was more sensitive than submerged culture for toxicity detection of PSNPs. PSNPs adhered to the BEAS-2B cell surface, were ingested by the cell, and accumulated in the cytoplasm. PSNPs induced oxidative stress and inhibited cell growth through apoptosis and autophagy. A noncytotoxic dose of PSNPs (1 ng/cm2) increased the expression levels of inflammatory factors (ROCK-1, NF-κB, NLRP3, ICAM-1, etc) in BEAS-2B cells, whereas a cytotoxic dose (1000 ng/cm2) induced apoptosis and autophagy, which might inhibit the activation of ROCK-1 and contribute to reducing inflammation. In addition, the noncytotoxic dose increased the expression levels of zonula occludens-2 (ZO-2) and α1-antitrypsin (α-AT) proteins in BEAS-2B cells. Therefore, in response to PSNP exposure, a compensatory increase in the activities of inflammatory factors, ZO-2, and α-AT may be triggered at low doses as a mechanism to preserve the survival of BEAS-2B cells. In contrast, exposure to a high dose of PSNPs elicits a noncompensatory response in BEAS-2B cells. Overall, these findings suggest that PSNPs may be harmful to human pulmonary health even at an ultralow concentration.

Rapid Internalization of Nanoparticles by Human Cells at the Single Particle Level

Nanoparticle uptake by cells has been studied for applications both in nanomedicine and in nanosafety. While the majority of studies have focused on the biological mechanisms underlying particle internalization, less attention has been given to questions of a more quantitative nature, such as how many nanoparticles enter cells and how rapidly they do so. To address this, we exposed human embryonic kidney cells to 40-200 nm carboxylated polystyrene nanoparticles and the particles were observed by live-cell confocal and super-resolution stimulated emission depletion fluorescence microscopy. How long a particle remained at the cell membrane after adsorbing onto it was monitored, distinguishing whether the particle ultimately desorbed again or was internalized by the cell. We found that the majority of particles desorb, but interestingly, most of the particles that are internalized do so within seconds, independently of particle size. As this is faster than typical endocytic mechanisms, we interpret this observation as the particles entering via an endocytic event that is already taking place (as opposed to directly triggering their own uptake) or possibly via an as yet uncharacterized endocytic route. Aside from the rapidly internalizing particles, a minority of particles remain at the membrane for tens of seconds to minutes before desorbing or being internalized. We also followed particles after cell internalization, observing particles that appeared to exit the cell, sometimes as rapidly as within tens of seconds. Overall, our results provide quantitative information about nanoparticle cell internalization times and early trafficking.

Mesoporous Polydopamine-Encapsulated Fluorescent Nanodiamonds: A Versatile Platform for Biomedical Applications

Fluorescent nanodiamonds (FNDs) are versatile nanomaterials with promising properties. However, efficient functionalization of FNDs for biomedical applications remains challenging. In this study, we demonstrate mesoporous polydopamine (mPDA) encapsulation of FNDs. The mPDA shell is generated by sequential formation of micelles via self-assembly of Pluronic F127 (F127) with 1,3,5-trimethyl benzene (TMB) and composite micelles via oxidation and self-polymerization of dopamine hydrochloride (DA). The surface of the mPDA shell can be readily functionalized with thiol-terminated methoxy polyethylene glycol (mPEG-SH), hyperbranched polyglycerol (HPG), and d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS). The PEGylated FND@mPDA particles are efficiently taken up by, and employed as a fluorescent imaging probe for, HeLa cells. HPG-functionalized FND@mPDA is conjugated with an amino-terminated oligonucleotide to detect microRNA via hybridization. Finally, the increased surface area of the mPDA shell permits efficient loading of doxorubicin hydrochloride. Further modification with TPGS increases drug delivery efficiency, resulting in high toxicity to cancer cells.

Recent Advances in Pharmaceutical Approaches of Antimicrobial Agents for Selective Delivery in Various Administration Routes

Globally, the increase of pathogenic bacteria with antibiotic-resistant characteristics has become a critical challenge in medical treatment. The misuse of conventional antibiotics to treat an infectious disease often results in increased resistance and a scarcity of effective antimicrobials to be used in the future against the organisms. Here, we discuss the rise of antimicrobial resistance (AMR) and the need to combat it through the discovery of new synthetic or naturally occurring antibacterial compounds, as well as insights into the application of various drug delivery approaches delivered via various routes compared to conventional delivery systems. AMR-related infectious diseases are also discussed, as is the efficiency of various delivery systems. Future considerations in developing highly effective antimicrobial delivery devices to address antibiotic resistance are also presented here, especially on the smart delivery system of antibiotics.

Extending the analogy between intracellular motion in mammalian cells and glassy dynamics

How molecules, organelles, and foreign objects move within living cells has been studied in organisms ranging from bacteria to human cells. In mammalian cells, in particular, cellular vesicles move across the cell using motor proteins that carry the vesicle down the cytoskeleton to their destination. We have recently noted several similarities between the motion of such vesicles and that in disordered, "glassy", systems, but the generality of this observation remains unclear. Here we follow the motion of mitochondria, the organelles responsible for cell energy production, in mammalian cells over timescales from 50 ms to 70 s. Qualitative observations show that single mitochondria remain within a spatially limited region for extended periods of time, before moving longer distances relatively quickly. The displacement distribution is roughly Gaussian for shorter distances (≲0.05 μm) but exhibits exponentially decaying tails at longer distances (up to 0.40 μm). This behaviour is well-described by a model developed to describe the motion in glassy systems. These observations are extended to in total 3 different objects (mitochondria, lysosomes and nano-sized beads enclosed in vesicles), 3 different mammalian cell types (HEK 293, HeLa, and HT22), from 2 different organisms (human and mouse). Further evidence that supports glass-like characteristics of the motion is a difference between the time it takes to move a longer distance for the first time and subsequent times, as well as a weak ergodicity breaking of the motion. Overall, we demonstrate the ubiquity of glass-like motion in mammalian cells, providing a different perspective on intracellular motion.

Polystyrene nanoplastics differentially influence the outcome of infection by two microparasites of the host Daphnia magna

The accumulation of micro- and nanoplastic particles in freshwater bodies has given rise to much concern regarding their potential adverse effects on aquatic biota. Beyond their known effects on single species, recent experimental evidence suggests that host-parasite interactions can also be affected by environmental concentrations of micro- and nanoplastics. However, investigating the effects of contaminants in simplified infection settings (i.e. one host, one parasite) may understate their ecological relevance, considering that co-infections are common in nature. We exposed the cladoceran Daphnia magna to a fungal parasite of the haemolymph (Metschnikowia bicuspidata) and a gut microsporidium (Ordospora colligata), either in single or co-infection. In addition, Daphnia were raised individually in culture media containing 0, 5 or 50 mg l^-1 of polystyrene nanoplastic beads (100 nm). Only few infections were successful at the higher nanoplastic concentration, due to increased mortality of the host. While no significant effect of the low concentration was detected on the microsporidium, the proportion of hosts infected by the fungal parasite increased dramatically, leading to more frequent co-infections under nanoplastic exposure. These results indicate that nanoplastics can affect the performance of distinct pathogens in diverging ways, with the potential to favour parasite coexistence in a common zooplanktonic host. This article is part of the theme issue 'Infectious disease ecology and evolution in a changing world'.

Temperature-responsive and biocompatible nanocarriers based on clay nanotubes for controlled anti-cancer drug release

Administration of temperature-responsive drug carriers that release anticancer drugs at high temperatures can benefit hyperthermia therapies because of the synergistic effect of anticancer drug molecules and high temperature on killing the cancer cells. In this study, we design and characterize a new temperature-responsive nanocarrier based on a naturally occurring and biocompatible clay mineral, halloysite nanotubes. Poly(N-isopropylacrylamide) brushes were grown on the surface of halloysite nanotubes using a combination of mussel-inspired dopamine polymerization and surface-initiated atom transfer radical polymerization. The chemical structure of the hybrid materials was investigated using X-ray photoelectron spectroscopy, thermogravimetric analysis and energy-dispersive X-ray spectroscopy. The hybrid material was shown to have a phase transition temperature of about 32 °C, corresponding to a 40 nm thick polymer layer surrounding the nanotubes. Cell studies suggested that grafting of poly(N-isopropylacrylamide) brushes on the polydopamine-modified halloysite nanotubes suppresses the cytotoxicity caused by the polydopamine interlayer and drug release studies on nanotubes loaded with doxorubicin showed that thanks to the poly(N-isopropylacrylamide) brushes a temperature-dependent drug release is observed. Finally, a fluorescent dye molecule was covalently attached to the polymer-grafted nanotubes and stimulated emission depletion nanoscopy was used to confirm the internalization of the nanotubes in HeLa cells.

Surface functionalization-dependent inflammatory potential of polystyrene nanoplastics through the activation of MAPK/ NF-κB signaling pathways in macrophage Raw 264.7

Increasing amounts of nanoplastics (NPs) in the environment are a great threat to human health, causing intestinal inflammation when consumed through seafood and water. There is, however, still a lack of understanding of the immunomodulatory role of NPs in immune cells, especially the early signal events behind inflammation resulting from NPs ingestion. In this study, we explored the dynamic internalization of polystyrene NPs and their carboxy and amino-functionalized products (PS, PS-COOH and PS-NH₂) followed by activation of ROS-MAPK/NF-κB signaling pathways in macrophage RAW 264.7. The inflammatory and cytotoxic potentials of NPs were evaluated by ELISA and apoptosis assays. Results showed that PS-COOH accumulated most in cells and induced more pronounced ROS and apoptosis than PS, PS-NH₂ and PS-μm. PS-COOH and PS-NH₂ showed stronger MAPK/NF-κB activation potential to at a low concentration of 10 μg/mL than unmodified PS, followed by production of IL-6 and TNF-α cytokines. Furthermore, PS-COOH induced MAPK/NF-κB activation and cytokine secretion could be inhibited by NAC, indicating that ROS was responsible for signal dysregulation and immunogenicity of PS-COOH, but not for PS-NH₂. The results suggested that the MAPK and NF-κB pathways were involved in NPs-induced macrophage inflammation, which was influenced by surface functionalization of NPs, with carboxylated PS NPs exhibiting a greater pro-inflammatory and cytotoxic potential.

Toxicity of polystyrene nanoparticles for mouse ovary and cultured human granulosa cells

The issue of global environmental contamination of microplastics has recently been receiving widespread attention. However, the effects of polystyrene nanoparticles (Nano-PS) on the female reproductive system remain unclear. We investigated the toxicity and explored the potential underlying mechanisms of Nano-PS in both mouse ovarian tissue in vivo and human ovarian granulosa cell lines in vitro. In vivo experiments: Mice were fed different concentrations of Nano-PS for 8 weeks. In vitro experiments: COV434 cells were treated with increasing concentrations of Nano-PS. In the present study, ovarian reserve was found to decrease significantly, while oxidative stress and apoptosis levels increased. Nano-PS increased the proportion of metestrum and diestrus periods, and decreased the proportion of estrous period. The implantation rates and the number of pups per litter decreased. In COV434 cells, Nano-PS reduced cell viability and mitochondrial membrane potential, increased the expression of apoptotic and oxidative stress markers and led to subsequent cell cycle arrest. Specifically, Nano-PS exert their toxic effects on mouse ovarian tissue and COV434 cells by inducing oxidative stress. A potential strategy to overcome this could be to activate the nuclear factor-E2-related factor 2 (Nrf2) signaling pathway to mitigate Nano-PS-induced oxidative stress.

Physical and biomimetic treatment methods to reduce microplastic waste accumulation

Background

Since the Covid-19 pandemic in 2019, the use of plastics has increased exponentially, so it is imperative to manage and dispose of these plastic wastes safely.

Objectives

This review focuses on the management strategies governed by the policies of each country to reduce plastic waste through physical collection methods and methods that use eco-imitation technologies.

Results

Thus far, physical treatment methods have been applied to sewage and drinking water treatment. The abilities of bio-inspired treatment methods are being assessed in terms of capturing microplastics (MPs) and nanoplastics (NPs), extracting substances from marine organisms, reducing toxicity, and developing alternatives to petroleum-based plastics.

Conclusions

Various post-treatment methods have been proposed to collect and remove MPs and NPs that have reached into aquatic ecosystems and subsequently reduce their toxicity. However, there are limitations that the effectiveness of these methods is hindered by the lack of policies governing the entire process of plastic use before the post-treatment.

Purpose of Review

We purpose to reduce plastic waste through methods that use eco-imitation technologies.

Recent Findings

These eco-imitation methods are attracting attention as viable future plastic waste treatment options in line with the goals of sustainable development.

Recognition and movement of polystyrene nanoplastics in fish cells

Although nanoplastics are being increasingly scrutinized, little is known about their kinetic behavior in living organisms, especially in cellular systems. Herein, nonspecific interactions of three polystyrene nanoplastics (pristine-PS, NH₂-PS, and COOH-PS, with size range of 90-100 nm and at concentrations of 0-100 μg mL^-1) with zebrafish cells were quantified for their cellular uptake and exocytosis. Cell uptake of nanoplastics reached a peak within 2 h and then decreased. The overall nanoplastics uptake was dominated by PS-particle internalization. The estimated uptake rate was comparable among the different types of PS (pristine-PS, NH₂-PS, and COOH-PS), but the uptake capacity was related to their functionality. The clathrin-mediated and caveolae-mediated pathways were mainly involved in the uptake of the three nanoplastics. The internalized PS-particles were initially delivered to the cytoplasm but then transported to lysosomes using energy. Meanwhile, these PS particles were released by the cells via energy-free penetration and energy-dependent lysosomal exocytosis. PS-particles were removed by the cells at a relatively slow rate, and the estimated retention half-lives of these PS-particles were 10.1 h, 12.0 h and 15.1 h for pristine-PS, NH₂-PS and COOH-PS particles, respectively, in fish cells based on our kinetic measurements. Intracellular trajectory modeling of nanoplastics movement is critical for the environmental and human health risk assessment.

Tuning Liposome Stability in Biological Environments and Intracellular Drug Release Kinetics

Ideal drug carriers should be stable in biological environments but eventually release their drug load once inside the targeted cells. These two aspects can be in contrast with each other, thus they need to be carefully tuned in order to achieve the desired properties for specific applications. Quantifying drug release profiles in biological environments or inside cells can be highly challenging, and standard methods to determine drug release kinetics in many cases cannot be applied to complex biological environments or cells. Within this context, the present work combined kinetic studies by flow cytometry with aging experiments in biological fluids and size-exclusion chromatography to determine drug release profiles in biological environments and inside cells. To this purpose, anionic and zwitterionic liposomes were used as model nanomedicines. By changing lipid composition, liposome stability in serum and intracellular release kinetics could be tuned and formulations with very different properties could be obtained. The methods presented can be used to characterize liposome release profiles in complex biological media, as well as inside cells. In this way, liposome composition can be tuned in order to achieve formulations with optimal balance between stability and release kinetics for specific applications.

On predicting heterogeneity in nanoparticle dosage

Nanoparticles are increasingly employed as a vehicle for the targeted delivery of therapeutics to specific cell types. However, much remains to be discovered about the fundamental biology that dictates the interactions between nanoparticles and cells. Accordingly, few nanoparticle-based targeted therapeutics have succeeded in clinical trials. One element that hinders our understanding of nanoparticle-cell interactions is the presence of heterogeneity in nanoparticle dosage data obtained from standard experiments. It is difficult to distinguish between heterogeneity that arises from stochasticity in nanoparticle-cell interactions, and that which arises from heterogeneity in the cell population. Mathematical investigations have revealed that both sources of heterogeneity contribute meaningfully to the heterogeneity in nanoparticle dosage. However, these investigations have relied on simplified models of nanoparticle internalisation. Here we present a stochastic mathematical model of nanoparticle internalisation that incorporates a suite of relevant biological phenomena such as multistage internalisation, cell division, asymmetric nanoparticle inheritance and nanoparticle saturation. Critically, our model provides information about nanoparticle dosage at an individual cell level. We perform model simulations to examine the influence of specific biological phenomena on the heterogeneity in nanoparticle dosage in the absence of heterogeneity in the cell population. Under certain modelling assumptions, we derive analytic approximations of the nanoparticle dosage distribution. We demonstrate that the analytic approximations are accurate, and show that nanoparticle dosage can be described by a Poisson mixture distribution with rate parameters that are a function of Beta-distributed random variables. We discuss the implications of the analytic results with respect to parameter estimation and model identifiability from standard experimental data. Finally, we highlight extensions and directions for future research.

Impacts of size-fractionation on toxicity of marine microplastics: Enhanced integrated biomarker assessment in the tropical mussels, Perna viridis

Accumulation of microplastics (MP) in oceanic waters is eroding the health of marine biota. We investigated how size-fractionated MP influence the toxicity risks towards a tropical keystone species, Perna viridis. Tissue-specific bioaccumulation and in vivo toxicity of polystyrene (PS) particles (0.5, 5, and 50 μm) were measured upon continuous exposure for 7 days, followed by 7 days depuration. P. viridis were exposed to equivalent mass (0.6 mg/L), corresponding to 4.0-4.6 particles/mL, 4.6-7.1 × 10³ particles/mL, and 1.1-4.8 × 10⁶ particles/mL for 50 μm, 5 μm and 0.5 μm PS particles, respectively. Onset toxicity were quantified through the enhanced integrated multi-biomarker response (EIBR) model, measured by weighting of biological organisation levels of eight biomarkers: (i) molecular (i.e., DNA damage (comet), 7-ethoxy resorufin O-deethylase (EROD), Catalase (CAT), Superoxide dismutase (SOD), Ferric Reducing Antioxidant Power (FRAP)); (ii) cellular (i.e., Neutral red retention (NRR), phagocytosis); and (iii) physiological (i.e., filtration rate). Data showed slightly elevated lysosomal instability (NRR) and antioxidant defences (FRAP, SOD, CAT, EROD) in specimens exposed to nano-PS (0.5 μm) compared to micro-PS (5 and 50 μm). Immunotoxicity (phagocytosis) and genotoxicity (comet) for haemocyte cells were significantly higher in specimens exposed to nano-PS (p < 0.05). EIBR index corroborated increasing toxicity modulated by MP sizes in descending order: 0.5 μm > 5 μm > 50 μm, with nano-PS exerted significantly higher biological effects (EIBR = 19.77 ± 5.89) than the unexposed group (EIBR = 10.97 ± 2.02; p < 0.05). Symptomatic organismal depression was manifested by the depleting filtering proficiency and weakened defence against invasive Zymosan bioparticles in the phagocytosis assay. Although impaired mussels duly recovered during depuration, individuals affected by nano-PS showed immunocompetence deficiency and gill responses that were not readily reversible, which could potentially increase their vulnerability towards further environmental stressors.

Insights into the mapping of green synthesis conditions for ZnO nanoparticles and their toxicokinetics

Research on ZnO nanoparticles (NPs) has broad medical applications. However, the green synthesis of ZnO NPs involves a wide range of properties requiring optimization. ZnO NPs show toxicity at lower doses. This toxicity is a function of NP properties and pharmacokinetics. Moreover, NP toxicity and pharmacokinetics are affected by the species type and age of the animals tested. Physiologically based pharmacokinetic (PBPK) modeling offers a mechanistic platform to scrutinize the colligative effect of the interplay between these factors, which reduces the need for in vivo studies. This review provides a guide to choosing green synthesis conditions that result in minimal toxicity using a mechanistic tool, namely PBPK modeling.

Low-dose exposure to phytosynthesized gold nanoparticles combined with glutamine deprivation enhances cell death in the cancer cell line HeLa via oxidative stress-mediated mitochondrial dysfunction and G0/G1 cell cycle arrest

Cancer cells use nutrients like D-glucose (Glc) and L-glutamine (Q) more efficiently for their development. This increased nutritional dependency of malignant cells has been commonly employed in various in vitro and in vivo models of anticancer therapies. This study utilized a combination of a low dose (25 μg mL^-1) of S2, a phytosynthesized gold nanoparticle (AuNP) that was previously proven to be non-toxic, and deprivation of extracellular glutamine as an anticancer strategy in the human cervical cancer cell line HeLa. We discovered that 24 h Q deprivation led to a less significant decrease in the viability of HeLa cells while a low dose of S2 caused a non-significant reduction in the viability of HeLa cells. However, combining these two treatments resulted in highly significant inhibition of cell growth, as measured by the MTT test and morphological examination. Glutamine starvation in HeLa cells was found to induce cellular uptake of S2 via clathrin-mediated endocytosis, thus facilitating the improved antitumor effects of the combined treatment. Flow cytometry-based assays using fluorescent probes H₂DCFDA and MitoSOX Red confirmed that this combination therapy involved the development of oxidative stress conditions owing to a surplus of cytosolic reactive oxygen species (cytoROS) and mitochondrial superoxide (mtSOX) generation. Furthermore, the investigated combinatorial treatment also indicated mitochondrial inactivity and disintegration, as evidenced by the drop in the mitochondrial membrane potential (Δψ_m) and the decrease in the mitochondrial mass (mtMass) in a flow-cytometric assay utilizing the probes. Tetramethylrhodamine ethyl ester and MitoTracker Green FM, respectively. Cell cycle arrest in the G0/G1 phase, induction of cell death via apoptosis/necrosis, and inhibition of migration capacities of HeLa cells were also seen after the combined treatment. Thus, this research provides insight into a new combinatorial approach for reducing the dose of nanoparticles and increasing their efficacy to better inhibit the growth of human cervical cancer cells by leveraging their extracellular glutamine dependence.

An analytical workflow for dynamic characterization and quantification of metal-bearing nanomaterials in biological matrices

To assess the safety of engineered nanomaterials (ENMs) and to evaluate and improve ENMs' targeting ability for medical application, it is necessary to analyze the fate of these materials in biological media. This protocol presents a workflow that allows researchers to determine, characterize and quantify metal-bearing ENMs (M-ENMs) in biological tissues and cells and quantify their dynamic behavior at trace-level concentrations. Sample preparation methods to enable analysis of M-ENMs in a single cell, a cell layer, tissue, organ and physiological media (e.g., blood, gut content, hemolymph) of different (micro)organisms, e.g., bacteria, animals and plants are presented. The samples are then evaluated using fit-for-purpose analytical techniques e.g., single-cell inductively coupled plasma mass spectrometry, single-particle inductively coupled plasma mass spectrometry and synchrotron X-ray absorption fine structure, providing a protocol that allows comprehensive characterization and quantification of M-ENMs in biological matrices. Unlike previous methods, the protocol uses no fluorescent dyes or radiolabels to trace M-ENMs in biota and enables analysis of most M-ENMs at cellular, tissue and organism levels. The protocols can be applied by a wide variety of users depending on the intended purpose of the application, e.g., to correlate toxicity with a specific particle form, or to understand the absorption, distribution and excretion of M-ENMs. The results facilitate an understanding of the biological fate of M-ENMs and their dynamic behavior in biota. Performing the protocol may take 7-30 d, depending on which combination of methods is applied.

Environmental health impacts of microplastics exposure on structural organization levels in the human body

The ubiquitous prevalence of microplastics pollution has raised concerns about microplastics' potential risks and impacts on the global environment. However, the potential human health risks and impacts of microplastics remain largely unexplored. By providing an overview regarding the interaction of microplastics and human health, this review extends current knowledge on the potential impacts of microplastics pollution on humans from an environmental health perspective. The paper firstly presents the characteristics of microplastics as well as the status of global microplastics pollution. As for human health, the potential hazards of microplastics are reflected by toxic chemical components, vectors of contaminants, and physical damage. Extensive microplastic pollution on ecosystems due to human activities leads to inevitable human exposure, which may occur by dietary, inhalation and/or skin contact. Accordingly, microplastics exposure is closely associated with human health. This study explores the potential interactions of microplastics with the biological organization at various levels, including chemical, cellular, tissue, organ, and system levels. The review concludes by highlighting five urgent perspectives and implications for future research on microplastics: 1) Developing a standard terminology and research methods; 2) Reinforcing microplastics pollution governance; 3) Exploring innovative strategies and technologies; 4) Engaging the public and change behaviour; and 5) Adopting a transdisciplinary approach.

Effects of polyethylene microplastics on cell membranes: A combined study of experiments and molecular dynamics simulations

Microplastics (MPs), widely distributed within the environment, can be ingested by humans easily and cause various biological reactions such as oxidative stress, immune response and membrane damage, ultimately representing a threat to health. Cell membranes work as first barrier for MPs entering the cell and playing biological effects. For now, the researches on interactions of MPs on cell membranes lack an in-depth and effective theoretical model to understand molecular details and physicochemical behaviors. In present study, observations of calcein leakage established polyethylene plastic nanoparticles (PE PNPs), especially of high concentrations, harming cell membrane integrity. SYTOX green and lactate dehydrogenase (LDH) assays supported the evidence that the exposure of cells to PE PNPs caused significant cell membrane damage in dose-response. Molecular dynamics (MD) simulations were further applied to determine the effects of PE on the properties of dipalmitoyl phosphatidylcholine (DPPC) bilayer. PE permeated into lipid membranes easily resulting in significant variations in DPPC bilayer with lower density, fluidity changes and membrane thickening. Besides, PE aggregates bound were more likely to cause pore formation and serious damage to the DPPC bilayer. The interaction mechanisms between MPS and cell membrane were explored which provided valuable insights into membrane effect of MPs.

Magnetic Nano-Platform Enhanced iPSC-Derived Trabecular Meshwork Delivery and Tracking Efficiency

Purpose

Transplantation of stem cells to remodel the trabecular meshwork (TM) has become a new option for restoring aqueous humor dynamics and intraocular pressure homeostasis in glaucoma. In this study, we aimed to design a nanoparticle to label induced pluripotent stem cell (iPSC)-derived TM and improve the delivery accuracy and in vivo tracking efficiency.

Methods

PLGA-SPIO-Cypate (PSC) NPs were designed with polylactic acid-glycolic acid (PLGA) polymers as the backbone, superparamagnetic iron oxide (SPIO) nanoparticles, and near-infrared (NIR) dye cypate. In vitro assessment of cytotoxicity, iron content after NPs labeling, and the dual-model monitor was performed on mouse iPSC-derived TM (miPSC-TM) cells, as well as immortalized and primary human TM cells. Cell function after labeling, the delivery accuracy, in vivo tracking efficiency, and its effect on lowering IOP were evaluated following miPSC-TM transplantation in mice.

Results

Initial in vitro experiments showed that a single-time nanoparticles incubation was sufficient to label iPSC-derived TM and was not related to any change in both cell viability and fate. Subsequent in vivo evaluation revealed that the use of this nanoparticle not only improves the delivery accuracy of the transplanted cells in live animals but also benefits the dual-model tracking in the long term. More importantly, the use of the magnet triggers a temporary enhancement in the effectiveness of cell-based therapy in alleviating the pathologies associated with glaucoma.

Conclusion

This study provided a promising approach for enhancing both the delivery and in vivo tracking efficiency of the transplanted cells, which facilitates the clinical translation of stem cell-based therapy for glaucoma.

Comparative In Vitro Cytotoxicity Study of Carbon Dot-Based Organometallic Nanoconjugates: Exploration of Their Cell Proliferation, Uptake, and Localization in Cancerous and Normal Cells

Organometallic nanoconjugates have raised great interest due to their bimodal properties and high stability. In the present study, we analyzed the cytotoxicity property of carbon dots (CDs) and a series of organometallic nanoconjugates including gold@carbon dots (Au@CDs) and silver@carbon dots (Ag@CDs) synthesized via an aqueous mode. We aimed to divulge a comparative analysis of cell proliferation, uptake, and localization of the particles in HeLa and HEK293 cell lines. Our results showed dose-dependent cytotoxicity of Au@CDs, Ag@CDs, and CDs. However, Ag@CDs showed the highest inhibition through HeLa cells with an IC₅₀ value of around 50 ± 1.0 μg/mL. Confocal imaging signified the uptake of the particles suggested by blue fluorescence in the interior region of HeLa cells. Furthermore, the TEM micrographs depicted that the particles are entrapped by endocytosis assisted through the cell microvilli. The CDs and Au@CDs were thus observed to be relatively safe up to a concentration of 100 μg/mL and did not induce any morphological changes in the cells. Moreover, the cell proliferation assay of these nanoconjugates against HEK 293 cells signified the nontoxic nature of the nanoconjugates. The results thus revealed two major facts: firstly, the Ag@CDs had potent therapeutic potential, signifying their potential as a promising anticancer drug, and secondly, the CDs and Au@CDs at a defined dose could be used as probes for detection and also bioimaging agents.

Permeability, anti-inflammatory and anti-VEGF profiles of steroidal-loaded cationic nanoemulsions in retinal pigment epithelial cells under oxidative stress

Age-related macular degeneration (AMD) is defined as a degenerative, progressive and multifactorial disorder that affects the macula with a complex etiology. The retinal pigment epithelium is a monolayer of cells that has the function to separate the surface of the choroid from the neural retina that is involved in the signal transduction leading to vision. The blood-aqueous barrier and the blood retinal barrier limit the permeation of drugs into the retina and thereby reducing their efficacy. Triamcinolone acetonide (TA) is widely used as anti-inflammatory and immunomodulatory drug that promotes the inhibition of the inflammatory processes. The factors that stimulate or inhibit angiogenesis in AMD create a local balance that is responsible for the growth of sub-retinal neovascularization. In AMD, the main angiogenic stimulus is the vascular endothelial growth factor (VEGF). In this work, nanoemulsions with cationic surfactants (mono- and dicationic DABCO and quinuclidine) were produced to deliver TA, and were found to reduce the production of tumor necrosis factor alpha (TNF-α), which stimulates the choroidal neovascularization development by upregulating the VEGF production, and consequently decreased the VEGF levels. Our results support the potential use of mono- and dicationic DABCO and quinuclidine-based cationic nanoemulsions for the delivery of TA in the treatment of AMD.

coupled Hydrodynamic Flow Focusing (cHFF) to Engineer Lipid–Polymer Nanoparticles (LiPoNs) for Multimodal Imaging and Theranostic Applications

An optimal design of nanocarriers is required to overcome the gap between synthetic and biological identity, improving the clinical translation of nanomedicine. A new generation of hybrid vehicles based on lipid–polymer coupling, obtained by Microfluidics, is proposed and validated for theranostics and multimodal imaging applications. A coupled Hydrodynamic Flow Focusing (cHFF) is exploited to control the time scales of solvent exchange and the coupling of the polymer nanoprecipitation with the lipid self-assembly simultaneously, guiding the formation of Lipid–Polymer NPs (LiPoNs). This hybrid lipid–polymeric tool is made up of core–shell structure, where a polymeric chitosan core is enveloped in a lipid bilayer, capable of co-encapsulating simultaneously Gd-DTPA and Irinotecan/Atto 633 compounds. As a result, a monodisperse population of hybrid NPs with an average size of 77 nm, with preserved structural integrity in different environmental conditions and high biocompatibility, can be used for MRI and Optical applications. Furthermore, preliminary results show the enhanced delivery and therapeutic efficacy of Irinotecan-loaded hybrid formulation against U87 MG cancers cells.

How the Physicochemical Properties of Manufactured Nanomaterials Affect Their Performance in Dispersion and Their Applications in Biomedicine: A Review

The growth in novel synthesis methods and in the range of possible applications has led to the development of a large variety of manufactured nanomaterials (MNMs), which can, in principle, come into close contact with humans and be dispersed in the environment. The nanomaterials interact with the surrounding environment, this being either the proteins and/or cells in a biological medium or the matrix constituent in a dispersion or composite, and an interface is formed whose properties depend on the physicochemical interactions and on colloidal forces. The development of predictive relationships between the characteristics of individual MNMs and their potential practical use critically depends on how the key parameters of MNMs, such as the size, shape, surface chemistry, surface charge, surface coating, etc., affect the behavior in a test medium. This relationship between the biophysicochemical properties of the MNMs and their practical use is defined as their functionality; understanding this relationship is very important for the safe use of these nanomaterials. In this mini review, we attempt to identify the key parameters of nanomaterials and establish a relationship between these and the main MNM functionalities, which would play an important role in the safe design of MNMs; thus, reducing the possible health and environmental risks early on in the innovation process, when the functionality of a nanomaterial and its toxicity/safety will be taken into account in an integrated way. This review aims to contribute to a decision tree strategy for the optimum design of safe nanomaterials, by going beyond the compromise between functionality and safety.

Facilely prepared aggregation-induced emission (AIE) nanocrystals with deep-red emission for super-resolution imaging

Organic nanocrystals (NCs) with high brightness are highly desirable for biological imaging. However, the preparation of NCs by a facile and fast method is still challenging. Herein, an aggregation-induced emission (AIE) luminogen of 4,4'-(5,6-difluorobenzo[c][1,2,5]thiadiazole-4,7-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (DTPA-BT-F) in the deep-red region is designed with intensive crystalline features to obtain NCs by kinetically controlled nanoprecipitation. The prepared AIE NCs with high brightness and good photo-stability are then applied in super-resolution imaging via stimulated emission depletion (STED) nanoscopy. As observed, the nanostructures in lysosomes of both fixed and live cells are well visualized with superior lateral resolutions under STED nanoscopy (full width at half maximum values, 107 and 108 nm) in contrast to that in confocal imaging (548 and 740 nm). More importantly, dynamic monitoring and long-term tracking of lysosomal movements in live HeLa cells, such as lysosomal contact, can also be carried out by using DTPA-BT-F NCs at a superior resolution. To the best of our knowledge, this is the first case of AIE NCs prepared by nanoprecipitation for STED nanoscopy, thus providing a new strategy to develop high performance imaging agents for super-resolution imaging.

Drug Targeting and Nanomedicine: Lessons Learned from Liver Targeting and Opportunities for Drug Innovation

Drug targeting and nanomedicine are different strategies for improving the delivery of drugs to their target. Several antibodies, immuno-drug conjugates and nanomedicines are already approved and used in clinics, demonstrating the potential of such approaches, including the recent examples of the DNA- and RNA-based vaccines against COVID-19 infections. Nevertheless, targeting remains a major challenge in drug delivery and different aspects of how these objects are processed at organism and cell level still remain unclear, hampering the further development of efficient targeted drugs. In this review, we compare properties and advantages of smaller targeted drug constructs on the one hand, and larger nanomedicines carrying higher drug payload on the other hand. With examples from ongoing research in our Department and experiences from drug delivery to liver fibrosis, we illustrate opportunities in drug targeting and nanomedicine and current challenges that the field needs to address in order to further improve their success.

Simultaneous Exposure of Different Nanoparticles Influences Cell Uptake

Drug delivery using nano-sized carriers holds tremendous potential for curing a range of diseases. The internalisation of nanoparticles by cells, however, remains poorly understood, restricting the possibility for optimising entrance into target cells, avoiding off-target cells and evading clearance. The majority of nanoparticle cell uptake studies have been performed in the presence of only the particle of interest; here, we instead report measurements of uptake when the cells are exposed to two different types of nanoparticles at the same time. We used carboxylated polystyrene nanoparticles of two different sizes as a model system and exposed them to HeLa cells in the presence of a biomolecular corona. Using flow cytometry, we quantify the uptake at both average and individual cell level. Consistent with previous literature, we show that uptake of the larger particles is impeded in the presence of competing smaller particles and, conversely, that uptake of the smaller particles is promoted by competing larger particles. While the mechanism(s) underlying these observations remain(s) undetermined, we are partly able to restrain the likely possibilities. In the future, these effects could conceivably be used to enhance uptake of nano-sized particles used for drug delivery, by administering two different types of particles at the same time.

Methods, models, mechanisms and metadata: Introducing the Nanotoxicology collection at F1000Research

Nanotoxicology is a relatively new field of research concerning the study and application of nanomaterials to evaluate the potential for harmful effects in parallel with the development of applications. Nanotoxicology as a field spans materials synthesis and characterisation, assessment of fate and behaviour, exposure science, toxicology / ecotoxicology, molecular biology and toxicogenomics, epidemiology, safe and sustainable by design approaches, and chemoinformatics and nanoinformatics, thus requiring scientists to work collaboratively, often outside their core expertise area. This interdisciplinarity can lead to challenges in terms of interpretation and reporting, and calls for a platform for sharing of best-practice in nanotoxicology research. The F1000Research Nanotoxicology collection, introduced via this editorial, will provide a place to share accumulated best practice, via original research reports including no-effects studies, protocols and methods papers, software reports and living systematic reviews, which can be updated as new knowledge emerges or as the domain of applicability of the method, model or software is expanded. This editorial introduces the Nanotoxicology Collection in F1000Research. The aim of the collection is to provide an open access platform for nanotoxicology researchers, to support an improved culture of data sharing and documentation of evolving protocols, biological and computational models, software tools and datasets, that can be applied and built upon to develop predictive models and move towards in silico nanotoxicology and nanoinformatics. Submissions will be assessed for fit to the collection and subjected to the F1000Research open peer review process.

The joint adverse effects of aged nanoscale plastic debris and their co-occurring benzo[α]pyrene in freshwater mussel (Anodonta anatina)

Although the presence of small-scale plastics, including nanoscale plastic debris (NPD, size <1 μm), is expected in the environment, our understanding of their potential uptake and biodistribution in organisms is still limited. This mostly is because of the limitations in analytical techniques to characterize NPD in organisms' bodies. Moreover, it is still debatable whether aged NPD can sorb and transfer chemicals into organisms. Here, we apply iron oxide-doped polystyrene nanoparticles (Fe-PS NPs) of 270 nm size to quantify the uptake and biodistribution of NPD in freshwater mussels (Anodonta anatina). The Fe-PS NPs were, first, oxidized using heat-activated potassium persulfate treatments to produce NPD (aged particles). Then, the sorption of benzo[a]pyrene (B[α]P), as a model of organic chemicals, into the aged NPD was studied. Chemical oxidation (i.e. aging) significantly decreased the sorption of B[α]P into the particles over 5 days when compared to pristine particles. After 72-h of exposure, A. anatina accumulated NPD in the gills and digestive gland. When exposed to the mixture of NPD and B[α]P, the number of particles in the gills and digestive gland increased significantly compared to the mussels exposed to NPD alone. Moreover, the mixture of NPD and B[α]P increased the activity of Superoxide dismutase and Catalase enzymes in the exposed mussels when compared to the control and to the NPD alone. The present study provides evidence that aged NPD not only could accumulate and alter the toxicity profile of organic chemicals in aquatic organisms, but the chemicals also could facilitate the uptake of NPD (combined effects).

Polystyrene nanoplastics and microplastics can act as Trojan horse carriers of benzo(a)pyrene to mussel hemocytes in vitro

In this work we studied the ability of polystyrene (PS) nanoplastics (NPs) and microplastics (MPs) to transfer benzo(a)pyrene (BaP) to mussel hemocytes and to produce toxic effects in vitro. For this, intracellular fate and toxicity of PS NPs (0.05 μm) and MPs (0.5 and 4.5 μm) alone or with BaP and of BaP alone were assessed. Particles of 0.05 and 0.5 µm largely aggregated in the exposure medium whereas presence of BaP reduced particle aggregation. Cells internalized PS NPs and MPs alone or with BaP and these were found inside and outside lysosomes, depending on their size. PS particles alone or with BaP were cytotoxic to hemocytes only at the highest concentrations tested. The same was true for most sublethal endpoints except for increased phagocytic activity provoked by NPs and 0.5 μm MPs at lower concentrations. Plastic particles appeared to be the main drivers for reduced plasma membrane integrity and increased phagocytic and lysosomal activities whereas BaP appeared to contribute more to reduced cell viability and phagocytosis and increased ROS production and genotoxicity. Overall, PS NPs and MPs can act as carriers of BaP to mussel hemocytes, rising concerns about risks plastics associated to pollutants may pose to aquatic organisms.

Sources of variability in nanoparticle uptake by cells

Understanding how nano-sized objects are taken up by cells is important for applications within medicine (nanomedicine), as well as to avoid unforeseen hazard due to nanotechnology (nanosafety). Even within the same cell population, one typically observes a large cell-to-cell variability in nanoparticle uptake, raising the question of the underlying cause(s). Here we investigate cell-to-cell variability in polystyrene nanoparticle uptake by HeLa cells, with generalisations of the results to silica nanoparticles and liposomes, as well as to A549 and primary human umbilical vein endothelial cells. We show that uptake of nanoparticles is correlated with cell size within a cell population, thereby reproducing and generalising previous reports highlighting the role of cell size in nanoparticle uptake. By repeatedly isolating (using fluorescence-activated cell sorting) the cells that take up the most and least nanoparticles, respectively, and performing RNA sequencing on these cells separately, we examine the underlying gene expression that contributes to high and low polystyrene nanoparticle accumulation in HeLa cells. We can thereby show that cell size is not the sole driver of cell-to-cell variability, but that other cellular characteristics also play a role. In contrast to cell size, these characteristics are more specific to the object (nanoparticle or protein) being taken up, but are nevertheless highly heterogeneous, complicating their detailed identification. Overall, our results highlight the complexity underlying the cellular features that determine nanoparticle uptake propensity.

Multifunctional superparamagnetic nanoparticles with a fluorescent silica shell for the in vitro study of bio-nano interactions at the subcellular scale

Despite the high level of interest in bio-nano interactions, detailed intracellular mechanisms that govern nanoscale recognition and signalling still need to be unravelled. Magnetic nanoparticles (NPs) are valuable tools for elucidating complex intracellular bio-nano interactions. Using magnetic NPs, it is possible to isolate cell compartments that the particles interact with during intracellular trafficking. Studies at the subcellular scale rely heavily on optical microscopy; therefore, combining the advantages of magnetic recovery with excellent imaging properties to allow intracellular NP tracking is of utmost interest for the nanoscience field. However, it is a challenge to prepare highly magnetic NPs with a suitable fluorescence for the fluorescence imaging techniques typically used for biological studies. Here we present the synthesis of biocompatible multifunctional superparamagnetic multicore NPs with a bright fluorescent silica shell. The incorporation of an organic fluorophore in the silica surrounding the magnetic multicore was optimised to enable the particles to be tracked with the most common imaging techniques. To prevent dye loss resulting from silica dissolution in biological environments, which would reduce the time that the particles could be tracked, we added a thin dense encapsulating silica layer to the NPs which is highly stable in biological media. The synthesised multifunctional nanoparticles were evaluated in cell uptake experiments in which their intracellular location could be clearly identified using fluorescence imaging microscopy, even after 3 days. The magnetic properties of the iron oxide core enabled both efficient recovery of the NPs from the intracellular environment and the extraction of cell compartments involved in their intracellular trafficking. Thus, the NPs reported here provide a promising tool for the study of the processes regulating bio-nano interactions.

Data-Driven Modeling of the Cellular Pharmacokinetics of Degradable Chitosan-Based Nanoparticles

Nanoparticle drug delivery vehicles introduce multiple pharmacokinetic processes, with the delivery, accumulation, and stability of the therapeutic molecule influenced by nanoscale processes. Therefore, considering the complexity of the multiple interactions, the use of data-driven models has critical importance in understanding the interplay between controlling processes. We demonstrate data simulation techniques to reproduce the time-dependent dose of trimethyl chitosan nanoparticles in an ND7/23 neuronal cell line, used as an in vitro model of native peripheral sensory neurons. Derived analytical expressions of the mean dose per cell accurately capture the pharmacokinetics by including a declining delivery rate and an intracellular particle degradation process. Comparison with experiment indicates a supply time constant, τ = 2 h. and a degradation rate constant, b = 0.71 h⁻¹. Modeling the dose heterogeneity uses simulated data distributions, with time dependence incorporated by transforming data-bin values. The simulations mimic the dynamic nature of cell-to-cell dose variation and explain the observed trend of increasing numbers of high-dose cells at early time points, followed by a shift in distribution peak to lower dose between 4 to 8 h and a static dose profile beyond 8 h.

Long-Term Effects of Polystyrene Nanoplastics in Human Intestinal Caco-2 Cells

The increasing presence of micro- and nanoplastics (MNPLs) in the environment, and their consequent accumulation in trophic niches, could pose a potential health threat to humans, especially due to their chronic ingestion. In vitro studies using human cells are considered pertinent approaches to determine potential health risks to humans. Nevertheless, most of such studies have been conducted using short exposure times and high concentrations. Since human exposure to MNPLs is supposed to be chronic, there is a lack of information regarding the potential in vitro MNPLs effects under chronic exposure conditions. To this aim, we assessed the accumulation and potential outcomes of polystyrene nanoparticles (PSNPs), as a model of MNPLs, in undifferentiated Caco-2 cells (as models of cell target in ingestion exposures) under a relevant long-term exposure scenario, consisting of eight weeks of exposure to sub-toxic PSNPs concentrations. In such exposure conditions, culture-media was changed every 2–3 days to maintain constant exposure. The different analyzed endpoints were cytotoxicity, dysregulation of stress-related genes, genotoxicity, oxidative DNA damage, and intracellular ROS levels. These are endpoints that showed to be sensitive enough in different studies. The obtained results attest that PSNPs accumulate in the cells through time, inducing changes at the ultrastructural and molecular levels. Nevertheless, minor changes in the different evaluated genotoxicity-related biomarkers were observed. This would indicate that no DNA damage or oxidative stress is observed in the human intestinal Caco-2 cells after long-term exposure to PSNPs. This is the first study dealing with the long-term effects of PSNPs on human cultured cells.