Colloidal stabilization of CeO2 nanomaterials with polyacrylic acid, polyvinyl alcohol or natural organic matter

Effect of water-soluble polymers on the transport of functional group-modified polystyrene nanoplastics in goethite-coated saturated porous media

The research on the impact of water-soluble polymers (WSPs) on the migration and fate of plastic particles is extremely limited. This article explored the effects of polyacrylic acid (PAA, a common WSP) and physicochemical factors on the transport of polystyrene nanoparticles (PSNPs-NH2/COOH) with different functional groups in QS (quartz sand) and FOS (goethite-modified quartz sand, simulates mineral colloids). Research has shown that PAA can selectively adsorb onto the surface of PSNPs-NH2, forming ecological corona heterogeneous aggregates. This process increased the spatial hindrance and elastic repulsion, resulting in the recovery of PSNPs-NH2 always exceeding that of PSNPs-COOH. Overall, PAA can hinder the migration of PSNPs in QS but can promote their migration in FOS. When multivalent cations coexist with PAA, the transport of PSNPs in the media is primarily affected by cation bridging and CH-cation-π interaction. The presence of oxyanions and PAA prevents PSNPs from following the Hofmeister rule and promotes their migration (PO43-: 82.34 ± 0.16% to 94.63 ± 2.82%>SO42-: 81.38 ± 2.73% to 91.15 ± 0.93%>NO3-: 55.85 ± 0.70%-87.16 ± 3.80%). The findings of this study contribute significantly to a better understanding of the migration of WSPs and group-modified NPs in complex saturated porous media.

Breaking boundaries: Artificial intelligence for pesticide detection and eco-friendly degradation

Pesticides are extensively used agrochemicals across the world to control pest populations. However, irrational application of pesticides leads to contamination of various components of the environment, like air, soil, water, and vegetation, all of which build up significant levels of pesticide residues. Further, these environmental contaminants fuel objectionable human toxicity and impose a greater risk to the ecosystem. Therefore, search of methodologies having potential to detect and degrade pesticides in different environmental media is currently receiving profound global attention. Beyond the conventional approaches, Artificial Intelligence (AI) coupled with machine learning and artificial neural networks are rapidly growing branches of science that enable quick data analysis and precise detection of pesticides in various environmental components. Interestingly, nanoparticle (NP)-mediated detection and degradation of pesticides could be linked to AI algorithms to achieve superior performance. NP-based sensors stand out for their operational simplicity as well as their high sensitivity and low detection limits when compared to conventional, time-consuming spectrophotometric assays. NPs coated with fluorophores or conjugated with antibody or enzyme-anchored sensors can be used through Surface-Enhanced Raman Spectrometry, fluorescence, or chemiluminescence methodologies for selective and more precise detection of pesticides. Moreover, NPs assist in the photocatalytic breakdown of various organic and inorganic pesticides. Here, AI models are ideal means to identify, classify, characterize, and even predict the data of pesticides obtained through NP sensors. The present study aims to discuss the environmental contamination and negative impacts of pesticides on the ecosystem. The article also elaborates the AI and NP-assisted approaches for detecting and degrading a wide range of pesticide residues in various environmental and agrecultural sources including fruits and vegetables. Finally, the prevailing limitations and future goals of AI-NP-assisted techniques have also been dissected.

Study on the poly(methyl methacrylate-acrylic acid)/calcium phosphate cement composite bound by chelation with enhanced water absorption and biomechanical properties

Polymethylmethacrylate (PMMA) bone cement has been widely used as a critical material for fixing prostheses and filling bone defects. The shrinkage of PMMA bone cement was addressed by the additives, however, the uneven integral water absorption and expansion performance as well as the deteriorated mechanical properties of the modified bone cement after immersion in phosphate buffered saline (PBS) and simulation body fluid (SBF) affected the long-term stability after implantation. Calcium phosphate cement (CPC) is a biomaterial with promising applications in orthopedics, whose hydration reaction provides an important driving force for the transfer of water. Besides, the mechanical properties of CPC can be enhanced with the curing process. In this study, CPC was utilized to modify the poly(methyl methacrylate-acrylic acid) [P(MMA-AA)] bone cement. The results demonstrated the successful construction of interconnected CPC water delivery networks in the P(MMA-AA)/CPC composite, the water absorption ratio and expansion ratio of the composite were up to 131.18 ± 9.14% and 168.19 ± 5.44%, respectively. Meanwhile, the transformation of CPC water delivery networks into rigid mechanical support networks as well as the chelation interaction between organic-inorganic enhanced the mechanical properties of the composite after immersion, the compressive strength after immersion reached 62.97 ± 0.97 MPa, which was 27.65% higher than that before immersion. The degradation ratio of the composite was up to 13.76 ± 0.23% after 9 days of immersion, which was 16.4% higher than that of CPC. Furthermore, composites exhibited superior biocompatibility as the release of Ca2+. Therefore, P(MMA-AA)/CPC composite serves as a promising medical filling material for clinical use.

Ultrasound-mediated mesoporous silica nanoparticles loaded with PDLIM5 siRNA inhibit gefitinib resistance in NSCLC cells by attenuating EMT

Epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKIs) was one of the main drugs in the treatment of non-small cell lung cancer (NSCLC). Previous studies had demonstrated that PDZ and LIM Domain 5 (PDLIM5) played an important role in EGFR TKIs resistance. However, there was no feasible method to eliminate EGFR TKIs resistance by suppressing this gene. Here, we formulated a novel mesoporous silica-loaded PDLIM5 siRNA (Small interfering RNA) nanoplatforms. The results have shown that PDLIM5 siRNA could be effectively bound to the nanoplatforms and had good biocompatibility. Further exploration suggested that the nano-platform combined with ultrasonic irradiation could be very effective for siRNA delivery and ultrasound imaging. Moreover, Epithelial-mesenchymal transformation (EMT) changes occurred in PC-9 Gefitinib resistance (PC-9/GR) cells during the development of drug resistance. When PDLIM5 siRNA entered PC-9/GR cells, the sensitivity of drug-resistant cells to gefitinib could be restored through the transforming growth factor-β (TGF-β)/EMT pathway. Therefore, PDLIM5 may be an important reason for the resistance of NSCLC cells to gefitinib, and this nanoplatform may become a novel treatment for EGFR TKIs resistance in NSCLC patients.

Aqueous Dispersions of Polypropylene: Toward Reference Materials for Characterizing Nanoplastics

Microplastics and nanoplastics pollute the natural environment all over the world, but the full extent of the hazards posed by this waste is unclear. While research on microplastics is well advanced, little work has been done on nanoplastics. This discrepancy is mainly due to the lacking ability to detect nanoplastics in biologically and environmentally relevant matrices. Nanoplastics reference materials can help the development of suitable methods for identifying and quantifying nanoplastics in nature. The aim is to synthesize nanoplastics made from one of the most commonly used plastics, namely polypropylene. An easy way to produce long-term stable aqueous dispersions of polypropylene nanoparticles (nano polypropylene) is reported. The nanoplastic particles, prepared by mechanical breakdown, show a mean hydrodynamic diameter of D_h = 180.5 ± 5.8  nm and a polydispersity index of PDI = 0.084 ± 0.02. No surfactant is needed to obtain dispersion which is stable for more than 6 months. The colloidal stability of the surfactant-free nano polypropylene dispersions is explained by their low zeta potential of ζ = -43 ± 2 mV.

Facile Synthesis of Stable Cerium Dioxide Sols in Nonpolar Solvents

A method is proposed for the preparation of stable sols of nanocrystalline cerium dioxide in nonpolar solvents, based on surface modification of CeO₂ nanoparticles obtained by thermal hydrolysis of concentrated aqueous solutions of ammonium cerium(IV) nitrate with residues of 2-ethylhexanoic and octanoic acids. The synthesis was carried out at temperatures below 100 °C and did not require the use of expensive and toxic reagents. An assessment of the radical-scavenging properties of the obtained sols using the superoxide anion-radical neutralization model revealed that they demonstrate notable antioxidant activity. The results obtained indicate the potential of the nanoscale cerium dioxide sols in nonpolar solvents to be used for creating nanobiomaterials possessing antioxidant properties.

Ion compositions in artificial media control the impact of humic acid on colloidal behaviour, dissolution and speciation of CuO-NP

The toxicity of copper oxide nanoparticles (CuO-NP) strongly depends on their interactions with the surrounding environment, impacting their dissolution and colloidal stability. This behaviour is studied quite extensively for simplified electrolytes, but information on the behaviour of CuO-NP in more complex artificial media are lacking. In our study, we analysed the colloidal behaviour and considered the speciation of CuO-NP in pure water and three artificial media of different complexity which are used in ecotoxicology. Measurements were done over 7 days in the absence and presence of humic acid (HA) as a model organic molecule. In pure water, the addition of HA lowered the zeta potential from +11 to -41 mV, while in all artificial media, it stayed constantly at about -20 mV. The hydrodynamic diameter of CuO-NP remained unaffected by HA in pure water and seawater, while in porewater and especially in freshwater, HA suppressed strong agglomeration. In pure water, HA strongly increased dissolution to the highest observed value (3% of total Cu), while HA reduced dissolution in all artificial media. Speciation calculations revealed that cations from the media competed with Cu from the NP surface for complexing sites of the HA. This competition may have caused the reduced dissolution in the presence of ions. Furthermore, speciation calculations also suggest that ion composition drove agglomeration behaviour rather than ion concentration: agglomeration was high when divalent cations where the major interaction partner and dominant in relative terms. HA may have reduced the relative dominance and thus altered the agglomeration, aligning it in all media. Summarizing, ion composition and the presence of HA strongly drive the dissolution and agglomeration of CuO-NP in artificial media, consequently, analysing complexation can help to predict environmental behaviour and toxicity.

The crucial role of heavy metals on the interaction of engineered nanoparticles with polystyrene microplastics

Despite continuous research on microplastics (MPs), studies exploring the complexity of interaction between MPs and other aqueous constituents in multi-solute systems are scarce. In this study, the uptake and release of nanoceria (CeNPs) by various polystyrene MPs (PSMPs) were investigated. Results showed that PSMPs in the presence of heavy metals (HMs) exhibited a substantially higher sorption affinity for isotropic charged CeNPs than PSMPs alone; this enhanced affinity was attributed to the formation of PSMP-HM-CeNP complexes. FE-SEM imaging reaffirmed that CeNP clusters adhered to PSMP surfaces in the presence of HMs. Such attachment varied dependent on valence state, atomic size of coexisting metal cations, surface texture, and functionalities of MPs. The HM-mediated complex formation on PSMP particles was suppressed at higher ionic strength because of competitive sorption and double-layer compression. Subsequent release of MP-adhered CeNPs and HMs varied significantly between aquatic media and various simulated digestive fluids, verifying the crucial role of MPs for transfer of engineered nanoparticles (ENPs) from natural environments into biota via ingestion of MPs and trophic transfer. Our results highlight the enhanced potential for MPs to accumulate and to transport ENPs when metallic contaminants are present, which adds to the current understanding of the environmental fate and adverse effects of MPs along with various waterborne contaminants in actual environments.

Fucoidan- and carrageenan-based biosynthetic poly(vinyl alcohol) hydrogels for controlled permeation

Since the permeation of the inflammatory cytokines into hydrogel scaffolds has been shown to cause dysfunction of encapsulated cells, appropriate design strategies to circumvent this are essential. In the present work, it was hypothesized that highly crosslinked PVA-fucoidan and PVA-carrageenan hydrogels can control permeation of the trefoil-shaped inflammatory cytokine IL-1β while allowing the permeation of the globular protein albumin. PVA, fucoidan, and carrageenans were functionalized with methacrylate groups and the functionalized polymers were co-crosslinked by UV photopolymerization. The resultant hydrogels were characterized physicochemically and the release of fucoidan and carrageenans was quantified by developing a colorimetric assay, which was validated by XPS analysis. The permeability characteristics of the hydrogels were evaluated using bovine serum albumin (BSA), IgG, and IL-1β. The results demonstrated an increase in hydrogel swelling through the incorporation of the polysaccharides with minimal overall mass loss. The release studies showed hydrogel stability, where the formulations exhibited ~43% retention of fucoidan and ~60-80% retention of carrageenans consistently up to 7 days. The permeation data revealed very low permeation of IgG and IL-1β through the hydrogels, with <1% permeation after 24 h, while allowing >6% permeation of BSA. These data indicate that such hydrogels can be used as the basis for cytokine-protective implantable devices for clinical applications.

Pollutant toxicology with respect to microalgae and cyanobacteria

Microalgae and cyanobacteria are fundamental components of aquatic ecosystems. Pollution in aquatic environment is a worldwide problem. Toxicological research on microalgae and cyanobacteria can help to establish a solid foundation for aquatic ecotoxicological assessments. Algae and cyanobacteria occupy a large proportion of the biomass in aquatic environments; thus, their toxicological responses have been investigated extensively. However, the depth of toxic mechanisms and breadth of toxicological investigations need to be improved. While existing pollutants are being discharged into the environment daily, new ones are also being produced continuously. As a result, the phenomenon of water pollution has become unprecedentedly complex. In this review, we summarize the latest findings on five kinds of aquatic pollutants, namely, metals, nanomaterials, pesticides, pharmaceutical and personal care products (PPCPs), and persistent organic pollutants (POPs). Further, we present information on emerging pollutants such as graphene, microplastics, and ionic liquids. Efforts in studying the toxicological effects of pollutants on microalgae and cyanobacteria must be increased in order to better predict the potential risks posed by these materials to aquatic ecosystems as well as human health.

Recovery of rare earth elements by nanometric CeO2 embedded into electrospun PVA nanofibres

Rare earth elements (REEs) are critical raw materials with a wide range of industrial applications. As a result, the recovery of REEs via adsorption from REE-rich matrices, such as water streams from processed electric and electronic waste, has gained increased attention for its simplicity, cost-effectiveness and high efficacy. In this work, the potential of nanometric cerium oxide-based materials as adsorbents for selected REEs is investigated. Ultra-small cerium oxide nanoparticles (CNPs, mean size diameter ≈ 3 nm) were produced via a precipitation-hydrothermal procedure and incorporated into woven–non-woven polyvinyl alcohol (PVA) nanofibres (d ≈ 280 nm) via electrospinning, to a final loading of ≈34 wt%. CNPs, CNP–PVA and the benchmark material CeO₂ NM-212 (JRCNM02102, mean size diameter ≈ 28 nm) were tested as adsorbents for aqueous solutions of the REEs Eu³⁺, Gd³⁺ and Yb³⁺ at pH 5.8. Equilibrium adsorption data were interpreted by means of Langmuir and Freundlich data models. The maximum adsorption capacities ranged between 16 and 322 mg_REE g_CeO2⁻¹, with the larger value found for the adsorption of Yb³⁺ by CNP. The trend of maximum adsorption capacity was CNPs > NM-212 > CNP–PVA, which was ascribed to different agglomeration and surface area available for adsorption. Langmuir equilibrium constants K_L were substantially larger for CNP–PVA, suggesting a potential higher affinity of REEs for CNPs due to a synergistic effect of PVA on adsorption. CNP–PVA were effectively used in repeated adsorption cycles under static and dynamic configurations and retained the vast majority of adsorptive material (>98% of CeO₂ retained after 10 adsorption cycles). The small loss was attributed to partial solubilisation of fibre components with change in membrane morphology. The findings of this study pave the way for the application of CNP–PVA nanocomposites in the recovery of strategically important REEs from electrical and electronic waste.

Electrospun poly(vinyl alcohol) membranes with nano CeO₂ could effectively recover rare earth ions from model water solutions.

NOM mitigates the phytotoxicity of AgNPs by regulating rice physiology, root cell wall components and root morphology

Natural organic matter (NOM) affects the environmental behaviors of AgNPs, which may change their phytotoxicity to plants. However, more evidence can be provided to illustrate how NOM influences AgNPs-induced phytotoxicity. In this study, using rice (Oryza sativa) as a model, the effects of NOM, Suwannee River humic acid (SRHA) and fulvic acid (FA), on the dissolution and phytotoxicity of AgNPs were investigated. Silver ions decreased in both AgNPs and AgNO₃ solution in the presence of NOM, and the effect of SRHA was stronger than FA. Image-XRF (iXRF) results showed that Ag mainly remained in the root rather than the shoot of rice seedling exposed to AgNPs. NOM mitigated the negative effects of AgNPs and AgNO₃ on rice with lower germination inhibition rate, less chlorophyll reduction, more relative biomass and less O₂^•- content. Moreover, NOM improved root cell viability according to FDA fluorescent dye as well as maintained the normal root morphology. Interestingly, the neutral sugars content from pectin, hemicellulose 1, hemicellulose 2 and cellulose of root cell wall in AgNPs and AgNO₃ treatments differed from the control, while it was close to the regular content in AgNPs/AgNO₃+SRHA/FA groups, which implied that NOM regulated the changes. Besides, SRHA led to less germination and less relative biomass than FA due to different chemical characters. Thus, NOM needs to be considered when studying the phytotoxicity of AgNPs.

Enhanced efficacy of propranolol therapy for infantile hemangiomas based on a mesoporous silica nanoplatform through mediating autophagy dysfunction

Infantile hemangioma is one of the most common vascular tumors, which might result in morbidity and mortality without timely intervention. Propranolol is currently the first-line therapy for hemangiomas, but its potential side effects and high frequency of administration make it urgent to develop a suitable drug delivery system for propranolol. In the present study, we formulated a propranolol delivery system based on mesoporous silica nanoparticles (PRN@MSN) and investigated the interplay between autophagic activities mediated by nanoparticles and improved therapeutic efficacy of PRN@MSN. The results showed that PRN@MSN nanoparticles exhibited higher cytotoxicity compared with free propranolol in vitro and in vivo, which could induce excessive autophagosome accumulation through increased autophagosome formation and impaired autophagic degradation. Inhibition of autophagy in the early stage could attenuate the cytotoxicity of PRN@MSN. ROS generation was essential for nanoparticle-mediated autophagy and cytotoxicity, and PRN@MSN-induced autophagy dysfunction could enhance endoplasmic reticulum (ER) stress in hemangioma stem cells. Our study revealed a promising PRN delivery system based on a mesoporous silica nanoplatform that could induce autophagy dysfunction with excessive autophagosome accumulation to promote the therapeutic efficacy of PRN therapy. PRN@MSN drug delivery system combined with autophagy modulation may act as a promising treatment pattern in the treatment of hemangiomas.

Nanoplastics display strong stability in aqueous environments: Insights from aggregation behaviour and theoretical calculations

Nanoplastics are inevitably released into aquatic environments due to their extensive use and the continuous fragmentation of plastics. Therefore, it is imperative to understand the aggregation behaviours that determine the transport and fate of nanoplastics in aquatic environments. In this study, the effects of various metal cations, pH, aging and extracellular polymeric substances (EPS) on the aggregation of polystyrene nanoplastics (nano-PS) in aqueous solutions were systematically evaluated based on aggregation kinetics experiments and Derjaguin-Landau-Verwey-Overbeek (DLVO) theoretical calculation. The concentration, valence and hydration ability of metal cations jointly affected the aggregation of nano-PS. The critical coagulation concentration (CCC) of nano-PS was significantly higher than the ionic strengths in aquatic environments, indicating that the aggregation rate of nano-PS is relatively low in aquatic environments. The results of the aggregation kinetics experiments were consistent with DLVO theory, which showed that the energy barrier of nano-PS was dependent on electrostatic repulsion forces and van der Waals forces, and increased with pH. Nano-PS was artificially aged by UV-H₂O₂, which reduced the hydrophobic nature of the particle surfaces, consequently enhancing the stability of the nanoplastics. EPS (excreted from Chlorella pyrenoidosa) decreased the aggregation rates of nano-PS due to steric effects, which was confirmed by the extend DLVO model. Our results highlight the high stability of nano-PS in aquatic environments, which could help facilitate the evaluation of their environmental impact.

Transport and retention of differently coated CeO2 nanoparticles in saturated sediment columns under laboratory and near-natural conditions

Where surface-functionalized engineered nanoparticles (NP) occur in drinking water catchments, understanding their transport within and between environmental compartments such as surface water and groundwater is crucial for risk assessment of drinking water resources. The transport of NP is mainly controlled by (i) their surface properties, (ii) water chemistry, and (iii) surface properties of the stationary phase. Therefore, functionalization of NP surfaces by organic coatings may change their fate in the environment. In laboratory columns, we compared the mobility of CeO₂ NP coated by the synthetic polymer polyacrylic acid (PAA) with CeO₂ NP coated by natural organic matter (NOM) and humic acid (HA), respectively. The effect of ionic strength on transport in sand columns was investigated using deionized (DI) water and natural surface water with 2.2 mM Ca²⁺ (soft) and 4.5 mM Ca²⁺ (hard), respectively. Furthermore, the relevance of these findings was validated in a near-natural bank filtration experiment using HA-CeO₂ NP. PAA-CeO₂ NP were mobile under all tested water conditions, showing a breakthrough of 60% irrespective of the Ca²⁺ concentration. In contrast, NOM-CeO₂ NP showed a lower mobility with a breakthrough of 27% in DI and < 10% in soft surface water. In hard surface water, NOM-CeO₂ NP were completely retained in the first 2 cm of the column. The transport of HA-CeO₂ NP in laboratory columns in soft surface water was lower compared to NOM-CeO₂ NP with a strong accumulation of CeO₂ NP in the first few centimeters of the column. Natural coatings were generally less stabilizing and more susceptible to increasing Ca²⁺ concentrations than the synthetic coating. The outdoor column experiment confirmed the low mobility of HA-CeO₂ NP under more complex environmental conditions. From our experiments, we conclude that the synthetic polymer is more efficient in facilitating NP transport than natural coatings and hence, CeO₂ NP mobility may vary significantly depending on the surface coating.

Propranolol-Loaded Mesoporous Silica Nanoparticles for Treatment of Infantile Hemangiomas

Infantile hemangioma (IH) is one of the most common neoplasm of infancy. Although with the potential to involute slowly after proliferation, IH has several subsets that could develop severe complications and lead to functional impairment or permanent disfigurement. In the present study, a novel propranolol (PRN) delivery system is developed that encapsulated in mesoporous silica nanoparticles (MSN). The primary nanoparticles are further treated with polyvinyl alcohol (PVA) to form PVA-MSN-PRN nanoparticles. The encapsulation efficiency is 58.8% ± 7.2%, and nanoparticles could release PRN in a controlled-release way. It is discovered that PVA-MSN-PRN could significantly suppress hemangioma stem cell (Hemsc) proliferation, promote Hemsc apoptosis in vitro, and inhibit the growth of hemangiomain xenografts in vivo. A conclusion could be made that this novel nanodrug delivery system has high therapeutic efficacy, low cytotoxicity, low administration frequency, and provides an attractive strategy for efficient IH therapy.