Behavior Of Nanoparticles Research Articles

MRI on ion exchange resins at different length scales

AbstractIon exchange resins were studied on different length scales by magnetic resonance imaging (MRI) with the focus on their interactions with nanoparticles (NP) and molecular clusters. On the length scale of resin beds (bed diameters <20 mm), the behavior of NP and of molecular clusters was shown to depend on the kind of ion exchange resin and nanoscale moiety. The kinetics of absorption and penetration into the resin beads was quantified on a smaller length scale of a stack of resin beads (sample with an outer diameter of 1.7 mm). Finally, using an MRI μ‐coil (3D spatial resolution ≥8 μm), adsorption of superparamagnetic NP on individual resin beads was observed via the magnetic field disturbance characteristic for magnetic dipoles. As a result, this allows the detection of NP (diameter ≤100 nm) by MRI on much larger length scales of several micrometers.

AI-driven design and optimization of nanoparticle-based drug delivery systems

Nanoparticle-based drug delivery systems represent a transformative advancement in targeted therapeutics, providing meticulous drug delivery, enhanced bioavailability, and diminished side effects. However, designing nanoparticles (NPs) optimal for specific drugs and diseases remains a complex challenge. The advancements in artificial intelligence (AI) have provided innovative approaches to design and optimize these systems, improving their efficacy and adaptability. This review encompasses the integration of AI in the conceptualization and development of NP drug delivery systems, signifying its potential to revolutionize the field. The review discusses the different AI methods such as machine learning, neural networks, and optimization algorithms that simplify the fabrication of NPs with tailored characteristics such as size, surface chemistry, and drug release profiles. AI can also standardize these characteristics to enhance drug loading capacity, targeting specificity, and controlled release at the chosen site of action. AI-based predictive modeling enables the quick screening of numerous parameters, thus quickening the discovery of optimal NP configurations tailored to specific therapeutic needs. Furthermore, the review also discusses the case studies where AI has efficaciously forecasted NP behavior in biological environments, crucial for enhanced targeting and diminished off-target effects. The amalgamation of AI and nanotechnology not only streamlines the drug development process but also paves the way for personalized medicine. The review also entails the different challenges associated with implementing AI in this field, such as data quality, algorithm transparency, and regulatory specifications. By utilizing AI, researchers and healthcare providers can unlock new potentials in novel drug delivery systems, ultimately advancing the precision and effectiveness of treatments for various diseases. Finally, the review discusses the future directions of AI-based NP design, highlighting its benefits to transform drug delivery and augment patient outcomes.

A simple, rapid, and low-cost approach for colloidal nanoparticle-based surface enhanced Raman Scattering detection of endosulfan pesticide at trace levels

Abstract Surface Enhanced Raman Spectroscopy (SERS) is a highly specific, sensitive, and portable technique with great potential for on-site pesticide detection and monitoring. Endosulfan, an organochlorine pesticide known for its high toxicity, slow degradation, and bioaccumulation, has poor affinity for metallic SERS substrates. This study presents a label-free SERS detection method for endosulfan, using aggregating agents like potassium chloride (KCl), potassium hydroxide (KOH), potassium bromide (KBr), and sodium hydroxide (NaOH) to modify the behavior of Ag colloidal nanoparticles (NPs) and enhance the SERS signal of endosulfan molecules trapped within formed hot-spots. We analyzed the UV–Vis spectra, the hydrodynamic diameter, and zeta-potential of Ag NPs with the addition of these agents and endosulfan. Successful detection of both α- and ß- endosulfan isomers at μM concentrations in both ethanol and methanol was achieved with KOH-treated Ag NPs. The method was also applied to detect endosulfan in real water samples, along with simultaneous detection of λ-cyhalothrin, showcasing its capability to identify multiple analytes. The selectivity and specificity were confirmed using a mixture of endosulfan and thiabendazole, highlighting the crucial role of selecting the appropriate aggregating agent for each analyte. Overall, the findings emphasize the potential of aggregating agents to mediate the SERS enhancement of endosulfan, facilitating simple and rapid protocols for environmental pollutant detection, while shedding light on the intricate interplay between NP behavior, surface chemistry, and analyte interaction.

Rate-Controlled Washing of Surface-Modified Nanoparticles Using Rationally Designed Supercritical CO2 Media.

In practical applications of surface-modified nanoparticles (NPs), the washing stage has a number of challenges, such as insufficient washing, long treatment time, and various waste liquors. Cosolvent-enhanced supercritical CO2 (scCO2) is an appealing solvent system for complete, rapid, and eco-friendly washing owing to its high diffusivity and recyclability. In this paper, we report a rapid washing guideline for surface-modified NPs using ethanol-enhanced scCO2. Kinetic analysis was performed on the washing behavior of oleic acid-modified NPs mixed with various modifiers (C10 to C18 fatty acids) at 40 °C and 20.0 MPa while designing scCO2 media based on rationally estimated modifier solubilities. Notably, the scCO2 medium showed superior washing rates to that of ethanol for various modifiers with a wide range of solubilities in scCO2. The washing rate was dependent on solubility and could be organized into two regions, with a threshold value of 0.016 mol kg-1: solubility/diffusivity-controlled and diffusivity-controlled washing. These findings provide valuable guidelines for designing cosolvent-enhanced scCO2 media for the rapid washing of surface-modified NPs.

Navigating the nano-bio immune interface: advancements and challenges in CNS nanotherapeutics.

In recent years, significant advancements have been made in utilizing nanoparticles (NPs) to modulate immune responses within the central nervous system (CNS), offering new opportunities for nanotherapeutic interventions in neurological disorders. NPs can serve as carriers for immunomodulatory agents or platforms for delivering nucleic acid-based therapeutics to regulate gene expression and modulate immune responses. Several studies have demonstrated the efficacy of NP-mediated immune modulation in preclinical models of neurological diseases, including multiple sclerosis, stroke, Alzheimer's disease, and Parkinson's disease. While challenges remain, advancements in NPs engineering and design have led to the development of NPs using diverse strategies to overcome these challenges. The nano-bio interface with the immune system is key in the conceptualization of NPs to efficiently act as nanotherapeutics in the CNS. The biomolecular corona plays a pivotal role in dictating NPs behavior and immune recognition within the CNS, giving researchers the opportunity to optimize NPs design and surface modifications to minimize immunogenicity and enhance biocompatibility. Here, we review how NPs interact with the CNS immune system, focusing on immunosurveillance of NPs, NP-induced immune reprogramming and the impact of the biomolecular corona on NPs behavior in CNS immune responses. The integration of NPs into CNS nanotherapeutics offers promising opportunities for addressing the complex challenges of acute and chronic neurological conditions and pathologies, also in the context of preventive and rehabilitative medicine. By harnessing the nano-bio immune interface and understanding the significance of the biomolecular corona, researchers can develop targeted, safe, and effective nanotherapeutic interventions for a wide range of CNS disorders to improve treatment and rehabilitation. These advancements have the potential to revolutionize the treatment landscape of neurological diseases, offering promising solutions for improved patient care and quality of life in the future.

Impact of TiO2, ZnO, and Ag nanoparticles on anammox activity in enriched river Nile sediment cultures: unveiling differential effects and environmental implications

BackgroundThe increasing use of nanoparticles (NPs) necessitates investigation of their impact on wastewater treatment processes, particularly anammox, a critical biological nitrogen removal pathway. This study explored the effects of short-term exposure to TiO2, ZnO, and Ag-NPs on anammox activity in enriched cultures derived from River Nile sediments.Materials and methodsAnammox bacteria were identified and enriched, with activity confirmed through 16S rRNA and hydrazine oxidoreductase (hzo) gene amplification and sequencing. Activity assays demonstrated efficient ammonium removal by the enriched culture. Subsequently, the impact of different sized and concentrated NPs on anammox activity was assessed.ResultsXRD analysis confirmed NP behavior within the microcosms: TiO2 transformed, ZnO partially dissolved, and Ag remained ionic. hzo gene expression served as a biomarker for anammox bacterial activity. Interestingly, 100 nm TiO2-NPs up-regulated hzo expression, potentially indicating a non-inhibitory transformed phase. Conversely, ZnO and Ag-NPs across all sizes and concentrations significantly down-regulated hzo expression, suggesting detrimental effects. Ag-NPs amended microcosms showed a significant reduction (79%) in hzo gene expression and a detrimental effect on bacterial populations. Overall, anammox activity mirrored hzo expression patterns, with TiO2 (21 and 25 nm, respectively) exhibiting the least inhibition, followed by ZnO and Ag-NPs.ConclusionThis study highlights the differential effects of NPs on anammox, with the order of impact being Ag > ZnO > TiO2. These findings provide valuable insights into the potential environmental risks of NPs on anammox-mediated nitrogen cycling in freshwater ecosystems.

Dysprosium chromite nanoparticles: A promising photocatalyst for the remediation of ciprofloxacin and methylene blue from wastewater

A facile sol-gel synthesis method was employed to synthesize dysprosium chromite (DyCrO3) nanoparticles (NPs), which were subsequently calcined at 750 ∘C to investigate their structural, optical, and photocatalytic properties. Rietveld refinement of powder X-ray diffraction patterns revealed a single-phase orthorhombic structure for the DyCrO3 NPs, exhibiting good crystallinity and belonging to the Pbnm space group. Furthermore, Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy imaging revealed a promising morphology with an average particle size of 30 ± 7 nm. Optical assessments indicated an energy band gap of 2.72 eV, suggesting potential for solar light harvesting as a photocatalyst. Mott-Schottky plots confirmed the n-type semiconductor behavior of the DyCrO3 NPs, and valence band X-ray photoelectron spectroscopy analysis supported these findings. Electronic band structure calculations showed a substantial conduction band minimum and a positive valence band maximum, essential for promoting oxygen reduction and oxidation reactions, respectively, which are crucial for photocatalytic activity. Moreover, the synthesized DyCrO3 NPs demonstrated significant potential as efficient photocatalysts, effectively decomposing the antibiotic ciprofloxacin (CIP) under solar light. Notably, the DyCrO3 NPs achieved 83 % degradation of CIP within 240 min of solar irradiation. Similarly, under identical conditions, the DyCrO3 NPs photocatalyst showed promise in degrading 70 % of the colored organic pollutant methylene blue (MB). Interestingly, during the first 120 min, the degradation of CIP was approximately 25 % greater than that of MB. The ability of DyCrO3 NPs to efficiently degrade both colored and colorless pollutants highlights the catalyst’s inherent photocatalytic nature, rather than merely relying on dye-sensitization effects. Furthermore, the presence of DyCrO3 NPs reduced the activation energy for CIP degradation from 31.657 kJ mol−1 K−1 to 20.846 kJ mol−1 K−1, providing additional evidence of their true catalytic efficacy. Apparent quantum yield values of 40 % for CIP and 35 % for MB degradation further illustrate their superior solar energy harvesting ability. A comprehensive mechanism was developed to explain the impressive photocatalytic performance of the synthesized NPs, highlighting their potential in degrading pharmaceutical antibiotics.

Enhanced optical nonlinearity in suspensions of dual-resonance gold–copper chalcogenide core–shell nanoparticles

Plasmonic copper chalcogenide (Cu2−xE, E = S, Se, Te) nanoparticles (NPs) possess high potentials in photothermal therapy and photoacoustic tomography for their unique localized surface plasmon resonant absorption in the second near-infrared biologically transparent window. In this study, strong thermal-induced nonlinear negative-lens effect in aqueous suspensions containing Cu2−xSe NPs was observed. Furthermore, the nonlinear absorption was notably enhanced in aqueous suspensions containing Au@Cu2−xSe core–shell NPs, as the positive nonlinear absorption coefficient increased by 20-fold, attributed to the strong plasmonic coupling in Au@Cu2−xSe core–shell NPs. This finding underscores the importance of the nonlinear optical behaviors of plasmonic NPs in biomedical applications, as they offer extra strategy for optimizing systems and incorporating additional functionalities.

Understanding the Interactions of Nanoparticles and Dissolved Organic Matter at the Molecular Level by 1H 2D Multi-Exponential Transverse Relaxation NMR Spectroscopy.

The interaction between humic acid (HA) and engineered nanoparticles (NPs) is critical in environmental sciences, especially for understanding the behavior of NPs in natural waters. This study employs 1H 2D Multi-Exponential Transverse Relaxation (METR) NMR spectroscopy to examine the molecular-level interactions between Pahokee Peat humic acid (HA) and carboxyl-functionalized iron oxide nanoparticles (NPCOs). First, 1H 2D METR NMR spectroscopy allowed not only the identification of HA in terms of its chemical composition but also the separation of molecules with the same chemical shift values but different rates of molecular tumbling. Then, using solutions with varying NPCO concentrations (0, 10, 40, and 100 μM), we observed significant changes in the T2 relaxation times of HA components, indicating interactions between HA and NPCO. Analysis showed the biggest effect on two chemical shift regions, corresponding to lipids and carbohydrates, revealing that smaller molecules within these regions exhibit the most significant changes in T2 values upon the addition of NPCO. This suggests that these molecules are the initial sites of interaction, with the entire HA system being affected at higher NPCO concentrations. These findings highlight the utility of METR NMR spectroscopy in studying complex environmental mixtures and provide insights into the behavior of HA and NPs, essential for understanding the fate of NPs in the environment.

Assessing nanotoxicity of food-relevant particles: A comparative analysis of cellular responses in cell monolayers versus 3D gut epithelial cultures

Engineered nanoparticles (NPs) are extensively used in the food industry, yet safety concerns remain. The lack of validated methodologies is a bottleneck towards resolving this uncertainty. Hence, the current study aims to compare two cell models by examining the toxicological impacts of two food-relevant NPs (SiO2 and Ag) on intestinal epithelia using monolayer Caco-2 cells and full-thickness 3D tissue models of human small intestines (EpiIntestinal™). Comprehensive characterization and dosimetric analysis of the NPs were performed to determine effective doses and model realistic exposures. Neither genotoxicity nor cytotoxicity were detected in the 3D tissues after NP treatment, while the 2D cultures exhibited cytotoxic response from Ag NP treatment for 24 h at 1 μg/ml. Hyperspectral imaging and transmission electron microscopy confirmed uptake of both NPs by cells in both 2D and 3D culture models. Ag NPs caused an increase in autophagy, whereas SiO2 NPs induced increased cytoplasmic vacuolization. Based on realistic exposure levels studied, the 3D small intestinal tissue model was found to be more resilient to NP treatment compared to 2D cell monolayers. This comparative approach towards toxicological assessment of food relevant NPs could be used as a framework for future analysis of NP behavior and nanotoxicity in the gut.

In Situ TEM Imaging Reveals the Dynamic Interplay Between Attraction, Repulsion and Sequential Attraction-Repulsion in Gold Nanoparticles.

Recent efforts on manipulating metal nanoparticles (NPs)using an electron beam have offered new insights into nanoparticle behavior, structural transition, and the emergence of new properties. Despite an increasing understanding of the dynamics of electron beam-induced coalescence of NPs, several phenomena are yet to be investigated. Here, we show that repulsion between two NPs is as favorable as coalescence under electron beam irradiation at room temperature. Using small-sized (D ≈ 5.9nm) and large-sized (D ≈ 11.0nm) gold (Au) NPs, and different electron dose rates, a unique sequential attraction-repulsion between NPs is disclosed. The real-time in situ transmission electron microscopy imaging suggest that at a low dose rate, two small-sized AuNPs with 1.0nm particle-particle distance undergo repulsion to 18nm with a diffusion rate of 0.4nmmin-1. For large-sized AuNPs, the repulsion rate is 0.08nmmin-1 at a low dose rate and is comparable to that of small-sized AuNPs at a high dose rate. Surprisingly, large-sized AuNPs at a high electron dose rate displayed attraction in the first 15min, followed by rapid repulsion. This unique sequential attraction-repulsion behavior of NPs offers possibilities to manipulate interparticle distance and properties without inducing dimensional changes for advanced photonic and plasmonic nanodevices.

Stick, Slide, or Bounce: Charge Density Controls Nanoparticle Diffusion.

The diffusion and interaction dynamics of charged nanoparticles (NPs) within charged polymer networks are crucial for understanding various biological and biomedical applications. Using a combination of coarse-grained molecular dynamics simulations and experimental diffusion studies, we investigate the effects of the NP size, relative surface charge density (ζ), and concentration on the NP permeation length and time. We propose a scaling law for the relative diffusion of NPs with respect to concentration and ζ, highlighting how these factors influence the NP movement within the network. The analyses reveal that concentration and ζ significantly affect NP permeation length and time, with ζ being critical, as critical as concentration. This finding is corroborated by controlled release experiments. Further, we categorize NP dynamics into sticking, sliding, and bouncing regimes, demonstrating how variations in ζ, concentration, and NP size control these behaviors. Through normalized attachment time (NAT) analyses, we elucidate the roles of electrostatic interactions, steric hindrance, and hydrodynamic forces in governing NP dynamics. These insights provide guidance for optimizing NP design in targeted drug delivery and advanced material applications, enhancing our understanding of NP behavior in complex environments.

Thermally Stable Oxide-Capsulated Metal Nanoparticles Structure for Strong Metal-Support Interaction via Ultrafast Laser Plasmonic Nanowelding.

Strong metal-support interaction (SMSI) has drawn much attention in heterogeneous catalysts due to its stable and excellent catalytic efficiency. However, construction of high-performance oxide-capsulated metal nanostructures meets great challenge in materials thermodynamic compatibility. In this work, dynamically controlled formation of oxide-capsulated metal nanoparticles (NPs) structures is demonstrated by ultrafast laser plasmonic nanowelding. Under the strong localized electromagnetic field interaction, metal (Au) NPs are dragged by an optical force toward oxide NPs (TiO2). Intense energy is simultaneously injected into this heterojunction area, where TiO2 is precisely ablated. With the embedding of metal into oxide, optical force on Au gradually turned from attractive to repulsive due to the varied metal-dielectric environment. Meanwhile, local ablated oxides are redeposited on Au NP. Upon the whole coverage of metal NP, the implantation behavior of metal NP is stopped, resulting in a controlled metal-oxide eccentric structure with capsulated oxide layer thickness ≈0.72-1.30nm. These oxide-capsulated metal NPs structures can preserve their configurations even after thermal annealing in air at 600°C for 10min. This ultrafast laser plasmonic nanowelding can also extend to oxide-capsulated metal nanostructure fabrication with broad materials combinations (e.g., Au/ZnO, Au/MgO, etc.), which shows great potential in designing/constructing nanoscale high-performance catalysts.

Organic matter excreted by the protozoan Tetrahymena thermophila and its effects on the bioaccumulation of nanoparticles

Although organic matter (exudate) excreted by aquatic organisms is an important component of dissolved organic matter (DOM) in the natural environment, its potential effects on the bioaccumulation of nanoparticles (NPs) remain unclear. In the present study, we examined the effects of the exudates from the protozoan Tetrahymena thermophila on the bioaccumulation (including uptake and cell surface adsorption) of iron oxide (Fe2O3, polyacrylate coated) and silica (SiO2) NPs in T. thermophila. The exudates were mostly (93.6%, in carbon) composed of < 1-kDa molecules (e.g., lipids). When the exudates were mixed with the NPs, significant adsorption occurred on SiO2 NPs but not on Fe2O3 NPs. Independent of their adsorption by the NPs, the exudates significantly inhibited the bioaccumulation of both SiO2 NPs and Fe2O3 NPs by T. thermophila. This inhibitory effect was shown to be mainly due to their inhibition of NP adsorption on the cell surface. By contrast, the exudates had negligible effects on the uptake of either NP type, most likely due to their low molecular weight. Since DOM in the aquatic environment is dominated by molecules < 1kDa, the potential effects of low-molecular-weight DOM, such as exudates from aquatic organisms, on the bioaccumulation of NPs merits greater attention. Environmental ImplicationNanoparticles (NPs) are hazardous materials widespread in the natural environment. Previous studies showed that dissolved organic matter (DOM) in aquatic environments determine the environmental behavior and ecological effects of NPs. Although organic matter (exudate) excreted by aquatic organisms is an important component of DOM, its potential effects on the bioaccumulation of NPs remain unclear. In the present study, we found that the exudates inhibited the cell-surface adsorption of NPs but had no effects on NP uptake, as different from the well-known effects of DOM on NP bioaccumulation. This finding merits attention during evaluations of the environmental risks of NPs.

Surface Gold Atoms Determine Peroxidase Mimic Activity in Gold Alloy Nanoparticles.

The development of peroxidase mimic nanocatalysts is relevant for oxidation reactions in biosensing, environmental monitoring and green chemical processes. Several nanomaterials have been proposed as peroxidase mimic, the majority of which consists of noble metals and oxide nanoparticles (NPs). Yet, there is still limited information about how the change in the composition influences their catalytic activity. Here, the peroxidase mimic behaviour of gold NPs is compared to a traditional nanoalloy as Au-Ag and to the Au-Fe and the Au-Co nanoalloys, which were not tested before as oxidation catalysts. Since the alloys of gold with iron and cobalt are thermodynamically unstable, laser ablation in liquid (LAL) is exploited for the synthesis of these NPs. Using LAL, no chemical stabilizers or capping agents are present on the NPs surface, allowing the evaluation of the oxidation behaviour as a function of the alloy composition. The results point to the importance of surface gold atoms in the catalytic process, but also indicate the possibility of obtaining active nanocatalysts with a lower content of Au by alloying it with iron, which is earth-abundant, non-toxic and low cost. Overall, Au nanoalloys are worth consideration as a more sustainable alternative to pure Au nanocatalysts for oxidation reactions.

Eco-friendly synthesis of Co3O4 nanoparticles using Millettia pinnata towards increased anti-oxidant, anti-biofilm and cytocompatibility properties against biofilm producing bacteria and human pulmonary alveolar basal cells

Biofilm architecture is an emerging threat worldwide due to enhanced antibiotic resistance against existing antibiotics, thus heightening the need to discover the alternative therapies that can eradicate the biofilm colonization. Current study highlights the eco-friendly, non-toxic nature of Co3O4 nanoparticles (NPs) using Millettia pinnata (M. pinnata) leaves extract and their application in anti-oxidants, anti-bacterial, anti-biofilm and cytocompatibilities. The GC-MS and FT-IR spectral data suggested that phytochemical derivatives of M. pinnata leaf extract simultaneously contributed in bio-reduction process and capping agent of Co3O4 NPs, which might be reason for anti-oxidant activities. Further, XRD analysis confirms the polycrystalline behaviour of Co3O4 NPs having hexagonal crystal system. FESEM, HRTEM, EDAX and elemental mapping revealed the formation of agglomerated granular shape along with nanorods on the surface of Co3O4 NPs, which confirms the presence of carbon and oxygen. Additionally, the characteristic band and thermal decomposition of Raman and TGA spectral data confirmed the molecular structure of Co3O4 NPs. Subsequently, both the M. pinnata leaves extract and Co3O4 NPs were found to be excellent source of antioxidants and produced significant DPPH and hydroxyl scavenging activities. Furthermore, the sub-biofilm inhibitory concentration of biosynthesized Co3O4 NPs reduced the biofilm growth in S. aureus and K. pneumoniae by crystal violet assay at increasing concentration. In addition, the membrane integrity of biofilm damages and architecture destruction was evidently proved due to the biosynthesized Co3O4 NPs by confocal laser scanning electron microscope and scanning electron microscope observation. Finally, the cytotoxicity experiment results indicated, biosynthesized Co3O4 NPs has no toxicity against human pulmonary alveolar epithelial cells at maximum concentration. Accordingly, findings of this study supported the utility of safety and efficiency of biosynthesized Co3O4 NPs against biofilm producing bacteria, and deserve as promising future drug discovery target for various bacterial infections.

The physical mechanism of heat transfer enhancement for Al2O3-water nanofluid forced flow in a microchannel with two-phase lattice Boltzmann method

PurposeThe purpose of this paper is to analyze the mechanism of nanofluid enhanced heat transfer in microchannels and promote the application of nanofluids in industrial processes such as solar collectors, electronic cooling and automotive batteries.Design/methodology/approachThe two-phase lattice Boltzmann method was used to calculate the flow and heat transfer characteristics of Al2O3 nanofluids in a microchannel at Re = 50. By comparing the simulation results of pure water, nanofluids without calculated nanoparticle-fluid interaction forces and nanofluids with calculated nanoparticle-fluid interaction forces, the effects of physical properties improvement and interaction forces on flow and heat transfer are quantified.FindingsThe findings show that the nanofluid (φ = 3%, R = 10 nm) increases the average Nusselt number by 22.40% at Re = 50. In particular, 16.16% of the improvement relates to nanoparticles optimizing the thermophysical parameters of the base fluid. The remaining 6.24% relates to the disturbance of the thermal boundary layer caused by the interaction between nanoparticles and the base fluid. Moreover, the nanoparticle has a negligible effect on the average Fanning friction factor. Ultimately, we conclude that the nanofluid is an excellent heat transfer working medium based on its performance evaluation criterion, PEC = 1.225.Originality/valueTo the best of the authors' knowledge, this research quantifies for the first time the contribution of nanoparticle-liquid interactions and nanofluids physical properties to enhanced heat transfer, advancing the knowledge of the nanoparticle's behavior in liquid systems.

Investigating the dielectric and ferromagnetic behaviour of Ni and Co dual doped ZnO for diluted magnetic semiconductor

Herein, Ni/Co co-doped ZnO nanoparticles (NPs) were successfully prepared via chemical co-precipitation process. The structural, purity and crystallite size of as-prepared particles were confirmed by using x-ray diffraction (XRD). The results revealed the hexagonal wurtzite structure of ZnO without any impurity phase of as-prepared samples. The crystallite size decreased from 34.9 to 9.6 nm, whereas lattice strain reduced to 0.00086. The change in crystallite size, lattice parameters, strains and dislocation density further indicates the successful incorporation of dopants in ZnO host lattice. The dielectric properties, ac conductivity, and magnetic behaviour were steadily examined. The dielectric constant has been found to be 1070 with 5wt% at low frequency and become constant at higher frequency. It was revealed that dopant additions lead to attain high dielectric constant and low loss possibly attributed to interface polarization, and dipole polarization due to oxygen vacancy defects. M-H measurement observed that ferromagnetism at room temperature pure and doped ZnO samples. The ferromagnetic behaviour of pure ZnO NPs with Ms = 0.17 emu g−1, Mr = 0.11 emu g−1 and Hc = 67 which was increased to Ms = 0.85 emu g−1 and Mr = 0.65 emu/g for 5wt% Co. This improvement with increasing Co concentration indicates that oxygen defects may stabilize the ferromagnetic order. These interesting features encouraging to use this material for ultrahigh dielectric materials and spintronics.

The fate and impact of Co3O4 nanoparticles in the soil environment: Observing the dose effect of nanoparticles on soybeans

The widespread presence and distribution of metal-based nanoparticles (NPs) in soil is threatening crop growth and food security. However, little is known about the fate of Co3O4 NPs in the soil-soybean system and their phytotoxicity. The study demonstrated the effects of Co3O4 NPs on soybean growth and yield in soil after 60 days and 140 days, and compared them with the phytotoxic effects of Co2+. The results showed that Co3O4 NPs (10–500 mg/kg) had no significant toxic effect on soybeans. Soil available Co content was significantly increased under 500 mg/kg Co3O4 NPs treatment. Compared with Co2+, Co3O4 NPs mainly accumulated in roots and had limited transport to the shoots, which was related to the particle size, surface charge and chemical stability of Co3O4 NPs. The significant accumulation of Co3O4 NPs in roots further led to a significant decrease in root antioxidant enzyme activity and changes in functional gene expression. Co3O4 NPs reduced soybean yield after 140 days, but interestingly, at specific doses, it increased grain nutrients (Fe content increased by 17.38% at 100 mg/kg, soluble protein and vitamin E increased by 14.34% and 16.81% at 10 mg/kg). Target hazard quotient (THQ) assessment results showed that consuming soybean seeds exposed to Co3O4 NPs (≥100 mg/kg) and Co2+ (≥10 mg/kg) would pose potential health risks. Generally, Co3O4 NPs could exist stably in the environment and had lower environmental risks than Co2+. These results help to better understand the environmental behavior and plant effect mechanisms of Co3O4 NPs in soil-plant systems.

Use of magnetic nanoparticles of iron oxide and their derivatives in the adsorption of rhodamine 6G and rhodamine B dyes

Rhodamines are cationic dyes widely used in textiles and as laser media, despite their many severe health and environmental hazards. In this work, we have assessed the potential of magnetite and cobalt ferrite nanoparticles (NPs) for removing rhodamines B (Rh B) and 6G (Rh 6G) from aqueous solutions. The magnetite (Fe3O4) NPs were synthesized by the co-precipitation method, while the cobalt ferrite (CoFe2O4) NPs were obtained hydrothermally. The structures of cubic magnetite Fe3O4 and cubic CoFe2O4 were confirmed by XRD and by FTIR and Raman, while the surface morphology checked by SEM showed clusters of polydisperse particles with average diameters around 51.0 nm and 57.0 nm, respectively. These particles presented calculated BET surface areas of 33.8 m2/g (Fe3O4) and 47.3 m2/g (CoFe2O4). Hysteresis curves confirmed the ferromagnetic behavior for both NPs. The point of zero charge was 6.46 for Fe3O4 and 7.16 for CoFe2O4, and using pH 4 in the system, the overall percent removal (%R) were above 80 % for all samples during the uptake of Rh B and 6G. The system Rh 6 G-CoFe2O4 performed better at pH 6 (%R ∼93 %). In all cases, the Elovich and pseudo-second-order (PSO) models were chosen for fitting the kinetic data, and after equilibrium was reached (∼ 30 min), the adsorptive capacities were estimated to be above 138 mg g−1 for all systems. Adsorption isotherms at 301, 311 and 321 K were obtained. Good agreement between the experimental data and the Langmuir, Freundlich and Sips models was observed for Rh 6 G adsorption by both NPs (R2 ≥ 0.90). The Freundlich model was the only one that fitted well the experimental data for Rh B (R2 ≥ 0.90, for all systems). The thermodynamic parameters were also calculated from the isotherm data.