Dispersion Stability Research Articles

Voltammetric determination of uric acid using a miniaturized platform based on screen-printed electrodes modified with platinum nanoparticles

Disposable and sensitive screen-printed carbon electrodes (SPCE) modified with multi-walled carbon nanotubes (MWCNT) and platinum nanoparticles (PtNPs) were constructed to analyse uric acid (UA) in biological samples using a miniaturized smartphone potentiostat system. Combining the nanomaterials with Nafion® yielded a stable dispersion that could be successfully used as an electroactive layer. Transmission electron microscopy (TEM) and energy dispersive scanning (EDS) were used to characterize the morphology of PtNPs. These revealed approximately spherical shapes with emission lines characteristics of platinum. Furthermore, PtNPs/MWCNT/SPCE film was characterized by scanning electron microscopy (SEM), which demonstrated the tubular characteristic of MWCNT distributed and covered by carbon black (CB) spheres present in the screen-printed ink. An enhanced current response was observed for UA voltammetric analysis, especially due to the synergism effect of PtNPs and MWCNT, which reduced the Rct value. The values of Dapp (1.6 × 10−6 cm−2 s−1) and kcat (2.76 × 103 mol−1 L/s) were determined for UA using the proposed sensor. The sensor displayed linear response for UA in the range from 5.0 × 10−6 mol/L to 6.9 × 10−4 mol/L, with a detection limit of 4.9 × 10−7 mol/L. Along with detectability, excellent performances were verified in terms of repeatability, anti-interference features, and analysis of UA in the biological samples.

Fabrication of PVC-based electromagnetic interference shielding composite film by positively charged SMA enhancing the dispersibility of carbon nanomaterial

To address the weak binding force and poor dispersion stability of carbon (C) nanoparticles in current non-covalent modification methods, we employed organic amine-grafted styrene maleic anhydride copolymers (SMA-N) to modify C nanoparticles (C@SMA-N) through π–π conjugation and positive charge interactions. The obtained C@SMA-N has excellent dispersion in N, N-dimethylacetamide (DMAc), which is attributed to the enhanced steric hindrance and electrostatic repulsion from the grafted organic amine chains. To study the impact of surface modification on the electromagnetic interference shielding effectiveness (EMI SE), C@SMA-N was used as a conductive filler in polyvinyl chloride (PVC) composite films, which exhibits a higher EMI SE performance than pristine C nanoparticles. Particularly, the obtained C@SMA-N using polyether amine (PEA) (C@SMA-PEA) exhibits a better EMI SE performance. By optimizing the SMA-PEA grafting parameters, the PVC/C@SMA-PEA composite films transition from insulators to conductors at a C@SMA-PEA content of 0.3 wt%. To achieve a higher EMI SE performance, the filler content, mixed filler composition, and film thickness were optimized. The results indicate that with a total filler content of 20 wt% and a mixed filler comprising fibrous form carbon nanotubes (CNT) and particles form carbon black (CB) in a 10:1 mass ratio (CB@SMA-PEA to CNT@SMA-PEA), the composite film has a thickness of 0.08 mm and an EMI SE value of 20.2 dB. Increasing the thickness to 0.2 mm enhances the EMI SE value to 31.5 dB. These findings indicate that thinner films have a higher EMI SE performance and promising application prospects in the field of electromagnetic shielding.

Copper-coordinated nanomedicine for the concurrent treatment of lung cancer through the induction of cuproptosis and apoptosis

The resistance of tumor cells to apoptosis often leads to chemoresistance and treatment failure in clinic. In this study, we have developed a Cu2+-coordinated lignosulfonate (CLS) /doxorubicin (DOX) biological complex (referred to as LCD) with the aim of overcoming cellular resistance to apoptosis for combined lung cancer therapy. The copper complexes modified by CLS exhibit significant water solubility and excellent in vivo biocompatibility. The proportion of copper in the composite is simultaneously increased. Due to the coordination and π-π stacking effects, the self-assembled LCD exhibits nanometer-scale particle size, a narrow and homogeneous grain distribution, as well as excellent dispersion stability. Furthermore, LCD has the potential to disassemble in the presence of high levels of glutathione (GSH) and low pH, leading to effective drug release. Cu2+-mediated cuproptosis can lead to the down-regulation of FDX1 and DLAT protein expression by reducing mitochondrial membrane potential, resulting in non-apoptotic programmed cell death (PCD) regardless of cellular resistance to apoptosis. Moreover, the released DOX not only exhibits a preference for localizing in the cell nucleus to induce apoptosis for combined chemotherapy, but also generates a substantial amount of H2O2. This H2O2 further produces ROS to induce apoptosis through Fenton reaction with Cu2+. LCD demonstrates significant superiority over monotherapy in inhibiting tumor growth while minimizing systemic toxicity through the combined action of cuproptosis and apoptosis. This study may provide a potential avenue for the advancement of self-delivery nanomedicine to overcome resistance to apoptosis in tumor therapy.

Polydopamine modified carbon fiber to improve the comprehensive properties of carbon paper for proton exchange membrane fuel cell

In this study, polydopamine (PDA) was used to modify functional groups on the surface of carbon fiber (CF), and the effects of different dopamine hydrochloride (DPH) concentrations on the surface morphology, functional groups, contact angle and dispersion stability of CF were studied. Subsequently, the raw carbon paper (RCP), hot-pressed carbon paper (HPCP) and carbon paper (CP) were prepared successively using the modified CF through wet forming, impregnation/hot-pressing, and carbonization methods. The surface morphology, tensile strength, flexural strength, electrical resistivity, air permeability and pore size distribution were analyzed for these materials. It was observed that the introduction of −OH and − NH2 groups improved the hydrophilicity and dispersion of PDA modified CFs, resulting in an increase in formation index (FI) from 39.2 to 48.1 for RCP samples. With increasing DPH concentration, the tensile strength of CP initially increased but then decreased while its electrical resistivity showed an opposite trend. Finally, PDA modified CP was assembled into proton exchange membrane fuel cells (PEMFC). The PEMFC assembled from DPH-CP-2.5 achieved a maximum limiting current density of 1440.0 mA/cm2 and power density of 458.25 mW/cm2. Meanwhile, the lower material transmission impedance for DPH-CP-2.5 as well as excellent water management ability and gas transmission performance.

Carboxymethyl chitosan/polyvinyl alcohol hydrogel films by incorporating MSNs as ε-PL carrier with pH-responsive controlled release and antibacterial properties

A hydrogel film with pH-responsive release and excellent antibacterial properties was developed by utilizing mesoporous silica nanoparticles (MSNs) as carriers for ε-PL. Carboxymethyl chitosan (CMCS) is grafted onto aminated-MSNs through amine-bond reaction mediated, which is subsequently bound to polyvinyl alcohol (PVA) by esterification reaction. The addition of MSNs and optimization of CMCS proportion improved the dispersion stability of CMCS/PVA, resulting in a TSI value of 0.6 for 1.6CMCS/0.8PVA@MSNs-ε-PL, which is significantly lower than other groups. The proportion increase of CMCS improved the thermal stability and water oxygen barrier capacities of the 1.6CMCS/0.8PVA@MSNs-ε-PL by enhancing cross-linking with MSNs. The 1.6CMCS/0.8PVA@MSNs-ε-PL exhibited pH-responsive release behavior, with the extent of release increasing proportionally with higher pH levels. The 1.6CMCS/0.8PVA@MSNs-ε-PL exhibited significant antibacterial activity against Pseudomonas azotoformans MN10 in vitro, attributed to the ε-PL's ability to damage the bacterial membrane structure. Hence, the 1.6CMCS/0.8PVA@MSNs-ε-PL exhibits significant potential in food preservation.

Effect of salt ions (Na+, Ca2+ and Mg2+) and EOR anionic and nonionic surfactants on the dispersion stability of cellulose nanocrystals

The application of cellulose nanocrystals (CNCs) in enhanced oil recovery (EOR) is a developing hotspot. To improve the stability of CNCs in salt environments, the effects of sodium dodecylbenzene sulfonate (SDBS) and polyoxyethylene sorbitan monooleate (Tween 80) on the stability of CNCs in the presence of sodium (Na+), calcium (Ca2+) and magnesium (Mg2+) were investigated. The range of salt ions and the stability mechanism for improving the CNCs stability in the presence of SDBS and Tween 80 were pointed out. SDBS improved the stability of CNCs in the presence of 30–100 mM Na+, 1–2 mM Ca2+ and 2 mM Mg2+, respectively. Tween 80 improved the stability of CNCs in the presence of Na+ ≤ 300 mM, Ca2+ ≤ 10 mM and Mg2+ ≤ 10 mM, respectively. The mechanism was explained by the bridging effect of salt ions, electrostatic effect and spatial stability effect. The combined systems of surfactants (SDBS and Tween 80) with CNCs exhibited strong emulsifying properties, low interfacial tension (0.023 mN/m and 1.85 mN/m), and the ability to alter the wettability of oil wet rocks. This made the combined systems have better oil displacement performance.

Optimization of methylene blue dye degradation using heterogeneous Fenton-like reaction with Fe3O4 nanoparticles/PVDF macrospheres: A response surface methodology approach

Microplastics (MPs) are increasingly recognised for their significant impact on the environment and human health. Understanding MPs is crucial to grasp their widespread presence in various environmental areas. The unique properties of MPs, such as their small size, durability, and potential to adsorb and transport environmental pollutants, underscore the necessity of studying their characteristics. This study aims to investigate the physical and chemical characteristics of polypropylene microplastics (PPMPs) and address the dispersion stability issues associated with them. The PPMPs were characterised using scanning electron microscopy (SEM), revealing a surface structure marked by cracks, fractures, and a rough texture. The PPMPs were observed as irregularly shaped, white particles. Their size distribution spans from 14 to 96 µm, with a mean size of 50.00 µm. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of polypropylene functional groups, specifically identifying characteristic peaks at 2952-2846 cm-1 and 1456 -1376 cm-1, indicating C-H stretching and bending vibrations, respectively, with additional peaks suggesting degradation. The effect of different concentrations of sodium lauryl sulfate (SLS) on PPMPs dispersion indicated that 5% SLS led to superior dispersion of PPMPs, thereby addressing the stability issue. These findings provide comprehensive insights into the physical and chemical attributes of PPMPs and their dispersion stability, offering a foundation for informed environmental assessments and the development of effective mitigation strategies.

Insight into the physical and chemical attributes of polypropylene microplastics

Microplastics (MPs) are increasingly recognised for their significant impact on the environment and human health. Understanding MPs is crucial to grasp their widespread presence in various environmental areas. The unique properties of MPs, such as their small size, durability, and potential to adsorb and transport environmental pollutants, underscore the necessity of studying their characteristics. This study aims to investigate the physical and chemical characteristics of polypropylene microplastics (PPMPs) and address the dispersion stability issues associated with them. The PPMPs were characterised using scanning electron microscopy (SEM), revealing a surface structure marked by cracks, fractures, and a rough texture. The PPMPs were observed as irregularly shaped, white particles. Their size distribution spans from 14 to 96 µm, with a mean size of 50.00 µm. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of polypropylene functional groups, specifically identifying characteristic peaks at 2952-2846 cm-1 and 1456 -1376 cm-1, indicating C-H stretching and bending vibrations, respectively, with additional peaks suggesting degradation. The effect of different concentrations of sodium lauryl sulfate (SLS) on PPMPs dispersion indicated that 5% SLS led to superior dispersion of PPMPs, thereby addressing the stability issue. These findings provide comprehensive insights into the physical and chemical attributes of PPMPs and their dispersion stability, offering a foundation for informed environmental assessments and the development of effective mitigation strategies.

Two-Dimensional Materials-Based Thin Films and Coatings

Here, we highlight the research presented in this Special Issue, focusing on the innovative use of graphene and other two-dimensional (2D) materials to develop advanced coating technologies. The contributions herein address critical challenges such as the scalable fabrication and stable dispersion of such materials and their compatibility with conventional coating systems, offering solutions that enhance their mechanical strength, chemical stability, and multifunctionality. The featured studies demonstrate the diverse applications of these materials, from protective anticorrosive barriers to high-performance optoelectronic devices and environmental remediation. Moving forward, future research is encouraged to explore novel 2D materials, hybrid coating strategies, and advanced computational modeling to overcome existing limitations and unlock new possibilities.

The effect of anionic emulsifiers’ diversity and manufacturing processes on the stability and mechanical properties of the water-based epoxy-emulsified asphalt

Emulsified asphalt mixtures’ cold mix and paving features facilitate asphalt pavements in fulfilling dual-carbon and energy-saving demands. Anionic emulsifiers can enhance emulsion stability, ensure uniform dispersion of oil and water, possess good decompression viscosity, thickening, and lubricating properties, and maintain good stability under acidic conditions. Nevertheless, anionic emulsified asphalt is restricted in engineering applications due to problems like its storage stability. In this paper, eight anionic emulsifiers and two preparation procedures were chosen for stability tests. Through static tests, storage tests, sieve residue tests, and laser particle size tests, the impacts of emulsifiers on the storage stability and dispersion of asphalt were analyzed. Waterborne epoxy resin exhibits excellent adhesive properties, mechanical properties, chemical resistance, and heat stability. A fluorescence microscope test, static and storage test, laser particle size test, and cementation test were employed to explore the effects of different preparation processes and waterborne epoxy mixing ratios on emulsified asphalt’s storage stability, dispersion stability, and structural stability. The results showed that: (1) the emulsified asphalt prepared with the BWH-02 emulsifier exhibits the best storage stability, and blending with 20% of the waterborne epoxy modifier can notably enhance the bonding properties; (2) the shear strength of the BWH-02 waterborne epoxy emulsified asphalt prepared can reach 1.543 MPa, and the tensile viscosity can reach 0.848 MPa; (3), The emulsified asphalt prepared by the process of modification has better storage stability than that prepared by the side of the emulsification process. Moreover, the storage stability of emulsified asphalt prepared by emulsification and modification is superior to that of the emulsification and modification process. This research provides theoretical and technical support for popularizing and applying cold-mixed cold-paving asphalt mixtures.

Crystallization and intermolecular hydrogen bonding in carbamazepine-polyvinyl pyrrolidone solid dispersions: An experiment and molecular simulation study on drug content variation

The choice of drug content is a critical factor as far as the solid dispersion is concerned. This investigation aims to build the relationship between the drug content, intermolecular hydrogen bonding and the crystalline of the carbamazepine-polyvinyl pyrrolidone solid dispersion. In this work, the microstructural changes of solid dispersions were investigated using experimental characterization combined with molecular simulation. Experimental investigations demonstrated that increasing the drug content enhances the intermolecular hydrogen bonding between drugs, resulting in the crystalline phase of the drug emerged in the solid dispersion. This negatively affects the solubility and stability of solid dispersions. Molecular simulations were then used to analyze the changes of intermolecular hydrogen bonding at different drug content in the system. It revealed a tenfold increase in drug-drug hydrogen bonding concentration as drug content elevated from 10% to 50%, while the drug-excipient hydrogen bonding concentration decreased by 45%. The correlation analysis proves the significant relationships among the drug content, intermolecular hydrogen bonding, and crystallinity of solid dispersion. Using polynomial fitting analysis, the quantitative relationships between the drug content and crystalline properties were investigated. This study will offer valuable insights into the impact of drug content on the performance of solid dispersion.

Investigation of Mirabegron-loaded Nanostructured Lipid Carriers for Improved Bioabsorption: Formulation, Statistical Optimization, andIn-VivoEvaluation.

Overactive bladder (OAB) is a usual medical syndrome that affects the bladder, and Mirabegron (MBG) is preferred medicine for its control. Currently, available marketed formulations (MYRBETRIQ® granules and MYRBETRIQ® ER tablets) suffer from low bioavailability (29-35%) hampering their therapeutic effectiveness and compromising patient compliance. By creating MBG nanostructured lipid carriers (MBG-NLCs) for improved systemic availability and drug release, specifically in oral administration of OAB treatment, this study aimed to address these issues. MBG-NLCs were fabricated using a hot-melt ultrasonication technique. MBG-GMS; MBG-oleic acid interaction was assessed by in silico molecular docking. QbD relied on the concentration of Span 80 (X1) and homogenizer speed (X2) as critical material attribute (CMA) and critical process parameter (CPP) respectively, while critical quality attributes (CQA) such as particle size (Y1) and cumulative drug release at 24h (Y2) were estimated as dependent variables. 32 factorial design was utilized to investigate the interconnection in variables that are dependent and independents. Optimized MBG-NLCs with a particle size of 194.4 ± 2.25nm were suitable for lymphatic uptake. A PDI score of 0.275 ± 0.02 and zeta potential of -36.2 ± 0.721mV indicated a uniform monodisperse system with stable dispersion properties. MBG-NLCs exhibited entrapment efficiency of 77.3 ± 1.17% and a sustained release in SIF of 94.75 ± 1.60% for 24h. MBG-NLCs exhibited the Higuchi model with diffusion as a release mechanism. A pharmacokinetic study in Wistar rats exhibited a 1.67-fold higher bioavailability as compared to MBG suspension. Hence, MBG-NLCs hold promise for treating OAB by improving MBG's oral bio absorption.

Cyclic Continuous Glycation Enhanced Dispersibility of Myofibrillar Protein: Reaction Efficiency and Sites Modification.

Reaction efficiency in glycation lacks sufficient attention, leading to the waste of process costs. Cyclic continuous glycation (CCG) is an effective approach to accelerate covalent binding between myofibrillar protein (MP) and glucose. This study elucidated that CCG promoted the exposure of reactive glycated sites in MP with full unfolding of secondary and tertiary structures. Notably, the glycation rate was significantly increased by 65.43%. Physicochemical properties indicated that MP-glucose conjugates with high graft degree exhibited favorable solubility, dispersibility, and thermal stability. Furthermore, proteomics was applied to reveal the glycated sites and products in glycoconjugates of MP. Glycation preferentially acted on the tails of the myosin heavy chain. The glucosylation modification on the head region was enhanced by CCG contributing to the inhibition of the head-head interaction. Overall, this study systematically clarifies the mechanism of CCG, providing a theoretical basis for the application of glycation in innovative meat products.

Surfactant-Free Preparation of Conjugated Polymer Nanoparticles in Aqueous Dispersions Using Sulfate Functionalized Fluorene Monomers.

Conjugated polymer nanoparticles (CPNs) can be synthesized by a Suzuki-Miyaura cross-coupling miniemulsion polymerization to give stable dispersions with a high concentration of uniform nanoparticles. However, large amounts of added surfactants are required to stabilize the miniemulsion and prevent the aggregation of the nanoparticles. Removal of the excess surfactant is challenging, and residual surfactant in thin films deposited from these dispersions can reduce the performance of optoelectronic devices. We report a novel approach to prepare stable dispersions with no added surfactant using a fluorene monomer, 2,7-dibromo-9,9-bis(undecanesulfate)-9H-fluorene, with alkyl side chains terminated by negatively charged sulfate groups. This functionality mimics the structure of one of the most commonly used surfactants, sodium dodecyl sulfate (SDS). This charged monomer effectively stabilizes the miniemulsion through electrostatic repulsion without the use of any additional surfactant in molar ratios ranging from 2.0 to 20.0 mol % of total monomer content for the preparation of poly(9,9-dioctylfluorene) (PFO) and poly(9,9-dioctylfluorene-alt-bithiophene) (PF8T2). Incorporation of 5.0 mol % of the amphiphilic monomer gave stable dispersions with a surface potential below -40 mV and, and polymers with molar mass (Mn) above 10 kg mol-1. This method should be generally applicable to the preparation of dispersions of polyfluorenes for application in organic electronic and optoelectronic devices without the requirement for time-consuming processes to remove residual surfactant.

An ionic liquid crystal functionalized nanocellulose lubricant additives

Cellulose, one of nature's most abundant, clean, and sustainable resources, has often shown unsatisfactory results when used as bio-lubricant additives. Herein, nanocellulose (NC) from amorphous waste natural poplar was extracted using deep eutectic solvent encapsulation treatment and chlorine bleaching process. Subsequently, 1-hexadecyl-3-methylimidazolium bromide was integrated onto NC using a one-step hydrothermal treatment (high-temperature and high-pressure environment) to obtain ionic liquid crystal (ILC) functionalized products (named as ILC-NC). After ball-milling process and solid phase separation step, ILC-NC exhibits excellent dispersion stability and lubrication properties in the liquid phase (including water and vegetable oil). Based on the polar and colloidal activity properties of ILC, it can form an ordered molecular layer on NC surface and form a lubricating film-like structure, making NC smoother and sliding well. Compared to ILC/NC aqueous dispersion, ILC-NC reduces the coefficient of friction and wear rate on steel disk surface by 68.75 % and 74.07 %, respectively. The minimum coefficient of friction was further reduced to 0.032 as dispersing ILC-NC in sunflower oil, showing a reduction of 0.134 (77.91 %) compared to pure sunflower oil. Finally, the lubrication theoretical model calculation reveals the lubrication state of ILC-NC on the steel disk surface and proposes the lubrication mechanism.

Formulation and analysis of acrylic emulsion coatings with chrome yellow, phthalocyanine blue, and red oxide pigments using high speed disperser and bead mill techniques

A major commercial problem is achieving stable and fine particle pigment dispersion, especially for aqueous pigment dispersions. It is essential to optimize dispersants in order to moisten, disperse, and stabilize pigments throughout the milling process. This study focuses on formulating acrylic emulsion coatings using chrome yellow, phthalocyanine blue, and red oxide pigment concentrates. The formulations were developed using both high-speed dispersers (HSD) and bead mills. A quality evaluation of the products from the two milling techniques was carried out. Formulations made with chrome yellow, phthalocyanine blue, and red oxide pigment concentrates in a water-based, binder-free system using bead mills, Tween-80, SLS, and cocosulphosuccinate surfactants showed narrower particle size distributions and stronger color than those made with HSD. Specifically, formulations prepared with bead mills and the aforementioned surfactants demonstrated superior color strength compared to those prepared with HSD. The color shade of acrylic emulsion coatings formulated with phthalocyanine blue and red oxide pigment concentrates, along with Tween-80 and cocosulphosuccinate surfactants using HSD, matched the standard color shade formulations prepared in bead mills. However, formulations using phthalocyanine blue pigment concentrates with SLS and oleylsulphosuccinate surfactants in HSD did not match the standard color shade prepared in bead mills.

Evaluation of rheo-viscoelasticity of magnesium-silicate-hydrate mixes incorporating different superplasticizers

This study investigated rheo-viscoelastic behaviors of MgO-SiO2 pastes with three phosphate additives (sodium hexametaphosphate (SHMP), sodium trimetaphosphate (STMP), and sodium orthophosphate (SOP)) as superplasticizers. Static yield stress, dynamic yield stress, median differential viscosity, thixotropic loop area, structural recovery rate, and non-destructive structural build-up were analyzed. Furthermore, assessment of hydration and particle dispersion stability was facilitated by employing isothermal calorimetry, XRD, DTG, and zeta potential techniques. SHMP significantly decreased the static and dynamic rheology, thixotropy, and viscoelastic evolution. Samples incorporating 2 wt% SOP exhibited enhanced rheological parameters, particularly static yield stress, owing to increased brucite formation and a denser microstructure in the fresh paste. Adsorption of phosphate additives on MgO surfaces inhibited formation of brucite and improved interparticle electrostatic repulsion, thereby increasing suspension stability. High-efficiency adsorption of SHMP on MgO surfaces, coupled with the retardation of brucite nucleation-and-growth, and enhancement in suspension stability, greatly restrained the rheo-viscoelastic evolution of MgO-SiO2 system.

The long-lasting maintenance of the pore structure achieves the stability of lithium metal batteries

The separator is considered critical to the safety and performance of lithium metal batteries (LMBs), however, the separator structure fails under high temperature conditions due to damage resulting in decreased mechanical strength, which causes short-circuiting of the battery. This paper describes a novel process to prepare stable and uniform dispersions of aramid nanofibers (ANFs) by bottom-up low-temperature polymerization, and then crosslink the ANFs with N2 plasma-treated polypropylene (PP) separator through capping isocyanate crosslinkers. The composite separator not only has excellent mechanical properties with hardness and modulus of elasticity up to 0.35 and 2.26 GPa, which is three times higher than the PP separator, but also has high-temperature thermal stability, the size maintenance rate reaches 99.8 % at 200 °C. Meanwhile, real-time monitoring of the pore size at different temperatures by synchrotron radiation small-angle X-ray scattering (SR-SAXS) showed that the pore radius of gyration was kept at 8.81 nm and the size change rate was only 22.8 % at 200 °C, which demonstrated that the composite separator had an outstanding ability to maintain the pore structure to ensure the stability of the ionic transport channel. Therefore, the crosslinked composite separator has greater potential for improving the performance and safety of LMBs in extreme high-temperature environments.

Extraction and detection of sulfonamide antibiotics in milk using magnetic solid-phase adsorbent based on molecular mechanics and DFT calculations

Based on the foundation of calculations in molecular mechanics and density functional theory (DFT) for in-depth mechanistic studies, this paper proposes the sample multi-residue analysis method of five common sulfonamide antibiotics (SAs) in milk. Fe3O4 nanoparticles modified magnetic graphene oxide nanoribbons (Mag-GONRs) with superior dispersibility and dispersion stability, were developed and firstly utilized to rapidly extract residual SAs from milk. Therefore, various SAs in complex samples could be simultaneously determined solely by high performance liquid chromatography-ultraviolet detector (HPLC-UV) without the need for complicated pretreatment processes. In order to obtain satisfactory extraction efficiency, indispensable investigation and optimization were conducted on some parameters influencing the extraction efficiency. And the extracted SAs were determined by. Good linearity for all analytes was achieved with appropriate correlation coefficients (R2 higher than 0.9978). The limits of detection ranged from 0.060 to 0.075 ng·mL−1. Recoveries of the sulfonamides in spiked milk samples were between 79.6 % and 114.6 %, with relative standard deviations within 12 %. Interestingly, with the assistant of computational chemistry, the efficient extraction of Mag-GONRs onto SAs has been validated at the molecular and quantum levels, further elucidating the adsorption mechanism based on non-covalent interactions. In the context of theoretical research and experimental results mutually supporting each other, a practical detection method with actual application value has been proposed in monitoring the residual sulfonamides in milk by the common devices.

Assessing the size transformation of nanoplastics in natural water matrices

Understanding the stability of NPs in different aqueous environments, related with their size is crucial for assessing their potential risks. This is influenced by several factors, including pH, ionic strength, and the presence of biomolecules, or dissolved organic matter (DOM). In this study, dispersions of NPs derived from common plastic waste materials, including polystyrene (PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), and polycarbonate (PC), were synthesized by a nanoprecipitation method with sizes: 189 ± 7, 58 ± 3, 123 ± 4, 151 ± 7 and 182 ± 6 nm, respectively. Stability for a period of 14 days of these NPs was assessed in various natural water matrices. Different analytical techniques were used, including Asymmetric Flow Field-Flow Fractionation (AF4) coupled with UV–Vis and Dynamic Light Scattering (DLS) in series, batch DLS, Fourier-Transform Infrared Spectroscopy-Attenuated Total Reflection (FTIR-ATR), and Transmission Electron Microscopy (TEM). None of the studied NPs was stable in seawater and NPs were transformed in microplastics (MPs) by aggregation. PET was more prone to aggregation in all waters and PS was the most stable followed for PC, PVC and PMMA. However, bottle and tap waters maintained better the original size of NPs. For the most stable dispersion PS, the influence of heteroaggregation in tap and lagoon waters and aging from exposure to UV light in sea water were tested. In both cases, the stability over time was worse for PS. The results can contribute to a more comprehensive understanding of the fate and behaviour of NPs in natural aquatic environments, emphasizing the importance of studying a wide range of polymers.