Langmuir最新文献

Infections and thrombosis remain unsolved problems for implanted cardiovascular devices, such as left ventricular assist devices. Hence, the development of surfaces with improved blood compatibility and antimicrobial properties is imperative to reduce complications after artificial heart implantation. In this work, we report a novel approach to fabricate multifunctional surfaces for left ventricular transplanted ventricular assist devices (LVADs) by immobilizing nitric oxide (NO) generation catalysts and heparin and reducing silver nanoparticles in situ. The general view, structure, and chemical compositions of the pure/modified surfaces were characterized using digital imaging, scanning electron microscope (SEM), atomic force microscope (AFM), water contact angle (WCA), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma (ICP). All of the results demonstrated that the AgNPs and heparin were successfully immobilized on the surface. The Cu ions and NO release experimental results showed that the immobilized copper ions could catalyze the production of NO from S-nitrosothiols within the biological system. Meanwhile, due to the synergistic anticoagulant effect of NO and surface-immobilized heparin, the fabricated modified surfaces exhibited antiplatelet adhesion activities and good hemocompatibility. Finally, the antimicrobial activity of the samples was evaluated by Escherichia coli and Staphylococcus aureus, and cytocompatibility was measured using human umbilical vein endothelial cells (HUVECs). The results demonstrated that silver nanoparticles (AgNPs) immobilized by surface reduction reaction did not cause any significant inhibition of cell proliferation while providing stable and effective antimicrobial properties. We envision that this simple surface modification strategy with bifunctional activities of antimicrobial and anticoagulant will find widespread use in clinically used indwelling left ventricular assist devices.

Electrochemical water splitting required efficient electrocatalysts to produce clean hydrogen fuel. Here, we adopted greenway coprecipitation (GC) method to synthesize conducting polymer (CP) nanotunnel network affixed with luminal-abluminal CoNi hydroxides (GC-CoNiCP), namely, GC-Co₁Ni₂CP, GC-Co_1.5Ni_1.5CP, and GC-Co₂Ni₁CP. The active catalyst, GC-Co₂Ni₁CP/GC, has low oxygen evolution reaction (OER) overpotential (307 mV) and a smaller Tafel slope (47 mV dec^-1) than IrO₂ (125 mV dec^-1). The electrochemical active surface area (EASA) normalized linear sweep voltammetry (LSV) curve exhibited outstanding intrinsic activity of GC-Co₂Ni₁CP, which required 285 mV to attain 10 mA cm^-2. At 1.54 V, the estimated turnover frequency (TOF) of GC-Co₂Ni₁CP/GC (0.017337 s^-1) was found to be 3-fold higher than that of IrO₂ (0.0014 s^-1). Furthermore, the GC-Co₂Ni₁CP/NF consumed a very low overpotential (281 mV) with a small Tafel slope of 121 mV dec^-1. The ultrastability of GC-Co₂Ni₁CP for industrial application was confirmed by durability at 10 and 100 mA cm^-2 for the OER (GC/NF-8 h, 2.0%/100 h, 2.2%) and overall water splitting (100 h, 3.8%), which implies that GC-Co₂Ni₁CP had adequate kinetics to address the elevated rates of water oxidation. The effect of pH and addition of tetramethylammonium cation (TMA⁺) reveal that GC-Co₂Ni₁CP follows the lattice oxygen mechanism (LOM). The solar-powered water electrolysis at 1.55 V supports the efficacy of GC-Co₂Ni₁CP in the solar-to-hydrogen conversion. The environmental impact studies and solar-driven water electrolysis proved that GC-CoNiCP has excellent greenness and efficiency, respectively.

In the flotation process, there is galvanic corrosion between sulfide mineral particles, which increases the difficulty of separation between minerals. Therefore, the selection of suitable reagents to weaken this corrosion is of great significance. In this article, macromolecular organic reagent sodium lignosulfonate (SLC) was used to weaken the galvanic corrosion between galena and pyrite. Meanwhile, the effect of SLC on the mineral flotation behavior was studied, and the mechanism of SLC was further studied through ion dissolution tests, contact angle tests, infrared spectrum tests, and density functional theory (DFT) calculation. The adsorption of SLC on the mineral electrode increased the charge transfer resistance on the surface of the mineral electrode and hindered the resistance transfer; therefore, it could weaken the galvanic corrosion between galena and pyrite. SLC could selectively depress pyrite at low alkalinity. CaOH⁺ promoted the adsorption of SLC on the pyrite surface. When the pH of the slurry was adjusted by lime, SLC was more easily adsorbed on the pyrite surface, which hindered the adsorption of the collector on the surface of pyrite.

Palm leaves serve as a traditional recording medium and are widespread in south and southeast Asia, and they have a long history. However, they are sensitive to environmental fluctuations, especially moisture, which may severely affect their conservation status. In this research, the moisture absorption behaviors of palm leaves in different states, including raw, treated, naturally aged, and artificially aged ones, were investigated by intelligent gravimetric analysis (IGA) and water retention value (WRV) to analyze their moisture absorption characteristics. Mathematical model was employed to fit and analyze their water adsorption curves, aiming to explore the content and distribution of the adsorbed water in monolayered and multilayered. Then, the chemical and physical properties of different palm leaves were studied by chemical composition analysis, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM), and low-field nuclear magnetic resonance (low-field NMR), and the relationship between moisture absorption characteristics and their chemical composition and physical structures was analyzed. The results demonstrated that both treatment and aging processes could have a noticeable impact on the moisture absorption of palm leaves, as evidenced by reduced equilibrium moisture content (EMC) at high relative humidity (RH), decreased multilayer water adsorption content, and slightly increased monolayer water adsorption content. Besides, palm leaves exhibit a lower rate of moisture adsorption, at ∼30-50% RH, which facilitates their long-term conservation. The results of chemical and physical analyses revealed that the reduced content of hydrophilic groups was the primary reason for a decrease in palm leaves moisture absorption. Additionally, the fiber structure changes of palm leaves caused by treatment or aging may have different influences on their moisture adsorption, especially the content of monolayer adsorbed water.

Enrichment of metal particles in lubricating oil is a crucial pretreatment for wear debris analyses in applications of condition-based machinery maintenance. Current techniques using physical filter cleaning and magnetic attachment to enrich metal particles have limitations in terms of efficiency and selectivity. This work presents an innovative acoustic manipulation chip for efficiently enriching metallic particles from lubricating oil. The platform utilizes the hybrid acoustic forces to perform high throughput particle enrichment in microchannels, even in an intensive flow environment. Regarding the viscosity effect of lubricating oil, the temperature dependence upon the particle enrichment is explored, and the figure of merit is employed to quantify the enrichment performance from the captured microscopic images. Experimental results demonstrate the proposed platform shows great nonselectivity for enriching both magnetic and nonmagnetic particles. This method opens a new door for developing automatic filter-free pretreatment tools to perform efficient particle enrichment in lubricating oil, which have great potential in many application scenarios, such as advanced wear debris analyses, oil quality monitoring, etc.

Alginate hydrogels are frequently used in 3D bioprinting and tissue repair and regeneration. Establishing the structure-property-performance correlation of these materials would benefit significantly from high-resolution structural characterization in aqueous environments from the molecular level to continuum. This study overcomes technical challenges and enables high-resolution atomic force microscopy (AFM) imaging of hydrated alginate hydrogels in aqueous media. By combining a new sample preparation protocol with extremely gentle tapping mode AFM imaging, we characterized the morphology and regional mechanical properties of the hydrated alginate. Upon cross-linking, basic units of these hydrogel materials consist of egg-box dimers, which assemble into long fibrils. These fibrils congregate and pile up, forming a sponge-like structure, whose pore size and distribution depend on the cross-linking conditions. At the exterior, surface tension impacts the piling of fibrils, leading to stripe-like features. These structural features contribute to local, regional, and macroscopic mechanics. The outcome provides new insights into its structural characteristics from nanometers to tens of micrometers, i.e., at the dimensions pertaining to biomaterial and hydrogel-cell interactions. Collectively, the results advance our knowledge of the structure and mechanics from the nanometer to continuum, facilitating advanced applications in hydrogel biomaterials.

Low alloy steel faces localized corrosion issues in service environments, primarily due to pitting corrosion induced by inclusions. Conventional protective measures cannot significantly improve the corrosion resistance of the steel. In this study, an effective industrial approach was proposed to enhance the corrosion resistance of low alloy steels. Cerium (Ce) was added during the refining process to modify inclusions and alter the mechanism of inclusion-induced localized corrosion, thereby improving the substrate's ability to inhibit pitting corrosion. The effect of Ce treatment on the cleanliness of molten steel was investigated, and a kinetic model of inclusion evolution was established based on thermodynamic calculations. The pitting corrosion induced by CaS·C₁₂A₇ and CeAlO₃ inclusions was studied through immersion experiments over different durations. The degree of corrosion after being soaked for 20 min was significantly different. The size and depth of pitting pits induced by CeAlO₃ inclusions were much smaller than those induced by CaS·C₁₂A₇ inclusions. The electron back scatter diffraction tests confirmed that CaS·C₁₂A₇ inclusions exhibited a higher corrosion sensitivity compared to CeAlO₃, thus promoting the initiation of pitting. Electrochemical tests demonstrated a positive shift in the corrosion potential and a reduction in current density. This implies that CeAlO₃ inclusions can significantly inhibit pitting occurrences. Based on the dissolution behaviors of CaS·C₁₂A₇ and CeAlO₃ inclusions, a kinetic model was established to describe the initiation and propagation of pitting induced by these inclusions.

Ferroptosis has been recognized as an iron-based nonapoptotic-regulated cell death process. In the quest of resisting the unyielding vehemence of triple-negative breast cancer (TNBC), herein we have showcased the ferroptosis-inducing heteroleptic [LIr_cRu], [LIr_cIr_h], and [LIr_cRe] complexes, enabling them to selectively target "sialic acid", an overexpressed cancer cell-surface marker. The open-circuit potential (OCP) measurements in live cancer cells revealed the specific interaction between TNBC and the complexes, whereas control experiments with normal cells did not exhibit such interactions. GSH depletion, GPx4 inhibition, NADH/NADPH oxidation, lipid peroxidation, COX-2 activation, and Nrf2 inactivation were meticulously investigated upon treatment with these complexes to establish a strong basis for ferroptosis. Among all complexes, the complex [LIr_cIr_h] (IC₅₀ = 25 ± 2.17 μM) has been well-documented as a potent ferroptosis inducer, which unveils the sturdy interaction with sialic acid possessing the highest binding constant (K_b = 0.71 × 10⁵ M^-1, ΔG = -279345.8026 kcal/mol) along with the highest serum albumin binding affinity (K_HSA = 0.67 × 10⁶ M^-1) and significant DNA intercalation (K_b = 0.56 × 10⁵ M^-1, K_app = 1.06 × 10⁶ M^-1, and C₅₀ of intercalation is 76.56 μM), displaying the decreased current intensity in differential pulse voltammetry (DPV). Moreover, the complex [LIr_cIr_h] exhibited mitochondrial dysfunction and membrane damage (diminished MMP, ΔΨ_m) through the production of copious reactive oxygen species (ROS) in MDA-MB-231 cells upon considerable accumulation in mitochondria (Pearson's coefficient = 0.842). The analysis of the field emission scanning electron microscopy (FE-SEM) image has marked the vivid membrane damage induced by the complex [LIr_cIr_h], exhibiting ablaze evidence for the destruction of TNBC cells through ferroptosis.