INMdok (Leibniz Institute for New Materials)
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Acid-Free Electrochemical Regeneration of Sandrose-like Aluminum Layered Double Hydroxide Electrodes for Selective Lithium-Ion Recovery in Mixed Ion Solution
Full text linkThe demand for lithium production has seen a significant rise, with the growing electric vehicle and stationary battery markets requiring further development of sustainable and scalable extraction methods. Direct lithium extraction technologies have been developed to address potential shortages, with adsorption emerging as a key method due to its efficiency and low environmental impact. Given that Al(OH)3 is already utilized as an adsorbent in various industrial applications, the practical importance of Al-based alternative systems for lithium ion extraction is increasing, yet lithium ion recovery requires harsh chemicals. In this study, we report a novel lithium extraction method combining chemical adsorption and electrochemical release using a synthesized aluminum layered double hydroxide (Al-LDH) material, developed under mild reaction conditions. The performance of the Al-LDH electrode was evaluated against a commercial Al(OH)3 adsorbent. Comprehensive characterization using techniques such as X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy revealed detailed insights into the crystalline structure, particle size distribution, and surface morphology of the materials. The Al-LDH electrode exhibited a lithium ion adsorption capacity, achieving an average chemical uptake of lithium ions of 57.6 mg/g. In contrast, lithium-ion uptake capacity for Al(OH)3 was 1.0 mg/g over 15 cycles. Notably, this method operates under pH-neutral conditions, eliminating the need for harsh acidic or basic eluents. As a result, it prevents structural degradation and minimizes secondary pollution for potential future applications of lithium-ion recovery. The material’s layered structure selectively allowed lithium ion intake while blocking sodium ions, demonstrating its high selectivity and utility in lithium ion recovery processes. The integration of pH-neutral regeneration and high selectivity shows that Al-LDH electrodes as viable candidates for next-generation, green lithium extraction technologies
Quantification of collagen matrix deposition in 2D cell cultures: a comparative study of existing assays
Full text linkCollagen matrix deposition is an important biomarker to predict the regenerative capacity of new biomaterials or the therapeutic potential of new drugs in collagen-associated diseases. Several methods for the quantification of matrix collagen in tissue samples are established, e.g., Picro-Sirius red assay, hydroxyproline assay, antibody-based assays, or the 3,4-DHPAA-based assay. These methods have been extended to quantify deposited collagen in in vitro cell culture models, although their applicability has been questioned due to the much lower concentration and eventually lower relative abundance of deposited collagen in cell cultures than in tissue. Here we compare the performance of the above-mentioned methods for the quantification of deposited matrix collagen in 2D cell cultures under different conditions: culture time, addition of collagen deposition-stimulating molecules, and post-culture processing step (decellularization). We show that the available methods can deliver accurate results within different experimental windows. We provide a comprehensive analysis of the relevant experimental parameters that influence the assay, and the sensitivity limits for the different methods, as well as the involved effort. In a comparative table, we provide guidance for the selection of the most appropriate collagen quantification assay for different culture conditions
Expedient Access to Gold/Quantum‐Dot Nanohybrids Mediated by Poly(ethylene Glycol) Ligands of Distinct Macromolecular Architecture
Full text linkWe report a straightforward methodology to access structurally well‐defined hybrid assemblies of plasmonic and excitonic nanoparticles (NPs). The developed strategy is based on the incorporation of quantum dots (QDs) coated with zinc‐sulfide shells into poly(ethylene glycol) (PEG) brushes at gold NP surfaces, without the necessity of incorporating specialized functional groups to drive the supracolloidal assembly. Based on control experiments involving PEGs with distinct polymeric architecture and Fourier‐transform infrared spectroscopy analysis, we attribute the structure formation to attractive interactions between the QD surface and the monomeric repeat unit of the PEG brushes. This combination leads to short interparticle spacings and plasmon/exciton interactions, resulting in photoluminescence (PL) quenching upon assembly. However, using block‐copolymers comprising a NP‐adjacent spacer block in addition to a NP‐remote PEG block, the distance between gold NPs and QDs can be controlled, which in turn affects the PL properties. The versatility of the structure‐formation approach is demonstrated by the possibility of applying it to two distinct core/shell QDs (InP/ZnSe/ZnS and CdSe/CdS/ZnS). This offers new perspectives in the quest for efficient nanomaterial fabrication procedures
Solvent‐Free Phase Separation of Polystyrene‐block‐poly(2‐hydroxyethyl methacrylate) Forming Freestanding Photonic Films
Full text linkA solvent‐free approach to the formation of freestanding photonic material from amphiphilic polystyrene‐ block ‐poly(2‐hydroxyethyl methacrylate) (PS‐ b
‐PHEMA) is reported, where the application of shear force and pressure induces phase separation. This work demonstrates access to high molecular weight (HMW; 100 kg mol −1 ) PS‐ b ‐PHEMA with PHEMA contents up to 62 vol% using sequential anionic polymerization. By exploring hot pressing, the dependency of microstructure formation on temperature, pressure, and time is demonstrated using transmission electron microscopy and small‐angle X‐ray scattering measurements. Within 30 min, phase‐separated block copolymer (BCP) films are obtained. Although no highly ordered equilibrium structures are formed, photonic properties are observed for PS‐ b ‐PHEMA films with molecular weights higher than 140 kg mol −1 and PHEMA contents between 20 and 51 vol%. The photonic properties are investigated by ultraviolet–visible (UV–vis) and fluorescence spectroscopy as well as confocal fluorescence microscopy. The BCP films exhibit tailored transmittance that is dependent on molecular weight and microstructure, making them suitable for UV and blue light filter applications. Also, structure‐dependent reflection and fluorescence are demonstrated. Finally, the application in the field of sensors is addressed by demonstrating a reversible color change of BCP films with a co‐continuous microstructure, achieved through polar solvent infiltration and vaporation
Revealing the Hidden Electrochemical Pathway for Cathode Electrolyte Interface Formation in Lithium–Sulfur Batteries with Carbonate-Based Electrolytes
Full text linkThis study investigates the role of microporous carbons and carbonate-based electrolytes in addressing challenges related to polysulfides dissolution and electrolyte compatibility in lithium–sulfur (Li–S) batteries. By employing microporous carbons and varying the sulfur content, we investigate the formation of the cathode-electrolyte interphase (CEI) during the first discharge process. We propose an electrochemical nucleophilic mechanism for the formation of the CEI involving polysulfides and solvent molecules in the confined small pores of the cathode. This interphase, primarily composed of LiF, effectively seals the carbon pores, preventing further solvent intrusion and stabilizing the system. Furthermore, it allows the use of wider pores without compromising the system. Our findings reveal that an increased sulfur content within the micropores enhances cycling stability, contradicting trends observed in ether-based systems. These insights highlight the potential of designing Li–S systems with optimized pore structures and electrolyte compositions to achieve greater stability and capacity retention, marking a significant step forward in the development of practical Li–S batterie
Beyond global metrics in capacitive water deionization: Position-resolved ion concentration from operando X-ray transmission
Full text linkThe performance of novel electrode materials and the influence of cell geometry or flow rate on capacitive water deionization (CDI) are usually described by global metrics from the analysis of the effluent electrolyte together with the electrochemical response of the system. However, these approaches cannot provide information on local variations of ion concentration and related local efficiency within an operating device. Here, a novel approach of position-resolved operando synchrotron-based X-ray transmission is introduced to determine local ion concentration changes along the flow channel from the inlet (feedwater) to the outlet (effluent water) of a working CDI cell. A specific cell design allows the independent quantification of concentration changes within the bulk electrolyte in the flow channel as well as the two oppositely charged nanoporous electrodes. Results from a 15 mM CsCl feed solution using three flow rates and two carbon materials with hierarchical porosity reveal a complex spatial- and temporal ion distribution in the system. A distinct dependence of local concentration on the flow rate is observed, with generally decreasing local desalination capacity towards the outlet of the cell, particularly for slow flow rates. It is also found that a significantly better overall performance for one of the two materials can be related to dominant counter-ion adsorption within ultramicropores, which ions cannot access in their hydrated state at no applied potential (ionophobicity). Overall, the results demonstrate the unique potential of position-resolved operando X-ray techniques to get mechanistic insight into local ion redistribution in CDI systems, allowing ultimately guiding performance optimization
Tuning the biological scaffolds’ performance by the combination of two antioxidant and antimicrobial chitosan derivatives
Full text linkIn this study novel polymeric materials based on chitosan (CS) were synthesized by chemically modifying CS with two bioactive moieties: eugenol and a compound containing a thiazolium group. These modifications aimed to impart antioxidant and antimicrobial properties to the matrix. Additionally, the scaffolds were reinforced with chitin nanowhiskers (Nw) to improve their mechanical strength and stability. Porous three-dimensional scaffolds were fabricated via the freeze-drying process, resulting in highly interconnected pore networks suitable for cell infiltration and nutrient transport. Biological characterization revealed that the incorporation of the two bioactive groups significantly enhanced the antioxidant activity and antimicrobial efficacy against both Gram-positive and Gram-negative bacteria to the scaffolds. Mechanical testing demonstrated that the Nw reinforcement increased scaffold stiffness and resilience without compromising porosity. In vitro biological assays using fibroblasts showed favorable cytocompatibility and promoted sustained cell proliferation over three weeks. Fluorescence microscopy confirmed fibroblast adhesion and morphological adaptation within the scaffold architecture. Additionally, the scaffolds were evaluated for their immunomodulatory effects using macrophage cultures, revealing a balanced immune response with reduced proinflammatory signaling, which is critical for successful integration and reduced fibrosis in vivo. These results indicate that those are promising candidates for tissue engineering and regenerative medicine applications
Correction to “Acid-Free Electrochemical Regeneration of Sandrose-like Aluminum Layered Double Hydroxide Electrodes for Selective Lithium-Ion Recovery in Mixed Ion Solution”
Full text linkIn the original Article, Figure 1C shows an image from a different, morphologically similar sample rather than the sample investigated in the other panels and throughout the manuscript. A corrected version of Figure 1 (with the correct image for panel C) is provided below. This correction does not affect the results, discussion, or conclusions of the Article
The role of skin hydration, skin deformability, and age in tactile friction and perception of materials
Full text linkFriction between fingertip and surface is a key contribution to tactile perception during active exploration of materials. We explore the role of skin factors such as stratum corneum thickness and hydration, deformability, elasticity, or density of sweat glands and of Meissner corpuscles in friction and tactile perception. The skin parameters were determined non-invasively for the glabrous skin at the index finger pad of 60 participants. Sets of randomly rough plastic surfaces and of micro-structured fibrillar rubber surfaces were explored as model materials with well-defined parameterized textures. Friction varies greatly between participants, and this variation can be explained to 70% by skin factors for the randomly rough plastic surfaces. The predictability of friction by skin factors is much lower for micro-structured rubber surfaces with bendable fibrils, where 50% of variance is explained for the stiffest fibrils but only 20% for the most bendable fibrils. The participants’ age is the key predictor for their tactile sensitivity to perceive the fibrils, where age is negatively correlated to the density of Meissner corpuscles. The results suggest that stratum corneum hydration, skin deformability, and age are important factors for friction and perception in active tactile exploration of materials
Spectroscopic characterization of laser-induced luminescence for remote environmental thermometry
Full text linkLanthanide-doped upconversion microparticles (UCMP) enable composites for luminescence thermometry with long luminescence lifetime and narrowband absorption and emission spectra. Being non-toxic, easily synthesizable, and having a bright, stable emission makes them an attractive candidate for in-vivo monitoring of key environmental parameters such as temperature. We use them to create soft, biodegradable, miniaturized seed-like robots endowed with fluorescence tags for the sustainable environmental monitoring of topsoil and air above soil environments. Our aim is an airborne platform with a sufficient signal-to-noise ratio to identify the concentration of targeted soil parameters. Here, we study the photoluminescence of Er, Yb: NaYF4 UCMPs embedded in polylactic acid (PLA) polymeric matrix to assess their suitability for remote read-out. We assessed the signal-to-noise ratio in terms of excitation intensity, UCMP concentration, working distance, and sample orientation. We evaluated the signal stability over long exposure time as well as for amplitude-modulated excitation. Finally, we carried out ratiometric and lifetime measurements of luminescence emission in order to demonstrate the feasibility of such sensors in measuring the variation of temperature. Overall, the rare-earth doped UCMPs embedded in biodegradable polymer can be used for remote thermometry, displaying a significant signal-to-noise ratio for luminescence emission detection and subsequent derivation of temperature