Water-in-oil (W/O) emulsions have attracted heightened attention because of the ever-increasing interest in using non-calorific water to replace calorie-dense fat in food. However, designing clean-label and ultra-stable W/O emulsions is a longstanding challenge in colloid science. Herein, a novel, facile approach is introduced to designing cocoa butter (CB)-based crystals to stabilize Pickering W/O emulsions. Results using a combination of small- and wide-angle X-ray scattering and microscopy across length scales reveal that the fat crystals formed in an oleogel of CB with vegetable oil offer high stability to water droplets (up to 60% (v/v)) against coalescence and phase inversion, over storage for 7 months. Such extraordinary stability is attributed to the nanoplatelet-like CB crystals of βV polymorph located at the water–oil interface and to the inter-droplet fat crystal network formation, interlocking the water droplets. The increment in water volume fraction endows gel-like properties with the water droplets acting as “active fillers.” These newly designed Pickering W/O emulsions stabilized solely by fat crystals with unusual rigidity offer great promise for fabricating advanced functional materials in food, pharmaceutics, and cosmetic applications, where long-term stabilization of water droplets using sustainable particles is a necessity.

Metal halide perovskite semiconductors have shown great performance in solar cells, and including an excess of lead iodide (PbI2) in the thin films, either as mesoscopic particles or embedded domains, often leads to improved solar cell performance. Atomic resolution scanning transmission electron microscope micrographs of formamidinium lead iodide (FAPbI3) perovskite films reveal the FAPbI3:PbI2 interface to be remarkably coherent. It is demonstrated that such interface coherence is achieved by the PbI2 deviating from its common 2H hexagonal phase to form a trigonal 3R polytype through minor shifts in the stacking of the weakly van-der-Waals-bonded layers containing the near-octahedral units. The exact crystallographic interfacial relationship and lattice misfit are revealed. It is further shown that this 3R polytype of PbI2 has similar X-ray diffraction (XRD) peaks to that of the perovskite, making XRD-based quantification of the presence of PbI2 unreliable. Density functional theory demonstrates that this interface does not introduce additional electronic states in the bandgap, making it electronically benign. These findings explain why a slight PbI2 excess during perovskite film growth can help template perovskite crystal growth and passivate interfacial defects, improving solar cell performance.

Bacteria are difficult to be eliminated because of their multi-drug resistance, which brings significant threats to public health. Among the antibacterial methods, mechanobactericidal surfaces provide a possible approach to solving this problem. In this study, a generally used mechanical sterilization is developed by fabricating a nanostructured coating. The functional coating is simply fabricated by growing zeolitic imidazolate frameworks (ZIFs, ZIF-8 mixed with ZIF-67) nanospikes on the surface of the fabric substrate in situ. The fabricated ZIF nanospikes are stable and effective, with the sterilization efficiency approaching 99.9999%. This technique provides a fast, safe, and low-cost antibacterial method without drug resistance, which can be potentially used in hospitals, emergency treatments, and superbug protection in the future.

Graphene oxide (GO) with different oxidation degrees is prepared by a modified Hummers’ method varying KMnO4 amount from 0.5 to 6.0 g. X-ray powder diffraction (XRPD), micro–Raman, thermogravimetric analysis, X-ray photoeelectron spectroscopy, Boehm titrations, high–resolution transmission electron microscopy, and, finally, positron annihilation lifetime spectroscopy (PALS) are exploited to assess the properties of GO. Results show that increasing oxidant species can tune the interlayer gap between GO sheets up to a maximum value in the case of 4.0 g KMnO4 content. Moreover, these results validate the two-component-based model of GO in which, at low oxidation degree, there are unsplit/isolated graphene planes, instead at higher oxidant amounts, a five-layer sandwiched configuration occurs comprising graphene planes having functional groups decorating the edges (bwGO), hydrated oxidative debris (OD) and “empty” spaces (revealed by PALS as the distance between (bwGO + OD) two-component layers). In addition, by XRPD analysis, the total gap between two sheets is easily computed. In order to correlate these findings to pollutant removal capability, planar o-toluidine adsorption is studied. Since this molecule diffuses in an aqueous environment, the obtained adsorption percentages are compared to the thickness of the hydrated OD grafted onto bwGO. A strict connection between the pollutant removal efficacy and the variation of the hydrated interlayer distance is found.

Recently, membrane-modified mammalian exosomes have been considered strong candidates for targeted drug delivery carriers because of their biocompatibility, biodistribution, and low immune response. However, the widespread utilization of exosomes still requires overcoming several challenging issues, including low stability, high production cost, and low mass productivity. Therefore, artificial extracellular vesicles (EVs) derived from cell membranes or liposomes containing various lipids have been suggested. However, only a few meet the demands of cost-effective mass production and durability of EVs. Therefore, this study investigates the feasibility of replacing mammalian cell exosomes and liposomes with plant-derived extracellular vesicles (pEVs) as targeted drug delivery carriers. They are characterized by nontoxicity, high stability, and high yield. Adding a functionalizable lipid moiety with a maleimide group at the membrane of grapefruit-derived pEVs imparts targeting ability. The targeting function can be easily enhanced by attaching an aptamer using click chemistry. Indeed, treatment of brain cells with pEV-aptamers (hCMEC/D3 and U87MG) confirms that aptamer functionalization of pEV enhanced selective cellular uptake. Functionalization of the pEV membrane using aptamer is expected to be effective in providing low-cost and mass-producible targeted drug delivery carriers with similar efficacy as mammalian exosomes or liposomes.

HfO2 thin films are appealing for microelectronic applications such as high-κ dielectric layers, memristors, and ferroelectric memory devices. To fulfill the different requirements of each application, the properties of the deposited material need to be tuned accordingly. In this context, plasma-enhanced atomic layer deposition (PEALD) is a powerful processing route to tailor the properties of HfO2 thin films, especially at low temperatures. Herein, a comprehensive bottom-up approach is presented, ranging from the synthesis of molecularly engineered Hf precursors to the development of a HfO2 PEALD process and a detailed evaluation where plasma can be exploited to tune the dielectric properties. With the example of the newly synthesized bis-(dialkylamido)-bis-(formamidinato) Hf(IV) precursor, [Hf{η2-(iPrN)2CH}2(NMe2)2] which is reactive, thermally robust and volatile, successful implementation in a PEALD process for HfO2 at low temperatures is demonstrated. The typical atomic layer deposition (ALD) characteristics of precursor saturation, linearity, and ALD temperature window are demonstrated with constant growth of 0.7 Å per cycle from 125 to 200 °C, yielding high-purity layers. The effect of plasma pulse duration on the chemical composition alongside structural, topographical, as well as dielectric properties of the films is investigated. For the latter, the films are incorporated in metal-insulator semiconductor (MIS) structures.

Light-emitting transistors (LETs) are optoelectronic devices that perform switching and light-emitting functions in a single device. Hybrid LETS (HLETs) using inorganic metal oxide semiconductors as the transport layer with organic emissive layers and hole-injection layers (HILs) combine the excellent switching performance of metal oxides with the flexibility and tunability of organic semiconductors. However, the efficiency of n-HLETs typically suffers from unbalanced electron and hole injection. To overcome this issue, two hybrid polyelectrolytes—lithium poly(styrene sulfonate) (Li:PSS) and copper(II) poly(styrene sulfonate) (Cu:PSS)—are investigated as HILs in HLETs. HLETs employing Cu:PSS interlayers exhibit significantly enhanced brightness values of up to 4.89 × 103 cd m−2 and an external quantum efficiency (EQE) of 0.45%, compared to HLETs without HIL (no emission) and pristine poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) (2.17 × 102 cd m−2 with an EQE of 0.01%). To understand how the HILs influence the performance, ultraviolet photoelectron spectroscopy (UPS) analysis and photoluminescence (PL) quenching studies are performed, which reveal improved energy band structure and reduced quenching using metal:PSS HILs. This work provides useful information about the function that polyelectrolyte HILs perform in HLET devices which may be exploited to develop new materials and applied in other types of optoelectronic devices.

To understand the interfacial bond formation between polycarbonate (PC) and magnetron-sputtered metal nitride thin films, PC | X interfaces (X = AlN, TiN, (Ti,Al)N) are comparatively investigated by ab initio simulations as well as X-ray photoelectron spectroscopy. The simulations predict significant differences at the interface as N and Ti form bonds with all functional groups of the polymer, while Al reacts selectively only with the carbonate group of pristine PC. In good agreement with simulations, experimental data reveal that the PC | AlN and the PC | (Ti,Al)N interfaces are mainly defined by interfacial C─N bonds, whereas for PC | TiN, the interface formation is also characterized by numerous C─Ti and (C─O)─Ti bonds. Bond strength calculations combined with the measured interfacial bond density indicate the strongest interface for PC | (Ti,Al)N followed by PC | AlN, whereas the weakest is predicted for PC | TiN due to its lower density of strong interfacial C─N bonds. This study shows that the employed computational strategy enables prediction of the interfacial bond formation between PC and metal nitrides and that it is reasonable to assume that the research strategy proposed herein can be readily adapted to other organic | inorganic interfaces.

The hierarchy of newly formed bone contains elements of disorder within an ordered multiscale structure, spanning from the macroscale to below the nanoscale. With mineralized structures presenting in the shape of ellipsoids in mature and mineralizing tissue, this work characterizes the heterogeneity in the mineral ellipsoid packing at the interface of porous titanium implants. Using scanning transmission electron microscopy and plasma-focused ion beam–scanning electron microscopy, mineral ellipsoids are characterized at the implant interface in both 2D and 3D. Heterogeneous in their size and shape within the newly formed bone tissue, ellipsoids are observed with alternating orientations corresponding to unique lamellar packets within 23 µm of the titanium implant interface—although this motif is not universal, and a mineral-dense zone can also appear at the implant interface. Short-order ellipsoid orientation shifts are also present in the 3D probe of the implant interface, where a ≈90° misorientation angle between neighboring packets of mineral ellipsoids (and an intervening organic layer) resolves with increasing distance from the titanium. Combined with local patches of woven-to-lamellar transition, the early heterogeneity and transformation of peri-implant bone structure is a quintessential step in the development of a functional connection between implant and bone.

This paper describes a study where an argon cold plasma jet, generated by a dielectric-barrier discharge (DBD), is combined with nanosecond laser ablation (248 nm, 25 ns, 10 Hz) to deposit silver particle aerosols onto the substrate at atmospheric pressure. The deposition of the particle is examined using various microscopy techniques and absorption spectroscopy for the plasma jet produced by operating DBD in the normal and reversed mode. Plasma facilitated the deposition process by delivering the particle to the substrate and significantly influenced its morphology depending on the jet interaction, length, and substrate position. In both cases, the particles are clustered; however, there is less deposit for the plasma ignited in the reverse mode. The theoretical analysis of the deposition process is performed using ANSYS software and evaluated in terms of plasma-induced flow velocity. This study infers that the hybrid plasma-laser deposition scheme considered is attractive for material processing and deposition, especially overextended substrate distances, and for altering the properties of the deposited particles for practical utilization in surface-enhanced Raman spectroscopy, solar cells, and catalysis.

The preparation of adsorbate-free graphene with well-defined layer numbers is a current challenge in materials and surface science and required to fabricate graphene-based nanodevices, such as used in nanoelectromechanical systems. One strategy to tailor the layer number is oxygen-plasma treatment of few-layer graphene/graphite flakes. However, when graphitic materials are stored in air under ambient conditions, it is almost inevitable that adsorbates deposit on their surfaces. When precisely removing individual graphene layers from graphitic flakes by oxygen-plasma treatment, the amount and type of adsorbates strongly affect the required plasma-treatment process and duration. To examine the removal/etching mechanism involved in removing such layers, few-layer graphene/graphite flakes, with areas of different layer numbers, are stored in ambient air and stepwise exposed to oxygen plasma in a shielded configuration. The flakes are then successively analyzed by multifrequency atomic force microscopy together with Raman spectroscopy, focusing on etching rate, and adsorbate and defect evolution. Combined in-plane and out-of-plane tip–adsorbate–substrate interaction analysis facilitates discrimination of different types of adsorbates (water, polycyclic aromatic hydrocarbons, and linear alkanes) and their formation with time. The results demonstrate the potential regarding the development of an efficient method for cleaning of graphitic surfaces and ablation of individual graphene layers.

Bioinspired nanoplasmonic 3D crossed surface relief gratings and metasurfaces are fabricated on azobenzene molecular glass thin films to create effective antibacterial surfaces. A synergetic mechanical and photothermal interaction at the interface between the nanostructures and the Escherichia coli (E. coli) bacteria results in a significant decrease in the viable bacterial population. In particular, combined exposure to the interfacial nanospikes as well as the evanescent blue and red electromagnetic fields induced by the nanoplasmonic metasurface, results in a 97% reduction of the viable E. coli in only 25 min, when illuminated with a low-power white light.

Invisible hydrogen-induced cracking or stress corrosion cracking easily appears in high-pressure equipment in service. Mechanoresponsive luminogens (MRLs) can convert mechanical force into visible luminescence emission. Thus, MRL-based detection methods to damage of structures have been paid extensive attention in recent years. However, the structural damage-induced luminescence response and mechanism are still not fully comprehended. In this study, organic mechanochromic luminescent materials (1,1,2,2-tetrakis (4-nitrophenyl) ethene (TPE-4N)) are proposed to detect the invisible inner crack in high-pressure equipment. Because the high-pressure equipment in service is subjected to tensile loading, the inner crack-induced fluorescence response and mechanism under tension are investigated. The inner crack-induced local strain concentration can be transformed into a visible green fluorescence, which can be easily observed from the outside. According to the appearance of fluorescence, the position of the inner crack can be detected. Moreover, the depth level of the inner crack can be quantitatively estimated using applied tensile loading and the ratio of fluorescent area. The investigations may provide a new idea of non-destructive evaluation material and method for invisible damage in high-pressure equipment.

The unambiguous detection and classification of volatile organic compounds (VOCs) are crucial in many fields. For using VOC-sensing to explore the alteration and spoilage of food, very inexpensive sensors are desired. Simple colorimetric sensors seem highly attractive for these applications. Here, a label-free, colorimetric sensor array made of metal-organic-framework-based (MOF-based) Fabry-Pérot (FP) films is presented where the signal read-out is performed either by their optical spectra or by pictures taken with a smartphone camera. Exposing the FP-MOF-films to various VOCs causes a reversible shift of the photonic pattern, where the magnitude of the shift depends on the VOC type, its concentration, and the MOF structure. The application of machine- learning- algorithms on the sensor data allows to identify the VOCs with a high classification accuracy (92% at 100 ppm). It is shown that the sensor array read-out can also be performed with a common smartphone camera, also precisely classifying the VOC analytes. Moreover, fresh and spoiled food, like milk and meat, is distinguished by its head space. Thus, the study presents a very inexpensive platform of small colorimetric sensors that allow determining the quality, alteration, and spoilage of food, and it may contribute to realizing smart labels and intelligent packaging.

Metal nanoparticles (NPs) are suggested as a vaccine delivery platform. At present, there is limited description of cuboidal Ag nanocubes (AgNCs; nonporous) and Au nanocages (AuNCs; porous) as a protein carrier for vaccination. Here, the intrinsic protein binding ability of AgNC and AuNC is first investigated, using ovalbumin (OVA) as a model antigen, to determine its suitability as a vaccine carrier. Next, the effect of AgNCs and AuNCs on bone-marrow-derived dendritic cells (BMDCs) is assessed in vitro. Finally, in vivo humoral and cellular immune responses of AgNC–OVA and AuNC–OVA following intramuscular immunization and their prophylactic effects in B16F10-OVA mice tumor model are investigated. In terms of OVA loading efficiency, AgNCs are superior to AuNCs. Both nanomaterials are found not to induce BMDC maturation at subtoxic doses. After administration of nanovaccines, serum immunoglobulin G (IgG) responses are comparable between groups. However, there are slight alterations in relative frequencies of lymphocyte subpopulations, with AgNC–OVA-immunized mice exhibiting lower memory T cells and reduced B cell and T follicular helper cell populations in spleen. Overall, AgNC–OVA and AuNC–OVA immunizations do not alter tumor growth. This study characterizes the intrinsic immunomodulatory properties of AgNCs and AuNCs, as protein subunit vaccine carriers.

In this study, a flexible and wearable chemiresistive biosensor (FWCB) is developed for the real-time analysis of glucose in sweat on the human skin surface based on a novel detection strategy of p-type reduced graphene oxide (rGO) sensing film, which met the requirements of rapid, nondestructive testing. The proposed FWCB is fabricated in the form of interdigital electrodes (IEs) made of laser-induced graphene (LIG) synthesized by the laser inducing of a polyimide (PI) film. Additionally, a semiconducting rGO sensing film modified on the surface of IEs is synthesized by thermal reduction of graphene oxide (GO), which is functionalized with glucose oxidase (GOx) by chemical cross-linking to obtain GOx/FWCB. Moreover, the key parameters for FWCB fabrication are optimized, and the sensing strategy of the proposed GOx/FWCB is also investigated. The results show that the proposed GOx/FWCB can be used for the detection of glucose in the range of 0.01–3.0 mM with satisfactory selectivity, and the limit of detection (LOD) is calculated to be as low as 0.8 µM (S/N = 3). These dramatic advantages endow the proposed FWCB with broad application prospects in the field of portable, wearable, and real-time detection of glucose in human sweat for health monitoring.

Orthopedic implants provide patients with an opportunity to regain functionality lost from illness, disease, or injury. Recent advancements in additive manufacturing (AM) techniques have allowed for the increased customization of Ti-6Al-4V ELI (extra low interstitials) implants to complement natural variations in the human anatomy. Yet, the low bioactivity of Ti-6Al-4 V ELI and possible adverse effects from the leeching of aluminum and vanadium complicate the post-operation recovery process. In this work, Ti-6Al-4 V ELI samples are printed using the electron beam melt technique in two directions and coated with diamond-like carbon (DLC) to examine whether their biological properties can be improved. By conducting in vitro studies with Saos-2 osteosarcoma cells, the effects of morphology and surface chemistry are correlated to the bioactivities of the coated and uncoated samples. The outcome of the study suggested that DLC coating is a viable method for controlling the surface bioactivity of a material. It indicates that a carbon coating, along with an appropriate topography, has the potential to promote the proliferation and maturity of bone cells and hence enhance the performance of additively manufactured products in next-generation biomedical applications.

Multiferroics have been investigated extensively in the last decades due to their wide range of applications in high-density multistate storage, spintronics, and novel multifunctional magnetic–electric devices. One peculiar subgroup of multiferroic materials comprises 3D perovskite metal–organic frameworks (MOFs) with the general formula ABX3 (A = monovalent organic cation (such as an alkali metal or protonated amine), B = divalent metal cation, X = organic anion), for their coexistence of multiple orders (electric, magnetic, and elastic, et al.). The purpose of this review is to give a representative overview of the recent progress in the field of ABX3-type multiferroic MOFs, containing 3d magnetic metal ions at B-site. First, the perovskite multiferroic MOFs in which X-site is occupied by formate, is examined and summarized. In particular, magnetoelectric coupling effects, such as electric-field tuning of magnetic properties and magnetic field control of electric polarization, and pressure control of structural/magnetic/electric properties, are described and discussed. Then, it is focused on the structural phase transitions and ferroic orders by analyzing several representative multiferroic MOFs compounds with none-formate. To motivate the researchers in this area, some promising topics that have not yet been fully explored in perovskite multiferroic MOFs are finally proposed.

Photodetectors play a crucial role in converting light signals into electrical signals and have significant applications in various fields such as communications, imaging, and sensing. However, the fabrication of a photodetector is a complex process that involves precise control of surface preparation, lithography, and deposition techniques. Here the study demonstrates that GaN/Ga2O3 heterojunctions can be fabricated utilizing laser processing to transform the surface of GaN into Ga2O3. The GaN/Ga2O3 heterojunctions exhibit good reproducibility, uniformity, and ability to operate under zero bias, with a responsivity of 110.22 mA W−1, a detection rate of 5.56 × 1011 jones, and an external quantum efficiency of 42.34%. Moreover, an 8 × 8 photodetector array based on GaN/Ga2O3 heterojunction is fabricated via laser writing and is demonstrated to have ultraviolet imaging capabilities. This report presents the pioneering fabrication of a photodetector array using laser writing. The findings offer a versatile and scalable approach for the production of large-area heterojunction photodetector arrays.

Mineralized fibrils are important building blocks in bone tissue, formed by the hierarchical assembly of collagen molecules and crystalline hydroxyapatite (HAp). The mineralization pathway of HAp is reported as a nonclassical-crystallization, but the nanoconfined crystallization in collagen fibrils remains poorly understood. The mechanism of intrafibrillar mineralization of collagen-PDA fibrils in modified-simulated body fluid (m-SBF) solution is studied. Collagen-amorphous calcium phosphate (ACP) fibrils are obtained by assembling collagen-PDA fibrils with polyaspartic acid (pAsp) as a stabilizer. The ACP undergoes a phase transformation to HAp within the fibrils upon adjusting the phosphate concentration. It is found that the phase transformation of ACP to HAp in collagen fibrils can be accelerated with a 12 h incubation with 1/10 ratio of Ca2+ to [PO4]3−. A lower ratio of 1/1 and 1/5 results in a much slower phase transformation. This finding suggests that an elevated concentration of [PO4]3− is crucial for faster phase transformation. The relationship between the crystallization rate of HAp in the fibrils and the degree of mineralization is found to be linear in all cases, indicating an interface-controlled process. This gives a better understanding of the mechanism of HAp mineralization in collagen fibrils, providing an effective approach to material design.