25,435 research outputs found

    Design of TiO<sub>2</sub>@Carbon@Prussian Blue Core–Shell Nanorod Arrays for Enhanced Photoelectrochemical Performance

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    The thoughtful design of effective photoanodes has drawn significant attention. Here, a Z-scheme core–shell TiO2@carbon@prussian blue (TiO2@C@PB) is designed for photoelectrochemical water splitting. TiO2@C@PB composite film has a larger absorption range, and the band gap is decreased from 3.10 to 2.65 eV. Under illumination conditions, the TiO2@C@PB composite photoanode achieves a photocurrent density of 2.78 mA/cm2 at 1.23 V vs RHE, nearly 2.5 times higher than that of pure TiO2. The enhancement is ascribed to the suppressed recombination of photogenerated charges facilitated by the Z-scheme heterojunction and the excellent conductivity of carbon. This study offers an effective approach for developing highly efficient photoelectrochemical water-splitting photoanodes

    Multifunctional engineering on the ultrasensitive driven-dual plasmonic heterogenous dimer system of 1D semiconductor for accurate SERS sensitivity and quantitation

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    Self-assembled functional nanomaterials with electromagnetic (EM) hot spots and chemical (CM) enhancement have been recognized as a key in surface-enhanced Raman scattering (SERS) analysis. Herein, a dual-hybrid plasmonic coupling SERS sensor composed of rutile TiO2 nanorod arrays (r-TNRs), Au nanospheres (AuNSs), and Ag nanocubes (AgNCs) has been designed to achieve ultrasensitive detection and obtain unique molecular fingerprints. The AgNCs/AuNSs/r-TNRs-based SERS chip shows an extremely promising SERS enhancement factor (EF) of 1.2 ×1011, detectability at sub-picomolar concentrations (down to the single-molecule level, 10-13 M), and excellent signal reproducibility with a relative standard deviation (RSD) of 3.4 %. Furthermore, this system has been applied for fingerprint detection in complex mixtures, demonstrating impressive specificity and accuracy. The photocatalytic decomposition efficiency of the AgNCs/AuNSs/r-TNRs platform reaches approximately ∌99 % within 20 min. Additionally, the Raman intensity of crystal violet only declined by 15 % after 21 days, illustrating the outstanding stability of the as-proposed ternary SERS sensor

    Multikomponentelle Assemblierungen aus Halbleiter- und Edelmetallnanopartikeln

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    Die folgende Arbeit handelt von Nanopartikeln verschiedener Materialien und deren Assemblierung (Gelierung) mit Hilfe verschiedener Techniken. Konkret werden multikomponentelle Systeme bestehend aus CdSe/CdS (Kern-Schale) NanostĂ€bchen und Au bzw. Pt Nanopartikeln und -kabeln (im Falle von Au) verwendet und als Modellsysteme zur Untersuchung der Eigenschaften der Netzwerkstrukturen genutzt. Hierbei finden verschiedene Gelierungsmethoden Anwendung, die einen direkten Einfluss auf die Partikel-KonnektivitĂ€t und deren elektronischen Ladungsaustausch nehmen. Konkret handelt es sich zum einen um oxidative Assemblierungsprozesse mittels Wasserstoffperoxid und zum anderen um Gelierungsmethoden mittels Ionen (Ba2+, Ca2+, S2−, Y3+ und Yb3+). Es wird zunĂ€chst untersucht, welchen Einfluss diese verschiedenen Gelierungsmittel auf die resultierende Anordnung anisotroper CdSe/CdS NanostĂ€bchen innerhalb eines Netzwerkes nehmen (siehe Kapitel 4). Desweiteren werden kolloidale Mischungen von halbleitenden CdSe/CdS NanostĂ€bchen und Au Nanopartikeln in unterschiedlichen PartikelverhĂ€ltnissen durch verschiedene Kationen (Ba2+, Ca2+, Y3+ und Yb3+) geliert. Die Mischgele werden hinsichtlich der Struktur im resultieren den Netzwerk untersucht (Kapitel 5). In diesem Zusammenhang werden die spektroskopischen Eigenschaften der Systeme umfangreich analysiert. Unter Anwendung von Röntenphotonenspektroskopie (XPS) werden die BindungszustĂ€nde auf den OberflĂ€chen der gemischten Systeme genauer untersucht, um RĂŒckschlĂŒsse auf die möglichen Gelierungsmechanismen zu erhalten. Um den LadungstrĂ€gertransport in halbleitenden CdSe/CdS NanostĂ€bchen-Netzwerken mit einer experimentellen Methode nachzuvollziehen, werden gemischte CdSe/CdS:Au Gele mit unterschiedlichen NanostĂ€bchen zu Nanopartikel-VerhĂ€ltnissen durch die Zugabe von Wasserstoffperoxid hergestellt und spektroskopisch charakterisiert. Durch die Variation des Au-Nanopartikelanteils werden im System statistisch verteilt Bausteine zum Auslöschen des LadungstrĂ€gertransfers eingebaut. Diese werden abschließend dazu genutzt, um die Distanz, die ein photonisch generierter LadungstrĂ€ger in Form eines Elektrons im Verbund der HalbleiternanostĂ€bchen zurĂŒcklegen kann, zu quantifizieren. Siehe hierzu Kapitel 6. Kapitel 7 umfasst die Arbeiten an Strukturen, die als interpenetrierte Netzwerke bezeichnet werden können. Hierbei werden Au-NanodrĂ€hte mit CdSe/CdS-NanostĂ€bchen kombiniert und so ein durchwachsenes Netzwerk erhalten. Die strukturellen Unterschiede werden mit Hilfe von Elektronenmikroskopie (TEM und REM) untersucht. Zur Charakterisierung der elektronischen Eigenschaften der interpenetrierten Netzwerke werden Photo-Elektrochemische Messungen verwendet.The following work is about nanoparticles of different materials and their assembly (gelation) using different techniques. Specifically, multicomponent systems consisting of CdSe/CdS (core-shell) nanorods and Au or Pt nanoparticles and nanowires (in case of Au) are used as model systems to investigate the properties of the network structures. Various gelation methods are applied here, which have a direct influence on the particle connectivity and their electronic charge exchange. Specifically, these are oxidative assembly processes using hydrogen peroxide on the one hand and gelation methods using ions (Ba2+, Ca2+, S2−, Y3+ and Yb3+) on the other. The influence of these different gelling agents on the resulting arrangement of anisotropic CdSe/CdS nanorods within a network is first investigated (see chapter 4). In the further course, the effect of spherical metal nanoparticles on the gelation with semiconducting Cd- Se/CdS nanorods by means of cations (Ba2+, Ca2+, Y3+ and Yb3+) is investigated (chapter 5). In this context, the spectroscopic properties of the systems are extensively analysed. By means of X-ray photon spectroscopy (XPS), the binding states of the mixed systems are investigated in more detail in order to draw conclusions about the possible gelation mechanisms. In order to analyze the charge carrier transport in semiconducting CdSe/CdS nanorod networks with an experimental method, mixed Cd- Se/CdS:Au gels with different nanorod:nanoparticle ratios are prepared using hydrogen peroxide and spectroscopically characterised. By varying the Au nanoparticle fraction, building blocks are incorporated into the system in a statistically distributed manner to quench charge carrier transfer. Finally, these are used to quantify the distance that a photonically generated charge carrier in the form of an electron can travel in the backbone of semiconductor nanorod networks, see chapter 6. Chapter 7 covers work on structures that can be described as interpenetrated networks. Here, Au nanowires are combined with CdSe/CdS nanorods to obtain a interpenetrated networks. The structural differences are intensively investigated by electron microscopy (TEM and SEM). Photo-electrochemical measurements are used to characterize the electronic properties of the interpenetrated networks

    Integrating plasmonic supercrystals in microfluidics for ultrasensitive, label-free, and selective surface-enhanced raman spectroscopy detection

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    Surface-enhanced Raman spectroscopy (SERS) microfluidic chips for label-free and ultrasensitive detection are fabricated by integrating a plasmonic supercrystal within microfluidic channels. This plasmonic platform allows the uniform infiltration of the analytes within the supercrystal, reaching the so-called hot spots. Moreover, state-of-the-art simulations performed using large-scale supercrystal models demonstrate that the excellent SERS response is due to the hierarchical nanoparticle organization, the interparticle separation (IPS), and the presence of supercrystal defects. Proof-of-concept experiments confirm the outstanding performance of the microfluidic chips for the ultradetection of (bio)molecules with no metal affinity. In fact, a limit of detection (LOD) as low as 10–19 M was reached for crystal violet. The SERS microfluidic chips show excellent sensitivity in the direct analysis of pyocyanin secreted by Pseudomonas aeruginosa grown in a liquid culture medium. Finally, the further integration of a silica-based column in the plasmonic microchip provides charge-selective SERS capabilities as demonstrated for a mixture of positively and negatively charged molecules.Agencia Estatal de Investigación | Ref. TEC2017-85376-C2-1-RAgencia Estatal de Investigación | Ref. TEC2017-85376-C2-2-RXunta de Galicia | Ref. GRC ED431C 2016−486 048Gobierno de Extremadura | Ref. IB18073Agencia Estatal de Investigación | Ref. IJCI-2016-2910

    Sialic acids in infection and their potential use in detection and protection against pathogens

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    In structural terms, the sialic acids are a large family of nine carbon sugars based around an alpha-keto acid core. They are widely spread in nature, where they are often found to be involved in molecular recognition processes, including in development, immunology, health and disease. The prominence of sialic acids in infection is a result of their exposure at the non-reducing terminus of glycans in diverse glycolipids and glycoproteins. Herein, we survey representative aspects of sialic acid structure, recognition and exploitation in relation to infectious diseases, their diagnosis and prevention or treatment. Examples covered span influenza virus and Covid-19, Leishmania and Trypanosoma, algal viruses, Campylobacter, Streptococci and Helicobacter, and commensal Ruminococci

    Laser-induced forward transfer: fundamentals and applications

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    Laser-induced forward transfer (LIFT) is a digital printing technique that uses a pulsed laser beam as the driving force to project material from a donor thin film toward the receiving substrate whereon that material will be finally deposited as a voxel. This working principle allows LIFT to operate with both solid and liquid donor films, which provides the technique with an unprecedented broad spectrum of printable materials, and thus makes it very competitive over other digital technologies, like inkjet printing. It is not only that LIFT can access a much wider range of ink viscosities and loading particle sizes; the possibility of printing from solid films allows the single-step printing of multilayers and entire devices, and even makes possible 3D printing. This versatility translates, in turn, into a broad field of applications, from graphics production to printed electronics, from the fabrication of chemical sensors to tissue engineering. This monograph provides an extensive review of the LIFT technique, from its origins to the most recent achievements, focusing on the fundamental aspects of both its working principle and transfer dynamics, as well as on its broad range of applications

    Application of disposable chiral plasmonics for biosensing and Raman spectroscopy

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    This thesis explores the capabilities of disposable chiral plasmonic metafilm assays, termed Disposable Plasmonic Assays, as a promising platform for biosensing and surface-enhanced Raman spectroscopy. The sensing and Raman properties of these metafilms arise from the excitation of surface plasmons when exposed to incident light. These plasmonic properties strongly depend on the geometric characteristics of the constituent nanostructures found in the metafilms. Specifically, the primary nanostructure employed throughout this research is the chiral 'shuriken' star, which generates chiral electromagnetic fields exhibiting greater chiral asymmetry than circularly polarized light. Monitoring changes in the resonance positions of the characteristic optical rotatory dispersion spectra produced by the Disposable Plasmonic Assays allows for the observation of surface binding events. By measuring resonance shift data and through the utilisation of various gold film functionalisation techniques, these assays are demonstrated as versatile, label-free biosensing platforms capable of specifically detecting a wide range of target proteins and virus particles from complex solutions. Furthermore, the multiplexing performance of these assays is showcased, enabling the detection of multiple different antigens and virions in a single experiment. These results highlight the potential of plasmonic metafilms as rapid and disposable point-of-care immunoassays for diagnostic applications. In addition to biosensing, the chiral geometry of Disposable Plasmonic Assays is exploited for the chiral discrimination of metal nanoparticles and small molecules using Surface Enhanced Raman Spectroscopy (SERS). By linking helicoid shaped gold nanoparticles to the metafilm surface via a dithiol linker, the chiral properties of both nanoparticles and metafilms combine, resulting in the creation of differential electromagnetic 'hotspot' regions based on their symmetry combinations. The electromagnetic intensity in these regions corresponds to the SERS signal obtained from the achiral dithiol linker molecule, facilitating a deeper understanding of the chirally dependent SERS phenomenon. These findings serve to validate and explain the differential SERS data obtained enantiomers of biomolecules and drug molecules from silver modified Disposable Plasmonic Assays

    Whispering-Gallery Mode Optoplasmonic Microcavities: From Advanced Single-Molecule Sensors and Microlasers to Applications in Synthetic Biology

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    This is the final version. Available on open access from the American Chemical Society via the DOI in this recordOptical microcavities, specifically, whispering-gallery mode (WGM) microcavities, with their remarkable sensitivity to environmental changes, have been extensively employed as biosensors, enabling the detection of a wide range of biomolecules and nanoparticles. To push the limits of detection down to the most sensitive single-molecule level, plasmonic nanorods are strategically introduced to enhance the evanescent fields of WGM microcavities. This advancement of optoplasmonic WGM sensors allows for the detection of single molecules of a protein, conformational changes, and even atomic ions, marking significant contributions in single-molecule sensing. This Perspective discusses the exciting research prospects in optoplasmonic WGM sensing of single molecules, including the study of enzyme thermodynamics and kinetics, the emergence of thermo-optoplasmonic sensing, the ultrasensitive single-molecule sensing on WGM microlasers, and applications in synthetic biology.Biotechnology and Biological Sciences Research Council (BBSRC)Engineering and Physical Sciences Research Council (EPSRC

    Heterostructured WO3–TiVO4 thin-film photocatalyst for efficient photoelectrochemical water splitting

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    This is the final version. Available from Elsevier via the DOI in this record. Data availability: Data associated with this study have not been deposited into a publicly available repository. Data will be made available on request to the corresponding author.Photoelectrochemical water splitting via solar irradiation has garnered significant interest due to its potential in large-scale renewable hydrogen production. Heterostructure materials have emerged as an effective strategy, demonstrating enhanced performance in photoelectrochemical water-splitting applications compared to individual photocatalysts. In this study, to augment the performance of sprayed TiVO4 thin films, a hydrothermally prepared WO3 underlayer was integrated beneath the spray pyrolised TiVO4 film. The consequent heterostructure demonstrated notable enhancements in optical, structural, microstructural attributes, and photocurrent properties. This improvement is attributed to the strategic deposition of WO3 underlayer, forming a heterostructure composite electrode. This led to a marked increase in photocurrent density for the WO3/TiVO4 photoanode, reaching a peak of 740 ÎŒA/cm2 at an applied potential of 1.23 V vs RHE, about nine-fold that of standalone TiVO4. Electrochemical impedance spectroscopy revealed a reduced semicircle for the heterostructure, indicating improved charge transfer compared to bare TiVO4. The heterostructure photoelectrode exhibited enhanced charge carrier conductivity at the interface and sustained stability over 3 h. The distinct attributes of heterostructure photoelectrode present significant opportunities for devising highly efficient sunlight-driven water splitting systems.Engineering and Physical Sciences Research Council (EPSRC)Saudi Arabia Culture Bureau in the United Kingdo

    Literature Review : Sintesis Hidroksiapatit dari Bahan Alam sebagai Biomaterial

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    Bone damage or bone defects are a significant global health problem that can cause loss of daily productivity and even death. The large number of cases of bone defects has led to an increase in demand for biomaterials or bone substitutes. Hydroxyapatite (HAp) is one of the most promising biomaterials for the treatment of bone defects. Synthetic hydroxyapatite risks being an expensive, complex, time-consuming method, producing hydroxyapatite with low biological performance with trace element deficiencies. Synthesis of hydroxyapatite using natural sources of calcium is an alternative. Several researchers have investigated the synthesis of hydroxyapatite from various sources, such as eggshells, snail shells, mammalian bones, etc. The purpose of this literature review is to provide information regarding the synthesis of hydroxyapatite using natural sources of calcium to assist in finding the best method with the resulting hydroxyapatite meeting the requirements for bone treatment applications. The article search method for compiling a literature review was carried out using the Boolean method on the Sciencedirect database of 2873 articles, then screening resulted in 38 articles. The article then creates a synthesis matrix to combine several elements to then obtain conclusions. The results of the Literature Review show that the choice of method and source of synthetic materials influences the particle size, crystallinity and stoichiometric composition of the resulting hydroxyapatite. Mechanochemical, hydrothermal, sol-gel and calcination methods tend to produce hydroxyapatite with small particle sizes and narrow particle size distributions. Calcination and hydrothermal methods tend to produce hydroxyapatite with higher crystallinity than other methods. The mechanochemical method can maintain stoichiometric composition and the hydrothermal method produces close to stoichiometric. The mechanochemical method is the simplest method with a shorter time. The natural material dolomite is free from any risk of infection and is safer to use than other material sources
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