Metals Au Research Articles

THE INVESTIGATION OF ALTERNATIVE METALS OF Au, Ag, Al AND Cu FOR BACK CONTACT USED IN FABRICATED ZnS/SnS HETEROJUNCTION FOR SOLAR CELL APPLICATION

THE INVESTIGATION OF ALTERNATIVE METALS OF Au, Ag, Al AND Cu FOR BACK CONTACT USED IN FABRICATED ZnS/SnS HETEROJUNCTION FOR SOLAR CELL APPLICATION

Dual External Field Strategy in Regulating the Superhalogen Characteristics of the Non-Noble Metal Constituted Tantalum Oxide Clusters.

The identification of the non-noble metal constituted TaO cluster as a potential analogue to the noble metal Au is significant for the development of tailored materials. It leverages the superatom concept to engineer properties with precision. However, the impact of incrementally integrating TaO units on the electronic configurations and properties within larger TaO-based clusters remains to be elucidated. By employing the density functional theory calculations, the global minima and low-lying isomers of the TanOn (n = 2-5) clusters were determined, and their structural evolution was disclosed. In the cluster series, Ta5O5 was found to possess the highest electron affinity (EA) with a value of 2.14 eV, based on which a dual external field (DEF) strategy was applied to regulate the electronic property of the cluster. Initially, the electron-withdrawing CO ligand was affixed to Ta5O5, followed by the application of an oriented external electric field (OEEF). The CO ligation was found to be able to enhance the Ta5O5 cluster's electron capture capability by adjusting its electron energy levels, with the EA of Ta5O5(CO)4 peaking at 2.58 eV. Subsequently, the introduction of OEEF further elevated the EA of the CO-ligated cluster. Notably, OEEF, when applied along the +x axis, was observed to sharply increase the EA to 3.26 eV, meeting the criteria for superhalogens. The enhancement of EA in response to OEEF intensity can be quantified as a functional relationship. This finding highlights the advantage of OEEF over conventional methods, demonstrating its capacity for precise and continuous modulation of cluster EAs. Consequently, this research has adeptly transformed tantalum oxide clusters into superhalogen structures, underscoring the effectiveness of the DEF strategy in augmenting cluster EAs and its promise as a viable tool for the creation of superhalogens.

Sequential Selective Dissolution of Coinage Metals in Recyclable Ionic Media.

Coinage metals Cu, Ag, and Au are essential for modern electronics and their recycling from waste materials is becoming increasingly important to guarantee the security of their supply. Designing new sustainable and selective procedures that would substitute currently used processes is crucial. Here, we describe an unprecedented approach for the sequential dissolution of single metals from Cu, Ag, and Au mixtures using biomass-derived ionic solvents and green oxidants. First, Cu can be selectively dissolved in the presence of Ag and Au with a choline chloride/urea/H2O2 mixture, followed by the dissolution of Ag in lactic acid/H2O2. Finally, the metallic Au, which is not soluble in either solution above, is dissolved in choline chloride/urea/Oxone. Subsequently, the metals were simply and quantitatively recovered from dissolutions, and the solvents were recycled and reused. The applicability of the developed approach was demonstrated by recovering metals from electronic waste substrates such as printed circuit boards, gold fingers, and solar panels. The dissolution reactions and selectivity were explored with different analytical techniques and DFT calculations. We anticipate our approach will pave a new way for the contemporary and sustainable recycling of multi-metal waste substrates.

Sequential Selective Dissolution of Coinage Metals in Recyclable Ionic Media

AbstractCoinage metals Cu, Ag, and Au are essential for modern electronics and their recycling from waste materials is becoming increasingly important to guarantee the security of their supply. Designing new sustainable and selective procedures that would substitute currently used processes is crucial. Here, we describe an unprecedented approach for the sequential dissolution of single metals from Cu, Ag, and Au mixtures using biomass‐derived ionic solvents and green oxidants. First, Cu can be selectively dissolved in the presence of Ag and Au with a choline chloride/urea/H2O2 mixture, followed by the dissolution of Ag in lactic acid/H2O2. Finally, the metallic Au, which is not soluble in either solution above, is dissolved in choline chloride/urea/Oxone. Subsequently, the metals were simply and quantitatively recovered from dissolutions, and the solvents were recycled and reused. The applicability of the developed approach was demonstrated by recovering metals from electronic waste substrates such as printed circuit boards, gold fingers, and solar panels. The dissolution reactions and selectivity were explored with different analytical techniques and DFT calculations. We anticipate our approach will pave a new way for the contemporary and sustainable recycling of multi‐metal waste substrates.

Probe Beam Deflection study of Au Nanoparticles Supported into TiO2 Mesoporous Films

Mesoporous thin films modified with nanoparticles of metal (Au) have been used for the fabrication of an ultra‐microelectrode array (UMEA). For the first time, UMEAs were studied using probe beam deflection (PBD) and cyclic voltammetry. The study was carried out using the [Fe(CN)6]3‐/ [Fe(CN)6]4‐ couple as a redox probe. The electrochemical response is that of an array of nanoelectrodes. The effects of scan rate on the current and PBD signal profiles are discussed in the context of mass transport within the pores and at the solution‐electrode interface. The study suggests that the combination of PBD and CV allows a better understanding on the mass transport phenomena in this type of UMEAs of complex architecture.

Investigation on New Orthorhombic AuR (R = Ho, Tb, Y) and PdR (R = Eu,Gd,Y) Equiatomic Compounds’ Structural, Vibrational, and Thermal Properties

Herein, first‐principles calculations using the planewave pseudopotential technique to assess the structural, elastic, vibrational, and thermal properties of equiatomic intermetallic consisting of rare earth elements (Eu, Gd, Ho, Y, Tb) and noble metals (Au, Pd) are used. This approach involves optimizing novel orthorhombic structures by minimizing the total energy and interatomic forces. The computed structural features for the investigated intermetallics closely align with available experimental data. By evaluating stability criteria using the derived elastic constants, this analysis verifies the stability of these intermetallics in an orthorhombic structure at zero pressure. Furthermore, various mechanical parameters are determined, including (Young's E, bulk B, shear G, Pugh's) modulus, Poisson's ratio, and anisotropy factors. These parameters are derived from the computed single‐crystal elastic constants using the Voigt–Reuss–Hill average method. This investigation delves into the relationship between temperature and variations in heat capacity at constant volume (Cv) and entropy (S), comprehensively exploring these variables.

Revealing pretreatment-induced structure evolution of LaFeO3 supported Au catalyst for CO oxidation reaction

Heterogeneous catalysts play a pivotal role in the chemical industry. Pretreatments in reducing or oxidizing atmospheres have been widely utilized to alter the structure of heterogeneous catalysts, with the aim of enhancing their catalytic performance. However, the pretreatment atmosphere can, at times, trigger unexpected structural changes in catalysts and even lead to catalytic degradation. Hence, the selection of an appropriate pretreatment atmosphere for heterogeneous catalysts is critical and requires a clear understanding of their corresponding dynamic evolution to improve their performance in a targeted manner, particularly relying on in situ observation. In this study, a promising CO oxidation catalyst, LaFeO3 supported Au nanoparticles (Au/LFO) is selected, and the influence of the pretreatments in different atmospheres on Au/LFO is explored by using in situ transmission electron microscopy (TEM) and density functional theory (DFT) calculation. Our findings reveal that the commonly used reducing pretreatment for noble-metal catalysts triggered strong metal-support interactions in Au/LFO, suppressing its CO adsorption performance. In contrast, the oxidizing pretreatment preserves the metallic Au and the metal/support interface as efficient active sites to promote CO oxidation activity and stability simultaneously. This work discloses the structure evolution at the interface between noble metals and perovskite oxide supports in response to different gas phase treatments and clarifies their structure-property relationships.

Preparation of Au–Ni bimetallic-coated monodisperse PS@Ni/Au microspheres with excellent conductivity and their application in acrylate-based anisotropic conductive adhesives

Anisotropic conductive adhesives (ACAs) provide an efficient and easy method of interconnecting small electronic devices compared to traditional solder joint connections. In this paper, PS@Ni/Au metal composite microspheres with excellent electrical conductivity in the size of 2.76 μm were prepared by chemical plating technique and in situ redox method. The effects of PS@Ni metal composite microspheres with different shell thicknesses and compactness on the preparation of Ni–Au bimetallic shell layers were investigated, and the effects of different Au:PS@Ni mass ratios on the volumetric conductivity of PS@Ni/Au metal composite microspheres were discussed. The composite microspheres were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy spectrometry (EDS), and X-ray diffraction (XRD). Thick and compact Ni metal shells are the key to preparing PS@Ni/Au metal composite microspheres with the complete degree of encapsulation. When the mass ratio of Au:PS@Ni was 0.15:1, the conductivity was as high as 1.3 × 105 S cm−1. The acrylate pressure-sensitive containing 3.1–8.3 vol% conductive particles presented an obvious anisotropy. When the mass ratio of the conductive particles was higher than 8.3 vol%, the conductive particles appear to be significantly aggregated. The research ideas and methods have great application potential for replacing the traditional solder joint connections.

Improving photocatalytic efficiency of ZnO nanoflowers through gold incorporation for Rhodamine B photodegradation

In this study, we reported the synthesis and characterization of Au-doped ZnO hybrid nanostructures via a wet chemical approach and assessed their photocatalytic efficiency for the removal of Rhodamine (Rh–B). X-ray powder diffraction (XRD) has been done to verify the crystal structure, i.e. phase identification, crystallite size, texture, stress, and strain. The XRD patterns demonstrate that the wurtzite structure has been retained and that Au nanoparticles were effectively ingested into the ZnO nanoflowers lattice. This demonstrates that Au nanoparticles are effectively absorbed into the ZnO nanoflowers lattice, considering that peaks shifted in the direction of smaller Bragg's angles. As a result, the size of the crystallites increases from (20.7–25.3) nm, and their microstrain decreases from (0.92–0.72) x 10−3 A0 for pure-ZnO to Au-doped ZnO heterostructures, respectively. Scanning Electron Microscopy (SEM) investigation reveals flower-like structures of pure ZnO while a further closed look indicates that these flowers are made up of a variety of oriented, thorn-like branched NWs with diameters ranging from (50–90) nm and lengths ranging from a few microns. The corresponding EDS evaluation of pure ZnO nanoflowers and Au-doped ZnO heterostructures clearly shows that the noble metal Au NPs are deposited, and enormously safeguard the surface of ZnO nanoflowers. Reducing the Au-doped ZnO band gap which generated a red shift in light absorption, was confirmed by the PL spectra which in turn increased the photocatalytic efficiency and reduced the dye degradation time of Rh–B. The photocatalytic ability of Au-doped ZnO heterostructures considerably increased the photodegradation efficiency of Rh–B molecules from 28 min for pure ZnO to 10 min for Au-doped ZnO heterostructures. Due to their wide surface area and distinct morphology as compared to pure ZnO nanoflowers.

Investigation of transition metals (Ag, Au, Pd, Pt and Ru)-doped boron nitride nanocarrier for drug delivery process of favipiravir: An intuition from DFT

The scientific community is keenly interested in developing efficient drug delivery systems using B12N12, particularly for carrying anti-influenza drugs like Favipiravir (FAV) against life-threatening RNA virus infections. This study delves into the exploration of transition metal-doped B12N12 nanostructures as potential carriers for drug delivery. Using density functional theory (DFT) calculations at the wB97XD/6-311++G(d,p) level of theory, the research specifically investigates the efficacy of transition metal-doped (Ag, Au, Pd, Pt, and Ru) boron nitride nanocages as effective agents for delivering the FAV drug. The systematic exploration of adsorption energy, electronic features, and thermodynamic properties (ΔG and ΔH) of FAV interacting with B12N12 and transition metals-doped (Ag, Au, Pd, Pt, and Ru) nanocages reveals a significant improvement in drug-carrying capacity, marked by notable physisorption capabilities as evident from negative adsorption energies. The confirmation of FAV’s interaction with doped-B12N12 nanocages was supported by a comprehensive analysis encompassing frontier molecular orbitals, adsorption energy, fractional charge transfer, molecular electrostatic potential (MEP), non-covalent interaction(NCI), and natural bond orbital (NBO) assessments. The frontier molecular orbitals (FMO), density of states (DOS), and natural bond orbital (NBO) analyses reveal nanocages as charge acceptors and drug as charge donor during the adsorption process. The band gap energies decreased upon FAV adsorption on both pristine and doped nanocages except Au and Pd doped nanocages. Among the doped cases, the Ag-doped B12N12 nanocage exhibits the most significant reduction in the HOMO-LUMO energy difference, and therefore should be the most effective nanocarrier for FAV. The results of this study offer novel insights for the development of B12N12 nanocages as carriers for the FAV drug.

Plastic Optical Fiber Sensor for Sensing Refractive Index of Citric Acid Based on Surface Plasmon Resonance

Using plastic optical fiber with multimode (MPOF), an optical fiber sensor (OFS) based on Surface Plasmon Resonance (SP.R) was created and put into use. The sensor is used to determine performance metrics including signal to noiseratio (SNR), Sensitivity(S), Figure of merit(FOM), and Resolution(R) in addition to detecting and measuring the refractive index of different concentrations of citric acid. With a sensing region exposed to 50 nm of gold (Au) metal layer, the optical fiber-based SPR sensor was found to have a sensitivity value of 1250nm, an SNR of 0.27, a figure of merit of 93.3 and a resolution 8×10-4.

The Chain of Processes Forming Porphyry Copper Deposits—An Invited Paper

Abstract Porphyry-related mineral deposits are giant geochemical anomalies in the Earth’s crust with orders-of-magnitude differences in the content and proportion of the three main ore metals Cu, Au, and Mo. Deposit formation a few kilometers below surface is the product of a chain of geologic processes operating at different scales in space and time. This paper explores each process in this chain with regard to optimizing the chances of forming these rare anomalies. On the lithosphere scale, deposits with distinct metal ratios occur in provinces that formed during brief times of change in plate motions. Similar metal ratios of several deposits in such provinces compared with global rock reservoirs suggest preceding enrichment of Au or Mo in lithospheric regions giving rise to distinct ore provinces. The largest Cu-dominated deposits and provinces are traditionally explained by selective removal of Au during generation or subsequent evolution of mantle magmas, but the possibility of selective Cu pre-enrichment of lithosphere regions by long-term subduction cannot be dismissed, even though its mechanism remains speculative. Evolution of hydrous basaltic melts to fertile magmas forming porphyry Cu deposits requires fractionation toward more H2O-rich magmas in the lower crust, as shown by their adakite-like trace element composition. The prevailing interpretation that this fractionation leads to significant loss of chalcophile ore metals by saturation and removal of magmatic sulfide might be inverted to a metal enrichment step, if the saturating sulfides are physically entrained with the melt fraction of rapidly ascending magmas. Ascent of fertile magma delivers a large mass of H2O-rich ore fluid to the upper crust, along points of weakness in an overall compressive stress regime, within a limited duration as required by mass and heat balance constraints. Two mechanisms of rapid magma ascent are in debate: (1) wholesale emplacement of highly fractionated and volatile-rich granitic melt into a massive transcrustal channelway, from which fluids are exsolved by decompression starting in the lower crust, or (2) partly fractionated magmas filling a large upper crustal magma chamber, from which fluids are expelled by cooling and crystallization. Transfer of ore-forming components to a hydrothermal ore fluid is optimized if the first saturating fluid is dense and Cl rich. This can be achieved by fluid saturation at high pressure, or after a moderately H2O rich intermediate-composition melt further crystallizes in an upper crustal reservoir before reaching fluid saturation. In either case, metals and S (needed for later hydrothermal sulfide precipitation) are transferred to the fluid together, no matter whether ore components are extracted from the silicate melt or liberated to the ore fluid by decomposition of magmatic sulfides. Production and physical focusing of fluids in a crystallizing upper crustal magma chamber are controlled by the rate of heat loss to surrounding rocks. Fluid focusing, requiring large-scale lateral flow, spontaneously occurs in mushy magma because high water content and intermediate melt/crystal ratio support a network of interconnected tubes at the scale of mineral grains. Calculated cooling times of such fluid-producing magma reservoirs agree with the duration of hydrothermal ore formation measured by high-precision zircon geochronology, and both relate to the size of ore deposits. Ore mineral precipitation requires controlled flow of S- and metal-rich fluids through a vein network, as shown by fluid inclusion studies. The degree of hydrothermal metal enrichment is optimized by the balance between fluid advection and the efficiency of cooling of the magmatic fluid plume by heat loss to convecting meteoric water. The depth of fluid production below surface controls the pressure-temperature (P-T) evolution along the upflow path of magmatic fluids. Different evolution paths controlling density, salinity, and phase state of fluids contribute to selective metal precipitation: porphyry Au deposits can form at shallow subvolcanic levels from extremely saline brine or salt melt; high-grade Au-Cu coprecipitation from coexisting and possibly rehomogenizing brine and vapor is most efficient at a depth of a few kilometers; whereas fluids cooling at greater depth tend to precipitate Cu ± Mo but transport Au selectively to shallower epithermal levels. Exhumation and secondary oxidation and enrichment by groundwater finally determine the economics of a deposit, as well as the global potential of undiscovered metal resources available for future mining.

Characteristics of epithermal gold-base metals prospect in the Anggai block, northern Obi Island, Indonesia

The Obi island, located in the North Moluccas Au-Ag-Cu province, hosts several mineral prospects, one of which is gold-base metals in the Anggai block. Several companies have historically explored the area since the end of the 1900s. The ore bodies are white to smoky and brownish-white, banded, laminated, colloform, crustiform, and massive quartz vein structures or textures, trending north northwest to south southeast. The ore bodies consist of gold and base metals hosted in the Bacan Formation and are enveloped by dominantly argillic alteration and the addition of silicic alteration. In this study, we provide several analyses, namely petrography, measurements using Portable Infrared Mineral Analyser (PIMA), Atomic Absorption Spectrometry (AAS), and fluid inclusion analysis, to understand geological and geochemical characteristics related to formation of gold-base metals in the Anggai block. Under the microscope, gold (i.e., electrum) is freely observed and closely occurs with argentite. While galena, chalcopyrite, sphalerite, covellite, chalcocite, and pyrite are mainly observed together. The correlation coefficient between Au and other metals shows a strong positive correlation with Zn (r = 0.810188) and a weak positive correlation with Ag (r = 0.459857). Ag shows only a weak positive correlation to Au, while the other elements show a strong positive correlation. In addition, Cu, Pb, and Zn show a strong positive correlation with each other. The micro-thermometry analysis of fluid inclusions shows two modes of homogenization temperature (Th) and salinity: 180-200 °C and 240-280 °C, and 1.4-1.6 and 1.9-2.2 wt% NaCl eq., respectively, suggesting overprinting evidence to enrich the ore bodies with occurrences of gold and base metals in the quartz veins. Gold-base metals were probably carried by the sulfide complex, which later precipitated during the cooling of the hydrothermal fluid.

A Plasmonic Optoelectronic Resistive Random-Access Memory for In-Sensor Color Image Cryptography.

The optoelectronic resistive random-access memory (RRAM) with the integrated function of perception, storage and intrinsic randomness displays promising applications in the hardware level in-sensor image cryptography. In this work, 2D hexagonal boron nitride based optoelectronic RRAM is fabricated with semitransparent noble metal (Ag or Au) as top electrodes, which can simultaneous capture color image and generate physically unclonable function (PUF) key for in-sensor color image cryptography. Surface plasmons of noble metals enable the strong light absorption to realize an efficient modulation of filament growth at nanoscale. Resistive switching curves show that the optical stimuli can impede the filament aggregation and promote the filament annihilation, which originates from photothermal effects and photogenerated hot electrons in localized surface plasmon resonance of noble metals. By selecting noble metals, the optoelectronic RRAM array can respond to distinct wavelengthsand mimic the biological dichromatic cone cells to perform the color perception. Due to the intrinsic and high-quality randomness, the optoelectronic RRAM can produce a PUF key in every exposure cycle, which can be applied in the reconfigurable cryptography. The findings demonstrate an effective strategy to build optoelectronic RRAM for in-sensor color image cryptography applications.

Measurements of Sensitivity and Figure of Merit for Noble Metals (Au, Ag, Cu) Thin Film Biosensor Based on SPR Simulation Characterizations

In this paper, we investigate the influence of varying the thickness of noble metals, namely gold (Au), silver (Ag) and copper (Cu), and the incident light wavelength on the surface plasmon resonance (SPR) properties for biosensor applications. Our analysis employs the Fresnel equations to examine the absorption characteristics of these metals when the refractive index shifts by (0.03,0.06). We explore metal layer thicknesses ranging from [Formula: see text][Formula: see text]nm and incident light wavelengths of [Formula: see text] and 600[Formula: see text]nm, with incident angles ([Formula: see text]) ranging from 0∘ to 90∘. Utilizing simulation analysis in MATLAB, we simulate the SPR responses of these metals when deposited on BK-7 glass prisms, with air as the surrounding medium. Our calculations reveal the absorption properties of Au, Ag and Cu, as indicated by the angle of incidence ([Formula: see text]SPR). Our findings demonstrate that the highest absorption occurs with copper (Cu) at [Formula: see text] (a.u.) for [Formula: see text][Formula: see text]nm and [Formula: see text][Formula: see text]nm. When [Formula: see text] is adjusted to 600[Formula: see text]nm, gold (Au) exhibits the highest absorption (A) at 0.997 (a.u.) with a thickness of [Formula: see text][Formula: see text]nm. Additionally, we calculate sensitivity values for all three metals, with copper (Cu) yielding the highest sensitivity of 101.6 Reflected Index Units (RIU-1) for both [Formula: see text] and 600[Formula: see text]nm. Furthermore, we compute the Figure Of Merit (FOM), with silver (Ag) achieving the highest FOM of 443 at [Formula: see text][Formula: see text]nm and 451 at [Formula: see text][Formula: see text]nm. These results provide important signs about noble metals’ SPR properties in biosensing, and serve as guides for optimizing the biosensors.

A theoretical equation of state to formulate the melting curve of metals with varying pressure

The objective of this study has been formulate mathematical equations for the melting temperature of metallic solids using various thermodynamics equation of state, specifically those proposed by Modified generalized Lennard – Jones(mGL-J) equation of state (EOS) and Usual-Tait EOS. The derived equations of state establish the relation between pressure, volume, melting temperature, bulk modulus and first-order pressure derivative at zero pressure. These equations of state are used to calculate melting curves for the metallic elements Pd, Cd, Pt, Mn, Au, Al, Zn and Ag up to 30 GPa. The obtained results from Modified generalized Lennard – Jones(mGL-J) equation of state display a significant rise in the melting curve because of a large increase in bulk modulus. The results of mGL-J EOS is the most consistent with the experimental data. The outcomes obtained from Usual-Tait equation of state diverges to a great extent with the experimental melting temperature. The study contributes to a better understanding of the quantitative effect of pressure on the melting temperature of various solids. The derived equations of state are useful to calculate melting temperature at larger pressures.

Nonthermal Plasma-Stimulated C-N Coupling from CH4 and N2 Depends on the Presence of Surface CHx and Plasma-Phase CN Species.

Formation of C-N containing compounds from plasma-catalytic coupling of CH4 and N2 over various transition metals (Ni, Pd, Cu, Ag, and Au) is investigated using a multimodal spectroscopic approach, combining polarization-modulation infrared reflection-absorption spectroscopy (PM-IRAS) and optical emission spectroscopy (OES). Through sequential experiments utilizing CH4 and N2 nonthermal plasmas, we minimize plasma-phase reactions and identify key intermediates for C-N coupling on metal surfaces. Results show that simultaneous CH4 and N2 exposure with plasma stimulation produces surface C-N species. However, N2-CH4 sequential exposure does not lead to C-N species formation, while CH4-N2 sequential exposure reveals the presence of CHx surface species and CN radical species as key precursors to C-N species formation. From further analysis using X-ray photoelectron spectroscopy and liquid chromatography-mass spectrometry, the influence of exposure conditions on the degree of nitrogen incorporation and the nature of C-N species formed were revealed. The work highlights the importance of surface chemistry and exposure conditions in surface C-N coupling with plasma stimulation.

Recent Advancements in Metallic Au- and Ag-Based Chitosan Nanocomposite Derivatives for Enhanced Anticancer Drug Delivery

The rapid advancements in nanotechnology in the field of nanomedicine have the potential to significantly enhance therapeutic strategies for cancer treatment. There is considerable promise for enhancing the efficacy of cancer therapy through the manufacture of innovative nanocomposite materials. Metallic nanoparticles have been found to enhance the release of anticancer medications that are loaded onto them, resulting in a sustained release, hence reducing the dosage required for drug administration and preventing their buildup in healthy cells. The combination of nanotechnology with biocompatible materials offers new prospects for the development of advanced therapies that exhibit enhanced selectivity, reduced adverse effects, and improved patient outcomes. Chitosan (CS), a polysaccharide possessing distinct physicochemical properties, exhibits favorable attributes for controlled drug delivery due to its biocompatibility and biodegradability. Chitosan nanocomposites exhibit heightened stability, improved biocompatibility, and prolonged release characteristics for anticancer medicines. The incorporation of gold (Au) nanoparticles into the chitosan nanocomposite results in the manifestation of photothermal characteristics, whereas the inclusion of silver (Ag) nanoparticles boosts the antibacterial capabilities of the synthesized nanocomposite. The objective of this review is to investigate the recent progress in the utilization of Ag and Au nanoparticles, or a combination thereof, within a chitosan matrix or its modified derivatives for the purpose of anticancer drug delivery. The research findings for the potential of a chitosan nanocomposite to deliver various anticancer drugs, such as doxorubicin, 5-Fluroacil, curcumin, paclitaxel, and 6-mercaptopurine, were investigated. Moreover, various modifications carried out on the chitosan matrix phase and the nanocomposite surfaces to enhance targeting selectivity, loading efficiency, and pH sensitivity were highlighted. In addition, challenges and perspectives that could motivate further research related to the applications of chitosan nanocomposites in cancer therapy were summarized.

Polydopamine-assisted immobilization of metallic nanoparticles confined regionally in bamboo microchannels as continuous-flow microreactors for enhanced catalysis

In contrast to conventional plant-based microreactors where the nanocatalyst is anchored on the inner walls of microchannel structures, this study presents a bamboo-based flow microreactor in which the metallic nanocatalyst is immobilized within polydopamine (PDA) region-modified bamboo microchannels. This novel design facilitates a large surface area for nanocatalyst loading, enhances mass transfer, and reduces nanocatalyst leaching. Firstly, the hierarchical PDA architecture was fabricated on the wall surface of required bamboo microchannels through an ammoniation-induced self-assembly process to serve as a nanocatalyst support layer. The thickness of PDA architectures was modulated by adjusting the flow duration. Secondly, the metallic nanoparticles (NPs), including Pd, Au, and Ag, were effectively immobilized within the hierarchical PDA architectures as highly efficient catalysts using a flow-assisted method with minimal chemical usage and low catalyst loading (Pd content: 0.011 wt%). The catalytic performances of the proposed Pd-PDA/bamboo microreactor were evaluated for the continuous hydrogenation of nitroaromatics under flow conditions, encompassing variations in Pd content, nitroaromatic concentration, and liquid flow rate. The optimized Pd-PDA/bamboo microreactor exhibited high average conversion (>97 %) of nitroaromatics during 20 days of continuous operation without any noticeable deactivation or loss in activity due to its excellent stability resulting from firm immobilization of active metallic NPs within hierarchical PDA architectures. Additionally, this bamboo microreactor demonstrated potential applicability in environmental pollution treatment through azo dye hydrogenation.

Manipulation of Goos–Hänchen shift via hybrid chiral quantum dots system

We present a flexible manipulation and enhancement of the Goos–Hänchen (GH) shifts via surface plasmon polaritons (SPPs) in a hybrid nanostructure configuration composed of metal (Au) and a chiral quantum dots (CQDs) medium. The proposed configuration consists of a hybrid nanostructure where CQDs and metal are organized, leading to the generation of SPPs when exposed to incident light. The interaction between the SPPs and the incident light leads to a significant enhancement in the GH shift of the left-circularly polarized (LCP) and right-circularly polarized (RCP) lights. It is observed that the RCP light induces numerous SPPs at the interface of the metal and CQDs nanostructure, thereby causing a larger GH shift. In contrast, the LCP light does not induce numerous SPPs at the interface of the metal and CQDs nanostructure, leading to a smaller GH shift. It is also studied that the GH shift can be tuned and enhanced by varying the intensity of the control field and electron tunneling strength in the hybrid system. The results have potential applications in the fields of sensing, imaging, nanotechnology, and quantum technology.