Gold Crystals Research Articles

From nanoparticles to crystals: one-pot programmable biosynthesis of photothermal gold structures and their use for biomedical applications

Inspired by nature, green chemistry uses various biomolecules, such as proteins, as reducing agents to synthesize metallic nanostructures. This methodology provides an alternative route to conventional harsh synthetic processes, which include polluting chemicals. Tuning the resulting nanostructure properties, such as their size and shape, is challenging as the exact mechanism involved in their formation is still not well understood. This work reports a well-controlled method to program gold nanostructures' shape, size, and aggregation state using only one protein type, mucin, as a reduction and capping material in a one-pot bio-assisted reaction. Using mucin as a gold reduction template while varying its tertiary structure via the pH of the synthesis, we demonstrate that spherical, coral-shaped, and hexagonal gold crystals can be obtained and that the size can be tuned over three orders of magnitude. This is achieved by leveraging the protein's intrinsic reducing properties and pH-induced conformational changes. The systematic study of the reaction kinetics and growth steps developed here provides an understanding of the mechanism behind this phenomenon. We further show that the prepared gold nanostructures exhibit tunable photothermal properties that can be optimized for various hyperthermia-induced antibacterial applications.

Direct Observation of Solvent–Reaction Intermediate Interactions in Heterogeneously Catalyzed Alcohol Coupling

The relative stability of reactive intermediates and reactants on a surface, which dictates the rate and selectivity of catalytic reactions in both gas and liquid phases, is dependent on numerous factors. One well-established example is secondary interactions, such as van der Waals interactions between the catalyst surface and the pendant group of the intermediate, which can govern reaction selectivity for coupling reactions. Herein, we directly show that interactions between adsorbed reaction intermediates and reactant molecules increase the binding energy and affects the geometrical arrangement of coadsorbed reactant/solvent molecules. Evidence for this effect is demonstrated for the oxidative coupling reaction of methanol on a single crystal gold (Au(110)) surface. The rate-limiting reaction intermediate for methanol self-coupling, methoxy, stabilizes excess adsorbed methanol, which desorbs as a result of beta-hydride decomposition of the adsorbed methoxy. Direct molecular-scale imaging by scanning tunneling microscopy, supplemented by density functional theory, revealed interactive structures formed by methoxy and coadsorbed methanol. Interactions between the methoxy intermediate and coadsorbed methanol stabilizes a hydrogen-bonded network comprising methoxy and methanol by a minimum of 0.13 eV per methanol molecule. Inclusion of such interactions between reaction intermediates and coadsorbed reactants and solvents in kinetic models is important for microkinetic analysis of the rates and selectivities of catalytic reactions in both the gas and liquid phases whenever appreciable coverages of species from the ambient phase exist.

In Situ Nano-Indentation of a Gold Sub-Micrometric Particle Imaged by Multi-Wavelength Bragg Coherent X-ray Diffraction.

The microstructure of a sub-micrometric gold crystal during nanoindentation is visualized by in situ multi-wavelength Bragg coherent X-ray diffraction imaging. The gold crystal is indented using a custom-built atomic force microscope. A band of deformation attributed to a shear band oriented along the (221) lattice plane is nucleated at the lower left corner of the crystal and propagates towards the crystal center with increasing applied mechanical load. After complete unloading, an almost strain-free and defect-free crystal is left behind, demonstrating a pseudo-elastic behavior that can only be studied by in situ imaging while it is invisible to ex situ examinations. The recovery is probably associated with reversible dislocations nucleation/annihilation at the side surface of the particle and at the particle-substrate interface, a behavior that has been predicted by atomistic simulations. The full recovery of the particle upon unloading sheds new light on extraordinary mechanical properties of metal nanoparticles obtained by solid-state dewetting.

Liposomal formulation of new arsenic schiff base complex as drug delivery agent in the treatment of acute promyelocytic leukemia and quantum chemical and docking calculations

The paper describes the synthesis of a new Schiff base As (III) complex followed by the encapsulation of Schiff base As (III) complex in liposomes. First, As (III) Schiff base complex was synthesized from gold crystal ligand in contact with Ascl3. Detailed characterization using Fourier transform infrared spectroscopy (FT-IR), Hydrogen-1 nuclear magnetic resonance (HNMR) and, Liquid chromatography–mass spectrometry (LC-MS) confirmed the successful synthesis of As (III) Schiff base complex. The physicochemical properties of liposomal formulations were characterized by Dynamic light scattering (DLS), Atomic force microscopy (AFM), and Transmission electron microscopy (TEM). Furthermore, Cytotoxicity results revealed higher cytotoxicity and lower IC50 for As (III) complex (2.004 μM) relative to ATO ones (3.968 μM). The expression of cell cycle genes and apoptosis were determined by Real-time technique. Moreover, the quantum chemical calculations of compounds were carried out to obtain information about the geometry and chemical reactivity by the DMol3 module in Materials studio 2017. Finally, docking calculations were performed with Formamidopyrimidine [fapy]-DNA glycosylase (Fpg) and Poly [ADP-ribose] polymerase-1 (PARP-1) to investigate the tendency of As (III) complex to bind to these two proteins. The results presented here may suggest further investigation for in vivo studies and successful targeted therapy.

Near-field probing of image phonon-polaritons in hexagonal boron nitride on gold crystals.

Near-field mapping has been widely used to study hyperbolic phonon-polaritons in van der Waals crystals. However, an accurate measurement of the polaritonic loss remains challenging because of the inherent complexity of the near-field signal and the substrate-mediated loss. Here we demonstrate that large-area monocrystalline gold flakes, an atomically flat low-loss substrate for image polaritons, provide a platform for precise near-field measurement of the complex propagation constant of polaritons in van der Waals crystals. As a topical example, we measure propagation loss of the image phonon-polaritons in hexagonal boron nitride, revealing that their normalized propagation length exhibits a parabolic spectral dependency. Furthermore, we show that image phonon-polaritons exhibit up to a twice longer normalized propagation length, while being 2.4 times more compressed compared to the case of the dielectric substrate. We conclude that the monocrystalline gold flakes provide a unique nanophotonic platform for probing and exploitation of the image modes in low-dimensional materials.

Single Crystal Copper and Gold Alloys for the Plasmonically Enhanced CO2 Reduction Reaction

Chemical fixation of carbon dioxide (CO2) into chemical fuels has raised a lot of interest due to its role in removing greenhouse gasses from the atmosphere to store them as a potential source of energy. CO2 removal techniques have been widely studied and are of great interest because they can be used synergistically as a low-cost source of carbon to supplement and support the existing chemical synthesis of feedstocks and hydrocarbon fuels. One of the most common approaches to the remediation of atmospheric CO2 is the electrochemical reduction of CO2. We have been studying the formation of copper (Cu) films and its alloys with gold (Au). Metal alloys have been shown to exhibit interesting properties to enhance chemical processes beyond those of their individual components, improving the applications in the plasmonic and catalysis fields.Cu and Au are both excellent plasmonic and catalytic materials that show tunable optical properties, strong absorptions in the visible and near infrared, and catalytic activity. However, the applications of Cu materials alone are limited due to Cu’s chemical instability and tendency to oxidation, which inhibits their plasmonic properties and reduces their catalytic performance. By alloying Cu with Au, we have overcome copper’s chemical instability and improved the catalytic properties due to synergistic effects.As a result of our studies, we have also developed a method to deposit Cu2O single crystal film, a material that exhibits semiconductor properties and opens a new line of opportunities for plasmonic applications. In this poster, we will show an overview of our results and discuss the potential applications to plasmonic electrocatalysis and sensors.

A Novel Electrochemical DNA Sensor Based on Redox Modulated Fluorescence Intensity

In clinical applications, a highly sensitive and specific biosensor is required for detecting the trace amount of genetic analyte1. There have been numerous techniques developed for improving the sensitivity and selectivity of the DNA biosensor. Many PCR-based techniques including gene sequencing and fluorescence quantitative polymerase chain reaction have shown advantages such as high accuracy and sensitivity2. However, these techniques are complicated to use and require professionally trained personal. On the other hand, electrochemistry-based measurements such as Square-wave Voltammetry and Cyclic Voltammetry usually assume the electron transfer kinetics of the redox-active monolayer assemblies are uniform. The signal generated is an average and the detailed information about the modified surface is difficult to obtain. Here we show a novel detection method using electrochemistry coupled with fluorescence microscopy. A mixed SAM composed of Methylene Blue (MB) or AlexaFluor488 (AF488) labeled single stranded DNA were electro-deposited on a single crystal gold bead electrode3. We observed a unique profile of fluorescence signal (AF488) modulated by the redox probe (MB) upon DNA hybridization events. In addition, we have found that different surface crystallographies exhibit different sensitivities to the complementary strand (e.g. target) which can be explained by differences in surface coverages4. We demonstrate a coupled electrochemical and fluorescence DNA sensor.

(Invited) Improved Thermal Stability of Low-Probe Density DNA SAMs Prepared with Electrodeposition

DNA self-assembled monolayer (SAM) on gold electrodes has been widely used for biosensing.1, 2 The sensor stability and performance determine the reliability of the test results in early disease detection and point-of-care use.3, 4 We have carefully examined the thermal stability of a mixed SAMs composed of a short alkylthiol and alkylthiol modified DNA prepared with electrodeposition vs. those prepared at OCP (Open Circuit Potential) on a single crystal gold bead electrode. The nature of these two types of SAMs were carefully studied in buffer after exposure to different temperatures using in-situ fluorescence microscopy and electrochemical measurements. The analysis showed that surfaces with hexagonal symmetry were thermally less stable than those with rectangular or square symmetry, suggesting that the crystallography of the gold substrate plays an important role in sensor stability and performance in addition to the DNA density.5 We also found that OCP deposition creates a surface with high DNA coverage (>1012 DNA/cm2) but with higher level of irreproducibility. Even though this kind of surface can be more thermally stable, it is not optimal for effective biosensing due to its high coverage.6 It also seems to be challenging to make DNA SAMs with both low coverage and high thermal stability by using current SAM preparation protocols (e.g., OCP). In this study, we show that electrodeposition can prepare DNA SAMs with both higher thermal stability than those made at OCP and with good control of low surface coverage. This study provides valuable insights on making high quality DNA SAMs with better stability and functionality and improved reproducibility.

Direct Atomic Observation of Reversible Orientation Switch in Monoatomic-Layered Gold Membrane Conducted by Dynamic Vortex.

Controlling the material structure at an atomic scale to tune their physicochemical and nanoengineering properties is a major driving force of nanotechnology. However, manipulating the structural variation in monoatomic-layered metals remains a challenge, hindering the full application of their novel properties. Here, we show by experiments and simulations that a reversible orientation rotation of monoatomic-layered gold membrane embedded in the gold crystal is performed through dynamic vortexing that is comprised of the circular motion of atoms. A pair of dynamic vortices are successively generated and together span the entire gold membrane to accomplish the orientation switch. Density functional theory calculations demonstrate that the gold membrane exhibits a Rashba-type spin splitting, while the spin direction reversibly flips with the switching orientation of the gold membrane. The results provide a conceptual approach for constructing a novel electronic system with monoatomic-layered metals and the reversible spin-flip has inspiring applications for future spintronics.

Mechanism of Interlayer Transport on a Growing Au(111) Surface: 2D vs. 3D Growth

The atomic scale transitions corresponding to diffusion and interlayer transport of a Au adatom on the low energy, close packed Au(111) surface are studied using density functional theory calculations within the generalized gradient approximation. Minimum energy paths and estimates of activation energy are calculated for processes that influence whether the crystal grows layer-by-layer, i.e. 2D growth, or whether new islands tend to nucleate on top of existing islands resulting in 3D growth. Kinks on island edges turn out to provide paths for adatom descent with lower activation energy than straight steps. The energy barrier for an adatom to round the corner and enter a kink site is significantly higher. A descent mechanism that places an adatom near but not at a kink site can therefore promote the formation of a new row of step atoms and lead to the introduction of additional kink sites, thereby opening up new low activation energy paths for descent and promotion of 2D growth. The sites adjacent and above the step edge provide large binding energy for the adatom, especially at the B-type step, and form a trough along which the adatom can migrate before descending, thereby increasing the probability that an adatom finds a kink on the B-type step. These features of the energy landscape representing the interaction of a Au adatom with the surface point to the possibility of a re-entrant layer-by-layer growth mode of the low energy, close packed surface of the gold crystal.

Molecular dynamics study of thermal hysteresis during melting-crystallization of noble metals

By constructing the thermal hysteresis of the enthalpy and density of the noble metals of gold (Au) and copper (Cu), non-equilibrium processes are investigated during the melting – crystallization phase transformations, i.e. during the solid–liquid transition. Thermal hysteresis is obtained from the atomistic modeling. The limiting temperatures of superheating of the solid phase during melting and undercooling of the liquid phase during crystallization of gold and copper are obtained. The possibility of the formation of highly superheated-undercooled metastable states of solid and liquid phases with rapid heating-cooling of the studied metals has been confirmed. The results obtained are compared with the results of alternative calculations.

Models of Nominating the Mining Objects of the Ural Gold and Rock Crystal Deposits in the Comparative Aspect

This article discusses the names of mining objects of gold and rock crystal located in the Southern, Middle, and Circumpolar Urals. These include names of mines, placers, veins, and other artificial objects located on the territory of deposits and associated with the extraction of these minerals. The purpose of the study is to identify the main models of object nomination and compare specific cases of using these models depending on the characteristics of the extracted raw materials, methods of their development and the geographical location of the deposit. The author analyses a total of 627 names. The article refers to specialised works on the history of gold mining, mining of rock crystal, and the history of the development of specific deposits. There are three main models of object nomination: anthroponymic, toponymic (according to the origin of the toponym) and object-motivated (according to the nomination situation). In different fields, these models are presented in different proportions and specific implementations. Thus, the anthroponymic model becomes the leading one for the Beryozovsky gold deposit, the toponymic one for the Circumpolar Ural deposits of rock crystal, and the object-motivated units are represented at each of the deposits, quantitatively significantly inferior to the names given based on other nomination models. It is concluded that the leading characteristic for the emergence and development of a particular nomination model for specific deposits is the nature of its development (private prospector / regular state), as well as the number of objects subject to naming. The economic development of the territory of the deposit prior to the start of mining on it also plays a role. At the same time, the nature of the extracted mineral does not matter significantly.

Nos bastidores da Casa Arte Sacra Fânzeres: da materialidade à espiritualidade da escultura sacra

The Casa Arte Sacra Fânzeres, located in Fânzeres (Gondomar), is specialized in the artisanal execution of sacred sculpture and furniture. This workshop, founded over fifty years ago, brings together employees who learned this art in a workshop context, as in the past. It also preserves the «traditional know-how» of the arts of wood carving, upholstery and sacred painting, as well as the application of gold leaf and crystal eyes in the images. In addition to the quality of the technical execution, this workshop also articulates with other local «ways of doing», such as goldsmithery, sewing and handcraft embroidery. The aim of this study is to address the materiality of the sacred image before it takes on spirituality in sacred spaces, as an appeal to the senses and transmission of meanings

Study of the FCC-Au properties in a wide range of temperatures and pressures

The properties of the FCC-of the gold crystal were calculated using an analytical method (without computer modeling) in the temperature range: T=10-1337 K and pressures: P=0-110 GPa. The following properties were calculated: state equation, Debye temperature, first and second Gruneisen parameters, elastic modulus (BT), thermal expansion coefficient (αp), isochoric (Cv) and isobaric (Cp) heat capacity, specific surface energy. Derivatives of these properties also have been calculated both by temperature along three isobars and by pressure along three isotherms. The obtained results showed good agreement with the other authors results. It was shown that there is a certain temperature TB in which the product α_pBT does not change during the crystal compression. At T>TB, the α_pBT function increases, and at T<TB, it decreases with an increase in pressure. For FCC-Au has been received T_B=132 K. It was shown that the isotherms of the baric derivative of elastic modulus B'(P) intersect at the point: P>21.58 GPa, and B'(P)=7.43. At P<21.58 GPa, the C'v(P) function increases, and at P>21.58 GPa, it decreases with increasing temperature. It was shown that the isotherm of the baric derivative of the isochoric heat capacity C'v(P) has a minimum, and the isotherm of the baric derivative of the isobaric heat capacity C'_p(P) has both a minimum and a maximum. Based on the obtained dependencies, some approximations, which are used to calculate the properties of the crystal under high P-T-conditions, have been analyzed. Keywords: gold, pressure, elastic modulus, thermal expansion, heat capacity, Debye temperature, Gruneisen parameter, surface energy.

SINGLE-STEP GREEN SYNTHESIS OF GOLD NANOPARTICLES (GNPS) MEDIATED Rhizopohra stylosa LEAF EXTRACT AND ANTIBACTERIAL EFFECT

This study investigated the single-step synthesis and antibacterial activity of gold nanoparticles (GNPs), produced using leaves aqueous extract of Mangrove Rhizophora stylosa. The reaction of the extract with chloroauric acid caused a reduction of auric chloride and the formation of GNPs in 60 minutes at room temperature. The size, shape, and elemental composition of the nanoparticles (NP) were studied using a transmission electron microscope (TEM) with an average particle size of 27 nm with the dominant shape being spherical and partly hexagonal, and trigonal. X-Ray Diffraction (XRD) analysis showed gold crystals with 4 diffraction peaks with PCC crystalline nature. UVvis spectroscopy shows the SPR peaks found in the wavelength range of 530-546 nm. Furthermore, the NP biological capping agents identified by Fourier-transform infrared spectroscopy (FT-IR) were carbonyl, amine, and polyphenol. Leaf extract serves as an effective bio-reducing agent for the synthesis of GNPs. The results showed that the GNPs synthesized using Rhizophora stylosa mangrove aqueous extract had the potential for antibacterial activity.

Изучение свойств ГЦК-Au в широком диапазоне температур и давлений

The properties of the FCC of the gold crystal were calculated using an analytical method (without computer modeling) in the temperature range: T = 10 – 1337 K and pressures: P = 0 – 110 GPa. The following properties were calculated: state equation, Debye temperature, first and second Gruneisen parameters, elastic modulus (BT), thermal expansion coefficient (p), isochoric (Cv) and isobaric (Cp) heat capacity, specific surface energy. Derivatives of these properties also have been calculated both by temperature along three isobars and by pressure along three isotherms. The obtained results showed good agreement with the other authors results. It was shown that there is a certain temperature TB in which the product pBT does not change during the crystal compression. At T > TB, the pBT function increases, and at T < TB, it decreases with an increase in pressure. For FCC-Au has been received TB =132 K. Показано, что изотермы производной модуля упругости по давлению B(P) пересекаются в точке: P = 21.58 GPa, B(P) = 7.43. It was shown that the isotherms of the baric derivative of elastic modulus B(P) intersect at the point: P = 21.58 GPa, and B(P) = 7.43. At P < 21.58 GPa, the B(P) function increases, and at P > 21.58 GPa, it decreases with increasing temperature. It was shown that the isotherm of the baric derivative of the isochoric heat capacity Cv(P) has a minimum, and the isotherm of the baric derivative of the isobaric heat capacity Cp(P) has both a minimum and a maximum. Based on the obtained dependencies, some approximations, which are used to calculate the properties of the crystal under high P-T conditions, have been analyzed.

Dynamics of artisanal gold mining in Gashaka local government area of Taraba State, Nigeria

Despite the fact that gold has been mined in Gashaka, Taraba State for over a century and has continued to present day in the area, not much is known about this activity and its associated environmental impact in the state. This study therefore, examines the dynamics of artisanal small scale gold mining activities in Gashaka Local Government Area of Taraba State, Nigeria. The study adopted survey research design approach which involves the use of direct fieldwork observation and interview of key informants. The findings of the study reveals that alluvial gold is mined along the streams and farmlands on the floodplains in the area. The gold exists as alluvial gold dust and nugget gold. The artisanal gold mining activity is carried out with rudimentary materials such as pickaxes, diggers, shovels, spades, pans and water pumps. Some of the local mining communities are Gayam, Jamtari, Karamti, Serti, Goje, Bodel, Mayo Jim, Bashishir, Kurr and Garbabi. The 3 major methods employed by artisanal gold miners in the study area include panning method, use of locally constructed devices and picking of gold nuggets or crystals from dug pit on the floodplain. The artisanal gold miners use sulphuric acid and white mercury in purifying the collected gold. The miners do not use any protective gears such as face masks, rubber gloves, leather boots or head coverings in the mining process. All golds collected from the mining activities are sold in the town (Serti/Baruwa). There is a ready market with both local buyers residing in the town and distant buyers coming from different parts of the country. Artisanal gold mining is an important livelihood activity in the study area despite the fact that many of them are carried out illegally. Based on the findings, the study recommended the establishment of a goldsmith industry, improvement in security in the local communities and organizing the artisanal gold miners into cooperative organizations.

Crystallization of Polyethylene Brushes and Its Effect on Interactions with Water

The crystallization process of brushes of polyethylene chains is investigated using all-atom molecular dynamics simulations at degrees of polymerization of 40 and 120. Through temperature reduction in nanosecond time scales, spontaneous crystallization is observed for polymer chains that are grafted on gold crystals and are in contact with vacuum on the other side. Crystalline nuclei form in the middle region of the brushes separated by nanometers from the gold and vacuum interfaces. The crystallization actually begins when the density of carbon atoms exceeds a threshold value. Increases in the grafting density and/or the degree of polymerization result in an increase in the density of carbon atoms in the middle region of the brush and thus leads to an elevation in the crystallization temperature. The free energy of inserting a water molecule into the brush is also analyzed. It is found to be more unfavorable in the crystalline brush than in the fluid state. This is due to the high density of the crystalline state, and in locally disordered regions in the crystalline brush, the insertion free energy is comparable to that in the fluid.

AFM and Cu Electrodeposition Studies of Reduced Graphene Oxide Modified Au(111) Facets Prepared using Electrodeposition and Post-Deposition Pulse Treatment

The structural and electrochemical characteristics of electrodeposited graphene oxide (GO) onto a single crystal gold bead electrode was studied using AFM and Cu electrodeposition. Optimal deposition uniformity was realized by rotation of the electrode, suggesting an initial electrophoretic deposition occurs followed by some reduction of the GO. Potential pulse treatments to reducing potentials for a short time significantly improve the electrochemical characteristics of the electrochemical reduced graphene oxide (ERGO). Both under-potential and over-potential Cu electrodeposition was used to characterize the quality of the ERGO deposit and showed that the gold surface was completely coated with ERGO only after potential pulsing treatments. AFM analysis of ERGO modified Au(111) facet on the gold bead electrode revealed the deposition was composed of sheets of GO/ERGO as well as much rougher deposits. AFM showed that the potential pulsing treatment resulted in the nucleation and growth of electrodeposited Cu nanoparticles over much of the ERGO surface, in contrast to the limited deposition of nanoparticles on the untreated GO deposit. The ERGO modified gold surface prepared using electrodeposition followed by potential pulse treatments results in conductive and electrochemically active ERGO surfaces.

Magmatic-hydrothermal origin for Carlin-type Au deposits: Evidences from in-situ S-Pb isotopic compositions of sulfides, the Chang’an Au deposit, southern Ailaoshan tectonic zone

The Chang’an Au deposit is a large Au deposit located in the south of the Ailaoshan-Red River tectonic zone, southwestern margin of the South China block. The deposit exhibit characters similar to Carlin-type Au deposits in Nevada and Dian-Qian-Gui “Golden Triangle”, including tectonic evolution (deformed and rifted cratonic margins), orebody controlled by lithology and structure and invisible Au ionically bound in arsenian pyrite and pyrite. Mineralization is controlled by a strike-slip fault and occurs as barren milky quartz veins, disseminated gold-bearing pyrite and arsenopyrite in the Early Paleozoic sandstone, siltstone and limestone. Gold is invisibly and ionically bound in arsenopyrite and pyrite or locally occurs as isolated native gold crystals (micron scale). Wall rock alteration includes sulfide, silicic, sericite and decarbonized alterations. Three hydrothermal mineralizing stages (I, II, III) can be identified: milky quartz-pyrite (I), quartz-sericite-pyrite-arsenopyrite (II) and dolomite-calcite-quartz (III). Different from those deposit in Dian-Qian-Gui, numerous plutons intruded in and around the mine. The syenite dikes are pyritized, thus, formed prior to the mineralization while lamprophyre dikes are unaltered and crosscut by the syenite dikes. The syenite dikes yielded zircon U − Pb ages of ca. 35.8 Ma and the lamprophyre yielded similar Ar-Ar age of ca. 36.6 Ma, largely constraining the age of Au mineralization. In situ S–Pb isotopic compositions for ore pyrite and arsenopyrite were measured by fs-LA-MC-ICP-MS. Sulfides from Chang’an show a uniform range from –6.4‰ to + 4.6‰, a typical characteristic of magmatic-derived S. Such sulfur isotopic compositions are similar to those of sulfides from Carlin-type Au deposits, but different from those of sulfides from orogenic-type deposit, which commonly exhibit a wide range of δ34S values. Pb isotopic ratios of pyrite and arsenopyrite are similar to those of the intrusive rocks in the deposit with more radiogenic Pb, suggesting that the metal is probably sourced from the coeval intrusive rocks and sedimentary wall rocks. Combined with the low Au concentrations of the sedimentary wall rocks, Au in the Chang’an deposit are probably sourced from the intrusive rocks. Differences between the Chang’an deposit and typical orogenic-type Au deposit include: (1) Orebodies in the Chang’an deposit exhibit transitional contact relationship with the host rocks and boundaries between them are defined by cut-off grade while these boundaries in typical orogenic-type deposits are clearly defined. (2) Sulfidized and decarbonized alterations are quite significant in the Chang’an deposit but commonly absent in typical orogenic-type deposits. (3) The Chang’an deposit have lower CO2 contents of ore-forming fluids and more shallow ore-forming depth relative to typical orogenic-type deposits. Based on the ore deposit geology, dating and isotopic data, the Chang’an mineralization is similar to typical Carlin-type gold deposit, formed by ore fluids originated from a deep magmatic S source in an post-collisional intracontinental setting at ca. 36 Ma.