Concentration Of HAuCl4 Research Articles

Optimization of the Electrodeposition of Gold Nanoparticles for the Application of Highly Sensitive, Label-Free Biosensor.

A highly sensitive electrochemical biosensor with a signal amplification platform of electrodeposited gold nanoparticle (AuNP) has been developed and characterized. The sizes of the synthesized AuNP were found to be critical for the performance of biosensor in which the sizes were dependent on HAuCl4 and acid concentrations; as well as on scan cycles and scan rates in the gold electro-reduction step. Systematic investigations of the adsorption of proteins with different sizes from aqueous electrolyte solution onto the electrodeposited AuNP surface were performed with a potentiometric method and calibrated by design of experiment (DOE). The resulting amperometric glucose biosensors was demonstrated to have a low detection limit (>50 μM) and a wide linear range after optimization with AuNP electrodeposition.

Eco-friendly synthesis of gold nanoparticles using carboxymethylated gum Cochlospermum gossypium (CMGK) and their catalytic and antibacterial applications

Gold nanoparticles (AuNPs) were synthesized by the green method with activated Cochlospermum gossypium (carboxymethylated Cochlospermum gossypium gum or carboxymethylated gum kondagogu: CMGK) as stabilizer and reducing agent. The obtained size of AuNPs was 11 ± 2 nm. The impacts of HAuCl4 concentration, CMGK concentration, and reaction time on the synthesis of AuNPs were investigated. The techniques, UV − visible spectroscopy, FTIR, DLS, TEM, and powder XRD, were used for characterization. The reducing capacity of the synthesized CMGK-AuNPs was tested for reduction of 4-nitrophenol (4-NP) along with NaBH4. The effects of NaBH4, catalyst dose, and temperature were studied for reduction of 4-NP. The AuNPs showed good antibacterial activity against E. coli and Bacillus subtilis. The outcomes of the study indicated that CMGK–AuNPs have notable antimicrobial and environmental applications.

In Situ Observations of Shell Growth and Oxidative Etching Behaviors of Pd Nanoparticles in Solutions by Liquid Cell Transmission Electron Microscopy.

It is demonstrated that the redox reaction behaviors of Pd nanoparticles in HAuCl4 solutions can be substantially modified by the introduction of hexadecyl trimethyl ammonium bromide (CTAB) agents through systematic liquid cell transmission electron microscopy (LCTEM) investigations. The gradual dissolution of Pd nanoparticles is observed when HAuCl4 solution is pumped into liquid flow cells, the etching characteristics of which are depended on both HAuCl4 concentrations and incident electron doses. In comparison, with the presence of CTAB agents, the dominated phenomenon appears to be the precipitation of Au species and incorporation onto the surface of Pd seeds. It is also observed that the rapid growth of Au on Pd seeds occurs by loading Pd and HAuCl4 solutions into static liquid cells. The resultant Au shells exhibit rather sparse structural configurations and are formed possibly by homogeneous nucleation/coalescence of Au species as well as monomer attachments. The observed Au-shell growth instead of Pd dissolution is attributed to the presence of the residual regents, which may be also responsible for the initially already existing small Au adsorptions at the corner/edge sites of Pd seeds. The study provides a useful reference for the convenient fabrication of complex nanostructures and functional nanomaterials in a controllable way.

A simple one-step fabrication of gold nanoparticles-based surface-enhanced Raman scattering substrates using rice grains

Metal nanoparticles synthesized using the green methods are essential for utilization of the nanoparticles in diagnostic and therapeutic applications. The usual syntheses of the metallic nanoparticles often involve toxic chemicals, which limit the use of metal nanoparticles in biochemical applications. An in-situ synthesis of gold nanoparticles (AuNPs) on the rice grain surfaces using the phenolic acid content of rice as the reducing agent, and utilization of the AuNPs-decorated rice (Au-rice) as a surface-enhanced Raman scattering (SERS) substrate are demonstrated. An increase in the HAuCl4 concentration of the reaction mixture was shown to cause almost a linear increase in the size of AuNPs on the rice grains. By varying the HAuCl4 concentration, the size of the synthesized AuNPs can be adjusted between 41 ± 13 nm and 177 ± 38 nm. Among the as-produced Au-rice samples, rice grains with the AuNP size of 131 ± 30 nm were found to be the most effective in the SERS analysis of 4-aminothiophenol (4-ATP). The effectiveness of the Au-rice samples as SERS substrates was demonstrated with a 4-ATP detection limit of 10−6 M and an analytical enhancement factor (AEF) of 1.5 × 105.

Controlled synthesis of multi-branched gold nanodendrites by dynamic microfluidic flow system

The synthesis of gold nanostructures with unique architectures has attracted a great deal of attention because of their architecture-dependent sensing, optical, and electrical properties. Gold nanodendrites with a tailored morphology have unique properties due to their enhanced surface areas caused by nanoscale branches. Although gold nanodendrites have been synthesized by many different methods, controllable and high-yield synthesis of gold nanodendrites remains a challenge. Here, for the first time, we show that multi-branched gold nanodendrite synthesis can be controlled using a dynamic microfluidic flow system with high yield and fluid dynamics that control the branching structure of the nanodentrites. The study shows that the architecture of the gold nanodendrites mainly depends on synthesis conditions such as flow dynamics, HAuCl4 concentration, and reaction time. Dendrites grew faster when the flow rate reached 3 µL min−1. We further show that by using microfluidic-assisted synthesis, simple and rapid gold nanodendrite length tuning (0.7 cm) is possible with a threefold branching and textured structure. It is shown that the growth of gold nanodendrites is significantly enhanced (1.7 times faster) under flow conditions in the microfluidic channel. This bottom-up method reduces undesirable effects related to the poor control of static growth and increased reproducibility. Such highly controllable and inexpensive microfluidic flow systems could potentially be used to fabricate high-yield gold nanodendrites for bioelectronics and sensing applications.

Synthesis of Gold Nanoparticles Using <i>p</i>-Aminobenzoic Acid and <i>p</i>-Aminosalicylic Acid as Reducing Agent

Synthesis of gold nanoparticles (AuNPs) by reduction of HAuCl4 with p-aminobenzoic acid and p-aminosalicylic acid as a reducing agent was investigated. This work was conducted in order to determine the optimum condition of AuNPs synthesis and examine the effect of the hydroxyl group in p-aminosalicylic acid towards the size, shape, and stability of the synthesized gold nanoparticles (AuNPs). The optimum condition of the gold nanoparticles synthesis was determined by UV/Vis spectrophotometer, the shape and size of gold nanoparticles were measured by Transmission Electron Microscope (TEM). The synthesis process was started by reacting HAuCl4 and the reducing agents in an aqueous solution at 86 ºC. The initial gold concentration, reducing agents concentration and pH were varied in order to obtain the optimum condition. In the optimum condition, the results showed that p-aminosalicylic acid containing both hydroxyl and amino groups performed higher reduction ability compared to p-aminobenzoic acid that only containing an amino group. Reducing agents which have a hydroxyl group (p-aminosalicylic acid) could produce AuNPs with a smaller concentration of HAuCl4 than p-aminobenzoic acid. Gold nanoparticles that were synthesized with p-aminosalicylic acid were more stable and had a smaller particle size compared to its counterpart that is synthesized with p-aminobenzoic acid.

Green synthesis of colloidal gold nanoparticles using latex from Hevea brasiliensis and evaluation of their in vitro cytotoxicity and genotoxicity.

Latex extracted from Hevea brasiliensis tree has been used as a green alternative for preparing gold nanoparticles (Au NPs); however, no study evaluating the cytotoxic and genotoxic potential of Au NPs synthesised using H. brasiliensis has been published. The present study aimed to synthesise and characterise colloidal Au NPs using latex from H. brasiliensis and to evaluate their in vitro cytotoxicity and genotoxicity. Ideal conditions for the green synthesis of Au NPs were studied. In vitro cytotoxicity and genotoxicity of Au NPs in CHO-K1 cells was also evaluated. Our findings indicated that the ideal synthesis conditions of pH, temperature, reduction time, and concentrations of latex and HAuCl4 were 7.0, 85°C, 120 min, 3.3 mg/mL, and 5.0 mmol/L, respectively. LC5024 h of Au NPs was 119.164 ± 5.31 μg/mL. Lowest concentration of Au NPs tested presented minimal cytotoxicity and genotoxicity. However, high concentrations of Au NPs promoted DNA damage and cell death via apoptosis. On the basis of these findings, the authors optimised the use of an aqueous solution of H. brasiliensis latex as a reducing/stabilising agent for the green synthesis of Au NPs. Low concentrations of these NPs are biocompatible in normal cell types, suggesting that these NPs may be used in biological applications.

Effect of Independent Variables on the Stability of the Synthesized Gold Nanoparticles Using Central Composite Design

Abstract Gold nanoparticles were successfully synthesis using four different independent variables: concentration of gold precursor (0.01 – 0.03 %), the concentration of palm oil frond extracts (POFE) (2 – 5 %), sonication amplitude (20 – 60 %), and sonication time (10 -30 min.). Thirty different experiments with six centre points were carryout to investigate the effect of the four independent variables on the zeta potential (stability) of the synthesised gold nanoparticles. It was found that an increase in the concentration of gold precursor and concentration of POFE increases the zeta potential. However, an increase in sonication amplitude and sonication time decreases the zeta potential. The optimised minimum zeta potential value of -25 mV was obtained when concentration of HAuCl4.3H2O = 0.01 % (w/w), concentration of POFE = 2.42 % (w/w), sonication amplitude = 54.00 %, and sonication time = 10.00 minutes. The adequacy of the model was predicted by the p-value of 0.0029 and not-significant value of the lack of fit value of 0.0942 with R – squared value of 0.4624 and adjustable R – squared value of 0.3764. The concentration of the POFE was found to be the major variable that controls the zeta potential, then followed by sonication amplitude, then sonication time, and finally by the concentration of gold precursor.

Gram-Scale Synthesis of Isolated Monodisperse Gold Nanorods.

Although gold nanorods (AuNRs) have strong potential applications in nanotechnology, plasmonics, and sensing, the scale-up synthesis of isolated AuNRs in gram quantities remains a challenge. Nearly all previously reported methods produce aqueous solutions of cetyltrimethylammonium bromide (CTAB)-coated AuNRs in milligram quantities with yields of approximately 20-30 % in terms of AuI to Au0 conversion. In addition, it is difficult to remove the CTAB bilayer from the surface of AuNRs and yet make them soluble and functionalized for further processing and chemical modification. This report describes the synthesis of monodisperse functionalized AuNRs (standard deviation, σ≈5 %) in gram quantities. Our approach involved increasing the concentration of HAuCl4 ⋅3 H2 O in the growth solution to produce larger quantities of starting AuNRs and further reducing the remaining AuI ions onto the surface of AuNRs. The slow and controlled addition of ascorbic acid as a reducing agent continued the conversion of AuI into Au0 (through a disproportionation reaction) onto the surface of the nanorods, which maintained their uniform morphology without creating any unwanted impurities of various shapes. In addition, this approach significantly narrowed the size distribution owing to continuous growth of the partially grown AuNRs during the initial stage of the synthesis. To isolate a 1 g quantity of the AuNRs and to make them functionalized for further chemical reactions, a ligand-exchange approach was utilized, in which the CTAB surfactant was replaced with 4-mercaptophenol. The thiol group from 4-mercaptophenol formed a covalent bond with the surface of the AuNRs, leaving free functional OH groups available for further chemical coupling reactions. For the ligand-exchange process, a concentrated solution of 4-mercaptophenol in tetrahydrofuran solution was introduced into the AuNRs solution. Pure AuNRs functionalized with 4-mercaptophenol were isolated by dispersion and rinsing with an excess amount of THF, followed by centrifugation.

Size controllable one step synthesis of gold nanoparticles using carboxymethyl chitosan

Gold nanoparticles (AuNPs) were synthesized by reducing chloroauric acid with nontoxic and biodegradable carboxymethyl chitosan (CMC) as dual roles of reducing agent and stabilizer. Several CMC with different molecular parameters, i.e., degree of substitution (DS), substitution position, degree of deacetylation (DD) and molecular weight (MW) have been investigated for their reducing and stabilizing ability on the synthesis of AuNPs. The obtained AuNPs were characterized with UV-vis spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The resulting AuNPs displayed controllable size and shape not only depending on the molecular parameters of CMC but experimental parameters, such as reaction temperature, time, pH, concentration of NaOH, HAuCl4 and CMC in solution. The results indicated the addition of NaOH to a solution containing HAuCl4 and CMC is essential to synthesize individual spherical AuNPs with a rather uniform size distribution. The –OH at C-6 and –NH2 at C-2 of CMC played important roles in the reduction of Au(III) to Au(0) and –COO– groups were accountable for the stabilizing ability of CMC to AuNPs.

Optimization of biosynthesis gold nanoparticles via central composite design toward monodisperse

sThe gold nanoparticles were synthesized using ultrasound radiation. The optimization process was achieved using a central composite design (CCD) and response surface methodology (RSM). The effects of gold precursor (HAuCl4.3H2O), concentration of stabilizing agent (oil palm leaves extracts, (OPLE)), sonication amplitude, and sonication time were investigated on the average hydrodynamical size and polydispersity index. The hydrodynamical size and polydispersity index of the synthesized AuNPs were measured using dynamic light scattering (DLS). The relationship between the independent variables and their corresponding responses were established by the non-linear regression equation obtained from the developed models. Analysis of variance was used for examining the effect of individual, cross and quadratic terms of the independent variables on the responses. As a result, very low p-value (<0.0001), non-significant lack of fit and coefficient of the determinant () demonstrate an effective correlation between the experimental results and the predicted values. The optimal conditions selected for the expected hydrodynamical size (75 nm) and the minimum polydispersity index (0.284) were modified as follows: concentration of HAuCl4.3H2O = 0.03 % concentration of OPLE = 2.00 %, Amplitude = 59.00 %, and time = 26.32 min. Under these conditions, the average hydrodynamical size and average polydispersity index were found to be 71.9 nm and 0.264 respectively, which tallies well with the predicted values.

Rapid mediated biosynthesis and quantification of AuNPs using persimmon (Diospyros Kaki L.f) fruit extract

Persimmon (Diospyros Kaki L.f), as a common fruit, is rich in polyphenols, flavonoids and sugars, having high ability for synthesis of nanoparticles. Thus, biosynthesis of AuNPs using persimmon fruit extract was investigated in this study. The results of UV–visible spectra, transmission electron microscopy images and dynamic light scattering demonstrated that the size and shape of AuNPs highly depended on the concentration of HAuCl4·4H2O and reaction temperature. When 1.0 and 1.5 mM of HAuCl4·4H2O were used as precursors, triangular and hexagonal AuNPs were formed; furthermore, 2.0 mM of HAuCl4·4H2O induced the formation of nanoaggregates. Although higher temperatures (e.g., 50, 60 and 70 °C) boosted the isotropic growth of AuNPs, they had no expressive impact on AuNPs size. Centrifugal ultrafiltration method with inductively coupled plasma-mass spectrometry was applied to assess the transformation efficiency of Au3+ during this biosynthesis procedure. So, the results indicated that more than 97% of Au3+ ions were successfully converted into AuNPs. In addition, the XRD analysis confirmed that AuNPs had face-centered cubic structure. Fourier transform infrared spectroscopy revealed that different functional groups (especially hydroxyl group) were mainly involved in the fabrication of AuNPs. The biosynthesized AuNPs exhibited good antioxidant and catalytic activities.

Genotoxic, cytotoxic, antimicrobial and antioxidant properties of gold nanoparticles synthesized by Nocardia sp. GTS18 using response surface methodology

This work focused on production of the gold nanoparticles (AuNPs) by easily available, safe to handle, eco-friendly, and cost effective method based on utilization of Nocardia sp. GTS18 supernatant. The different process variables affecting AuNPs synthesis were evaluated using both ‘one factor at time’ and ‘response surface’ methodologies. The optimum levels, detected through central composite design, were HAuCl4 concentration of 1.1 mM, pH 4.68, and 17.01 h incubation time. The AuNPs (40–45 nm) synthesized under optimum condition exhibited surface plasmon resonance band centered at 540–545 nm, characteristically. The x-ray diffraction analysis revealed that the crystallite size of synthesized nanoparticle was about 11.4 nm. Fourier transform infrared spectroscopy confirms that the significance of proteins and carbohydrates present in supernatant for reduction of HAuCl4 ions and stabilization of synthesized AuNPs. The synthesized AuNPs showed excellent antibacterial and moderate antioxidant properties. Furthermore, the AuNPs showed no particular signs of genotoxicity and cytotoxicity on lymphocytes at 12.5–100 μg ml−1 concentrations. This study is, as far as we know, the first report on microbial AuNPs synthesized through this statistical approach and their biological properties.

Facile method for decorations of Au nanoparticles on TiO2 nanorod arrays toward high-performance recyclable SERS substrates

High-performance recyclable SERS substrates with well-ordered hybrid nanostructure gold nanoparticles (Au NPs) decorated on titanium dioxide nanorods (TiO2 NRs) were successfully prepared by combining two methods. The TiO2 NRs were fabricated by electron-beam evaporation with glancing-angle deposition (GLAD) technique, then the Au NPs were decorated onto the TiO2 NRs surfaces by deposition-precipitation (DP). The physical structures of the obtained hybrid nanostructures were characterized by field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscope (TEM), and grazing incident angle X-ray diffraction (GIXRD). The results indicated that size and density of Au NPs on TiO2 NRs were controlled by HAuCl4 concentration for optimization of the SERS performance whose the detection of MB molecules was achieved at an enhancement factor of 6.5 × 107 with 9.76%-RSD at 1626 cm−1. More significantly, the optimized hybrid nanostructure SERS substrates exhibit excellent recyclability. These hybrid nanostructure SERS substrates were therefore promising towards detection of TNT for homeland security applications, as well as an on-site SERS platform.

Synergetic effects of acid treatment and localized surface plasmon resonance in PEDOT:PSS layers by doping HAuCl4 for efficient polymer solar cells

Abstract In this report, chloroauric acid (HAuCl4) is used to modify PEDOT:PSS by doping in the aqueous solution, and the effects of HAuCl4 concentration and annealing temperature on the characteristic of PEDOT:PSS have been investigated by a series of testing methods. The results show that HAuCl4 can induce phase segregation between conductive PEDOT and insulated PSS−, which thus leads to the conformation change of the conductive PEDOT chains. Moreover, Au nanoparticles (NPs) can be formed upon mixing with PEDOT:PSS aqueous solution and the distribution of the Au NPs sizes become narrower with post-annealing. Thus, the conductivity of PDOT:PSS can be greatly improved by HAuCl4 doping and post-annealing. Moreover, extinction and PL spectra indicate formed Au NPs in doping PEDOT:PSS layer also cause the effect of localized surface plasmon resonance (LSPR), which can enhance the light absorption in the polymer solar cells (PSCs). A champion PSC based on HAuCl4 doping PEDOT:PSS has been obtained with power conversion efficiency (PCE) of 4.01 ± 0.13%, which shows up to 54.2% enhancement of the PCE comparing with that of the reference device without HAuCl4 doping (2.60 ± 0.05%). The improvement can also be seen at PTB7:ICBA BHJ system with a high PCE of 8.05%, comparing with the reference device without HAuCl4 doping (5.88 ± 0.05%). Thus the results here indicate that synergetic effects of acid treatment and LSPR in HAuCl4 doping PEDOT:PSS layers are efficient for PSCs.

Regulation of gold nanoparticles for the rare earth luminescence enhancement based on nanoporous silica glass

A silica composite system with rare earth ions and gold nanoparticles was fabricated based on nanoporous silica glass. The formation and optical properties of the systems were controlled by the nanoparticles doping concentration and heat treatment. The luminescence intensity dependence on the HAuCl4 doping concentration and heat-treated temperature were investigated. At the optimized concentration of HAuCl4 and heat-treated temperature, the maximal luminescence intensity can be enhanced up to 14.33-fold for Yb2+ and 10.52-fold for Eu2+. It is indicated that the rare earth ions luminescence can be regulated by interactions distance between different types of RE ions and metal NPs as well as the state of nanopores.

A simple and rapid colorimetric probe for uric acid detection based on redox reaction of 3,3ʹ,5,5ʹ-tetramethylbenzidine with HAuCl4

A simple and economical colorimetric probe for the detection of uric acid (UA) based on redox reaction of 3,3ʹ,5,5ʹ-tetramethylbenzidine (TMB) with HAuCl4 was designed. A novel chromogenic reaction was primarily demonstrated based on the reaction between HAuCl4 and TMB, which produces many color responses from red to blue in the resulting solutions. In this method, the colorless TMB can be oxidized by HAuCl4 to generate oxidized TMB (oxTMB) and induce a blue color solution which corresponding to the absorption peak at 652 nm. However, HAuCl4 would be reduced in the presence of UA, which inducing a blue color diminishing of HAuCl4-TMB system and decrease of the absorbance at 652 nm because the content of HAuCl4 was declined in the solution. Based on this phenomenon, we proposed a method to detect UA which does not require nanomaterials or organic probes. The detection conditions, pH value, incubation time and the concentration of HAuCl4 and TMB were optimized. The probe displayed a linear response in the range of 0.001–8.0 μM and 8.0–80.0 μM, with a detection limit of 0.67 nM (S/N = 3). This method has been successfully applied to the determination of uric acid in human urine samples.

Fabrication of Highly Uniform Gold Nanoparticles-Titanium Dioxide Nanotube Arrays for H2O2 Sensing.

This research was to prepare the titanium dioxide nanotube arrays (TiNT arrays) and deposit the Au nanoparticles on its surface using the pulse electrodeposition technique. The Au nanoparticles-TiNT arrays (AuNP-TiNT arrays) were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction, and cyclic voltammetry. The results showed that the Au nanoparticles were uniformly dispersed on the TiNT array surface. The size and loading of Au nanoparticles can be controlled by deposition time, deposition potential, and concentration of HAuCl4. The AuNP-TiNT arrays were then used as a working electrode for hydrogen peroxide (H2O2) detection. Compared with the pure TiNT array electrode, the AuNP-TiNT array electrode had higher sensitivity for the detection of H2O2 and thus provided a simple, promising, and cost-effective sensing platform for the development of enzyme-based biosensors.

Nanoparticles synthesis by Agaricus soil basidiomycetes

We examined the effect of various concentrations of HAuCl4, AgNO3, Na2SeO3, Na2SiO3, and GeO2 on mycelial growth of the soil basidiomycetes Agaricus bisporus and A.arvensis in submerged and solid media. Fungal mycelial extracts and cell-free culture filtrates were able to reduce ions of Au, Ag, Se, Si, and Ge compounds, forming Au0, Ag0, Se0, Si0/SiO2 and Ge0/GeO2 nanoparticles. The physical characteristics of the mycogenic nanoparticles differed depending on the species of Agaricus and the type of extract. Au nanospheres obtained with cell-free culture filtrates were of 2-5nm diameter in A.bisporus and of 2-10nm in A.arvensis. Nanoparticles produced by extracts of mycelia were several times larger and highly heterogenous. Ag nanoparticles produced by cell-free culture filtrates were spherical or irregular-shaped and agglomerated, whereas with extracts of mycelia, small homogenous nanospheres of 1-10nm were formed. Se nanospheres obtained with cell-free culture filtrates were of 100-250nm diameter in A.bisporus and of 150-550nm diameter in A.arvensis. The particles synthesized with extracts of mycelia were of 40-140nm in A.bisporus and of 100-250nm in A.arvensis. Incubation of Na2SiO3 with cell-free culture filtrates resulted in porous Si nanoparticles of 30-65nm in A.bisporus and of 50-200nm in A.arvensis. Ge nanoparticles synthesized by both Agaricus species were mostly spheres of 50-250nm diameter.

Mechanistic study on galvanic replacement reaction and synthesis of Ag-Au alloy nanoboxes with good surface- enhanced Raman scattering activity to detect melamine

Tree-type multiple-head surfactant, bis (amidoethyl-carbamoylethyl) octadecylamine (C18N3), which functions as both reducing and capping agent in the reaction system, has been used to fabricate Ag nanocubes with size over hundreds nanometer. These as-prepared Ag nanocubes could be used as template to fabricate Ag-Au nanoboxes through galvanic replacement reaction by adding HAuCl4 aqueous solution. And the inner diameter of the Ag-Au nanoboxes could be adjusted by changing the concentration of HAuCl4 in the reacted solution. Other influences on the structure of the products of galvanic replacement reaction, such as temperature, were also studied. We find that the structure of the final products are totally different when adding ammonia into the reacted solution of galvanic replacement reaction, they became hexapod and spherical Ag-Au alloy nanostructures. It was suggested that the additive of ammonia water alter the mechanism of the Ag/Au galvanic replacement reaction, which is a new way to increase the types of prepared materials with various structures. We believe that our method opens a new way and will be useful for preparing other kinds of metallic nanostructures. And the SERS (Surface Enhanced Raman Scattering) measurements proved that the prepared Ag-Au alloy nanoboxes possess excellent potential applications in the field of food safety.