Pub Date : 2023-01-30DOI: 10.1007/s13404-023-00325-3
Francis Nsiah, Mark T. McDermott
Abstract
The paper presented herein provides a novel Raman mapping procedure developed to pattern-modified gold nanoparticles on planar gold substrates. This work began with the development of a simple approach to the fabrication and reading of protein microarrays based on the use of microfluidic channels in PDMS and SERS detection. The assay consisted of anti-bovine IgG which was tethered to the nanoparticle via a bifunctional coupling agent and surface-bound bovine IgG. The Raman spectral intensity of the symmetric nitro stretch of the DSNB-modified nanoparticle was used as a diagnostic tool for biomolecular interactions. The work described herein seeks to probe the binding event and also addresses the possible causes of the higher signals observed in such binding events. It is also a contribution to an ongoing investigation into the effect of Raman reporter labels on the observed signals in immunoassays which use SERS as the readout technique.
{"title":"Control of protein density on nanoparticles for SERS-based immunoassays","authors":"Francis Nsiah, Mark T. McDermott","doi":"10.1007/s13404-023-00325-3","DOIUrl":"10.1007/s13404-023-00325-3","url":null,"abstract":"<div><h2>Abstract\u0000</h2><div><p>The paper presented herein provides a novel Raman mapping procedure developed to pattern-modified gold nanoparticles on planar gold substrates. This work began with the development of a simple approach to the fabrication and reading of protein microarrays based on the use of microfluidic channels in PDMS and SERS detection. The assay consisted of anti-bovine IgG which was tethered to the nanoparticle via a bifunctional coupling agent and surface-bound bovine IgG. The Raman spectral intensity of the symmetric nitro stretch of the DSNB-modified nanoparticle was used as a diagnostic tool for biomolecular interactions. The work described herein seeks to probe the binding event and also addresses the possible causes of the higher signals observed in such binding events. It is also a contribution to an ongoing investigation into the effect of Raman reporter labels on the observed signals in immunoassays which use SERS as the readout technique.</p></div></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"56 1","pages":"31 - 42"},"PeriodicalIF":2.2,"publicationDate":"2023-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5146630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-17DOI: 10.1007/s13404-022-00324-w
Tao Wang, Qian Liu, Minshan Shi, Rong Chang, Jun Tang, Yalan He, Dongling Wu
Abstract
The high enhancement activity of litchi-like gold nanoparticles (Au NPs) is prepared in deep eutectic solvent (DES), and the prepared Au NPs as SERS active substrate exhibits excellent sensitivity when rhodamine 6G (R6G) is used as a probe molecule for detection. The enhancement factor (EF) is calculated to be about 1.8 × 1012, and the minimum detected concentration is outstanding in R6G aqueous solution at 10−12 M. In addition, the microtrace determination of penicillin G sodium (PG) in camel milk powder produced in Xinjiang was successfully achieved by using the prepared Au NPs. This work provides an environmentally friendly, simple, and rapid method to prepare efficient and sensitive surface-enhanced Raman scattering (SERS) materials. Meanwhile, it also uncovers a new possibility for the development of various nanoparticles with SERS prepared using DES as reactive solutions.
{"title":"Gold nanoparticles prepared with the aid of deep eutectic solvent and used as substrates for surface-enhanced Raman scattering","authors":"Tao Wang, Qian Liu, Minshan Shi, Rong Chang, Jun Tang, Yalan He, Dongling Wu","doi":"10.1007/s13404-022-00324-w","DOIUrl":"10.1007/s13404-022-00324-w","url":null,"abstract":"<div><h2>Abstract\u0000</h2><div><p>The high enhancement activity of litchi-like gold nanoparticles (Au NPs) is prepared in deep eutectic solvent (DES), and the prepared Au NPs as SERS active substrate exhibits excellent sensitivity when rhodamine 6G (R6G) is used as a probe molecule for detection. The enhancement factor (EF) is calculated to be about 1.8 × 10<sup>12</sup>, and the minimum detected concentration is outstanding in R6G aqueous solution at 10<sup>−12</sup> M. In addition, the microtrace determination of penicillin G sodium (PG) in camel milk powder produced in Xinjiang was successfully achieved by using the prepared Au NPs. This work provides an environmentally friendly, simple, and rapid method to prepare efficient and sensitive surface-enhanced Raman scattering (SERS) materials. Meanwhile, it also uncovers a new possibility for the development of various nanoparticles with SERS prepared using DES as reactive solutions.</p><h3>Graphical abstract</h3>\u0000 <figure><div><div><div><picture><source><img></source></picture></div></div></div></figure>\u0000 </div></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"56 1","pages":"1 - 7"},"PeriodicalIF":2.2,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4682603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-22DOI: 10.1007/s13404-022-00322-y
Monira M. Rageh, M. H. Gaber, Samar M. Mostafa
Abstract
Gold nanoparticles (AuNPs) are well-known biomedical and biotechnological applications because of their interesting properties. They easily cross the cell membranes and interact with intracellular materials. This study was designed to investigate the interaction of calf spleen DNA with AuNPs at a molar ratio of 2:1 in an aqueous solution with different ionic strengths (10, 50, and 100%). AuNPs and AuNPs/DNA complex were characterized by different techniques such as UV/Vis spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier transform IR spectrophotometry. The results revealed that the maximum absorption (λmax) of AuNPs synthesis was observed at 520 nm, and the average particle size was about 13 nm. In addition to a negative zeta potential (− 37 mV), the interaction of AuNPs with DNA was confirmed by melting point and TEM. The melting point that reflects the DNA became unstable in the presence of AuNPs, and the melting temperature decreased by about 3–5 °C with different ionic strength. Additionally, the TEM image of AuNPs/DNA complex obviously illustrated the location of AuNPs on the DNA groove. Finally, these results clearly indicate the attachment of AuNPs with DNA.
{"title":"Effect of ionic strength on the interaction of AuNPs with calf spleen DNA","authors":"Monira M. Rageh, M. H. Gaber, Samar M. Mostafa","doi":"10.1007/s13404-022-00322-y","DOIUrl":"10.1007/s13404-022-00322-y","url":null,"abstract":"<div><h2>Abstract\u0000</h2><div><p>Gold nanoparticles (AuNPs) are well-known biomedical and biotechnological applications because of their interesting properties. They easily cross the cell membranes and interact with intracellular materials. This study was designed to investigate the interaction of calf spleen DNA with AuNPs at a molar ratio of 2:1 in an aqueous solution with different ionic strengths (10, 50, and 100%). AuNPs and AuNPs/DNA complex were characterized by different techniques such as UV/Vis spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier transform IR spectrophotometry. The results revealed that the maximum absorption (<i>λ</i><sub>max</sub>) of AuNPs synthesis was observed at 520 nm, and the average particle size was about 13 nm. In addition to a negative zeta potential (− 37 mV), the interaction of AuNPs with DNA was confirmed by melting point and TEM. The melting point that reflects the DNA became unstable in the presence of AuNPs, and the melting temperature decreased by about 3–5 °C with different ionic strength. Additionally, the TEM image of AuNPs/DNA complex obviously illustrated the location of AuNPs on the DNA groove. Finally, these results clearly indicate the attachment of AuNPs with DNA.</p></div></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"56 1","pages":"23 - 30"},"PeriodicalIF":2.2,"publicationDate":"2022-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-022-00322-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4849783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-20DOI: 10.1007/s13404-022-00323-x
Doaa Sulaiman, Alwan M. Alwan, Walid K. Hamoudi
Abstract
Fixed laser pulse duty cycle at 20% using short laser wavelength (405 nm) at different values of laser power density (300–600 mW/cm2) were used to form Si nano-columns as based SERS layer. The idea was to synthesize SERS devices with excellent reproducibility and high enhancement factor to detect ultra-low residence of chlorpyrifos pesticide. The results indicated that the morphological aspects of silicon nano-columns layer and; hence, the performance of SERS devices could be well-regulated through the adjustment of laser power density. The SERS detection of ultra-low chlorpyrifos concentrations displayed an excellent reproducibility with less than 5% error. The highest chlorpyrifos enhancement factor (EF = 1.1 × 106) and minimum detection limit (LOD = 22 × 10−8 M) were obtained from high altitude Si nano-columns; partly populated with three dimensions AuNPs layer, and the use of 500mW/cm2 laser power density.
{"title":"Pesticide detection optimization of plasmonics gold nanoparticles/silicon nano-columns structures by controlling the coupling lasers power density","authors":"Doaa Sulaiman, Alwan M. Alwan, Walid K. Hamoudi","doi":"10.1007/s13404-022-00323-x","DOIUrl":"10.1007/s13404-022-00323-x","url":null,"abstract":"<div><h2>Abstract\u0000</h2><div><p>Fixed laser pulse duty cycle at 20% using short laser wavelength (405 nm) at different values of laser power density (300–600 mW/cm<sup>2</sup>) were used to form Si nano-columns as based SERS layer. The idea was to synthesize SERS devices with excellent reproducibility and high enhancement factor to detect ultra-low residence of chlorpyrifos pesticide. The results indicated that the morphological aspects of silicon nano-columns layer and; hence, the performance of SERS devices could be well-regulated through the adjustment of laser power density. The SERS detection of ultra-low chlorpyrifos concentrations displayed an excellent reproducibility with less than 5% error. The highest chlorpyrifos enhancement factor (EF = 1.1 × 10<sup>6</sup>) and minimum detection limit (LOD = 22 × 10<sup>−8</sup> M) were obtained from high altitude Si nano-columns; partly populated with three dimensions AuNPs layer, and the use of 500mW/cm<sup>2</sup> laser power density.</p></div></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"56 1","pages":"9 - 21"},"PeriodicalIF":2.2,"publicationDate":"2022-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-022-00323-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4783629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-09DOI: 10.1007/s13404-022-00319-7
Hossein Toghyani Dolatabadi, Mahdieh Izadi, Ali Mohammad Tamaddon
Healthy dairy products should be free of any substances that threaten human health. However, the use of antibiotics for the treatment of lactating animals can be a risk to human health, as their residues and metabolites can be transferred into milk. Various methods are used to ensure the purity of milk. In this study, a kit based on a specific penicillin aptamer bonded to gold nanoparticles was designed to measure penicillin in milk, and its measurement was performed using ELISA colorimetric method. After synthesis of gold nanoparticles, the molarity of gold nanoparticles was calculated by UV spectrophotometer, and its synthesis was confirmed by FTIR. Salt concentrations were also optimized to bind aptamer to gold nanoparticles. The gold nanoparticles were then bonded to the specific aptamer of penicillin, and the concentration of penicillin G in the milk sample was measured by a biosensor designed by ELISA. The choice of biosensor was also examined in the presence of similar antibiotics.
{"title":"Evaluation of penicillin residues in milk by ELISA using aptamer bonded to gold nanoparticles","authors":"Hossein Toghyani Dolatabadi, Mahdieh Izadi, Ali Mohammad Tamaddon","doi":"10.1007/s13404-022-00319-7","DOIUrl":"10.1007/s13404-022-00319-7","url":null,"abstract":"<div><p>Healthy dairy products should be free of any substances that threaten human health. However, the use of antibiotics for the treatment of lactating animals can be a risk to human health, as their residues and metabolites can be transferred into milk. Various methods are used to ensure the purity of milk. In this study, a kit based on a specific penicillin aptamer bonded to gold nanoparticles was designed to measure penicillin in milk, and its measurement was performed using ELISA colorimetric method. After synthesis of gold nanoparticles, the molarity of gold nanoparticles was calculated by UV spectrophotometer, and its synthesis was confirmed by FTIR. Salt concentrations were also optimized to bind aptamer to gold nanoparticles. The gold nanoparticles were then bonded to the specific aptamer of penicillin, and the concentration of penicillin G in the milk sample was measured by a biosensor designed by ELISA. The choice of biosensor was also examined in the presence of similar antibiotics.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"55 2","pages":"187 - 193"},"PeriodicalIF":2.2,"publicationDate":"2022-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-022-00319-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4376057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-02DOI: 10.1007/s13404-022-00316-w
Mohammad E. Khosroshahi, Yesha Patel, Roxana Chabok
Conjugation and characterization of poly-ethylene–glycol (PEG)-functionalized gold nanourchin (GNU) with breast cancer biomarker HER-II monoclonal antibody (mAb) (i.e., anti-HER-II) for selective targeting are described. After the functionalization of GNU with PEG, the surface plasmon resonance (SPR) peak was red-shifted, indicating the increase in the hydrodynamic size of the GNU. The Fourier-transform near-infrared spectroscopy (FT-NIR) second derivative result of GNU-PEG provided overtone and combination bands of fundamental vibrational modes of protein molecular structures between 4000 and 7500 cm−1. This mainly included C–H combination and CH2 bonds, O–H first stretch overtones, the C–H first stretch overtone, and the CH2 combination first overtone. The UV–Vis absorbance showed a strong absorption of light at 227 and 275 nm corresponding to tyrosine peaks. The fluorescence emission peak at 315 nm corresponds to Stokes shift when excited by 280 nm corresponding to tyrosine in the mAb, and the peak at 497 nm likely corresponds to alanine. After conjugation of GNU-PEG with mAb, the FT-NIR indicated the bands corresponding to NH2 combination and amino acids, first overtone symmetric and antisymmetric OH stretching, C–H combination, and the second overtones and combination modes. Surface-enhanced Raman scattering (SERS) provided useful information on the molecular structure and composition of the sample within 300–3500 cm−1. The intensity behavior of SERS signals exhibited a statistical nature due to Brownian fluctuating movement. In addition, the intensity and number of SERS lines varied with the laser power. The dominant peaks were corresponding to histidine, tyrosine, tryptophan, phenylalanine, and C–H, N–H, C–N, and O–H bonds.
{"title":"Characterization of breast cancer antibody (anti-HER-II) conjugated on PEGylated gold nanourchin for active targeting","authors":"Mohammad E. Khosroshahi, Yesha Patel, Roxana Chabok","doi":"10.1007/s13404-022-00316-w","DOIUrl":"10.1007/s13404-022-00316-w","url":null,"abstract":"<div><p>Conjugation and characterization of poly-ethylene–glycol (PEG)-functionalized gold nanourchin (GNU) with breast cancer biomarker HER-II monoclonal antibody (mAb) (i.e., anti-HER-II) for selective targeting are described. After the functionalization of GNU with PEG, the surface plasmon resonance (SPR) peak was red-shifted, indicating the increase in the hydrodynamic size of the GNU. The Fourier-transform near-infrared spectroscopy (FT-NIR) second derivative result of GNU-PEG provided overtone and combination bands of fundamental vibrational modes of protein molecular structures between 4000 and 7500 cm<sup>−1</sup>. This mainly included C–H combination and CH<sub>2</sub> bonds, O–H first stretch overtones, the C–H first stretch overtone, and the CH<sub>2</sub> combination first overtone. The UV–Vis absorbance showed a strong absorption of light at 227 and 275 nm corresponding to tyrosine peaks. The fluorescence emission peak at 315 nm corresponds to Stokes shift when excited by 280 nm corresponding to tyrosine in the mAb, and the peak at 497 nm likely corresponds to alanine. After conjugation of GNU-PEG with mAb, the FT-NIR indicated the bands corresponding to NH<sub>2</sub> combination and amino acids, first overtone symmetric and antisymmetric OH stretching, C–H combination, and the second overtones and combination modes. Surface-enhanced Raman scattering (SERS) provided useful information on the molecular structure and composition of the sample within 300–3500 cm<sup>−1</sup>. The intensity behavior of SERS signals exhibited a statistical nature due to Brownian fluctuating movement. In addition, the intensity and number of SERS lines varied with the laser power. The dominant peaks were corresponding to histidine, tyrosine, tryptophan, phenylalanine, and C–H, N–H, C–N, and O–H bonds.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"55 2","pages":"149 - 159"},"PeriodicalIF":2.2,"publicationDate":"2022-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4089711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-13DOI: 10.1007/s13404-021-00306-4
Paulina Abrica-González, E. Zumelzu, Jorge Nimptsch, José Abraham Balderas-López, Alejandro Muñoz-Diosdado, Ignacio Moreno-Villoslada, Mario E. Flores
Abstract
Gold nanoparticles (AuNPs) are nowadays used in many areas of science, particularly in medicine as drug release and gene carriers. The extensive use of these materials makes imperative the study of their effects on the environment after their disposal, that mostly affects the aquatic media. The present work explores the bioaccumulation and toxicity of chitosan-functionalized and non-functionalized gold nanoparticles, with primary producers (Lemna valdiviana) and primary consumers (Daphnia pulex) aquatic organisms. Bioaccumulation of 27.4 nm AuNPs and 43.1 nm chitosan-gold nanoparticles (CO-AuNPs) was evaluated in both microorganisms, finding accumulation of AuNPs and inhomogeneous aggregation of CO-AuNPs in Daphnia pulex gut, and internalization of both types of nanoparticles in Lemna valdiviana cell walls. The effective concentration of nanomaterial for 50% survival (LC50) of Daphnia pulex organisms was 1.13 mg/L for AuNPs and 0.96 mg/L for CO-AuNPs in the acute test. In Lemna valdiviana 7-day test, the EC50 for area and frond number were 1.19 mg/L and 1.26 mg/L, respectively, for AuNPs, 1.53 mg/L and 1.44 mg/L, respectively, for CO-AuNPs, finding higher toxicity of CO-AuNPs to Daphnia pulex, and AuNPs to Lemna valdiviana. The obtained results suggest that the effects of nanomaterials on the growth and survival of key organisms deserve further study, as this may lead to the development of appropriate environmental regulations.
{"title":"The effect of chitosan-modified gold nanoparticles in Lemna valdiviana and Daphnia pulex","authors":"Paulina Abrica-González, E. Zumelzu, Jorge Nimptsch, José Abraham Balderas-López, Alejandro Muñoz-Diosdado, Ignacio Moreno-Villoslada, Mario E. Flores","doi":"10.1007/s13404-021-00306-4","DOIUrl":"10.1007/s13404-021-00306-4","url":null,"abstract":"<div><h2>Abstract\u0000</h2><div><p>Gold nanoparticles (AuNPs) are nowadays used in many areas of science, particularly in medicine as drug release and gene carriers. The extensive use of these materials makes imperative the study of their effects on the environment after their disposal, that mostly affects the aquatic media. The present work explores the bioaccumulation and toxicity of chitosan-functionalized and non-functionalized gold nanoparticles, with primary producers (<i>Lemna valdiviana</i>) and primary consumers (<i>Daphnia pulex</i>) aquatic organisms. Bioaccumulation of 27.4 nm AuNPs and 43.1 nm chitosan-gold nanoparticles (CO-AuNPs) was evaluated in both microorganisms, finding accumulation of AuNPs and inhomogeneous aggregation of CO-AuNPs in <i>Daphnia pulex</i> gut, and internalization of both types of nanoparticles in <i>Lemna valdiviana</i> cell walls. The effective concentration of nanomaterial for 50% survival (LC50) of <i>Daphnia pulex</i> organisms was 1.13 mg/L for AuNPs and 0.96 mg/L for CO-AuNPs in the acute test. In <i>Lemna valdiviana</i> 7-day test, the EC50 for area and frond number were 1.19 mg/L and 1.26 mg/L, respectively, for AuNPs, 1.53 mg/L and 1.44 mg/L, respectively, for CO-AuNPs, finding higher toxicity of CO-AuNPs to <i>Daphnia pulex</i>, and AuNPs to <i>Lemna valdiviana</i>. The obtained results suggest that the effects of nanomaterials on the growth and survival of key organisms deserve further study, as this may lead to the development of appropriate environmental regulations.</p></div></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"55 1","pages":"77 - 91"},"PeriodicalIF":2.2,"publicationDate":"2022-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4539717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-29DOI: 10.1007/s13404-021-00299-0
Liqing Meng, Zongxiao Li, Yousheng Deng
Gold nanorods are of great significance in biomedical and sensing applications due to their local surface plasmon resonance absorption. The silver-mediated seeding method was used to prepare gold nanorods, the longitudinal local surface plasmon resonance (LSPR) absorption of the prepared gold nanorods was monitored, and the growth kinetics of the gold nanorods were discussed. The results show that the growth process of gold nanorods is characterized by a first-order reaction, and its activation energy is about 54.4 kJ/mol. This experimental conclusion provides a good theoretical guide for the preparation of gold nanorods during application research.
{"title":"Study on the growth kinetics of Au nanorods based on local surface plasmon resonance","authors":"Liqing Meng, Zongxiao Li, Yousheng Deng","doi":"10.1007/s13404-021-00299-0","DOIUrl":"10.1007/s13404-021-00299-0","url":null,"abstract":"<div><p>Gold nanorods are of great significance in biomedical and sensing applications due to their local surface plasmon resonance absorption. The silver-mediated seeding method was used to prepare gold nanorods, the longitudinal local surface plasmon resonance (LSPR) absorption of the prepared gold nanorods was monitored, and the growth kinetics of the gold nanorods were discussed. The results show that the growth process of gold nanorods is characterized by a first-order reaction, and its activation energy is about 54.4 kJ/mol. This experimental conclusion provides a good theoretical guide for the preparation of gold nanorods during application research.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"54 2","pages":"89 - 95"},"PeriodicalIF":2.2,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-021-00299-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5132642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-27DOI: 10.1007/s13404-021-00301-9
K. M. Saradesh, K. R. Ravi, G. S. Vinodkumar
The age hardenability of 22 karat gold (Au-5.8wt.%Cu-2.5wt.%Ag) alloyed with Ti at various concentrations (0.5, 0.75, and 1 wt.%) was studied. The addition level of Ti is compensated with Ag to maintain the purity of gold in 22 karat, i.e., 91.75 wt.%. The Ti containing 22 karat gold was prepared by melting Au, Cu, and Ag and adding Ti via Au-6wt.%Ti master alloy. The castings obtained were cold-rolled into thin sheet (90% reduction). Both the cast and cold-rolled sheets were subjected to age hardening treatment (solutionizing and artificial aging). Artificial aging was performed as a function of time at 550 °C to identify the peak aging. At all addition level of Ti, the 22 karat gold responded well to the age hardening treatment. The cold-worked sheet samples showed faster peak aging within 30 min. and higher peak hardness than their cast counterpart. Increasing the Ti concentration increases the peak hardness of both cold-rolled sheet and casting samples. Transmission electron microscopic analysis of the peak aged cold-rolled sheet samples shows uniformly distributed coherent Au4Ti precipitates in Au matrix which contribute to the higher hardness.
{"title":"The age hardenability of 22 karat gold (Au-5.8wt.%Cu-2.5wt.%Ag) alloyed with titanium","authors":"K. M. Saradesh, K. R. Ravi, G. S. Vinodkumar","doi":"10.1007/s13404-021-00301-9","DOIUrl":"10.1007/s13404-021-00301-9","url":null,"abstract":"<div><p>The age hardenability of 22 karat gold (Au-5.8wt.%Cu-2.5wt.%Ag) alloyed with Ti at various concentrations (0.5, 0.75, and 1 wt.%) was studied. The addition level of Ti is compensated with Ag to maintain the purity of gold in 22 karat, i.e., 91.75 wt.%. The Ti containing 22 karat gold was prepared by melting Au, Cu, and Ag and adding Ti via Au-6wt.%Ti master alloy. The castings obtained were cold-rolled into thin sheet (90% reduction). Both the cast and cold-rolled sheets were subjected to age hardening treatment (solutionizing and artificial aging). Artificial aging was performed as a function of time at 550 °C to identify the peak aging. At all addition level of Ti, the 22 karat gold responded well to the age hardening treatment. The cold-worked sheet samples showed faster peak aging within 30 min. and higher peak hardness than their cast counterpart. Increasing the Ti concentration increases the peak hardness of both cold-rolled sheet and casting samples. Transmission electron microscopic analysis of the peak aged cold-rolled sheet samples shows uniformly distributed coherent Au<sub>4</sub>Ti precipitates in Au matrix which contribute to the higher hardness.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"54 2","pages":"105 - 113"},"PeriodicalIF":2.2,"publicationDate":"2021-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-021-00301-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5064971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present study attempted to analyse the random-walk characteristics of the gold spot price of the London Bullion Market Association (LBMA) by using several linear and nonlinear models. The research collects two decades of daily data from 3rd February 2000 to 2nd October 2020. Econometric tests such as serial correlation test, unit-root tests, multiple variance ratio (MVR), and the BDS test were applied to examine the linear and nonlinear dependence of return series. Further, we employed all the tests from ARCH family to examine the volatility clustering of the gold return series. The results of serial correlation and the unit-root test suggest that the gold return is stationary, therefore does not follow the random-walk benchmark, and hence the gold market is inefficient. EGARCH results indicate that the positive news has a more significant impact on the gold return than the negative news. The findings have important implications for the efficient portfolio investments, and better hedging opportunities for the investors.
{"title":"Do LBMA gold price follow random-walk?","authors":"Biswabhusan Bhuyan, Subhamitra Patra, Ranjan Kumar Bhuian","doi":"10.1007/s13404-021-00300-w","DOIUrl":"10.1007/s13404-021-00300-w","url":null,"abstract":"<div><p>The present study attempted to analyse the random-walk characteristics of the gold spot price of the London Bullion Market Association (LBMA) by using several linear and nonlinear models. The research collects two decades of daily data from 3rd February 2000 to 2nd October 2020. Econometric tests such as serial correlation test, unit-root tests, multiple variance ratio (MVR), and the BDS test were applied to examine the linear and nonlinear dependence of return series. Further, we employed all the tests from ARCH family to examine the volatility clustering of the gold return series. The results of serial correlation and the unit-root test suggest that the gold return is stationary, therefore does not follow the random-walk benchmark, and hence the gold market is inefficient. EGARCH results indicate that the positive news has a more significant impact on the gold return than the negative news. The findings have important implications for the efficient portfolio investments, and better hedging opportunities for the investors.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"54 2","pages":"151 - 159"},"PeriodicalIF":2.2,"publicationDate":"2021-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4634373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号