Displaying publications 101 - 120 of 304 in total

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  1. Effect of Conductive Layer Condition on the Morphology of Anodic Aluminum Oxide Template-Assisted Indium Antimonide Nanowires
    Fayyadh OA, Arifin INA, Khairudin A, Hassan J, Abubakar S, Talib ZA, et al.
    J Nanosci Nanotechnol, 2020 May 01;20(5):3157-3163.
    PMID: 31635660 DOI: 10.1166/jnn.2020.17386
    Indium antimonide nanowires were synthesized by electrochemical deposition using anodic aluminum oxide template in the presence of gold film as conductive layers. Field emission scanning electron microscopy and energy dispersive X-ray spectrometry measurements were carried out to investigate the effect of adhesive insulated tape covered below the conductive layer. Results showed that the anodic aluminum oxide template covered with insulating tapes had better morphology with less presence of overgrown rough film on the topside of the anodic aluminum oxide template and it exhibited a smoother nanowire sidewall as compared to the uncovered ones. Additionally, the unique properties of anodic aluminum oxide were controllable pore diameter with a narrow size distribution at some intervals. It was evident from the energy dispersive X-ray spectrum that the nanowires synthesized from the covered template condition exhibited better InSb composition and stoichiometric ratio compared to the uncovered template condition.
    Matched MeSH terms: Gold
  2. Potential of a sonochemical approach to generate MRI-PPT theranostic agents for breast cancer
    Dheyab MA, Aziz AA, Khaniabadi PM, Jameel MS
    Photodiagnosis Photodyn Ther, 2021 Mar;33:102177.
    PMID: 33429101 DOI: 10.1016/j.pdpdt.2021.102177
    The production of nanomaterials integrating diagnostic and therapeutic roles within one nanoplatform is important for medical applications. Such theranostics nanoplatforms could provide information on imaging, accurate diagnosis and, at the same time, could eradicate cancer cells. Fe3O4@Au core@shell nanoparticles (Fe3O4@AuNPs) have gained broad attention due to their unique innovations in magnetic resonance imaging (MRI) and photothermal therapy (PTT). Seed-mediated growth procedures were used to produce the Fe3O4@AuNPs. In these processes, complicated surface modifications, resulted in unsatisfactory properties. This work used the ability of the sonochemical approach to synthesize highly efficient theranostics agent Fe3O4@AuNPs with a size of approximately 22 nm in 5 min. The inner core of Fe3O4 acts as an MRI agent, whereas the photothermal effect stands accomplished by near-infrared absorption of the gold shell (Au shell), which results in the eradication of cancer cells. We have shown that Fe3O4@AuNPs have great biocompatibility and no major cytotoxicity has been identified. Relaxivity value (r2) of synthesized Fe3O4@Au NPs, measured at 233 mM-1s-1, is significantly higher than those reported previously. The as-synthesized NPs have shown substantial photothermal ablation ability on MCF-7 in vitro under near-infrared laser irradiation. Consequently, Fe3O4@AuNPs synthesized in this study have great potential as an ideal candidate for MR imaging and PTT.
    Matched MeSH terms: Gold
  3. Fluorescence "turn-off/turn-on" biosensing of metal ions by gold nanoclusters, folic acid and reduced graphene oxide
    Wong XY, Quesada-González D, Manickam S, Muthoosamy K
    Anal Chim Acta, 2021 Aug 29;1175:338745.
    PMID: 34330444 DOI: 10.1016/j.aca.2021.338745
    Metal ions homeostasis plays an important role in biological processes. The ability to detect the concentration of metal ions in biological fluids is often challenged by the obvious interference or competitive binding nature of other alkaline metals ions. Common analytical techniques employed for metal ions detection are electrochemical, fluorescence and colorimetric methods. However, most reported metal ions sensors are complicated, time-consuming and involve costly procedures with limited effectiveness. Herein, a nanobiosensor for detecting sodium and potassium ions using folic acid-functionalised reduced graphene oxide-modified RNase A gold nanoclusters (FA-rGO-RNase A/AuNCs) based on fluorescence "turn-off/turn-on" is presented. Firstly, a facile and optimised protocol for the fabrication of RNase A/AuNCs is developed. The activity of RNase A protein after the formation of RNase A/AuNCs is studied. RNase A/AuNCs is then loaded onto FA-rGO, in which FA-rGO is used as a potential carrier and fluorescence quencher for RNase A/AuNCs. Finally, a fluorescence "turn-on" sensing strategy is developed using the as-synthesised FA-rGO-RNase A/AuNCs to detect sodium and potassium ions. The developed nanobiosensor revealed an excellent sensing performance and meets the sensitivity required to detect both sodium and potassium ions. To the best of our knowledge, this is the first work done on determining the RNase A protein activity in RNase A/AuNCs and exploring the potential application of RNase A/AuNCs as a metal ion sensor. This work serves as a proof-of-concept for combining the potential of drug delivery, active targeting and therapy on cancer cells, as well as biosensing of metal ions into a single platform.
    Matched MeSH terms: Gold
  4. Fulltext Random amplified polymorphic DNA-PCR and ERIC PCR analysis on Vibrio parahaemolyticus isolated from cockles in Padang, Indonesia
    Zulkifli, Y., Alitheen, N.B., Son, R., Raha, A.R., Samuel, L., Yeap, S.K., et al.
    International Food Research Journal, 2009;16(2):141-150.
    MyJurnal
    In this study, RAPD-PCR and ERIC-PCR were used to study the epidemiology of V. parahaemolyticus isolated from cockles in Padang, Indonesia. The Gold Oligo OPAR3 primer produced bands ranged from 1-8 with sizes from 0.2 – 5.0 kb and the Gold Oligo OPAR8 primer produced 1-7 bands with sizes 0.7 – 1.5 kb. Both primers produced twenty five RAPD patterns with a few isolates failed to produce any products. Based on phylogenetic dendrogram, all the isolates can be divided into 6 major clusters with similarity between 0 to 52%. For the ERIC primer, it produced bands ranged from 3-15 with sizes from 0.1 – 5.0 kb and twenty seven different ERIC patterns. Construction of the phylogenetic dendogram showed the isolates can be divided into 4 major clusters with similarity between 56 to 86%. The high diversity of both processes may be due to the multiple contamination sources of V. parahaemolyticus.
    Matched MeSH terms: Gold
  5. Fulltext Micro-Computed Tomography Detection of Gold Nanoparticle-Labelled Mesenchymal Stem Cells in the Rat Subretinal Layer
    Mok PL, Leow SN, Koh AE, Mohd Nizam HH, Ding SL, Luu C, et al.
    Int J Mol Sci, 2017 Feb 08;18(2).
    PMID: 28208719 DOI: 10.3390/ijms18020345
    Mesenchymal stem cells are widely used in many pre-clinical and clinical settings. Despite advances in molecular technology; the migration and homing activities of these cells in in vivo systems are not well understood. Labelling mesenchymal stem cells with gold nanoparticles has no cytotoxic effect and may offer suitable indications for stem cell tracking. Here, we report a simple protocol to label mesenchymal stem cells using 80 nm gold nanoparticles. Once the cells and particles were incubated together for 24 h, the labelled products were injected into the rat subretinal layer. Micro-computed tomography was then conducted on the 15th and 30th day post-injection to track the movement of these cells, as visualized by an area of hyperdensity from the coronal section images of the rat head. In addition, we confirmed the cellular uptake of the gold nanoparticles by the mesenchymal stem cells using transmission electron microscopy. As opposed to other methods, the current protocol provides a simple, less labour-intensive and more efficient labelling mechanism for real-time cell tracking. Finally, we discuss the potential manipulations of gold nanoparticles in stem cells for cell replacement and cancer therapy in ocular disorders or diseases.
    Matched MeSH terms: Gold
  6. Fulltext Update on blood pressure measurement in research and in clinical practice
    Faezah Sabirin
    Compendium of Oral Science, 2014;1(1):1-5.
    MyJurnal
    Blood pressure (BP) measurement was first recorded in 1700's by Hales who concluded that it was due to a pressure in the blood (1 , 2]. This is his well renowned discovery besides his other experiments on the capacity of ventricles and many other feature of circulatory system. The development of BP measurement was then rather quiet until about a century later. The accurate study of BP started with the introduction of mercury manometer by Poiseuille in 1800's who demonstrated that the arterial pressure was maintained in smaller arteries and that the blood flow through mesenteric bed did not depend on development of the venous change but varied directly with arterial pressure [3]. In the year of 1928, Poiseuille work was recognised when he won the gold medal of Royal Academy of Medicine for his doctoral dissertation on the measurement of BP using mercury manometer that was directly inserted with cannula filled with potassium bicarbonate as anticoagulant into an artery [3]. Later, his invention has enabled Carl Ludwig to develop kymograph, a method to record clinical physiological data including the BP measurements [3]. (Copied from article).
    Matched MeSH terms: Gold
  7. Fulltext Management of an unerupted, dilacerated maxillary permanent central incisor by a combined surgical - orthodontic approach: a case report
    Sockalingam, G., Ngah, I.
    Malaysian Dental Journal, 2007;28(2):99-102.
    MyJurnal
    This case report presents a combined surgical – orthodontic approach to the management of an unerupted maxillary right permanent central incisor in a 13 year-old Chinese male. Radiographic investigations revealed that the tooth was severely dilacerated, most likely as a result of trauma sustained to the upper maxillary right deciduous central incisor at the age of 3 years. After securing adequate space for the unerupted tooth by fixed appliance therapy, surgical exposure of the crown was carried out under local anaesthesia and oral sedation.
    A gold chain was bonded to the exposed crown of the tooth. Traction was then carried out and the tooth was successfully brought to its final and correct position in the arch after 36 months of active orthodontic treatment.
    Matched MeSH terms: Gold
  8. Fulltext Sensitivity study of Graphene Nanoribbon with NH3 at room temperature
    Guan Ling Sim, Mohd Nizar Hamidon, Kamilu Iman Usman
    Pertanika Journal of Science & Technology, 2017;25(102):259-266.
    MyJurnal
    This study presents the sensitivity of graphene nanoribbon (GNR) when exposed to ammonia gas at room temperature. Alumina were used as a substrate and coated with GNR as sensing film for ammonia gas detection. Four different concentration of GNR in the category of maximum, high, low, and minimum were prepared. Each category of GNR will be dispersed on alumina substrate with area of 1cm2 and 4cm2. 30nm of gold contacts are sputtered on both ends of the sensing film. The ammonia gas can be detected by measuring the changes in resistance. The GNR as ammonia sensor shows good responses at room temperature. In repeatability test, maximum GNR shows least variation when exposed to ammonia with the value of 1.01% (4cm2) and 2.12% (1cm2). In a sensitivity test, 0.25% to 1.00% of ammonia gas was used and tested on maximum GNR. Maximum GNR on 4cm2 substrate shows higher sensitivity as compared to 1cm2. Reaction time of GNR on ammonia gas decreased as the concentration of ammonia increased. Larger surface area of sensing element required lesser reaction time.
    Matched MeSH terms: Gold
  9. Sputtered Encapsulation as Wafer Level Packaging for Isolatable MEMS Devices: A Technique Demonstrated on a Capacitive Accelerometer
    Hamzah AA, Yunas J, Majlis BY, Ahmad I
    Sensors (Basel), 2008 Nov 19;8(11):7438-7452.
    PMID: 27873938
    This paper discusses sputtered silicon encapsulation as a wafer level packaging approach for isolatable MEMS devices. Devices such as accelerometers, RF switches, inductors, and filters that do not require interaction with the surroundings to function, could thus be fully encapsulated at the wafer level after fabrication. A MEMSTech 50g capacitive accelerometer was used to demonstrate a sputtered encapsulation technique. Encapsulation with a very uniform surface profile was achieved using spin-on glass (SOG) as a sacrificial layer, SU-8 as base layer, RF sputtered silicon as main structural layer, eutectic gold-silicon as seal layer, and liquid crystal polymer (LCP) as outer encapsulant layer. SEM inspection and capacitance test indicated that the movable elements were released after encapsulation. Nanoindentation test confirmed that the encapsulated device is sufficiently robust to withstand a transfer molding process. Thus, an encapsulation technique that is robust, CMOS compatible, and economical has been successfully developed for packaging isolatable MEMS devices at the wafer level.
    Matched MeSH terms: Gold
  10. Fulltext Dose enhancement effects by different size of gold nanoparticles under irradiation of megavoltage photon beam
    Wan Nordiana W Abd Rahman, Raizulnasuha Ab Rashid, Mahfuzah Muhammad, Khairunisak Abdul Razak, Norhayati Dollah, Moshi Geso
    Jurnal Sains Nuklear Malaysia, 2018;30(2):23-29.
    MyJurnal
    Gold nanoparticles (AuNPs) have been extensively investigated as dose enhancement agent to increase the lethal dose to the tumours while minimizing dose to the normal tissue. Their intriguing properties and characteristics such as small size and shape provide favorable option in increasing radiotherapy therapeutic efficiency. In this study, the effects of AuNPs size on the dose enhancement effects irradiated under megavoltage photon beams were investigated. The study was conducted in-vitro on HeLa cells using AuNPs of 5 nm and 15 nm sizes. The cells samples were incubated with AuNPs and irradiated with photon beam of energy 6 MV and 10 MV at 100 cm SSD and 10 cm x 10 cm field size. Clonogenic assay were performed to observe the dose enhancement effects on cell survival. Dose enhancement factor (DEF) were extrapolated and evaluated from the cell survival curves. The results show that both sizes of AuNPs produce dose enhancement with the larger size AuNPs of 15 nm produce more dose enhancement compare to 5 nm AuNPs for 6 MV photon beam. Dose enhancements were observed for 10 MV photon beams but DEF for both sizes AuNPs shows no differences. In conclusion, larger size AuNPs produce higher dose enhancement compare to small size of AuNPs which conclude that nanoparticles size is important factor that need to be taken into account for AuNPs to be applied in radiotherapy.
    Matched MeSH terms: Gold
  11. Dentine collagen cross-linking using tiopronin-protected Au/EDC nanoparticles formulations
    Daood U, Akram Z, Matinlinna JP, Fawzy AS
    Dent Mater, 2019 07;35(7):1017-1030.
    PMID: 31064669 DOI: 10.1016/j.dental.2019.04.005
    OBJECTIVE: The aim of this study was to investigate EDC-assisted collagen crosslinking effect with different concentrations of tiopronin-protected gold (TPAu) nanoparticles on demineralized dentine.

    METHODS: TPAu nanoparticles were fabricated from 0.31-g tetrachloroauric acid and 0.38-g of N-(2-mercaptopropionyl) glycine (2.4-mmol). Then co-dissolved using 35-mL of 6:1 methanol/acetic acid and mixed using NaBH4. EDC (0.3-M) was conjugated to TPAu nanoparticles at TPAU/EDC-0.25:1, and TPAU/EDC-0.5:1 treatment formulations ratios. Dentin specimens treated with 0.3-M EDC solution alone or left untreated were used as control. Nanoparticles formulations were characterized in term of particles morphology and size, Zeta potential, thermogravimetric analysis and small-angle X-ray scattering. Dentin substrates were characterized in term of TEM investigation, dentin proteases characterization, hydroxyproline liberation, elastic modulus measurement, Raman analysis and confocal microscopy viewing.

    RESULTS: TEM evaluation of tiopronin protected gold nanoparticles dispersion revealed nano-clusters formations in both groups. However, based on our TEM measurements, the particle-size was ranging from ˜20 to 50 nm with spherical core-shape which were almost similar for both TPAu/EDC ratios (0.5:1 and 0.25:1). Zeta potential measurements indicate negative nanoparticles surface charge. SAXS profiles for both formulations, suggest a typical profile for uni-lamellar nanoparticles. Superior dentin collagen cross-linking effect was found with the TPAu/EDC nanoparticles formulations compared to the control and EDC treated groups.

    SIGNIFICANCE: Cross-linking of dentin collagen using TPAu coupled with EDC through TPAu/EDC nanoparticles formulations is of potential significance in improving the biodegradation resistance, proteases inhibition, mechanical and structural stability of demineralized dentin substrates. In addition, the cross-linking effect is dependent on TPAu/EDC ratio, whereas higher cross-linking effect was found at TPAu/EDC ratio of 0.5:1.

    Matched MeSH terms: Gold
  12. Fulltext Amino Anthraquinone: Synthesis, Characterization, and Its Application as an Active Material in Environmental Sensors
    Ali S, Tahir M, Mehboob N, Wahab F, J Langford S, Mohd Said S, et al.
    Materials (Basel), 2020 Feb 21;13(4).
    PMID: 32098037 DOI: 10.3390/ma13040960
    This work reports synthesis, thin film characterizations, and study of an organic semiconductor 2-aminoanthraquinone (AAq) for humidity and temperature sensing applications. The morphological and phase studies of AAq thin films are carried out by scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray diffraction (XRD) analysis. To study the sensing properties of AAq, a surface type Au/AAq/Au sensor is fabricated by thermally depositing a 60 nm layer of AAq at a pressure of ~10-5 mbar on a pre-patterned gold (Au) electrodes with inter-electrode gap of 45 µm. To measure sensing capability of the Au/AAq/Au device, the variations in its capacitance and resistance are studied as a function of humidity and temperature. The Au/AAq/Au device measures and exhibits a linear change in capacitance and resistance when relative humidity (%RH) and temperature are varied. The AAq is a hydrophobic material which makes it one of the best candidates to be used as an active material in humidity sensors; on the other hand, its high melting point (575 K) is another appealing property that enables it for its potential applications in temperature sensors.
    Matched MeSH terms: Gold
  13. Dynamic Absorption Enhancement and Equivalent Resonant Circuit Modeling of Tunable Graphene-Metal Hybrid Antenna
    Ullah Z, Nawi I, Witjaksono G, Tansu N, Khattak MI, Junaid M, et al.
    Sensors (Basel), 2020 Jun 04;20(11).
    PMID: 32512718 DOI: 10.3390/s20113187
    Plasmonic antennas are attractive optical components of the optoelectronic devices, operating in the far-infrared regime for sensing and imaging applications. However, low optical absorption hinders its potential applications, and their performance is limited due to fixed resonance frequency. In this article, a novel gate tunable graphene-metal hybrid plasmonic antenna with stacking configuration is proposed and investigated to achieve tunable performance over a broad range of frequencies with enhanced absorption characteristics. The hybrid graphene-metal antenna geometry is built up with a hexagon radiator that is supported by the Al2O3 insulator layer and graphene reflector. This stacked structure is deposited in the high resistive Si wafer substrate, and the hexagon radiator itself is a sandwich structure, which is composed of gold hexagon structure and two multilayer graphene stacks. The proposed antenna characteristics i.e., tunability of frequency, the efficiency corresponding to characteristics modes, and the tuning of absorption spectra, are evaluated by full-wave numerical simulations. Besides, the unity absorption peak that was realized through the proposed geometry is sensitive to the incident angle of TM-polarized incidence waves, which can flexibly shift the maxima of the absorption peak from 30 THz to 34 THz. Finally, an equivalent resonant circuit model for the investigated antenna based on the simulations results is designed to validate the antenna performance. Parametric analysis of the proposed antenna is carried out through altering the geometric parameters and graphene parameters in the Computer Simulation Technology (CST) studio. This clearly shows that the proposed antenna has a resonance frequency at 33 THz when the graphene sheet Fermi energy is increased to 0.3 eV by applying electrostatic gate voltage. The good agreement of the simulation and equivalent circuit model results makes the graphene-metal antenna suitable for the realization of far-infrared sensing and imaging device containing graphene antenna with enhanced performance.
    Matched MeSH terms: Gold
  14. Fulltext A numerical study to investigate the effects of tumour position on the treatment of bladder cancer in mice using gold nanorods assisted photothermal ablation
    Cheong JK, Popov V, Alchera E, Locatelli I, Alfano M, Menichetti L, et al.
    Comput Biol Med, 2021 11;138:104881.
    PMID: 34583149 DOI: 10.1016/j.compbiomed.2021.104881
    Gold nanorods assisted photothermal therapy (GNR-PTT) is a new cancer treatment technique that has shown promising potential for bladder cancer treatment. The position of the bladder cancer at different locations along the bladder wall lining can potentially affect the treatment efficacy since laser is irradiated externally from the skin surface. The present study investigates the efficacy of GNR-PTT in the treatment of bladder cancer in mice for tumours growing at three different locations on the bladder, i.e., Case 1: closest to skin surface, Case 2: at the bottom half of the bladder, and Case 3: at the side of the bladder. Investigations were carried out numerically using an experimentally validated framework for optical-thermal simulations. An in-silico approach was adopted due to the flexibility in placing the tumour at a desired location along the bladder lining. Results indicate that for the treatment parameters considered (laser power 0.3 W, GNR volume fraction 0.01% v/v), only Case 1 can be used for an effective GNR-PTT. No damage to the tumour was observed in Cases 2 and 3. Analysis of the thermo-physiological responses showed that the effectiveness of GNR-PTT in treating bladder cancer depends not only on the depth of the tumour from the skin surface, but also on the type of tissue that the laser must pass through before reaching the tumour. In addition, the results are reliant on GNRs with a diameter of 10 nm and an aspect ratio of 3.8 - tuned to exhibit peak absorption for the chosen laser wavelength. Results from the present study can be used to highlight the potential for using GNR-PTT for treatment of human bladder cancer. It appears that Cases 2 and 3 suggest that GNR-PTT, where the laser passes through the skin to reach the bladder, may be unfeasible in humans. While this study shows the feasibility of using GNRs for photothermal ablation of bladder cancer, it also identifies the current limitations needed to be overcome for an effective clinical application in the bladder cancer patients.
    Matched MeSH terms: Gold
  15. Determination of cardiac disease biomarker by plasmonic sandwich ELISA
    Wei W, Tang Y, He H, Gopinath SCB, Wang L
    Biotechnol Appl Biochem, 2022 Feb;69(1):160-165.
    PMID: 33369762 DOI: 10.1002/bab.2092
    Acute myocardial infarction (AMI) is the heart attack happening when the blood flow is terminated to the heart muscles. C-reactive protein (CRP) level is raising significantly in AMI patients after the onset of symptom; also, temporal variations of CRP in plasma of AMI patient have also been found. Quantifying the concentration of CRP helps to identify the condition associated with AMI. Plasmonic enzyme-linked immunosorbent assay (ELISA) was utilized here to identify CRP by the sandwich of aptamer and antibody. Bare-eye CRP detection was achieved by plasmonic ELISA through the aggregation (blue color) of gold nanoparticle in the presence of CRP, whereas in the absence of CRP, it retains its red color (dispersion). Depending on the catalase presence on the ELISA surface, hydrogen peroxide (H2 O2 ) controls gold growth and differentiates with color changes. To achieve the lowest detection limit of CRP, H2 O2 (200 µM), gold seed (0.2 µM), and streptavidin-catalase (1:500) were found optimal. The detection limit was reached at 0.25 µg/mL, whereas it was 0.5 µg/mL in the CRP-spiked serum. This method of detection system is easier to detect the levels of CRP and helps diagnosing AMI.
    Matched MeSH terms: Gold
  16. Incorporation of surface plasmon resonance with novel valinomycin doped chitosan-graphene oxide thin film for sensing potassium ion
    Zainudin AA, Fen YW, Yusof NA, Al-Rekabi SH, Mahdi MA, Omar NAS
    Spectrochim Acta A Mol Biomol Spectrosc, 2018 Feb 15;191:111-115.
    PMID: 29024848 DOI: 10.1016/j.saa.2017.10.013
    In this study, the combination of novel valinomycin doped chitosan-graphene oxide (C-GO-V) thin film and surface plasmon resonance (SPR) system for potassium ion (K+) detection has been developed. The novel C-GO-V thin film was deposited on the gold surface using spin coating technique. The system was used to monitor SPR signal for K+ in solution with and without C-GO-V thin film. The K+ can be detected by measuring the SPR signal when C-GO-V thin film is exposed to K+ in solution. The sensor produces a linear response for K+ ion up to 100ppm with sensitivity and detection limit of 0.00948°ppm-1 and 0.001ppm, respectively. These results indicate that the C-GO-V film is high potential as a sensor element for K+ that has been proved by the SPR measurement.
    Matched MeSH terms: Gold
  17. Fulltext Preparation and Thermal Characterization of Annealed Gold Coated Porous Silicon
    Behzad K, Mat Yunus WM, Talib ZA, Zakaria A, Bahrami A
    Materials (Basel), 2012 Jan 16;5(1):157-168.
    PMID: 28817037 DOI: 10.3390/ma5010157
    Porous silicon (PSi) layers were formed on a p-type Si wafer. Six samples were anodised electrically with a 30 mA/cm² fixed current density for different etching times. The samples were coated with a 50-60 nm gold layer and annealed at different temperatures under Ar flow. The morphology of the layers, before and after annealing, formed by this method was investigated by scanning electron microscopy (SEM). Photoacoustic spectroscopy (PAS) measurements were carried out to measure the thermal diffusivity (TD) of the PSi and Au/PSi samples. For the Au/PSi samples, the thermal diffusivity was measured before and after annealing to study the effect of annealing. Also to study the aging effect, a comparison was made between freshly annealed samples and samples 30 days after annealing.
    Matched MeSH terms: Gold
  18. Fulltext Parametric Studies of Titania-Supported Gold-Catalyzed Oxidation of Carbon Monoxide
    Chong S, Yang TC
    Materials (Basel), 2017 Jul 05;10(7).
    PMID: 28773110 DOI: 10.3390/ma10070756
    This paper remarks the general correlations of the shape and crystallinity of titanium dioxide (TiO₂) support on gold deposition and carbon monoxide (CO) oxidation. It was found that due to the larger rutile TiO₂ particles and thus the pore volume, the deposited gold particles tended to agglomerate, resulting in smaller catalyst surface area and limited gold loading, whilst anatase TiO₂ enabled better gold deposition. Those properties directly related to gold particle size and thus the number of low coordinated atoms play dominant roles in enhancing CO oxidation activity. Gold deposited on anatase spheroidal TiO₂ at photo-deposition wavelength of 410 nm for 5 min resulted in the highest CO oxidation activity of 0.0617 mmol CO/s.gAu (89.5% conversion) due to the comparatively highest catalyst surface area (114.4 m²/g), smallest gold particle size (2.8 nm), highest gold loading (7.2%), and highest Au⁰ content (68 mg/g catalyst). CO oxidation activity was also found to be directly proportional to the Au⁰ content. Based on diffuse reflectance infrared Fourier transform spectroscopy, we postulate that anatase TiO₂-supported Au undergoes rapid direct oxidation whilst CO oxidation on rutile TiO₂-supported Au could be inhibited by co-adsorption of oxygen.
    Matched MeSH terms: Gold
  19. Fulltext Gold nanoparticles attenuate albuminuria by inhibiting podocyte injury in a rat model of diabetic nephropathy
    Alomari G, Al-Trad B, Hamdan S, Aljabali A, Al-Zoubi M, Bataineh N, et al.
    Drug Deliv Transl Res, 2020 Feb;10(1):216-226.
    PMID: 31637677 DOI: 10.1007/s13346-019-00675-6
    Several recent studies have reported that gold nanoparticles (AuNPs) attenuate hyperglycemia in diabetic animal models without any observed side effects. The present study was intended to provide insight into the effects of 50-nm AuNPs on diabetic kidney disease. Adult male rats were divided into three groups (n = 7/group): control (non-diabetic, ND), diabetic (D), and diabetic treated intraperitoneally with 50-nm AuNPs (AuNPs + D; 2.5 mg/kg/day) for 7 weeks. Diabetes was induced by a single-dose injection of 55 mg/kg streptozotocin. The result showed that AuNP treatment prevented diabetes-associated increases in the blood glucose level. Reduction in 24-h urinary albumin excretion rate, glomerular basement membrane thickness, foot process width, and renal oxidative stress markers was also demonstrated in the AuNP-treated group. In addition, the results showed downregulation effect of AuNPs in renal mRNA or protein expression of transforming growth factor β1 (TGF-β1), fibronectin, collagen IV, tumor necrosis factor-α (TNF-α), and vascular endothelial growth factor-A (VEGF-A). Moreover, the protein expression of nephrin and podocin, podocyte markers, in glomeruli was increased in the AuNPs + D group compared with the D group. These results provide evidence that 50-nm AuNPs can ameliorate renal damage in experimental models of diabetic nephropathy through improving the renal function and downregulating extracellular matrix protein accumulation, along with inhibiting renal oxidative stress and amelioration of podocyte injury.
    Matched MeSH terms: Gold/administration & dosage*; Gold/pharmacology; Gold/chemistry
  20. Identification of Mycoplasma pneumoniae by DNA-modified gold nanomaterials in a colorimetric assay
    Qin D, Gong Q, Li X, Gao Y, Gopinath SCB, Chen Y, et al.
    Biotechnol Appl Biochem, 2023 Apr;70(2):553-559.
    PMID: 35725894 DOI: 10.1002/bab.2377
    Mycoplasma pneumoniae is a highly infectious bacterium and the major cause of pneumonia especially in school-going children. Mycoplasma pneumoniae affects the respiratory tract, and 25% of patients experience health-related problems. It is important to have a suitable method to detect M. pneumoniae, and gold nanoparticle (GNP)-based colorimetric biosensing was used in this study to identify the specific target DNA for M. pneumoniae. The color of GNPs changes due to negatively charged GNPs in the presence of positively charged monovalent (Na+ ) ions from NaCl. This condition is reversed in the presence of a single-stranded oligonucleotide, as it attracts GNPs but not in the presence of double-stranded DNA. Single standard capture DNA was mixed with optimal target DNA that cannot be adsorbed by GNPs; under this condition, GNPs are not stabilized and aggregate at high ionic strength (from 100 mM). Without capture DNA, the GNPs that were stabilized by capture DNA (from 1 μM) became more stable under high ionic conditions and retaining their red color. The GNPs turned blue in the presence of target DNA at concentrations of 1 pM, and the GNPs retained a red color when there was no target in the solution. This method is useful for the simple, easy, and accurate identification of M. pneumoniae target DNA at higher discrimination and without involving sophisticated equipment, and this method provides a diagnostic for M. pneumoniae.
    Matched MeSH terms: Gold
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