Displaying publications 1 - 20 of 198 in total

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  1. Yusof NS, Ashokkumar M
    Chemphyschem, 2015 Mar 16;16(4):775-81.
    PMID: 25598360 DOI: 10.1002/cphc.201402697
    The sonochemical synthesis of gold nanoparticles (GNPs) with different shapes and size distributions by using high-intensity focused ultrasound (HIFU) operating at 463 kHz is reported. GNP formation proceeds through the reduction of Au(3+) to Au(0) by radicals generated by acoustic cavitation. TEM images reveal that GNPs show irregular shapes at 30 W, are primarily icosahedral at 50 W and form a significant amount of nanorods at 70 W. The size of GNPs decreases with increasing acoustic power with a narrower size distribution. Sonochemiluminescence images help in the understanding of the effect of HIFU in controlling the size and shapes of GNPs. The number of radicals that form and the mechanical forces that are generated control the shape and size of the GNPs. UV/Vis spectra and TEM images are used to propose a possible mechanism for the observed effects. The results presented demonstrate, for the first time, that the HIFU system can be used to synthesise size- and shape-controlled metal nanoparticles.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  2. Zamiri R, Zakaria A, Ahangar HA, Sadrolhosseini AR, Mahdi MA
    Int J Mol Sci, 2010;11(11):4764-70.
    PMID: 21151470 DOI: 10.3390/ijms11114764
    In this study we used a laser ablation technique for preparation of silver nanoparticles. The fabrication process was carried out by ablation of a silver plate immersed in palm oil. A pulsed Nd:YAG laser at a wavelength of 1064 nm was used for ablation of the plate at different times. The palm coconut oil allowed formation of nanoparticles with very small and uniform particle size, which are dispersed very homogeneously within the solution. The obtained particle sizes for 15 and 30 minute ablation times were 2.5 and 2 nm, respectively. Stability study shows that all of the samples remained stable for a reasonable period of time.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  3. Khavarian M, Chai SP, Mohamed AR
    J Nanosci Nanotechnol, 2013 Jul;13(7):4825-37.
    PMID: 23901504
    The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  4. Aziz MS, Suwanpayak N, Jalil MA, Jomtarak R, Saktioto T, Ali J, et al.
    Int J Nanomedicine, 2012;7:11-7.
    PMID: 22275818 DOI: 10.2147/IJN.S27417
    A new optical trapping design to transport gold nanoparticles using a PANDA ring resonator system is proposed. Intense optical fields in the form of dark solitons controlled by Gaussian pulses are used to trap and transport nanoscopic volumes of matter to the desired destination via an optical waveguide. Theoretically, the gradient and scattering forces are responsible for this trapping phenomenon, where in practice such systems can be fabricated and a thin-film device formed on the specific artificial medical materials, for instance, an artificial bone. The dynamic behavior of the tweezers can be tuned by controlling the optical pulse input power and parameters of the ring resonator system. Different trap sizes can be generated to trap different gold nanoparticles sizes, which is useful for gold nanoparticle therapy. In this paper, we have shown the utility of gold nanoparticle trapping and delivery for therapy, which may be useful for cosmetic therapy and related applications.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  5. Zamiri R, Zakaria A, Husin MS, Wahab ZA, Nazarpour FK
    Int J Nanomedicine, 2011;6:2221-4.
    PMID: 22114485 DOI: 10.2147/IJN.S23830
    In the present work, we prepared silver nanoparticles by laser ablation of pure silver plate in ethanol and then irradiated the silver nanoparticles using a 532 nm Q-switched Nd:YAG pulsed laser. Transmission electron microscopic images of the sample after irradiation clearly showed formation of big structures, such as microrods and microbelts in ethanol. The obtained microbelts had a width of about 0.166 μm and a length of 1.472 μm. The reason for the formation of such a big structure is the tendency of the nanoparticles to aggregate in ethanol before irradiation, which causes fusion of the nanoparticles.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  6. Darroudi M, Ahmad MB, Abdullah AH, Ibrahim NA, Shameli K
    Int J Mol Sci, 2010;11(10):3898-905.
    PMID: 21152307 DOI: 10.3390/ijms11103898
    Silver nanoparticles (Ag-NPs) were successfully synthesized in the natural polymeric matrix. Silver nitrate, gelatin, glucose, and sodium hydroxide have been used as silver precursor, stabilizer, reducing agent, and accelerator reagent, respectively. This study investigated the role of NaOH as the accelerator. The resultant products have been confirmed to be Ag-NPs using powder X-ray diffraction (PXRD), UV-vis spectroscopy, and transmission electron microscopy (TEM). The colloidal sols of Ag-NPs obtained at different volumes of NaOH show strong and different surface plasmon resonance (SPR) peaks, which can be explained from the TEM images of Ag-NPs and their particle size distribution. Compared with other synthetic methods, this work is green, rapid, and simple to use. The newly prepared Ag-NPs may have many potential applications in chemical and biological industries.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  7. Sadrolhosseini AR, Habibiasr M, Shafie S, Solaimani H, Lim HN
    Int J Mol Sci, 2019 Dec 06;20(24).
    PMID: 31817593 DOI: 10.3390/ijms20246153
    Platinum nanoparticles were synthesized in graphene oxide aqueous solution using a laser ablation technique to investigate the effect of optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution. The samples were prepared with different ablation times. The platinum nanoparticles that formed a spherical shape on the surface of graphene oxide solution were authenticated using UV-visible spectrum and transmission electron microscopy patterns. The particle size decreased with increasing ablation time, and the concentration and volume fraction of samples were increased. To obtain the optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution, UV-visible spectroscopy, Z-scan, thermal lens and photoacoustic techniques were used. Consequently, the linear and nonlinear refractive indices increased with an increase in the volume fraction of platinum nanoparticles. It was observed from the spatial self-phase modulation patterns that, the optical nonlinear property of the graphene oxide was enhanced in the presence of platinum nanoparticles, and the nonlinearity increased with an increase in the volume fraction of platinum nanoparticles inside the graphene oxide solution. The thermal diffusivity and thermal effusivity of platinum nanoparticles graphene oxide were measured using a thermal lens and photoacoustic methods, respectively. The thermal diffusivity and thermal effusivity of samples were in the range of 0.0341 × 10-5 m2/s to 0.1223 × 10-5 m2/s and 0.163 W s1/2 cm-2 K-1 to 0.3192 W s1/2 cm-2 K-1, respectively. Consequently, the platinum enhanced the optical and thermal properties of graphene oxide.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  8. Lee SY, Fazlina N, Tye GJ
    Anal. Biochem., 2019 09 15;581:113352.
    PMID: 31260647 DOI: 10.1016/j.ab.2019.113352
    DNA-templated silver nanocluster (AgNC), a new promising fluorescence probe has gained importance in biosensing and bioimaging in recent years. We employed a label-free AgNC to detect an intracellular transcription factor known as forkhead box p3 (FOXP3), which is the master regulator of regulatory T cells (Tregs) suppressive function. We developed an optimized method for the detection of messenger ribonucleic acid (mRNA) of FOXP3 by hybridizing AgNC and G-rich to the target FOXP3 mRNA of a MCF-7 cells. MCF-7 cells are chosen as a model as it readily expresses FOXP3. The hybridized samples were examined with UV illuminator and further verified with fluorescence spectroscopy, fluorescence microscope and flow cytometry. The successful hybridization of a three-way junction with AgNC, G-rich and mRNA FOXP3 target generated an improved fluorescence intensity with a spectral shift. We have successfully delivered the green fluorescing AgNC and G-rich into MCF-7 cells, producing a shift to red fluorescing cells corroborated by flow cytometry results. In summary, our approach enables the detection of intracellular FOXP3 nucleic acid and holds considerable potential in establishing a non-lethal intracellular detection system which would be crucial for the isolation of regulatory T-cells (Tregs) when combined with other cell surface markers.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  9. Gharibshahi E, Saion E
    Int J Mol Sci, 2012;13(11):14723-41.
    PMID: 23203091 DOI: 10.3390/ijms131114723
    Attempts to produce colloidal platinum nanoparticles by using steady absorption spectra with various chemical-based reduction methods often resulted in the fast disappearance of the absorption maxima leaving reduced platinum nanoparticles with little information on their optical properties. We synthesized colloidal platinum nanoparticles in an aqueous solution of polyvinyl pyrrolidone by gamma radiolytic reduction method, which produced steady absorption spectra of fully reduced and highly pure platinum nanoparticles free from by-product impurities or reducing agent contamination. The average particle size was found to be in the range of 3.4–5.3 nm and decreased with increasing dose due to the domination of nucleation over ion association in the formation of metal nanoparticles by the gamma radiolytic reduction method. The platinum nanoparticles exhibit optical absorption spectra with two absorption peaks centered at about 216 and 264 nm and the peaks blue shifted to lower wavelengths with decreasing particle size. The absorption spectra of platinum nanoparticles were also calculated using quantum mechanical treatment and coincidently a good agreement was obtained between the calculated and measured absorption peaks at various particle sizes. This indicates that the 216 and 264-nm absorption peaks of platinum nanoparticles conceivably originated from the intra-band transitions of conduction electrons of (n = 5, l = 2) and (n = 6, l = 0) energy states respectively to higher energy states. The absorption energies, i.e., conduction band energies of platinum nanoparticles derived from the absorption peaks increased with increasing dose and decreased with increasing particle size.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  10. Soltani N, Saion E, Erfani M, Rezaee K, Bahmanrokh G, Drummen GP, et al.
    Int J Mol Sci, 2012;13(10):12412-27.
    PMID: 23202906 DOI: 10.3390/ijms131012412
    Zinc sulfide semiconductor nanoparticles were synthesized in an aqueous solution of polyvinyl pyrrolidone via a simple microwave irradiation method. The effect of the polymer concentration and the type of sulfur source on the particle size and dispersion of the final ZnS nanoparticle product was carefully examined. Microwave heating generally occurs by two main mechanisms: dipolar polarization of water and ionic conduction of precursors. The introduction of the polymer affects the heating rate by restriction of the rotational motion of dipole molecules and immobilization of ions. Consequently, our results show that the presence of the polymer strongly affects the nucleation and growth rates of the ZnS nanoparticles and therefore determines the average particle size and the dispersion. Moreover, we found that PVP adsorbed on the surface of the ZnS nanoparticles by interaction of the C-N and C=O with the nanoparticle's surface, thereby affording protection from agglomeration by steric hindrance. Generally, with increasing PVP concentration, mono-dispersed colloidal solutions were obtained and at the optimal PVP concentration (5%), sufficiently small size and narrow size distributions were obtained from both sodium sulfide and thioacetamide sulfur sources. Finally, the sulfur source directly influences the reaction mechanism and the final particle morphology, as well as the average size.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  11. Karim Z, Adnan R, Ansari MS
    PLoS ONE, 2012;7(7):e41422.
    PMID: 22848490 DOI: 10.1371/journal.pone.0041422
    Chemical synthesis of Ag-NPs was carried out using reduction method. The reduction mechanistic approach of silver ions was found to be a basic clue for the formation of the Ag-NPs. The nanoparticles were characterized by UV-vis, FT-IR and TEM analysis. We had designed some experiments in support of our hypothesis, "low concentrations of novel nanoparticles (silver and gold) increases the activity of plant peroxidases and alter their structure also", we had used Ag-NPs and HRP as models. The immobilization/interaction experiment had demonstrated the specific concentration range of the Ag-NPs and within this range, an increase in HRP activity was reported. At 0.08 mM concentration of Ag-NPs, 50% increase in the activity yield was found. The U.V-vis spectra had demonstrated the increase in the absorbance of HRP within the reported concentration range (0.06-0.12 mM). Above and below this concentration range there was a decrease in the activity of HRP. The results that we had found from the fluorescence spectra were also in favor of our hypothesis. There was a maximum increase in ellipticity and α-helix contents in the presence of 0.08 mM concentration of Ag-NPs, demonstrated by circular dichroism (CD) spectra. Finally, incubation of a plant peroxidase, HRP with Ag-NPs, within the reported concentration range not only enhances the activity but also alter the structure.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  12. Ghadiry M, Gholami M, Lai CK, Ahmad H, Chong WY
    PLoS ONE, 2016;11(4):e0153949.
    PMID: 27101247 DOI: 10.1371/journal.pone.0153949
    Generally, in a waveguide-based humidity sensors, increasing the relative humidity (RH) causes the cladding refractive index (RI) to increase due to cladding water absorption. However, if graphene oxide (GO) is used, a reverse phenomenon is seen due to a gap increase in graphene layers. In this paper, this interesting property is applied in order to fabricate differential humidity sensor using the difference between RI of reduced GO (rGO) and nano-anatase TiO2 in a chip. First, a new approach is proposed to prepare high quality nano-anatase TiO2 in solution form making the fabrication process simple and straightforward. Then, the resulted solutions (TiO2 and GO) are effortlessly drop casted and reduced on SU8 two channels waveguide and extensively examined against several humid conditions. Investigating the sensitivity and performance (response time) of the device, reveals a great linearity in a wide range of RH (35% to 98%) and a variation of more than 30 dB in transmitted optical power with a response time of only ~0.7 sec. The effect of coating concentration and UV treatment are studied on the performance and repeatability of the sensor and the attributed mechanisms explained. In addition, we report that using the current approach, devices with high sensitivity and very low response time of only 0.3 sec can be fabricated. Also, the proposed device was comprehensively compared with other state of the art proposed sensors in the literature and the results were promising. Since high sensitivity ~0.47dB/%RH and high dynamic performances were demonstrated, this sensor is a proper choice for biomedical applications.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  13. Javed KR, Ahmad M, Ali S, Butt MZ, Nafees M, Butt AR, et al.
    Medicine (Baltimore), 2015 Mar;94(11):e617.
    PMID: 25789952 DOI: 10.1097/MD.0000000000000617
    Nanomaterials are being vigorously investigated for their use in anticancer drug delivery regimes or as biomarkers agents and are considered to be a candidate to provide a way to combat severe weaknesses of anticancer drug pharmacokinetics, such as their nonspecificity. Because of this weakness, a bigger proportion of the drug-loaded nanomaterials flow toward healthy tissues and result in undesirable side effects. It is very important to evaluate drug loading and release efficiency of various nanomaterials to find out true pharmacokinetics of these drugs.This observational study aims to evaluate various surface functionalized and naked nanomaterials for their drug loading capability and consequently strengthens the Reporting of Observational Studies in Epidemiology (STROBE). We analyzed naked and coated nanoparticles of transition metal oxides for their further loading with doxorubicin, a representative water-soluble anticancer drug.Various uncoated and polyethylene glycol-coated metal oxide nanoparticles were synthesized and loaded with anticancer drug using simple stirring of the nanoparticles in a saturated aqueous solution of the drug. Results showed that surface-coated nanoparticles have higher drug-loading capabilities; however, certain naked metal oxide nanoparticles, such as cobalt oxide nanoparticles, can load a sufficient amount of drug.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  14. Zamiri R, Zakaria A, Abbastabar H, Darroudi M, Husin MS, Mahdi MA
    Int J Nanomedicine, 2011;6:565-8.
    PMID: 21698083 DOI: 10.2147/IJN.S16384
    Silver nanoparticles were fabricated by ablation of a pure silver plate immersed in castor oil. A Nd:YAG-pulsed Q-switch laser with 1064-nm wavelength and 10-Hz frequency was used to ablate the plate for 10 minutes. The sample was characterized by ultraviolet-visible, atomic absorption, Fourier transform-infrared spectroscopies, and transmission electron microscopy. The results of the fabricated sample showed that the nanoparticles in castor oil were about 5-nm in diameter, well dispersed, and showed stability for a long period of time.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  15. Zak AK, Razali R, Majid WH, Darroudi M
    Int J Nanomedicine, 2011;6:1399-403.
    PMID: 21796242 DOI: 10.2147/IJN.S19693
    Zinc oxide nanoparticles (ZnO-NPs) were synthesized via a solvothermal method in triethanolamine (TEA) media. TEA was utilized as a polymer agent to terminate the growth of ZnO-NPs. The ZnO-NPs were characterized by a number of techniques, including X-ray diffraction analysis, transition electron microscopy, and field emission electron microscopy. The ZnO-NPs prepared by the solvothermal process at 150°C for 18 hours exhibited a hexagonal (wurtzite) structure, with a crystalline size of 33 ± 2 nm, and particle size of 48 ± 7 nm. The results confirm that TEA is a suitable polymer agent to prepare homogenous ZnO-NPs.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  16. Darroudi M, Ahmad MB, Zamiri R, Zak AK, Abdullah AH, Ibrahim NA
    Int J Nanomedicine, 2011;6:677-81.
    PMID: 21556342 DOI: 10.2147/IJN.S17669
    The application of "green" chemistry rules to nanoscience and nanotechnology is very important in the preparation of various nanomaterials. In this work, we successfully developed an eco-friendly chemistry method for preparing silver nanoparticles (Ag-NPs) in natural polymeric media. The colloidal Ag-NPs were synthesized in an aqueous solution using silver nitrate, gelatin, and glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag-NPs were studied at different reaction times. The ultraviolet-visible (UV-vis) spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM) and their size distributions. The prepared samples were also characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The use of eco-friendly reagents, such as gelatin and glucose, provides green and economic attributes to this work.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  17. Zamiri R, Azmi BZ, Sadrolhosseini AR, Ahangar HA, Zaidan AW, Mahdi MA
    Int J Nanomedicine, 2011;6:71-5.
    PMID: 21289983 DOI: 10.2147/IJN.S14005
    Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10(-8), 1.6 × 10(-8), 2.4 × 10(-8), respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  18. Choi JR, Hu J, Tang R, Gong Y, Feng S, Ren H, et al.
    Lab Chip, 2016 Feb 7;16(3):611-21.
    PMID: 26759062 DOI: 10.1039/c5lc01388g
    With advances in point-of-care testing (POCT), lateral flow assays (LFAs) have been explored for nucleic acid detection. However, biological samples generally contain complex compositions and low amounts of target nucleic acids, and currently require laborious off-chip nucleic acid extraction and amplification processes (e.g., tube-based extraction and polymerase chain reaction (PCR)) prior to detection. To the best of our knowledge, even though the integration of DNA extraction and amplification into a paper-based biosensor has been reported, a combination of LFA with the aforementioned steps for simple colorimetric readout has not yet been demonstrated. Here, we demonstrate for the first time an integrated paper-based biosensor incorporating nucleic acid extraction, amplification and visual detection or quantification using a smartphone. A handheld battery-powered heating device was specially developed for nucleic acid amplification in POC settings, which is coupled with this simple assay for rapid target detection. The biosensor can successfully detect Escherichia coli (as a model analyte) in spiked drinking water, milk, blood, and spinach with a detection limit of as low as 10-1000 CFU mL(-1), and Streptococcus pneumonia in clinical blood samples, highlighting its potential use in medical diagnostics, food safety analysis and environmental monitoring. As compared to the lengthy conventional assay, which requires more than 5 hours for the entire sample-to-answer process, it takes about 1 hour for our integrated biosensor. The integrated biosensor holds great potential for detection of various target analytes for wide applications in the near future.
    Matched MeSH terms: Metal Nanoparticles/chemistry
  19. Han TK, Fen LB, Nee NM, Johan MR
    ScientificWorldJournal, 2014;2014:847806.
    PMID: 24995365 DOI: 10.1155/2014/847806
    We report the synthesis of amorphous carbon nanotubes/silver (αCNTs/Ag) nanohybrids via simple chemical route without additional reactant and surfactant at low temperature. Field emission scanning microscope (FESEM) and transmission electron microscope (TEM) confirmed formation of CNTs. X-ray diffraction (XRD) pattern confirmed the amorphous phase of carbon and the formation of Ag nanoparticles crystalline phase. Raman spectra revealed the amorphous nature of α CNTs. UV-visible spectroscopy showed enhancement of optical properties of α CNTs/Ag nanohybrids.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
  20. Rabbani G, Khan MJ, Ahmad A, Maskat MY, Khan RH
    Colloids Surf B Biointerfaces, 2014 Nov 1;123:96-105.
    PMID: 25260221 DOI: 10.1016/j.colsurfb.2014.08.035
    The primary objective of this study is to explore the interaction of β-galactosidase with copper oxide nanoparticles (CuO NPs). Steady-state absorption, fluorescence and circular dichroism (CD) spectroscopic techniques have been employed to unveil the conformational changes of β-galactosidase induced by the binding of CuO NPs. Temperature dependent fluorescence quenching results indicates a static quenching mechanism in the present case. The binding thermodynamic parameters delineate the predominant role of H-bonding and van der Waals forces between β-galactosidase and CuO NPs binding process. The binding was studied by isothermal titration calorimetry (ITC) and the result revealed that the complexation is enthalpy driven, the ΔH°<0, ΔS°<0 indicates the formation of hydrogen bonds between β-galactosidase and CuO NPs occurs. Disruption of the native conformation of the protein upon binding with CuO NPs is reflected through a reduced functionality (in terms of hydrolase activity) of the protein CuO NPs conjugate system in comparison to the native protein and CuO NPs exhibited a competitive mode of inhibition. This also supports the general belief that H-bond formation occurs with NPs is associated with a lesser extent of modification in the native structure. Morphological features and size distributions were investigated using transmission electron microscopy (TEM) and dynamic light scattering (DLS). Additionally the considerable increase in the Rh following the addition of CuO NPs accounts for the unfolding of β-galactosidase. Chemical and thermal unfolding of β-galactosidase, when carried out in the presence of CuO NPs, also indicated a small perturbation in the protein structure. These alterations in functional activity of nanoparticle bound β-galactosidase which will have important consequences should be taken into consideration while using nanoparticles for diagnostic and therapeutic purposes.
    Matched MeSH terms: Metal Nanoparticles/chemistry*
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