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  1. δ- and γ-tocotrienols induce classical ultrastructural apoptotic changes in human T lymphoblastic leukemic cells
    Wong RS, Radhakrishnan AK, Ibrahim TA, Cheong SK
    Microsc Microanal, 2012 Jun;18(3):462-9.
    PMID: 22640960 DOI: 10.1017/S1431927612000177
    Tocotrienols are isomers of the vitamin E family, which have been reported to exert cytotoxic effects in various cancer cells. Although there have been some reports on the effects of tocotrienols in leukemic cells, ultrastructural evidence of tocotrienol-induced apoptotic cell death in leukemic cells is lacking. The present study investigated the effects of three isomers of tocotrienols (alpha, delta, and gamma) on a human T lymphoblastic leukemic cell line (CEM-SS). Cell viability assays showed that all three isomers had cytotoxic effects (p < 0.05) on CEM-SS cells with delta-tocotrienol being the most potent. Transmission electron microscopy showed that the cytotoxic effects by delta- and gamma-tocotrienols were through the induction of an apoptotic pathway as demonstrated by the classical ultrastructural apoptotic changes characterized by peripheral nuclear chromatin condensation and nuclear fragmentation. These findings were confirmed biochemically by the demonstration of phosphatidylserine externalization via flow cytometry analysis. This is the first study showing classical ultrastructural apoptotic changes induced by delta- and gamma-tocotrienols in human T lymphoblastic leukemic cells.
    Matched MeSH terms: Microscopy, Electron, Transmission
  2. Fulltext β-Cyclodextrin conjugated bifunctional isocyanate linker polymer for enhanced removal of 2,4-dinitrophenol from environmental waters
    Anne JM, Boon YH, Saad B, Miskam M, Yusoff MM, Shahriman MS, et al.
    R Soc Open Sci, 2018 Aug;5(8):180942.
    PMID: 30225083 DOI: 10.1098/rsos.180942
    In this work, we reported the synthesis, characterization and adsorption study of two β-cyclodextrin (βCD) cross-linked polymers using aromatic linker 2,4-toluene diisocyanate (2,4-TDI) and aliphatic linker 1,6-hexamethylene diisocyanate (1,6-HDI) to form insoluble βCD-TDI and βCD-HDI. The adsorption of 2,4-dinitrophenol (DNP) on both polymers as an adsorbent was studied in batch adsorption experiments. Both polymers were well characterized using various tools that include Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller analysis and scanning electron microscopy, and the results obtained were compared with the native βCD. The adsorption isotherm of 2,4-DNP onto polymers was studied. It showed that the Freundlich isotherm is a better fit for βCD-TDI, while the Langmuir isotherm is a better fit for βCD-HMDI. The pseudo-second-order kinetic model represented the adsorption process for both of the polymers. The thermodynamic study showed that βCD-TDI polymer was more favourable towards 2,4-DNP when compared with βCD-HDI polymer. Under optimized conditions, both βCD polymers were successfully applied on various environmental water samples for the removal of 2,4-DNP. βCD-TDI polymer showed enhanced sorption capacity and higher removal efficiency (greater than 80%) than βCD-HDI (greater than 70%) towards 2,4-DNP. The mechanism involved was discussed, and the effects of cross-linkers on βCD open up new perspectives for the removal of toxic contaminants from a body of water.
    Matched MeSH terms: Microscopy, Electron, Scanning
  3. Fulltext pH responsive N-succinyl chitosan/Poly (acrylamide-co-acrylic acid) hydrogels and in vitro release of 5-fluorouracil
    Bashir S, Teo YY, Naeem S, Ramesh S, Ramesh K
    PLoS One, 2017;12(7):e0179250.
    PMID: 28678803 DOI: 10.1371/journal.pone.0179250
    There has been significant progress in the last few decades in addressing the biomedical applications of polymer hydrogels. Particularly, stimuli responsive hydrogels have been inspected as elegant drug delivery systems capable to deliver at the appropriate site of action within the specific time. The present work describes the synthesis of pH responsive semi-interpenetrating network (semi-IPN) hydrogels of N-succinyl-chitosan (NSC) via Schiff base mechanism using glutaraldehyde as a crosslinking agent and Poly (acrylamide-co-acrylic acid)(Poly (AAm-co-AA)) was embedded within the N-succinyl chitosan network. The physico-chemical interactions were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscope (FESEM). The synthesized hydrogels constitute porous structure. The swelling ability was analyzed in physiological mediums of pH 7.4 and pH 1.2 at 37°C. Swelling properties of formulations with various amounts of NSC/ Poly (AAm-co-AA) and crosslinking agent at pH 7.4 and pH 1.2 were investigated. Hydrogels showed higher swelling ratios at pH 7.4 while lower at pH 1.2. Swelling kinetics and diffusion parameters were also determined. Drug loading, encapsulation efficiency, and in vitro release of 5-fluorouracil (5-FU) from the synthesized hydrogels were observed. In vitro release profile revealed the significant influence of pH, amount of NSC, Poly (AAm-co-AA), and crosslinking agent on the release of 5-FU. Accordingly, rapid and large release of drug was observed at pH 7.4 than at pH 1.2. The maximum encapsulation efficiency and release of 5-FU from SP2 were found to be 72.45% and 85.99%, respectively. Kinetics of drug release suggested controlled release mechanism of 5-FU is according to trend of non-Fickian. From the above results, it can be concluded that the synthesized hydrogels have capability to adapt their potential exploitation as targeted oral drug delivery carriers.
    Matched MeSH terms: Microscopy, Electron, Scanning
  4. pH dependent poly[2-(methacryloyloxyethyl)trimetylammonium chloride-co-methacrylic acid]hydrogels for enhanced targeted delivery of 5-fluorouracil in colon cancer cells
    Mishra RK, Ramasamy K, Ahmad NA, Eshak Z, Majeed AB
    J Mater Sci Mater Med, 2014 Apr;25(4):999-1012.
    PMID: 24398912 DOI: 10.1007/s10856-013-5132-x
    Stimuli responsive hydrogels have shown enormous potential as a carrier for targeted drug delivery. In this study we have developed novel pH responsive hydrogels for the delivery of 5-fluorouracil (5-FU) in order to alleviate its antitumor activity while reducing its toxicity. We used 2-(methacryloyloxyethyl) trimetylammonium chloride a positively charged monomer and methacrylic acid for fabricating the pH responsive hydrogels. The released 5-FU from all except hydrogel (GEL-5) remained biologically active against human colon cancer cell lines [HT29 (IC50 = 110-190 μg ml(-1)) and HCT116 (IC50 = 210-390 μg ml(-1))] but not human skin fibroblast cells [BJ (CRL2522); IC50 ≥ 1000 μg ml(-1)]. This implies that the copolymer hydrogels (1-4) were able to release 5-FU effectively to colon cancer cells but not normal human skin fibroblast cells. This is probably due to the shorter doubling time that results in reduced pH in colon cancer cells when compared to fibroblast cells. These pH sensitive hydrogels showed well defined cell apoptosis in HCT116 cells through series of events such as chromatin condensation, membrane blebbing, and formation of apoptotic bodies. No cell killing was observed in the case of blank hydrogels. The results showed the potential of these stimuli responsive polymer hydrogels as a carrier for colon cancer delivery.
    Matched MeSH terms: Microscopy, Electron, Scanning
  5. Fulltext dsRNA silencing of an R2R3-MYB transcription factor affects flower cell shape in a Dendrobium hybrid
    Lau SE, Schwarzacher T, Othman RY, Harikrishna JA
    BMC Plant Biol, 2015;15:194.
    PMID: 26260631 DOI: 10.1186/s12870-015-0577-3
    The R2R3-MYB genes regulate pigmentation and morphogenesis of flowers, including flower and cell shape, and therefore have importance in the development of new varieties of orchids. However, new variety development is limited by the long breeding time required in orchids. In this study, we identified a cDNA, DhMYB1, that is expressed during flower development in a hybrid orchid, Dendrobium hybrida (Dendrobium bobby messina X Dendrobium chao phraya) then used the direct application of dsRNA to observe the effect of gene silencing on flower phenotype and floral epidermal cell shape.
    Matched MeSH terms: Microscopy, Electron, Scanning
  6. Zoothamnium duplicatum infestation of cultured horseshoe crabs (Limulus polyphemus)
    Shinn AP, Mühlhölzl AP, Coates CJ, Metochis C, Freeman MA
    J Invertebr Pathol, 2015 Feb;125:81-6.
    PMID: 25499897 DOI: 10.1016/j.jip.2014.12.002
    An outbreak of the sessile peritrich Zoothamnium duplicatum in a pilot, commercial-scale Limulus polyphemus hatchery resulted in the loss of ∼96% (40,000) second/third instar larvae over a 61day period. peritrich growth was heavy, leading to mechanical obstruction of the gills and physical damage. The peritrichs were controlled without resultant loss of juvenile crabs by administering 10ppm chlorine in freshwater for 1h and the addition of aquarium grade sand; a medium into which the crabs could burrow and facilitate cleaning of the carapace. Peritrich identity was confirmed from a partial SSU rDNA contiguous sequence of 1343bp (99.7% similarity to Z. duplicatum).
    Matched MeSH terms: Microscopy, Electron, Scanning
  7. ZnO microstructures and nanostructures prepared by sol-gel hydrothermal technique
    Kamaruddin SA, Chan KY, Sahdan MZ, Rusop M, Saim H
    J Nanosci Nanotechnol, 2010 Sep;10(9):5618-22.
    PMID: 21133082
    Zinc oxide (ZnO) is an emerging material in large area electronic applications such as thin-film solar cells and transistors. We report on the fabrication and characterization of ZnO microstructures and nanostructures. The ZnO microstructures and nanostructures have been synthesized using sol-gel immerse technique on oxidized silicon substrates. Different precursor's concentrations ranging from 0.0001 M to 0.01 M (M=molarity) using zinc nitrate hexahydrate [Zn(NO3)2. 6H2O] and hexamethylenetetramine [C6H12N4] were employed in the synthesis of the ZnO structures. The surface morphologies were examined using scanning electron microscope (SEM) and atomic force microscope (AFM). In order to investigate the structural properties, the ZnO microstructures and nanostructures were measured using X-ray diffractometer (XRD). The optical properties of the ZnO structures were measured using photoluminescence (PL) and ultraviolet-visible (UV-Vis) spectroscopies.
    Matched MeSH terms: Microscopy, Electron, Scanning
  8. Fulltext ZnCr2O4 Nanoparticles: Facile Synthesis, Characterization, and Photocatalytic Properties
    Mousavi Z, Soofivand F, Esmaeili-Zare M, Salavati-Niasari M, Bagheri S
    Sci Rep, 2016 Feb 01;6:20071.
    PMID: 26832329 DOI: 10.1038/srep20071
    In this work, zinc chromite (ZnCr2O4) nanostructures have been synthesized through co-precipitation method. The effect of various parameters such as alkaline agent, pH value, and capping agent type was investigated on purity, particle size and morphology of samples. It was found that particle size and morphology of the products could be greatly influenced via these parameters. The synthesized products were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), fourier transform infrared (FT-IR) spectra, X-ray energy dispersive spectroscopy (EDS), photoluminescence (PL) spectroscopy, diffuse reflectance spectroscopy (DRS) and vibrating sample magnetometry (VSM). The superhydrophilicity of the calcined oxides was investigated by wetting experiments and a sessile drop technique which carried out at room temperature in air to determine the surface and interfacial interactions. Furthermore, the photocatalytic activity of ZnCr2O4 nanoparticles was confirmed by degradation of anionic dyes such as Eosin-Y and phenol red under UV light irradiation. The obtained ZnCr2O4 nanoparticles exhibit a paramagnetic behavior although bulk ZnCr2O4 is antiferromagnetic, this change in magnetic property can be ascribed to finite size effects.
    Matched MeSH terms: Microscopy, Electron, Scanning
  9. Fulltext Zinc/Aluminium⁻Quinclorac Layered Nanocomposite Modified Multi-Walled Carbon Nanotube Paste Electrode for Electrochemical Determination of Bisphenol A
    Zainul R, Abd Azis N, Md Isa I, Hashim N, Ahmad MS, Saidin MI, et al.
    Sensors (Basel), 2019 Feb 22;19(4).
    PMID: 30813385 DOI: 10.3390/s19040941
    This paper presents the application of zinc/aluminium-layered double hydroxide-quinclorac (Zn/Al-LDH-QC) as a modifier of multiwalled carbon nanotubes (MWCNT) paste electrode for the determination of bisphenol A (BPA). The Zn/Al-LDH-QC/MWCNT morphology was examined by a transmission electron microscope and a scanning electron microscope. Electrochemical impedance spectroscopy was utilized to investigate the electrode interfacial properties. The electrochemical responses of the modified electrode towards BPA were thoroughly evaluated by using square-wave voltammetry technique. The electrode demonstrated three linear plots of BPA concentrations from 3.0 × 10-8⁻7.0 × 10-7 M (R² = 0.9876), 1.0 × 10-6⁻1.0 × 10-5 M (R² = 0.9836) and 3.0 × 10-5⁻3.0 × 10-4 M (R² = 0.9827) with a limit of detection of 4.4 × 10-9 M. The electrode also demonstrated good reproducibility and stability up to one month. The presence of several metal ions and organic did not affect the electrochemical response of BPA. The electrode is also applicable for BPA determination in baby bottle and mineral water samples with a range of recovery between 98.22% and 101.02%.
    Matched MeSH terms: Microscopy, Electron, Scanning
  10. Zerumbone induces apoptosis in T-acute lymphoblastic leukemia cells
    Abdelwahab SI, Abdul AB, Mohan S, Taha MM, Syam S, Ibrahim MY, et al.
    Leuk. Res., 2011 Feb;35(2):268-71.
    PMID: 20708800 DOI: 10.1016/j.leukres.2010.07.025
    Zerumbone (ZER) is a potential anticancer natural compound, isolated from Zingiber zerumbet Smith. In this investigation, the anticancer properties of ZER were evaluated on cancer cells of T-acute lymphoblastic leukemia, CEM-ss. The results showed that ZER has cytotoxic effect against CEM-ss cells with an IC(50) of 8.4 ± 1.9 μg/ml (coefficient of variation < 30%). Comparatively, 5-fluorouracil (positive control), imposed an inhibitory effect on CEM-ss cells with an IC(50) of 1.94 ± 0.06 μg/ml. Scanning electron microscopy (SEM) results revealed abnormalities such as membrane blebbing, holes and cytoplasmic extrusions, all of which are characteristics of apoptosis. In addition, ZER has increased the number of TUNEL-positive stain and the cellular level of caspase-3, the hallmarks of apoptosis, on treated CEM-ss cells. It could be concluded that, ZER was able to produce apoptosis on T-acute lymphoblastic leukemia, CEM-ss. The current findings suggest that ZER might be helpful for improving the usefulness of anticancer agents in the therapy of leukemia.
    Matched MeSH terms: Microscopy, Electron, Scanning
  11. Fulltext Zeolite RHO Synthesis Accelerated by Ultrasonic Irradiation Treatment
    Ng TYS, Chew TL, Yeong YF, Jawad ZA, Ho CD
    Sci Rep, 2019 10 21;9(1):15062.
    PMID: 31636339 DOI: 10.1038/s41598-019-51460-x
    In recent years, there are increasing interest on applying ultrasonic irradiation for the synthesis of zeolite due to its advantages including remarkable shortened synthesis duration. In this project, the potential of ultrasonic irradiation treatment on the synthesis of zeolite RHO was investigated. Ultrasonic irradiation treatment time was varied from 30 to 120 minutes for the synthesis of zeolite RHO. The zeolite RHO solid samples were characterized with X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and nitrogen adsorption-desorption analysis. The application of ultrasonic irradiation treatment in this study has accelerated the synthesis of zeolite RHO where the synthesis duration has been significantly shortened to 2 days compared to 8 days required by conventional hydrothermal heating without ultrasonic irradiation treatment. Highly crystalline zeolite RHO crystals in truncated octahedron morphology were successfully formed.
    Matched MeSH terms: Microscopy, Electron, Scanning
  12. Zeolite Linde Type L as micro-solid phase extraction sorbent for the high performance liquid chromatography determination of ochratoxin A in coffee and cereal
    Lee TP, Saad B, Ng EP, Salleh B
    J Chromatogr A, 2012 May 11;1237:46-54.
    PMID: 22444432 DOI: 10.1016/j.chroma.2012.03.031
    Zeolite Linde Type L (LTL) crystals with different length, diameter and particle size (nanosized LTL, rod LTL, cylinder LTL and needle LTL) were synthesized, characterized and were used as sorbent in the micro-solid phase extraction of ochratoxin A (OTA) before the high performance liquid chromatography detection. Under the optimized conditions, the detection limits of OTA for coffee and cereal were 0.09 ng g(-1) and 0.03 ng g(-1), respectively, while the quantification limits were 0.28 ng g(-1) and 0.08 ng g(-1), respectively. The recoveries of OTA of coffee and cereal spiked at 0.5, 10 and 25 ng g(-1) ranged from 91.7 to 101.0%. The proposed method was applied to forty-five samples of coffee and cereal. The presence of OTA was found in twenty-five samples, ranging from 0.28 to 9.33 ng g(-1).
    Matched MeSH terms: Microscopy, Electron, Scanning
  13. Wild hosts and microscopic worlds: Investigating the morphology and surface ultrastructure of Blastocystis sp. in avian and non-human primate species
    Sanggari A, Attah AO, Yahaya ZS, Farah Haziqah MT
    Trop Biomed, 2023 Dec 01;40(4):392-399.
    PMID: 38308825 DOI: 10.47665/tb.40.4.003
    Blastocystis is a prevalent infectious agent found in the gastrointestinal tract of humans and animals. While the morphology of Blastocystis has been extensively studied, there is still a lack of comprehensive research on its ultrastructure, especially regarding surface characteristics and their correlation with pathogenic potential. Additionally, the subtyping of Blastocystis does not provide information on the isolate's pathogenicity. This study aimed to examine the morphology and the cell surface of Blastocystis in avian and non-human primates, including peafowl, pheasant, and lion-headed tamarin. By employing light microscopy and scanning electron microscopy (SEM), this study provides the first evidence of the cellular and surface features of Blastocystis in these animal species. Our findings revealed distinct variations in cell size, shape, and surface morphology among the different host species. Notably, the isolates from peafowl exhibited larger cell sizes compared to the isolates from the pheasant. However, interestingly, both animal species were found to exhibit the same Blastocystis ST6. It was also observed that the surface structure of Blastocystis from different hosts displayed a diverse range of patterns, including mesh-like appearances, deep indentations, and attachments to bacteria. Additionally, findings also revealed the presence of a rough surface structure in peafowl, a characteristic that has been previously linked to pathogenicity and symptomatic infection in animals, as indicated by earlier studies. The findings contribute to our understanding of the morphological features and the surface characteristic of Blastocystis in different host species, shedding light on the parasite's adaptations and potential implications for host health.
    Matched MeSH terms: Microscopy, Electron, Scanning
  14. White spot syndrome virus isolates of tiger shrimp Penaeus monodon (Fabricious) in India are similar to exotic isolates as revealed by polymerase chain reaction and electron microscopy
    Mishra SS, Shekhar MS
    Indian J Exp Biol, 2005 Jul;43(7):654-61.
    PMID: 16053274
    Microbiological analysis of samples collected from cases of white spot disease outbreaks in cultured shrimp in different farms located in three regions along East Coast of India viz. Chidambram (Tamil Nadu), Nellore (Andhra Pradesh) and Balasore (Orissa), revealed presence of Vibrio alginolyticus, Vibrio parahaemolyticus, and Aeromonas spp. but experimental infection trials in Penaeus monodon with these isolates did not induce any acute mortality or formation of white spots on carapace. Infection trials using filtered tissue extracts by oral and injection method induced mortality in healthy P. monodon with all samples and 100% mortality was noted by the end of 7 day post-inoculation. Histopathological analysis demonstrated degenerated cells characterized by hypertrophied nuclei in gills, hepatopancreas and lymphoid organ with presence of intranuclear basophilic or eosino-basophilic bodies in tubular cells and intercellular spaces. Analysis of samples using 3 different primer sets as used by other for detection of white spot syndrome virus (WSSV) generated 643, 1447 and 520bp amplified DNA products in all samples except in one instance. Variable size virions with mean size in the range of 110 x 320 +/- 20 nm were observed under electron microscope. It could be concluded that the viral isolates in India involved with white spot syndrome in cultured shrimp are similar to RV-PJ and SEMBV in Japan, WSBV in Taiwan and WSSV in Malaysia, Indonesia, Thailand, China and Japan.
    Matched MeSH terms: Microscopy, Electron
  15. Fulltext Wheat Germ Agglutinin-Conjugated Disulfide Cross-Linked Alginate Nanoparticles as a Docetaxel Carrier for Colon Cancer Therapy
    Chiu HI, Lim V
    Int J Nanomedicine, 2021;16:2995-3020.
    PMID: 33911862 DOI: 10.2147/IJN.S302238
    PURPOSE: In chemotherapy, oral administration of drug is limited due to lack of drug specificity for localized colon cancer cells. The inability of drugs to differentiate cancer cells from normal cells induces side effects. Colonic targeting with polymeric nanoparticulate drug delivery offers high potential strategies for delivering hydrophobic drugs and fewer side effects to the target site. Disulfide cross-linked polymers have recently acquired high significance due to their potential to degrade in reducing colon conditions while resisting the upper gastrointestinal tract's hostile environment. The goal of this project is, therefore, to develop pH-sensitive and redox-responsive fluorescein-labeled wheat germ agglutinin (fWGA)-mounted disulfide cross-linked alginate nanoparticles (fDTP2) directly targeting docetaxel (DTX) in colon cancer cells.

    METHODS: fDTP2 was prepared by mounting fWGA on DTX-loaded nanoparticles (DTP2) using the two-step carbodiimide method. Morphology of fDTP2 was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Dynamic light scattering (DLS) study was carried out to determine the mean diameter, polydispersity index (PDI) and zeta potential of fDTP2. Cellular uptake efficiency was examined using fluorescence microplate reader. Biocompatibility and active internalization of fDTP2 were conducted on HT-29.

    RESULTS: fDTP2 was found to exhibit a DTX loading efficiency of 19.3%. SEM and TEM tests revealed spherical nanoparticles. The in vitro DTX release test showed a cumulative release of 54.7%. From the DLS study, fDTP2 reported a 277.7 nm mean diameter with PDI below 0.35 and -1.0 mV zeta potential. HT-29 which was fDTP2-treated demonstrated lower viability than L929 with a half maximal inhibitory concentration (IC50) of 34.7 µg/mL. HT-29 (33.4%) internalized fDTP2 efficiently at 2 h incubation. The study on HT-29 active internalization of nanoparticles through fluorescence and confocal imaging indicated such.

    CONCLUSION: In short, fDTP2 demonstrated promise as a colonic drug delivery DTX transporter.

    Matched MeSH terms: Microscopy, Electron, Scanning
  16. Fulltext Wear of rotary instruments: a pilot study
    Abdul Aziz, A., Abu Kasim, N.H., Ramasindarum, C., Mohamad Yusof, M.Y.P., Paiizi, M., Ahmad, R.
    Ann Dent, 2011;18(1):1-7.
    MyJurnal
    The aim of this study was to assess the wear of tungsten carbide burs and round rotary diamond instruments through measurements of rake angle and visual observations respectively under a field emission scanning electron microscope. Sixty short and long head pear-shaped tungsten carbide burs and 18 round rotary diamond instruments that had been used to complete < 5, > 5 and > 10 cavity preparations (n=10/group) were selected from the 3rd and 4th year dental students, Faculty of Dentistry, University of Malaya. There were two control groups consisting of long and short tungsten carbide burs of ten each. Two-way ANOVA was used to analyse the rake angle data. The data from the two control groups were collectively analysed following multiple paired t-test (p>.05) which showed no significant difference between the two types of tungsten carbide bur (short and long head). The mean rake angle of the control group was significantly higher (p < .05) compared to the < 5, > 5 and > 10 cavity preparation groups. The rake angle of the > 10 cavity preparation group was significantly lower than the other two test groups (p < .05). Round rotary diamond instruments in the < 5 cavity preparation group showed intact diamond particles with distinct cutting facets comparable to the control group. However, diamonds instruments in the > 5 and > 10 cavity preparation groups showed blunt diamond particles. In conclusion, wear of tungsten carbide burs and round rotary diamond instruments were evident after repeated use. Wear was more pronounced when instruments were used to prepare more than ten cavities.
    Matched MeSH terms: Microscopy, Electron, Scanning
  17. Voltammetric sensing of formaldehyde by using a nanocomposite prepared by reductive deposition of palladium and platinum on polypyrrole-coated nitrogen-doped reduced graphene oxide
    Mahmoudian MR, Basirun WJ, Woi PM, Hazarkhani H, Alias YB
    Mikrochim Acta, 2019 05 22;186(6):369.
    PMID: 31119482 DOI: 10.1007/s00604-019-3481-y
    The study presents the synthesis of polypyrrole-coated palladium platinum/nitrogen-doped reduced graphene oxide nanocomposites (PdPt-PPy/N-rGO NC) via direct the reduction of Pd(II) and Pt(II) in the presence of pyrrole monomer, N-rGO and L-cysteine as the reducing agent. X-ray diffraction confirmed the presence of metallic Pd and Pt from the reduction of Pd and Pt cations. Transmission electron microscopy images revealed the presence of Pd, Pt and PPy deposition on N-rGO. Impedance spectroscopy results gave a decreased charge transfer resistance due to the presence of N-rGO. The nanocomposites were synthesized with different Pd/Pt ratios (2:1, 1:1 and 1:2). A glassy carbon electrode (GCE) modified with the nanocomposite showed enhanced electrochemical sensing capability for formaldehyde in 0.1 M sulfuric acid solution. Cyclic voltammetry showed an increase in the formaldehyde oxidation peak current at the GCE modified with Pd2Pt1 PPy N-rGO. At a typical potential of 0.45 V (vs. SCE), the sensitivity in the linear segment was 345.8 μA.mM -1. cm-2. The voltammetric response was linear between 0.01 and 0.9 mM formaldehyde concentration range, with a 27 µM detection limit (at S/N = 3). Graphical abstract Schematic presentation of formaldehyde detection by Pd2Pt1-PPy/nitrogen-doped reduced Graphene Oxide Nanocomposite (Pd2Pt1-PPy /N-Gr NC). The decrease of charge transfer resistance and the agglomeration of deposited metals in the presence of N-rGO enhance the current response of the electrochemical sensor.
    Matched MeSH terms: Microscopy, Electron, Transmission
  18. Fulltext Visualizing copper assisted graphene growth in nanoscale
    Rosmi MS, Yusop MZ, Kalita G, Yaakob Y, Takahashi C, Tanemura M
    Sci Rep, 2014;4:7563.
    PMID: 25523645 DOI: 10.1038/srep07563
    Control synthesis of high quality large-area graphene on transition metals (TMs) by chemical vapor deposition (CVD) is the most fascinating approach for practical device applications. Interaction of carbon atoms and TMs is quite critical to obtain graphene with precise layer number, crystal size and structure. Here, we reveal a solid phase reaction process to achieve Cu assisted graphene growth in nanoscale by in-situ transmission electron microscope (TEM). Significant structural transformation of amorphous carbon nanofiber (CNF) coated with Cu is observed with an applied potential in a two probe system. The coated Cu particle recrystallize and agglomerate toward the cathode with applied potential due to joule heating and large thermal gradient. Consequently, the amorphous carbon start crystallizing and forming sp(2) hybridized carbon to form graphene sheet from the tip of Cu surface. We observed structural deformation and breaking of the graphene nanoribbon with a higher applied potential, attributing to saturated current flow and induced Joule heating. The observed graphene formation in nanoscale by the in-situ TEM process can be significant to understand carbon atoms and Cu interaction.
    Matched MeSH terms: Microscopy, Electron, Transmission
  19. Visualization of Bacteria-Mediated Gene Delivery Using High-Resolution Electron and Confocal Microscopy
    Osahor AN, Ng AWR, Narayanan K
    Methods Mol Biol, 2021;2211:29-40.
    PMID: 33336268 DOI: 10.1007/978-1-0716-0943-9_3
    Visual analysis of the gene delivery process when using invasive bacteria as a vector has been conventionally performed using standard light and fluorescence microscopy. These microscopes can provide basic information on the invasiveness of the bacterial vector including the ability of the vector to successfully adhere to the cell membrane. Standard microscopy techniques however fall short when finer details including membrane attachment as well as internalization into the cytoplasm are desired. High-resolution visual analysis of bacteria-mediated gene delivery can allow accurate measurement of the adherence and internalization capabilities of engineered vectors. Here, we describe the use of scanning electron microscopy (SEM) to directly quantify vectors when they are external to the cell wall, and confocal microscopy to evaluate the vectors when they have internalized into the cytoplasm. By performing the invasion procedure on microscope coverslips, cells can be easily prepared for analysis using electron or confocal microscopes. Imaging the invasion complexes in high resolution can provide important insights into the behavior of bacterial vectors including E. coli, Listeria, and Salmonella when invading their target cells to deliver DNA and other molecules.
    Matched MeSH terms: Microscopy, Electron, Scanning
  20. Visible-Light Driven Effective Photocatalytic Degradation of Methylene Blue Dye Using Perforated Curly Zn0.1Ni0.9O Nanosheets
    Karthikeyan V, Gnanamoorthy G, Varun Prasath P, Narayanan V, Sagadevan S, Umar A, et al.
    J Nanosci Nanotechnol, 2020 Sep 01;20(9):5759-5764.
    PMID: 32331175 DOI: 10.1166/jnn.2020.17898
    Herein, we report the facile synthesis, characterization and visible-light-driven photocatalytic degradation of perforated curly Zn0.1Ni0.9O nanosheets synthesized by hydrothermal process. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies confirmed the cubic phase crystalline structure and growth of high density perforated curly Zn0.1Ni0.9O nanosheets, respectively. As a photocatalyst, using methylene blue (MB) as model pollutant, the synthesized nanosheets demonstrated a high degradation efficiency of ~76% in 60 min under visible light irradiation. The observed results suggest that the synthesized Zn0.1Ni0.9O nanosheets are attractive photocatalysts for the degradation of toxic organic waste in the water under visible light.
    Matched MeSH terms: Microscopy, Electron, Scanning
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