FABRICATION OF ORGANIC LIGHT EMITTING DIODES (OLEDs) FOR FLAT PANEL DISPLAYS

Organic light emitting diodes (OLEDs) are thin film devices in which organic materials are sandwiched between two electrodes. These devices emit light when electricity is passed through them. OLEDs have gained much attention because their potential applications to full color flat panel displays. Generally, OLEDs are assembled using an heterojunction architecture between three or more organic molecular materials: an electron injection layer, the emitting one and finally the hole injection layer. There are two types of OLED devices, depend on the type of molecular materials used in the devices. The first type is Small Molecule OLED. The production of small-molecule OLEDs require vacuum deposition. The second type is Light-Emitting Polymer. In this technology, the organic thin films can be deposited by spin coating or by a technique derived from commercial inkjet printing. This paper discusses the fabrication of both types of OLEDs. A small molecule blue organic light emitting diode was fabricated using thermal evaporation system with ITO/2-TNATA/NPB/DPVBi:dopant/ Alq3/LiF/Al structure, where the emitting molecules is 4,4’-bis(2,2’-diphenylvinyl)-1,1’-biphenyl (DPVBi). The typical brightness, the power consumption and the turn-on voltage of the device were 30 cd/m2, less than 50 mW and 5.0 V respectively. For polymer light-emitting diode, device with structure of ITO/PHF/Al structure was fabricated, where PHF is poly (4, 4’-diphenylene diphenylvinylene). This device has turn-on voltage at 23.0 V. A reduction of turn-on voltage of this device is achieved by using a nanocomposite layer consisting of PHF and SiO2 nanoparticles as the emitting layer. A white OLED combines with colour filters is one of the approaches to obtained full colour flat screen display. White light emitting devices were fabricated with structure of ITO/PHF:rubrene/Al where the white light was optimized through variation of mixing concentrations of PHF and rubrene. The results show that the combination of 0.6 wt% PHF and 0.06 wt% rubrene produced the optimum white light at CIE coordinate of (0.31,0.31). The standard coordinate for white light is (0.33,0.33). The turn-on voltage of this device is 14.0 V and the brightness is 6541 cd/m2. The turn-on of this device was reduced to 8.0 V through an annealing process at 150°C. Keywords : Organic light emitting diodes (OLEDs), small molecule device, polymer light-emitting diode, display

Association of Mitochondrial DNA 10398 Polymorphism in Invasive Breast Cancer in Malay Population of Peninsular Malaysia

Background: The mitochondrial DNA (mtDNA) 10398 polymorphism is hypothesised to alter a mitochondrial subunit of the electron transfer chain and is associated with several neurodegenerative disorders and cancers. Methods: In this study, an mtDNA polymorphism at nucleotide position 10398 was screened in 101 Malay female patients with invasive breast cancer and 90 age-matched healthy female controls using minisequencing analysis. Results: The Malay women with the 10398G variant showed a significantly increased risk of invasive breast cancer (OR = 2.29, 95% CI 1.25–4.20, P = 0.007). Immunohistochemistry analysis was conducted to investigate the effect of this polymorphism on the levels of apoptosis in breast cancer cells. The level of Bax (a pro-apoptotic protein) expression was significantly higher than that of Bcl-2 (an anti-apoptotic protein) in patients carrying the G allele (P = 0.016) but not in those carrying the A allele (P = 0.48). Conclusion: Based on these findings, we propose that the mtDNA 10398 polymorphism may be a potential risk marker for breast cancer susceptibility in the Malay population

Formulation and Characterization of Fe₃O₄@PEG Nanoparticles Loaded Sorafenib; Molecular Studies and Evaluation of Cytotoxicity in Liver Cancer Cell Lines

Iron oxide nanoparticles are one of the nanocarriers that are suitable for novel drug delivery systems due to low toxicity, biocompatibility, loading capacity, and controlled drug delivery to cancer cells. The purpose of the present study is the synthesis of coated iron oxide nanoparticles for the delivery of sorafenib (SFB) and its effects on cancer cells. In this study, Fe3O4 nanoparticles were synthesized by the co-precipitation method, and then sorafenib was loaded onto PEG@Fe3O4 nanoparticles. FTIR was used to ensure polyethylene glycol (PEG) binding to nanoparticles and loading the drug onto the nanoshells. A comparison of the mean size and the crystalline structure of nanoparticles was performed by TEM, DLS, and X-ray diffraction patterns. Then, cell viability was obtained by the MTT assay for 3T3 and HepG2 cell lines. According to FT-IR results, the presence of O–H and C–H bands at 3427 cm–1 and 1420 cm–1 peak correlate with PEG binding to nanoparticles. XRD pattern showed the cubic spinel structure of trapped magnetite nanoparticles carrying medium. The magnetic properties of nanoparticles were examined by a vibrating-sample magnetometer (VSM). IC50 values at 72 h for treatment with carriers of Fe3O4@PEG nanoparticle for the HepG2 cell line was 15.78 μg/mL (p 3O4 nanoparticles coated by polyethylene glycol and using them in the drug delivery process could be beneficial for increasing the effect of sorafenib on cancer cells

Palladium Nanoparticles on Chitosan-Coated Superparamagnetic Manganese Ferrite: A Biocompatible Heterogeneous Catalyst for Nitroarene Reduction and Allyl Carbamate Deprotection

Although metallic nanocatalysts such as palladium nanoparticles (Pd NPs) are known to possess higher catalytic activity due to their large surface-to-volume ratio, however, in nanosize greatly reducing their activity due to aggregation. To overcome this challenge, superparamagnetic chitosan-coated manganese ferrite was successfully prepared and used as a support for the immobilization of palladium nanoparticles to overcome the above-mentioned challenge. The Pd-Chit@MnFe2O4 catalyst exhibited high catalytic activity in 4-nitrophenol and 4-nitroaniline reductions, with respective turnover frequencies of 357.1 min−1 and 571.4 min−1, respectively. The catalyst can also be recovered easily by magnetic separation after each reaction. Additionally, the Pd-Chit@MnFe2O4 catalyst performed well in the reductive deprotection of allyl carbamate. Coating the catalyst with chitosan reduced the Pd leaching and its cytotoxicity. Therefore, the catalytic activity of Pd-Chit@MnFe2O4 was proven to be unrestricted in biology conditions

Succinyl-κ-carrageenan Silver Nanotriangles Composite for Ammonium Localized Surface Plasmon Resonance Sensor

This research investigates the physicochemical properties of biopolymer succinyl-κ-carrageenan as a potential sensing material for NH4+ Localized Surface Plasmon Resonance (LSPR) sensor. Succinyl-κ-carrageenan was synthesised by reacting κ-carrageenan with succinic anhydride. FESEM analysis shows succinyl-κ-carrageenan has an even and featureless topology compared to its pristine form. Succinyl-κ-carrageenan was composited with silver nanoparticles (AgNP) as LSPR sensing material. AFM analysis shows that AgNP-Succinyl-κ-carrageenan was rougher than AgNP-Succinyl-κ-carrageenan, indicating an increase in density of electronegative atom from oxygen compared to pristine κ-carrageenan. The sensitivity of AgNP-Succinyl-κ-carrageenan LSPR is higher than AgNP-κ-carrageenan LSPR. The reported LOD and LOQ of AgNP-Succinyl-κ-carrageenan LSPR are 0.5964 and 2.7192 ppm, respectively. Thus, AgNP-Succinyl-κ-carrageenan LSPR has a higher performance than AgNP-κ-carrageenan LSPR, broader detection range than the conventional method and high selectivity toward NH4+. Interaction mechanism studies show the adsorption of NH4+ on κ-carrageenan and succinyl-κ-carrageenan were through multilayer and chemisorption process that follows Freundlich and pseudo-second-order kinetic model

Ultra-thin MoS2 nanosheet for electron transport layer of perovskite solar cells

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