Noor Haida Mohd Kaus

Green synthesis of mesoporous anatase TiO2 nanoparticles and their photocatalytic activities

Titanium dioxide (TiO2) materials have been the focus of many promising applications due to their low-cost, availability and biocompatible properties. In this study, mesoporous anatase TiO2 nanoparticles were synthesised using a green chemistry approach. This visible-light active photocatalyst was prepared via a simple and solvent free precipitation method at low temperatures using titanium tetraisopropoxide (TTIP) as a precursor and soluble starch as the template. The effect of initial solution pH and concentration of TTIP on surface morphology and photocatalytic activities of TiO2 nanoparticles were evaluated. Based on the results obtained, the TiO2 nanocatalyst prepared using 0.01 mol of TTIP under basic conditions revealed the best photocatalytic activity. The as-synthesised nanoparticles were further characterised using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption analysis (NAA). The XRD spectrum confirmed that the catalyst was composed of anatase tetragonal TiO2 phase. The Brunauer–Emmett–Teller (BET) surface area of 81.59 m2 g−1 proved the presence of mesopores (average pore size = 8.7 nm) which partially contributed to and catalysed the photodegradation process of methylene blue (MB) solution under sunlight. The effects of various parameters such as initial dye concentration, catalyst dosage and recyclability of the catalyst were evaluated to determine the best conditions. Results obtained suggest that TiO2 nanoparticles synthesised through the green chemistry approach under optimum conditions exhibited an effective photodegradation process of MB solution under sunlight.

Interactions of Nanoparticles with Purple Membrane Films

Lamellar structures self-assembled from purple membranes (PM) of Halobacterium salinarum are promising building units for bio-electronic devices, due to proton pumping ability of the PM. The functionality and durability of such devices are hinged on the structural integrity of PM lamellae. Using X-ray diffraction, we examined the structure of PM multilayers on silicon when challenged with two types of nanoparticles (NPs): carboxymethyl-dextran coated magnetite (2.4 nm core size) and citrate-stabilised gold (5 nm core size). We tried to infiltrate the PM multilayers with the NPs using two alternative routes: facile penetration (FP) and co-assembly (CS) by solution mixing. We found that under all conditions the NPs did not disrupt the overall lamellar structure of the PM films or enter the inter-lamellar space, although the presence of NPs affected the self-assembly process of the PM films. This caused an increase in the disorder in the film structure, as assessed by the decreasing number of layers in the multilayer stack as the NP concentration increased. Despite this, UV-Vis spectroscopic measurements showed that the conformation of the retinal residue within the protein was intact so the proton pumping functionality of PM multilayers would be retained in all samples with added NPs. Our results show that the effects of NPs on the PM structure and functionality are subtle and complex, and we will discuss the structural integrity of lipid-protein composite PM films against NP infiltration in terms of their high bending modulus as compared with that of fluid lipid bilayers.

Assembly of poly(methacrylate)/purple membrane lamellar nanocomposite films by intercalation and in situ polymerisation

Thin films comprising ordered stacks of purple membrane (PM) sheets containing the light-driven proton pump bacteriorhodopsin (BR) were infiltrated with methacrylic acid (MA) monomers to produce lamellar bionanocomposites. Subsequent in situ polymerization and crosslinking of the guest MA molecules resulted in partially intercalated poly(methacrylate)/PM freestanding films, which showed increased stability in water, structural integrity and enhanced resistance to ethanol degradation compared with PM control films or non-polymerized MA/PM layered nanocomposites. Studies on photocycle kinetics confirmed that the polymerized PM films were functionally active, and showed an increase in the lifetime for the M-state intermediate of the photocycle. The results indicate that nanometre-thin layers of crosslinked poly(methacrylate) can be synthesized in situ between the PM sheets to produce novel functional bionanocomposites with proton transfer and photochromic properties.

The Influence of pluronic F68 and F127 nanocarrier on physicochemical properties, in vitro release, and antiproliferative activity of thymoquinone drug

Background: This study reports on hydrophobic drug thymoquinone (TQ), an active compound found in the volatile oil of Nigella sativa that exhibits anticancer activities. Nanoformulation of this drug could potentially increase its bioavailability to specific target cells. Objective: The aim of this study was to formulate TQ into polymer micelle, Pluronic F127 (5.0 wt %) and Pluronic F68 (0.1 wt %), as a drug carrier to enhance its solubility and instability in aqueous media. Materials and Methods: Polymeric micelles encapsulated TQ were prepared by the microwave-assisted solvent evaporation technique. Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometer were utilized for qualitative confirmation of micelles encapsulation. The surface morphology and mean particle size of the prepared micelles were determined by using transmission electron microscopy (TEM). Cytotoxicity effect was studied using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay. Results: Dynamic laser light scattering (DLS) technique showed hydrodynamic size distribution of optimized micelles of 50 nm, which was in close agreement with the mean particle size obtained from TEM of about 51 nm. Drug release study showed the maximum percentage of TQ release at 61% after 72 h, while the entrapment efficiency of TQ obtained was 46% using PF127. The cytotoxic effect of PF127-encapsulated TQ was considerably higher compared to PF68-encapsulated TQ against MCF7 cells, as they exhibited IC50value of 8 μM and 18 μM, respectively. Conclusion: This study suggests higher molecular weight Pluronic polymer micelles (F127) with hydrophilic-hydrophobic segments which could be used as a suitable candidate for sustainable delivery of TQ. However, comprehensive studies should be carried out to establish the suitability of Pluronic F127 as a carrier for other drugs with similar challenges as TQ.

In situ X-ray reflectivity studies of molecular and molecular-cluster intercalation within purple membrane films

It has been recently demonstrated that molecular and molecular cluster guest species can intercalate within lamellar stacks of purple membrane (PM), and be subsequently dried to produce functional bioinorganic nanocomposite films. However, the mechanism for the intercalation process remains to be fully understood. Here we employ surface X-ray scattering to study the intercalation of aminopropyl silicic acid (APS) or aminopropyl-functionalised magnesium phyllosilicate (AMP) molecular clusters into PM films. The composite films are prepared under aqueous conditions by guest infiltration into preformed PM films, or by co-assembly from an aqueous dispersion of PM sheets and guest molecules/clusters. Our results show that addition of an aqueous solution of guest molecules to a dried preformed PM film results in loss of the lamellar phase, and that subsequent air-drying induces re-stacking of the lipid/protein membrane sheets along with retention of a 2–3 nm hydration layer within the inter-lamellar spaces. We propose that this hydration layer is necessary for the intercalation of APS molecules or AMP oligomers into the PM film, and their subsequent condensation and retention as nano-thin inorganic lamellae within the composite mesostructure after drying. Our results indicate that the intercalated nanocomposites prepared from preformed PM films have a higher degree of ordering than those produced by co-assembly.

Physico-chemical characteristics of ZnO nanoparticles-based discs and toxic effect on human cervical cancer HeLa cells

In this study, we investigated physico-chemical properties of zinc oxide nanoparticles (ZnO NPs)-based discs and their toxicity on human cervical cancer HeLa cell lines. ZnO NPs (80 nm) were produced by the conventional ceramic processing method. FESEM analysis indicated dominant structure of nanorods with dimensions 100-500 nm in length, and 20-100 nm in diameter. The high content of ZnO nanorods in the discs probably played significant role in toxicity towards HeLa cells. Structural defects (oxygen vacancies and zinc/oxygen interstitials) were revealed by PL spectra peaks at 370-376 nm and 519-533 nm for the ZnO discs. The structural, optical and electrical properties of prepared sample have influenced the toxicological effects of ZnO discs towards HeLa cell lines via the generation of reactive oxygen species (ROS), internalization, membrane damage, and eventually cell death. The larger surface to volume area of the ZnO nanorods, combined with defects, stimulated enhanced toxicity via ROS generation hyd...

Facile route of biopolymer mediated ferrocene (FO) nanoparticles in aqueous dispersion

In this paper, we present a facile method for production stable aqueous dispersion of ferrocene (FO) nanoparticles. Ferrocene compounds were employed to achieve stable nanodispersions, stabilized with three different biopolymers namely, alginate, CM-dextran and chitosan. The nanoparticles produce are spherical, less than 10 nm in mean diameter and highly stable without any sedimentation. Fourier infrared transform (FTIR) and X-ray diffraction (XRD) studies confirmed the purity of ferrocene nanoparticles there is no modifications occur during the preparation route. FTIR spectra results were consistent with the presence of absorption band of cyclopentadienyl ring (C5H5− ion) which assigned to ν(C-C) vibrations (1409 cm-1), δ(C-H) stretching at 1001 cm−1 and π(C-H) vibrations at 812 cm−1. Furthermore, all functional group for biopolymers such as C O from carboxyl group of CM-dextran and sodium alginate appears at 1712 cm−1 and 170...