Copper phthalocyanine films deposited by liquid-liquid interface recrystallization technique (LLIRCT).

The simple recrystallization process is innovatively used to obtain the nanoparticles of copper phthalocyanine by a simple method. Liquid-liquid interface recrystallization technique (LLIRCT) has been employed successfully to produce small sized copper phthalocyanine nanoparticles with diameter between 3-5 nm. The TEM-SAED studies revealed the formation of 3-5 nm sized with beta-phase dominated mixture of alpha and beta copper phthalocyanine nanoparticles. The XRD, SEM, and the UV-vis studies were further carried out to confirm the formation of copper phthalocyanine thin films. The cyclic voltametry (CV) studies conclude that redox reaction is totally reversible one electron transfer process. The process is attributed to Cu(II)/Cu(I) redox reaction.

Controlled interlinking of Au and Ag nanoclusters using 4-aminothiophenol as molecular interconnects.

This work describes the formation of interlinked gold and silver nanoclusters at controlled pH using 4-aminothiophenol (ATP) as a molecular interconnect. UV-visible spectra give on intercrystal plasmon resonance band in the region 550-580 nm. The crystalline heteroassembly formation is also evident from the transmission electron microscopic (TEM) images, whereas X-ray photoelectron spectroscopic (XPS) analysis of the aggregates shows the presence of charged -N species, indicating electrostatic interaction of -N with Ag nanoclusters. Furthermore, electrochemical studies of these heteroassembled systems suggest that silver nanoclusters are not fully passivated by the monolayers of ATP and are accessible for redox reactions.

A low-temperature, soft chemistry method for the synthesis of zirconia nanoparticles in thermally evaporated fatty amine thin films.

We demonstrate the synthesis of zirconia nanoparticles in a lipid matrix by a simple, low temperature beaker-based process. This is accomplished by electrostatic entrapment of ZrF6(2-) ions within thermally evaporated octadecylamine (ODA) thin films followed by the low-temperature in situ hydrolysis of the entrapped metal ion complexes. The zirconia particles thus formed were of the monoclinic phase and were fairly monodisperse with particles of average size 40 nm. The zirconia crystallites appeared to exhibit preferred orientation indicating epitaxial growth of the crystals within the lipid matrix. The formation of zirconia nanoparticles in the lipid matrix was investigated using quartz crystal microgravimetry (QCM), optical absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques.

Phase transfer of silver nanoparticles from aqueous to organic solutions using fatty amine molecules.

We demonstrate the phase transfer of silver nanoparticles synthesized in an aqueous medium into hexane containing the cationic surfactant octadecylamine (ODA). During vigorous shaking of the biphasic mixture, rapid phase transfer of the silver nanoparticles into the organic phase was observed. The phase transfer of the silver nanoparticles arises due to coupling of the silver nanoparticles with the ODA molecules present in organic phase via either coordination bond formation or weak covalent interaction. This process renders the nanoparticles sufficiently hydrophobic and dispersible in the organic phase. The ODA-stabilized silver nanoparticles could be separated out from the organic phase in the form of a powder and are readily redispersible in different organic solvents. The nature of binding of the ODA molecules to the silver nanoparticle surface was characterized using UV-vis spectroscopy, thermogravimetry, transmission electron microscopy, nuclear magnetic resonance spectroscopy, X-ray photoemission spectroscopy, and Fourier transform infrared spectroscopy.

Investigation into the Interaction between Surface-Bound Alkylamines and Gold Nanoparticles.

In addition to alkanethiols and phosphine derivatives, alkylamines have been investigated as capping agents in the synthesis of organically dispersible gold nanoparticles. However, reports pertaining to gold nanoparticle derivatization with alkylamines are relatively scarce and their interaction with the underlying gold support is poorly understood. In this paper, we attempt a more detailed examination of this problem and present results on the Fourier transform infrared spectroscopy, thermogravimetry, nuclear magnetic resonance, and X-ray photoemission (XPS) characterization of gold nanoparticles capped with the alkylamines laurylamine (LAM) and octadecylamine (ODA). The capping of the gold nanoparticles with the alkylamines was accomplished during phase transfer of aqueous gold nanoparticles to chloroform containing fatty amine molecules. Thermogravimetry and XPS analysis of purified powders of the amine-capped gold nanoparticles indicated the presence of two different modes of binding of the alkylamines with the gold surface. The weakly bound component is attributed to the formation of an electrostatic complex between protonated amine molecules and surface-bound AuCl4-/AuCl2- ions, while the more strongly bound species is tentatively assigned to a complex of the form [AuCl(NH2R)]. The alkylamine monolayer on the gold nanoparticle surface may be place exchanged with other amine derivatives present in solution.

Fabrication, characterization, and enzymatic activity of encapsulated fungal protease--fatty lipid biocomposite films.

Encapsulation of an aspartic protease from the fungus Aspergillus saitoi (F-prot) in thermally evaporated fatty acid films by a simple beaker-based immersion technique under enzyme-friendly conditions is described. The approach is based on diffusion of the enzyme from aqueous solution, driven primarily by attractive electrostatic interaction between charged groups on the enzyme surface and ionized lipid molecules in the film. The encapsulated enzyme molecules could be "pumped out" of the biocomposite film into solution by modulating the electrostatic interaction between the enzyme and fatty acid molecules via solution pH variation. The kinetics of F-prot diffusion into the acid films was followed using quartz crystal microgravimetry measurements while the secondary and tertiary structure of the enzyme in the lipid matrix was studied using Fourier transform infrared (FT-IR) and fluorescence spectroscopies. FT-IR and fluorescence measurements indicated little perturbation to the native structure of the enzyme. A chemical analysis of the F-prot-fatty acid biocomposite film was also performed using X-ray photoelectron spectroscopy. The encapsulated F-prot molecules showed catalytic activity (as estimated by reaction with hemoglobin) comparable to free enzyme molecules in solution, indicating facile access of biological analytes/reactants in solution to the enzyme molecules. The advantages/disadvantages of this approach vis-à-vis methods currently used for encapsulation of biomolecules are briefly discussed.