Current Nanoscience - Volume 2, Issue 1, 2006

The discovery and utility of new methods based on different materials and chemical derivatisations for protein profiling of complex analytes is an ongoing field. This study includes the development, optimisation, validation and the application of a method based on the combined characteristics of physisorption and chemisorption of nano crystalline diamond (NCD) surfaces for serum profiling. Due to the expanded nano-structure, the numbers of potential binding sites are dramatically increased. For immobilised metal ion affinity chromatography (IMAC), diamond coated surfaces were derivatised with glycidyl methacrylate (GMA) under ultraviolet (UV) light at different wavelengths followed by further derivatisation with iminodiacetic acid (IDA) and loading with copper ions. This special kind of MALDI/TOF-MS, was termed as MELDI/TOF-MS (Material enhanced laser desorption ionization time of flight mass spectrometry), as it is based on various materials e.g. diamond, cellulose, silica and poly (glycidyl methacrylate/divinylbenzene). The diversity in the physical characteristics of these derivatised materials is responsible to get improved sensitivity, specificity, capacity and broad range of information. Human serum samples were assayed through MELDI/TOF-MS analysis to validate the capability, capacity, efficiency and reproducibility of the nano-structured diamond surfaces for protein profiling. Also the method was employed to search for the differences in human body fluids e.g. sera of different origin through matrix assisted laser desorption ionisation time of flight mass spectrometry (MALDI/TOF-MS).

Microwave plasma chemical vapor deposition (CVD) was used to grow nanostructured diamond onto mechanically polished superelastic Nitinol (NiTi) alloy. As determined by glancing-angle x-ray diffraction, mechanical polishing of the heavily oxidized as-received samples resulted in removal of nickel, Ni3Ti, and TiO2 surface phases, leaving the NiTi austenite (B2 type, CsCl structure) to be detected. Diamond nucleation and growth was impractically slow on the mechanically polished samples and could only yield continuous films at practical growth rates when they were first exposed to plasma annealing to allow formation of oxide and intermetallic phases (Ni3Ti, NiTi2). The ability of a surface layer (composed of oxides and/or the intermetallic phases) to act as a barrier to carbon diffusion may be responsible for an observed increase in interfacial TiC formation leading to practical diamond growth rates of about 1 m/hour.

Hafnia and zirconia films have been synthesized via solution deposition on sulfonate-terminated molecular self-assembled monolayers (SAMs) that are covalently anchored on surfaces of silicon wafers. As-prepared inorganic films, consisting of packed nanoparticles, were formed by heat-induced hydrolysis and condensation in acidic aqueous solutions of hafnium inorganic salt. The effects of several key synthesis process parameters-such as temperature, concentration of the hafnium salt, and acidity (i.e., concentration of added hydrochloric acid)-on the thickness, growth kinetics, and surface features of the films were studied through characterization by ellipsometry, atomic force microscopy, and transmission electron microscopy. In addition, solid particle precipitation in the bulk solutions was investigated with real-time dynamic light scattering and small-angle X-ray scattering techniques (for solid particle nucleation and growth kinetics) as well as with scanning electron microscopy (for visualizing solid size and morphology). The formation of hafnia films occurs right after the induction period, which is the time corresponding to the turbidity appearance due to solid particle formation in the bulk solutions. The initial growth rate of the film increases with increasing temperature and hafnium salt concentration and decreasing hydrochloric acid concentration. Our results suggest that the heterogeneous nucleation and growth mechanism might be responsible for the formation of the first layer of hafnia on the SAM surface. However, under the conditions tested, hafnia films seem to grow thicker mainly by a "cluster growth" mechanism due to adherence of nanoparticles from the bulk solutions. Although decreasing in the rate of nucleation and growth, nanoclusters or nanoparticles (continuously formed after the induction period) can still contribute to film deposition. The effects of process parameters on the film growth rate are consistent with the trend of their effects on particle growth rate in the bulk solutions. Tests of multiple batch deposition on the same surface, suggesting a liquid-flow deposition scheme, show a potential to improve film growth kinetics and to reduce film surface roughness. In comparison with zirconia systems, the hydrolysis and film growth rate for hafnia systems are slower; however, the film characteristics of hafnia are quite similar to those of zirconia.

During biological nitrogen fixation, the nitrogenase Fe-protein containing the [4Fe-4S] metal cluster has been shown to function in electron transfer to the MoFe-protein. This function of the Fe-protein is dependent on its conformational state and the metal cluster of the active site. This review will summarize the structures of the nucleotide bound (or "off") and amino-acid-substituted Fe-protein as well as the properties of the metal cluster in Fe-protein. The conformational changes in the nucleotide-dependent switch regions increase the driving force, leading to intermolecular electron transfer and macromolecular complex formation from the [4Fe-4S] metal cluster of the Fe-protein to the substrate reduction site of the MoFe-protein.

Nanomagnets are expected to expand the capabilities of widely established technologies such as data recording and to implement new functionalities of applicability in biosciences. The basis for these potential benefits of nanomagnets is their intrinsic small size and their outstanding properties derived from finite-size and surface effects as well as collective phenomena and unusual transport properties. This review aims to describe recent developments on the potential use of nanomagnets in data recording, which rest in three fundamental approaches and their combinations (composition, shape and exchange interactions). Aside from data recording, we also describe recent advances on the use of nanomagnets in biosciences from analytical (biosensors, magnetic resonance imaging, separation) to therapeutic applications (drug delivery, hyperthermia eradication of malignancy). Special emphasis has been set in understanding the physics behind the benefits of using nanomagnets of different characteristics. Finally, we have addressed some of the perspectives and challenges for the potential future development of nanomagnets and applications based on these systems.

The delivery of drugs via skin routes has been extensively investigated. Nevertheless, clinical applications are limited by the stratum corneum (SC), the predominant barrier of the skin. One of the possibilities for increasing skin absorption or permeation of drugs is the use of nano/submicron vesicular systems. Classic liposomes are of little value as carriers for drug delivery via the skin because they do not deeply penetrate it. Only specially designed liposomes have been shown to be capable of achieving enhanced delivery. Liposomes are tiny spheres ranging in diameter from 50 nm to several microns. This review article explores the types and mechanisms involved with liposomes with nanostructures for enhancing topical or transdermal drug delivery. The incorporation of some additives such as anionic surfactants and ethanol can fluidize the phospholipid bilayers, thus increasing the depths to which liposomes can penetrate into the intercellular pathways of the skin. Hair follicles are also important for the enhancement of transdermal liposomes. Niosomes, non-ionic surfactant vesicles, are alternatives to liposomes, which are also discussed in this review. Physical methods such as iontophoresis, ultrasound, and tape-stripping can further assist the delivery of drugs encapsulated in liposomes. Recent breakthroughs with liposomes are beneficial to topically applied permeants, especially for dermatological medications, cosmetic ingredients, and protein/peptide macromolecules.

Due to the remarkable specific physical and chemical properties as well as the potential application, onedimensional (1D) nanomaterials, such as nanowires, nanofibers, nanobelts, nanorods, etc., have attracted great research interests. This paper explores the fabrication strategies that enable rational design and predictable production of 1D nanomaterials, such as crystallization and electrospinning, discusses several methods for generating heterostructured 1D nanomaterials, and ends by evaluation of several large quantity and high quality bottom-up techniques for building up nanostructures using 1D nanomaterials, both ex situ assembly and in situ growth.