Current Nanoscience - Volume 1, Issue 3, 2005

Nanotechnology is a multidisciplinary scientific field with roots in medicine, communications, genomics, and robotics. Miniaturization provides cost effective and more rapidly functioning mechanical, chemical and biological components. But nanometer sized objects also possess self-ordering and assembly behaviors quite different from larger macro objects that when understood and harnessed will dramatically enhance the quality of human life. The potential applications of nanotechnology encompass virtually every aspect of our lives but one of the greatest values of nanotechnology will be the development of new and effective medical treatments (i.e. nanomedicine). This review focuses on the potential of nanomedicine including using nanoparticles for diagnostic and screening purposes, viral detection, developing artificial receptors, DNA sequencing using nanopores, manufacture of unique drug delivery systems, gene therapy applications, and the enablement of tissue engineering.

Viruses are nanometer size organisms (range from 18 to 250 nm) that can potentially contaminate the feedstocks from animal or human origins used to manufacture biopharmaceutical products. Various measures are taken to ensure the optimal viral safety of this class of products. Selection and screening of starting materials play an important role in safeguarding from the introduction of viruses into the downstream processing but they have limits in specificity and sensitivity. Purification methods of protein biopharmaceutical products may also contribute to viral reduction, but since viruses exhibit a wide range of biochemical characteristics and resistance to physico-chemical treatments, complete elimination of infectious agents is not guaranteed. Therefore, the viral safety of animal derived biopharmaceutical products is well recognized to rely largely upon the use of deliberately introduced and validated viral inactivation and/or removal steps. A major progress in viral safety has been made recently by the development and availability of biocompatible viral filtration (also known as nanofiltration) systems using membranes of a pore size as small as 15 nm; these systems are specifically designed to allow, depending upon membrane used, typically over 4 to 6 logs of virus removal under conditions ensuring good protein permeability and recovery. Validation studies and production experience throughout the world have demonstrated that viral nanofiltration is a robust and reliable viral reduction technique that can be applied to essentially all biological products. This review analyzes the virus risks of biopharmaceutical products (human plasma derivatives, horse and sheep plasma-derived products, recombinant proteins and monoclonal antibodies), the various viral inactivation methods used at present, and the increasing role that viral nanofiltration is playing in assuring the safety of biopharmaceutical products.

The blood brain barrier, formed by brain capillary endothelial cells, represents the major obstacle for drug entry into the central nervous system. Efforts are ongoing to overcome this barrier without causing permanent damage to brain tissue. The present review attempts to provide key information on cerebral microvessel anatomy, features contributing to barrier function and current approaches in overcoming the blood-brain barrier using cellular and molecular methodologies to transfer drugs to the brain as well as intelligent drug delivery systems.

Optical nano-phenomena are defined in the field of nanotechnology for nano-metric architectures and nanostructural devices. A short mini-review of the latest books is presented. The definitions of nano-photonics and nanofocusing are determined. An integrated optical scheme of the obtained near-field nanofocusing probe is discussed. Optical aspects of the nanofocusing recording probes are examined. Aberration conditions of the optical head intended for a higher-density disk memory are considered. The residual and technological aberrations are presented. The obtained optical configurations are shown using ray-trace modeling and wave-optics analysis. The nanofocused spot is computed as 25 nm for a vertical cavity surface emitting laser (VCSEL) beam of 8 μm and the far-field diffraction limit is calculated as 150 nm for a microlens diameter of 13 μm. The nanofocused spots from 20 nm at the geometrical limit and up to 130 nm at the diffraction size have been obtained using two-layer anti-reflection coating on both surfaces of the fabricated microlens structure. The optically integrated arrayed nanofocusing device is presented. The optical power density is compressed more than 1000 times to the exact nanofocused spot in comparison with the energy of the input VCSEL micro-beam. Nano-optical, bio-optical and nano-medicinal devices are underlined.

The design and application of bionanotechnologies aimed at the central nervous system (CNS) provide powerful new approaches for studying cell and molecular biology and physiology. Emerging clinically oriented bionanotechnologies are targeting CNS pathologies such as trauma or degenerative events. The successful and meaningful development of bionanotechnologies designed to interact with the CNS as research or clinical tools require an understanding of the relevant neurophysiology and neuropathology, an appreciation of the inherent 'nanoscale' structure of the CNS, and an understanding of the relevant chemistry and materials science and engineering. This review gives an introduction to the structure and organization of the CNS starting at the organ level and working down in spatial scale to the cellular and molecular levels, with specific examples of biological 'nanoengineering' in neural cells. This is followed by a discussion of some of the unique challenges and obstacles associated with developing bionanotechnologies aimed at the CNS, and a discussion of emerging nanotechnologies for neuroscience applications.

The increasing frequency at which poorly soluble new chemical entities are being discovered raises concerns in the pharmaceutical industry about drugability associated with erratic dissolution and low bioavailability of these hydrophobic compounds. Nanonization provides a plausible pharmaceutical basis for enhancing oral bioavailability and therapeutic effectiveness of these compounds by increasing their surface area. This paper surveys methods available to pharmaceutical manufacturing nanoparticles, including wet chemical processes, media milling, high pressure homogenization, gas-phase synthesis, and form-in-place processes, and elaborates physicochemical rational and gastrointestinal physiological basis upon which nano-drugs can be readily absorbed. Relevant examples are illustrated to show that nano-drugs permeate Caco-2 cell monolayer fast and are well absorbed into animal systemic circulation with high Tmax and AUC, resulting in oral bioavailability higher than their counterpart micro-drugs. The size-dependent permeability and bioavailability should be given particular consideration in the development of potent and selective drug candidates with poor aqueous solubility.

In this article we are concerned with several aspects related to atomic force microscopy electrostatic nanolithography (AFMEN). AFMEN technique is based on manipulation of nano-amounts of dielectric materials in strong 10 8 - 10 10 Vm-1 electric field. In polymer films of different physical-chemical properties AFMEN produces erasable nanostructures that are 10-300 nm in diameter and 0.5-20 nm in height through Joule heating of polymeric molecules between conductive AFM tip and substrate followed by electrostatic attraction of the softened polymer towards the tip. We discuss AFMEN for potential data storage applications in polymeric materials. Additionally, it is demonstrated that AFMEN manipulates bundles of Wiseana Iridovirus and produces noticeable changes in capsids composing individual virions.

TiS2 nanoparticles with nested fullerene-like structure (IF) 60-120 nm in size consisting of up to 100 concentric molecular layers and having quite a perfectly spherical shape were obtained by reacting TiCl4 and H2S using first a horizontal and subsequently a vertical reactor. The proposed growth mechanism of these nanoparticles, i.e. nucleation and growth, is radically different from the one proposed for the growth of the fullerene-like WS2 from the respective oxide nanoparticles. It was found that adding 1-2% IF-TiS2 improves the behavior of lubricating oil substantially. The improved performance of the additive was attributed to the nearly spherical shape of the nanoparticles which promotes rolling friction.

Nanotechnologies seem to have huge potential to bring benefits in areas as diverse as drug development, water decontamination, information and communication infrastructures, and the production of stronger, lighter and perfect nanomaterials. This potential attracts global investment from governments and private sectors in nanotechnologies with the hopes that R and commercial applications of nanomaterials, nanodevices, nanoparticles and nanodrugs will provide new impetus, after the ebb-tides of biotechnology and dotcom, to turn faltering economies around. The global governmental funding has been actively promoting industrial and academic cooperation to realize big prosperity from the nanotechnologies. This article summarizes historic trends and status of global governmental supports for nanotechnologies.