Current Nanoscience - Volume 5, Issue 2, 2009

The success of anti-cancer therapy largely relies on the development of high-efficient, low-toxic, long-circulated, and cancertargeted drug delivery systems. Currently used pharmaceutical nanocarriers, such as polymeric nanoparticles (NPs), liposomes, micelles, nanoemulsions, and many others demonstrate a variety of useful properties, including long circulation in the blood allowing for their accumulation in cancer sites with fenestrated vasculature and poor lymphatic drainage. Surface-modification of nanocarriers is attractive for their enhanced functions on imaging, targeting and delivery. Due to various targeting ligands attached to the surface of the nanocarriers, they could prolong circulation time, increase drug bioavailability, reduce undesirable side effects, and minimize non-specific uptake thus allow for specific cancer-targeting to certain target cells within the cancer sites or even intracellular localization to target organelles. This review highlights the different types of the surface modification of various drug or gene loaded nanocarriers for cancer therapy, focusing on their modification methods, advantages, applications and the probable associated drawbacks.

This review article discusses about the current cancer treatment techniques and the extensive recent research studies done on nanoparticles as carrier systems for the delivery of anticancer drug molecules in cancer treatment. A variety of nanoparticles of different structural and chemical formulations have been tested for their target-specificity and as drug carrier systems. Numerous scientific research works have been performed to test the use of magnetic nanoparticles in the treatment of carcinogenic brain tumour cells and breast cancer cells; colloid gold nanoparticles, liposomes and polymeric micelles as drug delivery systems to target tumour cells and deliver anticarcinogenic drug in a controlled manner. The article also discusses about ceramic nanoparticles and its applications in photodynamic therapy for cancer treatment. The article thus reviews the subject in brief with suitable references to original research articles and review articles discussing the earlier and current research findings about various types of nanoparticles as drug delivery systems in cancer therapy.

Nanotechnology is an area of science devoted to the design, construction and utilization of functional structures on the nanometer scale (often 100nm or smaller). Therapeutic applications of nanotechnologies include the treatment of cancer liver diseases. Avoiding the recognition by the liver is also possible by developing long circulating polymeric colloidal carriers (“stealth” systems) able to avoid the opsonisation process and the recognition by the macrophages. The design of such carriers is based on the physico-chemical concept of the “steric repulsion” by grafting polyethylene glycol chains at the surface of nanoparticles, the adsorption of steric proteins may be dramatically reduced due to steric hindrance. Such an approach allows maintaining the drug carrier for a longer time into the circulation and the resulting extravasation towards non reticuloendothelial-located cancers may become possible. Now, new applications and exciting perspectives are proposed for the delivery of drugs to previously non-accessible diseased sanctuaries, like the brain (treatment of glioma and autoimmune diseases of the brain) or the ocular tissues (treatment of the autoimmune uveitis). Ocular autoimmunity is especially intriguing because of the unique immunological characteristics of the eye. On the basis of laboratory data, the feeding of ocular antigens, has been proposed as a safe and efficacious therapy for uveitis. This review highlights how these obstacles can be overcome by polymer science and nanotechnology. New developments in polymer science coupled with cell-based delivery strategies support the notion that diseases that now have limited therapeutic options can show improved outcomes by advances in nanomedicine.

Water-soluble, thiol protected cadmium telluride CdTe quantum dots (QDs) exhibit size dependent excitation/emission wavelength tunability. The heating period ensuring the growth of CdTe nanocrystals capped with thioglycolic acid (CdTe@TGA) in aqueous solution is critical to reach a required/desirable diameter. Thus, reaction medium was monitored using a capillary zone electrophoresis (CZE) technique in order to select an appropriate heating time. QDs migrate as anionic species in a borate buffer pH 8.5 used as background electrolyte and they were separated according to their size (larger ones have shorter migration times), as confirmed by measuring their maximum wavelength of absorption, with on-line diode array detection. A relationship between electrophoretic mobilities and λmax was tentatively proposed. Efficiency of the purification process of crude QDs using multiple step alcohol precipitation was also confirmed with the developed CZE technique.

Due to their small size and red-shifted excitation and emission bands, lead sulfide (PbS) near-infrared (NIR) quantum dots (QDs) are potentially promising optical contrast agents for in vivo tumor imaging applications. In this phantom-based study, we correlated PbS NIR QD concentrations to feasible imaging depths. A fluorescence imaging system (FIS) was used to acquire images of QDfilled tumor models, which were embedded in liquid tissue phantoms. For the lowest tested concentration of 200 nM, PbS-QD-filled tumor models could be imaged at a tissue phantom depth of 15 mm. Additionally, the FIS was used to compare the imaging potential of PbS QDs to quantum dots that fluoresce in the visible spectral range. Results indicated that tumor models with photons emitted in the NIR region can be imaged with less distortion than those with photons emitted in the visible spectrum. As the phantom thickness over the tumors was increased from 0 to 1.75 mm, the half-intensity widths of normalized fluorescence images produced by red QDs (acquired peak at ∼645 nm) increased by ∼300%; for NIR QDs (acquired peak at ~880 nm), the widths increased by ∼140%. Due to the decreased scattering effect of the tissue phantoms in the NIR spectral range, the margins of PbS QD images were better defined than those of the corresponding red images.

In engineering and materials science, nanotechnology has made significant advances in the reduction of free radical damage. Despite such advances, there has been little application to biomedical problems. Cross-disciplinary interactions and the application of this technology to biological systems has led to the elucidation of novel nanoparticle antioxidants. Oxidative stress and free radical production are associated with neurodegenerative conditions, including aging, trauma, Alzheimer's and Parkinson's diseases, etc. The antioxidant properties of cerium oxide nanoparticles show promise in the treatment of such diseases. Recent reports suggest that CeO2 and other nanoparticles are potent, and probably regenerative, free radical scavengers in vitro and in vivo. In this work, the effects of CeO2 nanoparticles on an in vitro human AD model are investigated. The validation of new therapeutic agents implies the understanding of their mechanisms of action, therefore the following parameters were investigated under nanoparticles treatment: cell viability, cell death, neurite atrophy, neuronal marker localization and the expression of factors, i.e. PPARβ, BDNF, TrkB, involved in the signal transduction pathways of neuronal survival. The data obtained, demonstrate that CeO2 nanoparticles do not act as mere anti-oxidant agents, but they seems to affect, directly or indirectly, signal transduction pathways involved in neuronal death and neuroprotection, raising the possibility of their use as therapeutic tools for neurodegenerative diseases.

Iron oxide Ferromagnetic Nanoparticles (FNs) such as magnetite (Fe3O4) and maghemite (γ-Fe2O3) are currently employed in biomedical applications owing to their relatively high biocompatibility. Recently, we have introduced a novel application of Fe3O4 FNs in the so-called Magnetically Assisted Haemodialysis (MAHD), a promising concept that can be employed for the treatment of End-Stage Renal Disease. The key characteristic of MAHD is the selective removal of toxins that cannot be removed by current low- and high-flux dialysers that are extendedly used during conventional Haemodialysis (HD). In addition, MAHD could enable the more efficient removal of all toxins when compared to conventional HD so that the duration of dialysis session could be decreased. This is an important benefit that could significantly improve the quality of life of patient. The present work focuses on the in vitro evaluation of the biocompatibility of both bare Fe3O4 FNs and Fe3O4-Bovine Serum Albumin Conjugates (Fe3O4-BSA Cs) with blood cells, namely Red Blood Cells (RBCs), White Blood Cells (WBCs) and Platelets (Plts). Their solubility in whole human blood medium is also carefully evaluated. Both issues are fundamental for the MAHD application since the latter is based on the intravenous injection of FN Cs into the bloodstream of the patient. Atomic force microscopy and optical microscopy were employed for the investigation of both surface characteristics and overall morphology of blood cells, respectively. Samples of donated blood, where bare Fe3O4 FNs or Fe3O4-BSA Cs were added, were maturated under mild incubation for durations up to 120 min. We investigated two representative temperatures, T=20 oC owing to easy experimental realization, and T=37 oC trying to simulate human body conditions. We did not observe noticeable interference of either bare Fe3O4 FNs or Fe3O4-BSA Cs with RBCs, WBCs and Plts. More importantly we did not observe any degradation of the surface of RBCs and WBCs that were maturated under the presence of bare FNs or Cs in concentrations that strongly exceed the ones used for the treatment of iron-deficiency anaemia. Incidents where either bare FNs or Cs were bound onto the surface of RBCs or internalised by WBCs were very rare. Our observations suggest high biocompatibility of both bare Fe3O4 FNs and Fe3O4-BSA Cs with blood cells, while the solubility depends on the BSA content of the Fe3O4-BSA Cs.

Biomedical and biotechnological applications of polymeric nanotubes and nanorods have been of increasing recent research and development interest. Many new methods for the preparation and characterization of these novel nanomaterials have been developed. There are currently intensive research efforts to explore their potential applications in various medical fields, including clinical diagnostic assays, bioseparations, controlled drug delivery, and biosensing. In this paper, different approaches for making polymeric nanotubes and nanorods, and the current status of efforts to develop biomedical and biotechnological applications of these tubular nanostructures will be discussed.

Over the past few years, nanoscience and nanotechnology has emerged as a new exciting field in which studies on micro- and nanoscaffolding for tissue regeneration have become a focus exclusively. Micro- and Nanocomposite materials that can provide the appropriate matrix environment, integrate the desirable biological cues, as well as provide for the controlled, sequential delivery of multiple growth factors for different stages of the tissue repair process would help fulfill the promise of regenerative medicine. Also the development of relevant scaffold design using suitable biomaterials and incorporation of appropriate biomolecules and the selection of cell types plays a vital role in tissue repair. The present paper intends to illustrate the progress that has been achieved in the important field of scaffolding nanoscience includes primary view on biomaterials such as natural-origin and synthetic polymers, and inorganic biomaterials that might be potentially useful as carrier systems for active biomolecules (growth factors/genes) or as cell carriers for tissue regeneration. We also attempted to discuss the distinctive proteins or growth factors and cells which have been selectively studied for bone, cartilage, neural, skin, vascular and dental regeneration, with the aim of stimulating a broader interest in developing tissue regenerative nanoscience and nanotechnology.

The ferroelectric thin film was widely investigated in detail in recent years. The ferroelectric properties of the thin films are obviously dependent on the microstructure and orientation of the film, which were influenced mainly by some processing parameters for preparing the films, including precursor solution chemistry, nature of substrate, film thickness, and condition of heat treatment etc. In this paper, these processing dependences for preparing of the films were reviewed.

CrSb films with various thickness were deposited on KCl (100) substrates by magnetron sputtering. Strong ferromagnetism was observed in the CrSb films, which can be attributed to the ferromagnetic zinc blende-CrSb (ZB-CrSb) phase. The ZB-CrSb film with critical thickness about 5 nm is sufficiently thicker to be investigated the half-metallic nature of ZB-CrSb and to be practically applied in spintronics devices.

A simple and efficient dynamic model of oscillatory surface electrons under coulombic attraction is developed to illuminate the mechanism of split and shift fashion of surface plasmon resonance (SPR) in non-spherical symmetric gold nanoparticles. In this model, the oscillatory electron cloud has been simplified into a charged mass point. So the geometrical factors of the particle are introduced to the dynamic equation. And then the analytical expressions for SPR frequency dependence on aspect ratio of both gold nanorod and nanoprism are obtained. These shift fashions of SPR are in agreement with the experimental data and quasi-static simulations results. This simple and intuitive picture can also be used to understand the plasmon resonance behavior of asymmetric metallic nanostructures of greater geometrical complexity and to guide the design of metallic nanostructures and predict their SPR properties.

Proper selection of oils, surfactants and cosurfactants along with their optimum concentration is crucial to obtain stable, mild and clinically acceptable nanoemulsions. The focus of the present study was, therefore, to provide an efficient screening approach for the excipients selection for the optimum nanoemulsion formulation development. The oils studied included Lauroglycol 90, Capryol 90, olive oil, jojoba oil, oleic acid and Labrafil M1944. The drug solubility in the oil was taken as the criterion for oil selection. Labrasol, Cremophor EL, Tween 60 and Tween 80 were the surfactants evaluated for determining the solubilizing capacity for the oil. Among them Cremophor EL was found to be an efficient emulsifier for the oil phase. The effect of different cosurfactants such as ethanol, isopropyl alcohol, butanol, propylene glycol, PEG 400 and Carbitol on the phase behaviour of the pseudoternary system Capryol 90/Cremophor EL/cosurfactant/water was investigated. Nanoemulsion region obtained was used as an assessment criterion to evaluate the cosurfactants. The effect of Cremophor EL/carbitol mass ratio on the nanoemulsion formation was also studied by varying the ratio from 3:1 to 1:3 for the further optimization of the system. The highest nanoemulsion region was obtained at Cremophor EL: Carbitol in the mass ratio of 1:1. Formulations were selected from the phase diagram at this mass ratio at a fixed concentration of surfactant mixture (i.e. 45% wt/wt) with increasing concentration of oil (5, 10, 15, 20% wt/wt) and subjected to thermodynamic stability tests. The optimized formulations were characterized for particle size, viscosity, pH and refractive index measurements. The droplet size of all the selected formulations was found to be less than 100 nm. The formulations were thermodynamically stable and can be effectively used for the drug delivery applications.

Here we show the fundamental processes on nanoscale that may influence the design and extension of nanotechnology chips, sensors, and systems. The focus is on the breakdown of Ohm's Law in nanoscale devices extensively being used to assess the performance of a “system-on-a-chip,” may it be for bio, chemical, physical or engineering applications. Novel insights on theories of three sources of transformation of Ohm's Law are enumerated: quantum confinement in low-dimensional nanostructures, ballistic transport when conducting channel length is smaller than the mean free path, and high-field initiated carrier asymmetric distribution. The saturation velocity arising from the high-field initiated mobility degradation is shown to be the intrinsic velocity that depends on the nanostructure dimensionality, its carrier concentration, and the ambient temperature, in direct contrast to single number that is quoted in the literature. The ballistic intrinsic velocity is the ultimate saturation velocity that can be lowered by the onset of a quantum emission that may be an optical phonon or a quantum emitted from an excited quantized level to the ground state. The results presented will have profound impact in interpretation of data on a variety of nanotechnology devices and systems that may exist with varying low dimensionality, classical (analogue) in one or more of the three Cartesian directions, while other directions go quantum (digitized energies).

This study describes synthesis of FeCo nanoparticles by using a method which couples electrodeposition of metals with the employment of high power ultrasound. A 20 kH titanium alloy horn ultrasound generator, a “sonoelectrode”, generated short current pulses which were triggered and followed by ultrasonic pulses. The primary role of ultrasound is to induce cavitation phenomenon in the electrolyte and the ablation of the metallic nuclei from the cathodic surface. A rest time restores the initial conditions in the electrolyte close to the sonoelectrode. The final product is a suspension of nanoparticles with high purity and surface/volume ratio, which can be controlled by varying process parameters like time management and current density. The effects of bath's components on chemical, morphological and structural features of produced nanoparticles were investigated and evaluated. Nanopowders were characterized by TEM, XRF, XRD and X-EDS; results showed that (i) process efficiency was mainly affected by combined effects of organic additive and supporting electrolyte while (ii) chemical composition of produced nanoparticles was influenced by metal salt anions; (iii) nanoparticles with prevalent bcc crystalline structure were formed, and with (iv) an average grain size of 15÷25 nm; finally (v) morphological and structural features of nanoparticles were not influenced by bath's composition.

This study concentrates to investigate the relationship between laser fabrication parameters and reflectivity of fiber gratings. The fiber Bragg grating system, comprising Excimer Laser, Mask Aligner, Optical Spectrum Analyzer and Tunable Laser Source was utilized to fabricate the fiber gratings. A series of experiments were carried out for the fabrication of fiber gratings and to observe the effect of laser fabrication parameters on the reflectivity of fiber gratings. These samples were fabricated with different reflectivity's ranging from 27 to 93% at constant pulse rate i.e. 1Hz. The amount of reflectivity is the extent to which the index modulation in the fiber core changes. The higher the reflectivity of a fiber grating, the more microstructural changes occur within the lattice of the photosensitive core and the more the residual axial stress builds up within the cross section of the fiber. Here, we discussed only two laser fabrications parameters i.e. effect of pulse energy on reflectivity of fiber grating and effect of exposure time on reflectivity of fiber grating/Bragg wavelength. Based on the results of this study, it is inferred that reflectivity is exponentially increased, as the pulse energy increase at constant UV exposure time and attained saturation at pulse energy i.e. 165mJ. The low pulse energy produces a low reflectivity fiber Bragg grating even after a longer UV exposure time. It is also concluded that both reflectivity and Bragg wavelength are increased rapidly in the beginning with the increase of UV exposure time and then become saturated at UV exposure time i.e. 110min, even though pulse energy is constant. It means that the induced index of modulation was increased with the increasing of UV exposure time.

New cholesterol-saccharide conjugate gelator N-cholesteryl succinyl glucosamine (1) was synthesized and its gelation ability was evaluated in organic solvents in this study. It could gelate 1-butanol, iso-butanol, 4-heptanol, cyclohexanol and 1-octanol under the concentration of 5.0 mg/mL. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), circular dichroism (CD) and small-angle X-ray diffraction (SAXRD) were used to analyze the aggregation mode of 1 in the organogel phase. 1 exhibited a fibrous structure composed of thin micellar fibrils with ca.9∼10 nm diameters and these fibrils were packed into a disordered hexagonal mesophase structure with an interlayer distance of 8.01 nm. CD spectra showed that 1 adopted the helical arrangement in the aggregation. A hierarchical self-assembly model was proposed to explain the transition from molecular to primary and secondary structure. Moreover, sol-gel polymerization of tetraethoxysilane (TEOS) was carried out using 1 in the gel phase. The silica obtained from the 1 + 1-butanol gel showed the tubular structure with ca. 100 nm outer diameter.

A modified solid state reduction (SSR) method, by which the platinum salt is reduced into platinum nanoparticles by sodium formate in solid state and under low temperature (below 180 °C) conditions, is introduced here. The high performance catalysts based on carbon nanotubes (CNTs) supported platinum and platinum promoted by Mo (VI) and Si (IV) was prepared successfully by this method. The catalysts, with small particle size and uniform distribution were active toward the electrooxidation reaction of methanol. Among a few catalysts promoted by silicon, molybdenum and tungsten elements, catalysts co-promoted by silicon and molybdenum elements show best performance. The particle size of promoted Pt/CNTs, calculated from XRD patterns, is small as 3.0±1.5 nm, and the results of transmission electron microscopy (TEM) revealed that the distribution of particle size is uniform. In comparison with the liquid-state synthesis, the advantages of SSR method include environmental benefits due to less water usage and significantly reduced pollutants generation, as well as suitability for large scale preparation.