Most Cited Articles:

Abstracts


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Magnetic Nanoparticles for Cancer Therapy
G.F. Goya, V. Grazú, and M.R. Ibarra

Today, technologies based on magnetic nanoparticles (MNPs) are routinely applied to biological systems with diagnostic or therapeutic purposes. The paradigmatic example is the magnetic resonance imaging (MRI), a technique that uses the magnetic moments of MNPs as a disturbance of the proton resonance to obtain images. Similarly, magnetic fluid hyperthermia (MFH) uses MNPs as heat generators to induce localized cell death. The physical basis of these techniques relies on the interaction with external magnetic fields, and therefore the magnetic moment of the particles has to be maximized for these applications. Targeted drug-delivery based on ‘smart’ nanoparticles is the next step towards more efficient oncologic therapies, by delivering a minimal dose of drug only to the vicinity of the target. Current improvements in this fields relay on a) particle functionalization with specific ligands for targeting cell membrane receptors and b) loading MNPs onto cells (e.g., dendritic cells, T-cells, macrophages) having an active role in tumor grow. Here we review the current state of research on applications of magnetic carriers for cancer therapy, discussing the advances and drawbacks of both passive and targeted delivery of MNPs. The most promising strategies for targeted delivery of MNPs are analyzed, evaluating the expected impact on clinical MRI and MFH protocols.


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Mycosynthesis of Silver Nanoparticles Using the Fungus Fusarium acuminatum and its Activity Against Some Human Pathogenic Bacteria
Avinash Ingle, Aniket Gade, Sebastien Pierrat, Carsten Sönnichsen and Mahendra Rai

We report extracellular mycosynthesis of silver nanoparticles by Fusarium acuminatum Ell. and Ev. (USM-3793) isolated from infected ginger (Zingiber officinale). An aqueous silver nitrate solution was reduced to metallic silver when exposed to F. acuminatum cell extract leading to the appearance of a brown color within 15-20 minutes. The color is due to the formation of silver nanoparticles and the excitation of surface plasmons. The optical spectrum showed the plasmon resonance at 420 nm and analysis by transmission electron microscopy confirmed the presence of silver nanoparticles. The nanoparticles produced were spherical with a broad size distribution in the range of 5-40 nm with average diameter of 13 nm. The reduction of the silver ions occurs probably by a nitrate-dependent reductase enzyme, which we found to be present in the extra-cellular medium. We tested the silver particles for their broad-band antibacterial activity on different human pathogens. We observed efficient antibacterial activity against multidrug resistant and highly pathogenic bacteria, including multidrug resistant Staphylococcus aureus, Salmonella typhi, Staphylococcus epidermidis, and Escherichia coli. The synthesis of silver nanoparticles by the fungus F. acuminatum may therefore serve as a simple, cheap, eco-friendly, reliable and safe method to produce an antimicrobial material.


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Size Effect on the Phase Stability of Nanostructures
Q. Jiang and C. C. Yang

An extension of the classical thermodynamics to nanometer scale has been conducted to elucidate information regarding size dependence of phase transition functions and binary phase diagrams. The theoretical basis of the extension is Lindemann' s criterion for solid melting, Mott' s expression for vibrational melting entropy, and Shi' s model for size dependent melting temperature. These models are combined into a unified one without adjustable parameters for melting temperatures of nanocrystals. It is shown that the melting temperature of nanocrystals may drop or rise depending on interface conditions and dimensions. The model has been applied to size dependences of melting enthalpy and atomic cohesive energy, critical temperatures for glass transition, ferromagnetic transition, ferroelectric transition, superconductor transition and ferromagnetic-antiferromagnetic transition. Moreover, the above modeling has been utilized to determine the size-dependent continuous binary solution phase diagrams, bi-layer transition diagrams of metallic multilayers, and solid transition phase diagrams after modeling the transition entropy and atomic interaction energy functions of nanocrystals. Moreover, the model has been used to predict size dependence of diffusion activation energy and diffusion coefficient. These thermodynamic approachs have extended the capability of the classical thermodynamics to the thermodynamic phenomena in the nanometer regime.


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Critical Issues in Nanofluids Preparation, Characterization and Thermal Conductivity
Daxiong Wu, Haitao Zhu, Liqiu Wang and Lumei Liu

Nanofluids are fluids containing suspended solid nanoparticles. It is expected that the nanofluids will be the next generation of heat transfer fluids due to their unique thermal properties. At present, the study on nanofluids is still in its infancy. Some issues became the barriers to the development and application of the emerging nanofluid technology. In this paper, the critical issues in nanofluids preparation, characterization and thermal conductivity are present based on a review of available work in the literature.


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An Algorithm for Constructing Wiener Matrix of TUC₄C₈(R) Nanotubes
Shahram Yousefi and Ali Reza Ashrafi

The Wiener index of a graph G is defined as , where V(G) is the set of all vertices of G and for x,y ε V(G), d(x,y) denotes the length of a minimal path between x and y. In this paper an algorithm for computing the Wiener matrix of a TUC₄C₈ (R) nanotube T = T[p,q] is given. Using this matrix, an exact expression is given, for the Wiener index of T.


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Optically Active Gold Nanoclusters
Hiroshi Yao

In recent years, increasing attention has been paid for the construction of optically active nanomaterials. In particular, monolayer-protected gold nanoclusters are attractive for such systems. To date, optically active gold nanoclusters have been prepared by using chiral adsorbates or surface modifiers. In general, two major explanations have been proposed to interpret the optical activity: The first assumes a chiral core as a result of lattice distortion caused by the adsorbate. The other involves an achiral core with chirality induced by a chiral adsorption pattern or by dissymmetric fields (vicinal effect) from the chiral adsorbates. This mini-review gives an outline of the syntheses and chiroptical properties of the chiral monolayer-protected gold nanoclusters on the basis of our recent work as well as the other groups’ studies.


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Synthesis of Morphology-Controlled Titania Nanocrystals and Application for Dye-Sensitized Solar Cells
Motonari Adachi, Jinting Jiu and Seiji Isoda

Development of renewable energy resources in the near future is an urgent issue. One attractive strategy is the development of dye-sensitized solar cells (DSSCs); they are extremely promising, because they are made of low-cost materials and do not need elaborate apparatus to manufacture. Titania is the most promising material for the electrode of DSSCs, and then morphological control and carrier transport optimization are the key properties needed in titanium oxide materials for DSSCs. We review the formation procedures and characteristics of titanium oxide nanocrystalline products, which exhibit various morphological shapes in nanometer scale, i. e., nanotubes, nanorods, nanowires and nanosheets, and their arrays. We also present new findings in our laboratory on the formation of titania nanorods and network structures of single-crystal-like titania nanowires as well as their application for DSSCs. In order to evaluate the electrical properties of DSSCs with electrodes composed of various nanoscale titania materials, measurement procedures for electron transport processes in DSSCs are also reviewed, together with our results in electrochemical impedance spectroscopy to determine various parameters concerning about electron transport.


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Nanoparticle Preparation Using the Single Microemulsions Scheme
Maen M. Husein and Nashaat N. Nassar

Nanoparticles serve the need for advanced materials with specific chemical, physical, and electronic properties. These properties can be attained by manipulating the particle size. Consequently, size control has been recognized as a key factor for selecting a nanoparticle preparation technique. (w/o) Microemulsions, or reverse micelles, have been successfully used to prepare wide variety of nanoparticles with controlled sizes. Studies showed that adjusting microemulsion and/or operation variables provides a key to controlling nanoparticle size and polydispersity. The effect of a given variable, however, relies heavily on the reactant addition scheme. The mixing of two microemulsions scheme has been widely used in the literature, and the effect of microemulsion and operation variables on intermicellar nucleation and growth was detailed. The single microemulsions reactant addition scheme, on the other hand, enables intramicellar nucleation and growth, and therefore, may lead to a different response. Moreover, studies on nanoparticle preparation using the single microemulsions scheme involved more of reactive surfactants and introduced the concept nanoparticle uptake, which pertains to the maximum colloidal concentration of nanoparticles that can be stabilized in a microemulsion system. This review looks into the mechanisms controlling nanoparticle formation and compares literature trends reported for the effect of microemulsion and operation variables on the nanoparticle size and polydispersity for the single microemulsions reactant addition scheme. Moreover, it sheds some light on nanoparticle uptake and its significance.


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Magnetic Driven Alginate Nanoparticles for Targeted Drug Delivery
Gianni Ciofani, Vittoria Raffa, Yosuke Obata, Arianna Menciassi, Paolo Dario and Shinji Takeoka

The aim of this paper is to develop highly magnetized, biodegradable and biocompatible, polymeric nanoparticles for drug delivery in cell therapy. Alginate magnetic nanoparticles are realized by an emulsion/reticulation technique, after the dispersion of magnetite in an alginate solution. Such nanoparticles are characterized in terms of external morphology (FIB imaging), microstructure (TEM imaging), size distribution, zeta potential, magnetic properties (SQUID analysis) and drug release behaviour. Magnetization curves show the typical trend of superparamagnetic materials. Important parameters, such as magnetic permeability and magnetic momentum, are derived by employing Langevin theory. Experimental results reveal that a bi-exponential model fully describes the drug release. Finally, in vitro experiments on NIH/3T3 cells are carried out and demonstrate that our magnetic alginate nanoparticles can effectively drive the drug delivery towards an external magnetic field source.


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Nanoprobes for Medical Diagnosis: Current Status of Nanotechnology in Molecular Imaging
Jiang He, Henry F.VanBrocklin, Benjamin L. Franc, Youngho Seo and Ella Fung Jones

Molecular imaging has emerged as a powerful tool to visualize molecular events of an underlying disease, sometimes prior to its downstream manifestation. This presents a whole new paradigm disease diagnosis and monitor treatment. Nanotechnology is another rapidly growing field that offers new materials with unique physical and chemical properties that may find broad application in biomedical research. The merging of nanotechnology with molecular imaging provides a versatile platform for novel design of nano-probes that will have tremendous potential to enhance the sensitivity, specificity, and signaling capabilities of various biomarkers in human diseases. In this review, the general construct and key characteristics of nanoprobes in the context of molecular imaging are highlighted. The various designs of nanoprobes based on their targeting mechanisms, strategies for contrast enhancement, multi-modality imaging and imaging/therapy hybrid systems are outlined along with a discussion on the current status of imaging equipment design. Additionally, the potential challenges for adapting nanoprobes for molecular imaging including toxicity, biodistribution/pharmacokinetics, and synthetic feasibility are addressed.


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Promises of Nanotechnology for Drug Delivery to Brain in Neurodegenerative Diseases
Sara Baratchi, Rupinder Kaur Kanwar, Khashayar Khoshmanesh, Punj Vasu, Chauhan Ashok, Matta Hittu, Andrew Parratt, Subramanian Krishnakumar, Xueying Sun, Sanjeeb K Sahoo and Jagat Rakesh Kanwar

Brain is a delicate organ, isolated from general circulation and characterized by the presence of relatively impermeable endothelial cells with tight junctions, enzymatic activity and the presence of active efflux transporter mechanisms. These formidable obstacles often block drug delivery to the brain across the blood-brain barrier (BBB). Although several promising molecules have the potential in the in vitro settings but lack of in vivo response is probably because the molecule cannot reach the brain in a sufficient concentration. Drug delivery across the BBB is a major limitation in the treatment of central nervous system (CNS) disorders and CNS infections. This review deals with the role of nanobiotechnology in CNS drug delivery, in which three categories of carbon nanotubes, nanowires and nanoparticles (NPs) are explained. The small size of the NPs makes them an ideal choice to penetrate the BBB. Several mechanisms are involved in this process and various strategies are used. There are some concerns about the safety of NP entry in the brain that need to be resolved before human use. Although there is no approved nanotechnology-based CNS drug available the future for such neuro-nanobiotechnology based delivery system developments is promising.


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Novel PEGylated PPI dendritic nanostructures for sustained delivery of anti-inflammatory agent
Virendra Gajbhiye, P. Vijayaraj Kumar, Ajay Sharma and N.K. Jain

The present study was aimed at developing and exploring the use of long circulating biocompatible PEGylated PPI 5.0G dendrimers for delivery of an anti-inflammatory drug, Aceclofenac. The PPI 5.0G dendrimers were synthesized and PEGylated using N-hydroxysuccinimide-activated dicarboxylic acid PEG 2000 (COOH-PEG-COOH). PEGylation was confirmed by IR, NMR and MASS spectra. The Aceclofenac was loaded in PEGylated dendritic system and various parameters like, hemolytic toxicity, drug entrapment, pH dependent in vitro drug release and in vivo blood-level were determined. The PEGylated dendritic system has shown increased drug-loading capacity and reduced hemolytic toxicity as compared to non-PEGylated system. The in vitro release, in vivo blood level and tissue distribution studies in albino rats demonstrated suitability of PEGylated PPI 5.0G dendrimer for prolonged delivery of Aceclofenac. The carrageenan induced paw edema in albino rats revealed 69.41±0.7% and 77.08±0.4% inhibition of paw edema at 3^rd and 7^th hr, respectively that were maintained upto 52.17±0.9% until 48^th hr from drug-PEGylated dendrimer complex. However, for plain drug the percentage of inhibition were found to be 66. 35±0.4% at 3^rd hr, which was reduced to 28.44±0.3 % by 7^th hr. PEGylation is considered to be suitable for amendment of PPI dendrimers for reducing of drug leakage and hemolytic toxicity, improving drug-loading capacity and stabilizes the system in body. The results suggested that, such PEGylated dendrimeric system is suitable for sustained delivery of Aceclofenac.


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Confined photoreaction in nano-engineered multilayer microshells
Xia Tao and Jingmei Su

Nano-engineered multilayer microshells (microcapsules) as nano/microreactors are expected to expand the capabilities of confined photoreaction occurring in shell walls and in shell interiors and to explore new functionalities of application. The basis for optical reactions in multilayer microshells is their tailored wall components and particular properties originated from the permeability and stability of shell walls in response to external stimuli. This review aims at describing recent developments on the photochemical behaviors of photofunctionalized shell walls, mainly focusing on photocontrollable wall permeability by visible illumination. Apart from these, the photocatalytic reaction in spatially confined microshells is also reviewed, with an emphasis on recent advances in the visible light-assisted degradation of defined dye pollutants in the homogeneous or heterogeneous photo-Fenton system. The photoreaction mechanism occurring in the shells is also discussed. Finally, we have addressed some of the perspectives and challenges for the potential future development of microshells as photoreactors and applications based on these systems.


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Solid lipid nanoparticles (SLNs) as a rising tool in drug delivery science: One step up in nanotechnology
Shivani Rai, Rishi Paliwal, Prem N. Gupta, Kapil Khatri, Amit K. Goyal, Bhuvaneshwar Vaidya and S.P. Vyas

Colloid science has now been reframed in advance form as nanotechnology. Novel nanoparticulate carrier systems could make an important impact on clinical practice, not only in the field of targeted drug delivery but also for the delivery of diagnostic agents, gene therapy and vaccine delivery as well. Polymer based nanoparticles are full of numerous advantages in delivery science but at the same time they suffer from toxicity considerations and problems in industrial scale up of the formulations. Lipid based carrier systems i.e. emulsions, liposomes etc. have been tried to solve such problems related to the delivery technology. Currently lipid-based nanoparticles gained much interest as they combine both the technology of lipid sciences and nanosciences, and hence may be better alternative carriers. Many aspects related to the development of solid lipid nanoparticles (SLNs) like production technology, effect of process parameters, selection of ingredients and route of delivery are important for the industrial applications of nanoscience. In the present review a detail discussion of methods of production of solid lipid nanoparticles, influence of ingredients of composition on product quality, therapeutic moiety effect, characterization parameters and effects of sterilization have been focused. Role of solid lipid nanoparticles for controlled and targeted drug delivery, utility as a novel transfection agent and their potential as adjuvant for vaccine delivery are summed up in addition. Clinical therapeutics of SLNs in terms of advantages and limitations of various routes of delivery of SLNs has also been explored for the further advancement of practical applications of solid lipid nanoparticles.


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Formulation of nanosuspensions of albendazole for oral administration
Mittapalli Pavan Kumar, Yamasani Madhusudan Rao and Shashank Apte

Poorly water-soluble compounds like albendazole with dissolution limited bioavailability need novel approaches for enhancement of bioavailability and therapeutic efficacy. The use of nanosuspension approach offers an opportunity to address the issues associated with BCS class II molecules. High pressure homogenization technique can be employed to produce drug nanocrystals with a number of advantages in comparison to other techniques such as nanoprecipitation, sonication, milling and high speed homogenization. The present study shows the feasibility of formulating a stable formulation of albendazole with minimum particle size through high pressure homogenization technique. To point out the influence and importance of identifying right stabilizer (s) and process parameters the studies such as influence of number of homogenizing cycles on particle size, sequence of mixing of ingredients on the physical characteristics of nanosuspensions and desorption studies was done. Selected nanosuspension formulations containing different stabilizers were lyophilized to convert into solid dosage forms. These studies had indicated that the aqueous dispersion of drug nanoparticles could be converted into stable solid dosage forms with out affecting the size on reconstitution.


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Boron Nitride Nanotubes: A Novel Vector for Targeted Magnetic Drug Delivery
Gianni Ciofani, Vittoria Raffa, Jun Yu, Ying Chen, Yosuke Obata, Shinji Takeoka, Arianna Menciassi and Alfred Cuschieri

Whereas several biomedical applications of carbon nanotubes have been proposed, the use of boron nitride nanotubes (BNNTs) in this field has been largely unexplored despite their unique and potentially useful properties. Our group has recently initiated an experimental program aimed at the exploration of the interactions between BNNTs and living cells. In the present paper, we report on the magnetic properties of BNNTs containing Fe catalysts which confirm the feasibility for their use as nanovectors for targeted drug delivery. The magnetisation curves of BNNTs characterised by the present study are typical of superparamagnetic materials with important parameters, including magnetic permeability and magnetic momentum, derived by employing Langevin theory. In-vitro tests have demonstrated the feasibility for influencing the uptake of BNNTs by living cells by exposure to an external magnetic source. A finite element method analysis devised to predict this effect produced predictive data with close agreement with the experimental observations.