Naked Particles Research Articles

Surface Passivation of Carbon Nanoparticles with Branched Macromolecules Influences Near Infrared Bioimaging

A superior and commercially exploitable 'green synthesis' of optically active carbon nanoparticle (OCN) is revealed in this work. The naked carbon particles (<20 nm) were derived from commercial food grade honey. The fluorescence properties of these particles were significantly enhanced by utilizing hyberbranched polymer for surface passivation. A dramatic increase in near infrared emission was achieved compared to a linear polymer (PEG) coated carbon nanoparticles. Interestingly, as passivating agent becomes more extensively branched (pseudo generation 2 to 4), the average radiant efficiency amplifies considerably as a direct result of the increasing surface area available for light passivation. The particles showed negligible loss of cell viability in presence of endothelial cells in vitro. Preliminary in vivo experiment showed high contrast enhancement in auxiliary lymphnode in a mouse model. The exceptionally rapid lymphatic transport of these particles suggests that such an approach may offer greater convenience and reduced procedural expense, as well as improved surgical advantage as the patient is positioned on the table for easier resection.

Host factors involved in hepatitis B virus maturation, assembly, and egress

Hepatitis B virus (HBV) is a major cause of liver disease. Due to the tiny size of its genome, HBV depends on the critical interplay between viral and host factors for the generation of new viral particles from infected cells. Recent work has illuminated a multiplicity of spatially and temporally coordinated virus-host interactions that accompany HBV particle genesis. These interactions include the requirement of cellular chaperones for the maturation of the three viral envelope proteins, the cellular factors involved in dynamic modification, maturation, and intracellular trafficking of the nucleocapsids, and the host components of the multivesicular body (MVB) pathway enabling virion budding at intracellular compartments. Beside infectious virions, HBV produces at least two other types of particles, subviral empty envelope particles and subviral naked capsid particles, likely as a result of the engagement of different host factors by the viral structural proteins. Accordingly, HBV exploits distinct cellular pathways to release its particle types. Here, I review recent progress in these areas of the cell biology of HBV genesis.

Soot particles at an elevated site in eastern China during the passage of a strong cyclone

Atmospheric particles larger than 0.2μm were collected at the top of Mt. Tai (36.25°N, 117.10°E, 1534m a.s.l.) in eastern China in May 2008 during the passage of a strong cyclone. The particles were analyzed with electron microscopes and characterized by morphology, equivalent diameter and elemental composition. Soot particles with coating (coated soot particles) and those without apparent coating (naked soot particles) were predominant in the diameter range smaller than 0.6μm in all samples. The number–size distribution of the relative abundance of naked soot particles in the prefrontal air was similar to that in the postfrontal air and their size modes were around 0.2–0.3μm. However, the distribution of inclusions of coated soot particles showed a mode in the range of 0.1–0.3μm. The coating degree of coated soot particles, which was defined by the ratio of the diameter of inclusion to the diameter of particle body, showed a mode around 0.5 with the range of 0.3–0.6. These results indicate that the status of soot particles in the prefrontal and postfrontal air was similar although air pollution levels were dramatically different. In addition, the relative abundance of accumulation mode particles increased with the decrease of soot particles after the front passage.

MicroRNA therapeutics: principles, expectations, and challenges

MicroRNAs(miRNAs) are a class of highly abundant non-coding RNA molecules that are involved in several biological processes.Many miRNAs are often deregulated in several diseases including cancer.There is substantial interest in exploiting miRNAs for therapeutic applications.In this editorial,we briefly review current advances in the use of miRNAs or antisense oligonucleotides(antagomirs) for such therapies.One of the key issues related to therapy using miRNAs is degradation of naked particles in vivo.To overcome this limitation,delivery systems for miRNA-based therapeutic agents have been developed,which hold tremendous potential for improving therapeutic outcome of cancer patients.

TRANSFORMATION OF THE BANANA CULTIVAR 'NANJANGUD RASBALE' (SYN. 'RASTHALI', AAB, SILK SUBGROUP) WITH THE AMP GENE AND SCREENING FOR FUSARIUM RESISTANCE WITH A BIOASSAY

The banana cultivar ‘Nanjangud Rasbale’ (syn. ‘Rasthali’, AAB, Silk subgroup) is highly susceptible to Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc) race 1. This cultivar is facing extinction in its natural habitat. Transgenic plants of the cultivar were developed by transformation with the antimicrobial peptide (AMP) gene cloned from onion seeds and with constructs developed in pCAMBIA 2301. Apical meristems from in-vitro micropropagated plantlets were microwounded with naked gold particles, followed by co-cultivation with Agrobacterium containing the AMP gene. Rigorous selection in kanamycin 200 mg-1 took place for 8 months. Around 10% of the transformants that regenerated on the selection medium were further established. Integration of the genes npt II and AMP was confirmed by PCR, RT-PCR and Dot-blot technique. Plants regenerated from the suckers of these plants also tested positive for the presence of the gene by the above procedures. Regeneration and transformation percentage was 10% and 3%, respectively. The non-destructive, rapid bioassay developed by Companioni et al. (2003) was validated and used to screen for Fusarium resistance. Lesion development on leaves from sterile culture filtrates obtained from different incubation periods were studied, and an incubation period of 8 days was found to give maximum lesion development after inoculation. Leaves tested from 10-months old transformed plants had a lesion area of 1.61 mm2 ± 0.48 compared to controls with a lesion area of 6.24 mm2 ± 0.92. Transformants are being further multiplied for large-scale root challenging with Foc and further selection.

両面塗布原子核乾板を用いて発見した「裸のチャーム粒子」研究の歴史

両面塗布原子核乾板を用いて発見した「裸のチャーム粒子」研究の歴史

Au@ZIFs: Stabilization and Encapsulation of Cavity-Size Matching Gold Clusters inside Functionalized Zeolite Imidazolate Frameworks, ZIFs

The selective formation and stabilization of very small, naked metal particles inside the cavities of metal−organic frameworks (MOFs) and the simultaneous realization of an even distribution of the particles throughout the crystalline MOF host matrix over a wide range of metal loading are challenging goals. MOFs reveal high specific surface areas, tunable pore sizes, and organic linkers, which are able to interact with guests. The chemically very robust zeolite imidazolate frameworks (ZIFs) are a subclass of MOFs. We chose the microporous sodalite-like ZIF-8 (Zn(MeIM)2; IM = imidazolate) and ZIF-90 (Zn(ICA)2; ICA = imidazolate-2-carboxyaldehyde) as host matrices to influence the dispersion of imbedded gold nanoparticles (Au NPs). The metal loading was achieved via gas phase infiltration of [Au(CO)Cl] followed by a thermal hydrogenation step to form the Au NPs. Low-dose high-resolution transmission electron microscopy ((HR)TEM) and electron tomography reveal a homogeneous distribution of Au NPs throughout ...

Origin of the size dependence of Au nanoparticles toward molecular oxygen dissociation

Density functional theory calculations using a plane-wave basis set and a generalized gradient approach exchange-correlation potential have been carried out to study the dissociation of molecular oxygen by Au nanoparticles and its dependence with particle size. The analysis of the energy related data shows that the reactivity is dominated by the energy barrier height from adsorbed O2 to the dissociated state and by the stability of molecular oxygen on the nanoparticle. The energy barrier is found to be only slightly dependent on the particles size where large variations are found for the adsorption energy of the O2 molecule on the different nanoparticles. A careful analysis of the electronic structure shows that the driving force for O2 adsorption by these nanoparticles is the existence of a clear gap between occupied and unoccupied states for the naked particle. This allows accommodating bonding states with O2 below the Fermi level resulting in a strong interaction. On the contrary, the Au nanoparticles with a more metallic electronic structure have necessarily to accommodate bonding and antibonding states below the Fermi level with a concomitant weaker interaction with O2.

Prion-like transmission of protein aggregates in neurodegenerative diseases

Neurodegenerative diseases are commonly associated with the accumulation of intracellular or extracellular protein aggregates. Recent studies suggest that these aggregates are capable of crossing cellular membranes and can directly contribute to the propagation of neurodegenerative disease pathogenesis. We propose that, once initiated, neuropathological changes might spread in a 'prion-like' manner and that disease progression is associated with the intercellular transfer of pathogenic proteins. The transfer of naked infectious particles between cells could therefore be a target for new disease-modifying therapies.

Study on gene delivery via the bile duct to rat liver using naked DNA particles

To evaluate the efficacy of gene delivery to the right lateral lobe of the rat liver via a branch of the bile duct using naked DNA. We evaluated regional gene delivery to the right lateral lobe of the rat liver via a branch of the bile duct, using naked DNA, including pGL3, pCMV beta and Cy3 labeled CMV beta. Gene expression was observed in right lateral lobe of both the damaged and the normal rats liver. The gene delivery efficiency was similar in two groups (P > 0.05). Gene expression was found in the right lateral lobe of damaged and normal livers. Fluorescence was observed in the region of the portal triads, and occasionally, in the lobule. Retrograde infusion of naked DNA via the bile duct is an effective way to deliver genes to in both damaged and normal rat liver.

Immunogenicity testing in human papillomavirus virus-like-particle vaccine trials.

The recently introduced human papillomavirus (HPV) prophylactic vaccines are the first widely approved vaccines specifically designed to prevent a sexually transmitted infection and are only the second (after the hepatitis B virus vaccine) designed to prevent human cancer, in this case cervical cancer and several other anogenital and head and neck cancers. The antigens in the HPV vaccines are naked icosohedral virus-like particles (VLPs) composed of the major HPV virion protein L1. These subunit vaccines were independently developed and tested by 2 companies, GlaxoSmithKline (GSK) and Merck [1]. The GSK vaccine, Cervarix, is bivalent—it contains the VLPs of HPV-16 and -18, the types that cause ~70% of cervical cancers worldwide—and is produced in insect cells. Cervarix also contains the proprietary adjuvant AS04, which is composed of monophyosphoryl lipid A and an aluminum salt. The Merck vaccine, Gardasil, is tetravalent—it contains the HPV-16 and -18 VLPs and the VLPs of HPV-6 and -11, which cause 80%–90% of genital warts—and is produced in yeast. Gardasil is adjuvanted with a simple aluminum salt. The vaccines are delivered by intramuscular injection in 3 doses over 6 months. Both have been remarkably effective in phase 3 trials conducted in young women, providing nearly complete protection against persistent genital tract infection and premalignant neoplastic disease end points caused by the HPV types targeted by the respective vaccines [2]. Both vaccines have been licensed in >50 countries, starting with Merck’s in 2006 and GSK’s in 2007, and millions of doses have been sold. However, despite the rapid and successful introduction of these 2 vaccines, they can reasonably be viewed as introductory products that will likely be followed by second-generation vaccines that will target more types and/or be less expensive to produce and deliver. This article will focus on one aspect of HPV VLP vaccines, the assessment of immunogenicity.

ELECTRONIC STRUCTURES OF NAKED AND MOLECULAR ENCAPSULATED Au NANOPARTICLES

Naked and molecular encapsulated Au nanoparticles with a diameter of 3 nm were prepared on top of Si in order to elucidate the effect of the molecules on the electronic structures of Au nanoparticles. We have found that the naked particles showed the finite densities of states at the Fermi level while the molecular encapsulated particles exhibited the edge being away from the Fermi level, indicating that the naked and molecular encapsulated Au particles should show metallic and nonmetallic features, respectively. Furthermore, because the naked Au nanoparticles became nonmetallic upon the particles adsorbing the molecules, the highly occupied states of the molecules might be hybridized with the valence states of Au particles, resulting in nonmetallic properties of the molecular encapsulated nanoparticles in the present system.

The Behavior of Mold Spores Suspended in Indoor Air and an Alternative Method for Analyzing Filters Obtained from Sampling by Filtration

In indoor environments, air sampling normally involves drawing a sample from an air stream or room using equipment based on either the impaction or filtration methods. An international standard regarding sampling methods for the detection and enumeration of molds is about to be proposed. This ISO (ISO/TC 146/Sc 6/WG 10N 27), entitled ″Detection and enumeration of molds - sampling by filtration″ suggests that the process of suspension is necessary in order to spread mold spores filtered on the surface of a filter onto a growth media. However, airborne microbes suspended in air are rarely in the state of naked particles. Therefore, by the suspension process specified by the ISO method, the number of colony forming units (CFUs) on a culture medium will not accurately express the number of bio-aerosols actually suspended in air. The present study was conducted to clarify the behavior of bio-aerosols suspended in air and to demonstrate the inadequacies of a filtration method that uses the suspension process to quantify fungal spores on a filter surface. The authors found that fungal spores suspended in air are coagulation particles and not naked particles, as demonstrated by both the Andersen sampler as well as electron microscopy of W.sebi spores. Furthermore, by the process of suspension, the CFU number was several times the value of fungal spores actually suspended in air.

Dynamic Release of Propranolol HCl from Cationic Ion–Exchanger–Loaded Calcium Alginate Beads

The dynamic release of drug propranolol HCl from the propranolol HCl–resin complex (PRC) loaded calcium alginate beads has been studied in the buffer media of pH 1.2 at the physiological temperature 37°C. The PRC encapsulated beads demonstrated nearly 58.04% release while naked PRC particles released 98.00% drug in 24 h in the gastric fluid. The amount of drug released was found to increase with and decrease in the amount of sodium alginate in the beads. Similarly, with the increase in the amount of entrapped PRC particles within the beads, the quantity of drug released was also observed to increase. The degree of crosslinking of beads also affected the release kinetics. Interestingly, the release from naked PRC particles followed ‘first‐order’ kinetics while PRC particles, entrapped in calcium–alginate beads, exhibited ‘diffusion controlled’ release behavior as indicated by liner nature of fractional release vs. √t plot.

Discovery of naked charm particles and lifetime differences among charm species using nuclear emulsion techniques innovated in Japan

This is a historical review of the discovery of naked charm particles and lifetime differences among charm species. These discoveries in the field of cosmic-ray physics were made by the innovation of nuclear emulsion techniques in Japan. A pair of naked charm particles was discovered in 1971 in a cosmic-ray interaction, three years prior to the discovery of the hidden charm particle, J/Ψ, in western countries. Lifetime differences between charged and neutral charm particles were pointed out in 1975, which were later re-confirmed by the collaborative Experiment E531 at Fermilab. Japanese physicists led by K.Niu made essential contributions to it with improved emulsion techniques, complemented by electronic detectors. This review also discusses the discovery of artificially produced naked charm particles by us in an accelerator experiment at Fermilab in 1975 and of multiple-pair productions of charm particles in a single interaction in 1987 by the collaborative Experiment WA75 at CERN.

Evidence for cellular uptake of recombinant hepatitis C virus non-enveloped capsid-like particles

Although the hepatitis C virus (HCV) is an enveloped virus, naked nucleocapsids have been reported in the serum of infected patients, and most recently novel HCV subgenomes with deletions of the envelope proteins have been identified. However the significance of these findings remains unclear. In this study, we used the baculovirus expression system to generate recombinant HCV capsid-like particles, and investigated their possible interactions with cells. We show that expression of HCV core in insect cells can sufficiently direct the formation of capsid-like particles in the absence of the HCV envelope glycoproteins and of the 5′ untranslated region. By confocal microscopy analysis, we provide evidence that the naked capsid-like particles could be uptaken by human hepatoma cells. Moreover, our findings suggest that they have the potential to produce cell-signaling effects.

Carrier Cell-based Delivery of an Oncolytic Virus Circumvents Antiviral Immunity

Oncolytic viruses capable of tumor-selective replication and cytolysis have shown early promise as cancer therapeutics. However, the host immune system remains a significant obstacle to effective systemic administration of virus in a clinical setting. Here, we demonstrate the severe negative impact of the adaptive immune response on the systemic delivery of oncolytic vesicular stomatitis virus (VSV) in an immune-competent murine tumor model, an effect mediated primarily by the neutralization of injected virions by circulating antibodies. We show that this obstacle can be overcome by administering virus within carrier cells that conceal viral antigen during delivery. Infected cells were delivered to tumor beds and released virus to infect malignant cells while sparing normal tissues. Repeated administration of VSV in carrier cells to animals bearing metastatic tumors greatly improved therapeutic efficacy when compared with naked virion injection. Whole-body molecular imaging revealed that carrier cells derived from solid tumors accumulate primarily in the lungs following intravenous injection, whereas leukemic carriers disseminate extensively throughout the body. Furthermore, xenogeneic cells were equally effective at delivering virus as syngeneic cells. These findings emphasize the importance of establishing cell-based delivery platforms in order to maximize the efficacy of oncolytic therapeutics.

The Complete Nucleotide Sequence and Genomic Organization of Citrus Leprosis Associated Virus, Cytoplasmatic type (CiLV-C)

The Citrus leprosis disease (CiL) is associated to a virus (CiLV) transmitted by Brevipalpus spp. mites (Acari: Tenuipalpidae). CiL is endemic in Brazil and its recently spreading to Central America represents a threat to citrus industry in the USA. Electron microscopy images show two forms of CiLV: a rare nuclear form, characterized by rod-shaped naked particle (CiLV-N) and a common cytoplasmic form (CiLV-C) associated with bacilliform-enveloped particle and cytoplasmic viroplasm. Due to this morphological feature, CiLV-C has been treated as Rhabdovirus-like. In this paper we present the complete nucleotide sequence and genomic organization of CiLV-C. It is a bipartite virus with sequence similarity to ssRNA positive plant virus. RNA1 encodes a putative replicase polyprotein and an ORF with no known function. RNA2 encodes 4 ORFs. pl5, p24 and p61 have no significant similarity to any known proteins and p32 encodes a protein with similarity to a viral movement protein. The CiLV-C sequences are associated with typical symptoms of CiL by RT-PCR. Phylogenetic analysis suggests that CiLV-C is probably a member of a new family of plant virus evolutionarily related to Tobamovirus.

On the recalcitrant nature of the triazinic ring species, cyanuric acid, to degradation in Fenton solutions and in UV-illuminated TiO 2 (naked) and fluorinated TiO 2 aqueous dispersions

Attempts to mineralize a variety of s-triazine herbicides and dyes containing the triazine ring by the photocatalytic TiO 2 method or by the Fenton process have typically terminated at cyanuric acid as the end product or at precursors such as ammelide, rather than at CO 2 for the carbons and NH 4 + and/or NO 3 − ions for the nitrogens, when such triazines are subjected to OH radical (free or otherwise) oxidation. A recent study on the fate of triazoles (e.g. amitrole) in UV-illuminated titania dispersions [N. Watanabe, S. Horikoshi, A. Kawasaki, H. Hidaka, N. Serpone, Environ. Sci. Technol. 39 (2005) 2320] produced ring-expanded triazine intermediates that ultimately also terminated at cyanuric acid despite efforts to totally mineralize the triazole substrates. Another study [Y.-C. Oh, W.S. Jenks, J. Photochem. Photobiol. A: Chem. 162 (2004) 323] reported that the cyanuric acid ring is degraded by free OH radicals produced from the Fenton reagent and from UV-illuminated TiO 2 aqueous dispersions at various pHs (2–12) whose particle surface was fully fluorinated [C. Minero, G. Mariella, V. Maurino, E. Pelizzetti, Langmuir 16 (2000) 2632]. Our own studies have been unable to degrade cyanuric acid in Fenton solutions, in UV-irradiated naked TiO 2 and fluorinated TiO 2 dispersions, except in a hydrothermal/supercritical aqueous medium [S. Horikoshi, Y. Wada, N. Watanbe, H. Hidaka, N. Serpone, New J. Chem. 27 (2003) 1216] and as reported earlier by others on titania modified by metal complexes. Using various analytical methods (e.g. ESI-MS spectrometry, HPLC-ion chromatography, and UV/visible spectroscopy), we failed to detect any intermediates and mineralized end products that might have resulted from the degradation of this recalcitrant species. We also report ESR and electrochemical results for the characterization of naked TiO 2 and fluorinated TiO 2 specimens. Clearly, cyanuric acid remains a recalcitrant species where OH radicals are the oxidizing agents. The number of OH radicals produced from UV-irradiated TiO 2 (naked) and fluorinated TiO 2 depend on the incident light irradiance; at low light irradiance a greater number of OH radicals are formed on naked TiO 2, whereas at high light irradiance a greater number of OH radicals seems to form in fluorinated TiO 2 (F/TiO 2) than on naked TiO 2 dispersions owing to a rapid degradation of the DMPO spin trap by surface-bound OH radicals taking place on the naked particle surface.

Size-Controlled Synthesis of Nanoparticles. 1. “Silver-Only” Aqueous Suspensions via Hydrogen Reduction

A method for size-controlled synthesis of chemically clean silver nanoparticles is proposed and described. The synthesis is based on the reduction of silver(I) oxide by hydrogen gas in water and offers the advantages of being easily scalable and able to produce essentially naked particles still exhibiting long-term stability with the metal surface readily accessible to various chemical modifications. The method allows synthesis of particles of any diameter between 15 and 200 nm simply by varying the reaction time. The addition of filtration and centrifugation techniques produces suspensions of narrow size distribution and relatively high, 1012−1014 particles/mL, concentration. The addition of various complexating agents potentially allows control of nanoparticle shape. The nanoparticles were characterized by UV−vis spectroscopy, electron microscopy, and electron and X-ray diffraction techniques.