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Ruusunen Jarno Ihalainen Mika Koponen Tarmo Torvela Tiina Tenho Mikko Salonen Jarno Sippula Olli Joutsensaari Jorma Jokiniemi Jorma Lähde Anna 《Journal of nanoparticle research》2014,16(2):1-11
Enteric-coated formulations can delay the release of drugs until they have passed through the stomach. However, high concentration of drugs caused by rapidly released in the small intestine leads to the intestinal damage, and frequent administration would increase the probability of missing medication and reduce the patient compliance. To solve the above-mentioned problems, aspirin-loaded enteric-coated sustained-release nanoparticles with core–shell structure were prepared via one-step method using coaxial electrospray in this study. Eudragit L100-55 as pH-sensitive polymer and Eudragit RS as sustained-release polymer were used for the outer coating and inner core of the nanoparticles, respectively. The maximum loading capacity of nanoparticles was 23.66 % by changing the flow rate ratio of outer/inner solutions, and the entrapment efficiency was nearly 100 %. Nanoparticles with core–shell structure were observed via fluorescence microscope and transmission electron microscope. And pH-sensitive and sustained drug release profiles were observed in the media with different pH values (1.2 and 6.8). In addition, mild cytotoxicity in vitro was detected, and the nanoparticles could be taken up by Caco-2 cells within 1.0 h in cellular uptake study. These results indicate that prepared enteric-coated sustained-release nanoparticles would be a more safety and effective carrier for oral drug delivery. 相似文献
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Joutsensaari J. Ahonen P.P. Kauppinen E.I. Brown D.P. Lehtinen K.E.J. Jokiniemi J.K. Powels B. Van Tendeloo G. 《Journal of nanoparticle research》2000,2(1):53-74
Fullerene nanocrystals in the size range 30–300 nm were produced starting from atomized droplets of C60 in toluene. The experiments were carried out under well-controlled conditions in a laminar flow reactor at temperatures of 20–600°C. Particle transformation and crystallization mechanisms of polydisperse and monodisperse (size classified) fullerene aerosol particles were studied. The results show that fullerene particles are roughly spherical having pores and voids at temperatures of 300°C and below. Particles are already crystalline and likely fine-grained at 20°C and they are polycrystalline at temperatures up to 300°C. At 400°C monodisperse particles evaporate almost completely due to their low mass concentration. Polydisperse particles are crystalline, but sometimes heavily faulted. At 500°C most of the particles are clearly faceted. In certain conditions, almost all particles are hexagonal platelets having planar defects parallel to large (111) faces. We suggest that at 500°C fullerene particles are partially vaporized forming residuals with lamellar defects such as twins and stacking faults, which promote crystal growth during synthesis. Subsequently fullerene vapor is condensed on faces with defects and hexagonal particles are grown by a re-entrant corner growth mechanism. At 600°C particles are single crystals, but they have a less distinct shape due to higher vaporization of fullerene. The final size and shape of the particles are mainly determined at the reactor outlet in the short time when the aerosol cools. 相似文献
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J. Leskinen J. Joutsensaari J. Lyyränen J. Koivisto J. Ruusunen M. Järvelä T. Tuomi K. Hämeri A. Auvinen J. Jokiniemi 《Journal of nanoparticle research》2012,14(2):718
Nanoparticles are used in many applications because of their novel properties compared to bulk material. A growing number
of employees are working with nanomaterials and their exposure to nanoparticles trough inhalation must be evaluated and monitored
continuously. However, there is an ongoing debate in the scientific literature about what are the relevant parameters to measure
to evaluate exposure to level. In this study, three types of nanoparticles (ammonium sulphate, synthesised TiO2 agglomerates and aerosolised TiO2 powder, modes in a range of 30–140 nm mobility size) were measured with commonly used aerosol measurement instruments: scanning
and fast mobility particle sizers (SMPS, FMPS), electrical low pressure impactor (ELPI), condensation particle counter (CPC)
together with nanoparticle surface area monitor (NSAM) to achieve information about the interrelations of the outputs of the
instruments. In addition, the ease of use of these instruments was evaluated. Differences between the results of different
instruments can mainly be attributed to the nature of test particles. For spherical ammonium sulphate nanoparticles, the data
from the instruments were in good agreement while larger differences were observed for particles with more complex morphology,
the TiO2 agglomerates and powder. For instance, the FMPS showed a smaller particle size, a higher number concentration and a narrower
size distribution compared with the SMPS for TiO2 particles. Thus, the type of the nanoparticle was observed to influence the data obtained from these different instruments.
Therefore, care and expertise are essential when interpreting results from aerosol measurement instruments to estimate nanoparticle
concentrations and properties. 相似文献
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