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For an improved understanding of the relevant particle features for cutaneous use, we studied the effect of the surface charge of acrylic nanocapsules (around 150nm) and the effect of ...a chitosan gel vehicle on the particle penetration into normal and stripped human skin ex vivo as well as local tolerability (cytotoxicity and irritancy). Rhodamin-tagged nanocapsules penetrated and remained in the stratum corneum. Penetration of cationic nanocapsules exceeded the penetration of anionic nanocapsules. When applied on stripped skin, however, the fluorescence was also recorded in the viable epidermis and dermis. Cationic surface charge and embedding the particles into chitosan gel favored access to deeper skin. Keratinocytes took up the nanocapsules rapidly. Cytotoxicity (viability<80%), following exposure for ≥24h, appears to be due to the surfactant polysorbate 80, used for nanocapsuleś stabilization. Uptake by fibroblasts was low and no cytotoxicity was observed. No irritant reactions were detected in the HET-CAM test. In conclusion, the surface charge and chitosan vehicle, as well as the skin barrier integrity, influence the skin penetration of acrylic nanocapsules. Particle localization in the intact stratum corneum of normal skin and good tolerability make the nanocapsules candidates for topical use on the skin, provided that the polymer wall allows the release of the active encapsulated substance.
This review provides a comprehensive and updated overview of the state of the art related to the biomedical applications of nanoparticles coated with chitosan. Discussions were based on selected ...literature in the field. Here, we discussed nanoparticles constituted by polymer, lipid and metal materials, which have been coated with chitosan. In addition, the methodological aspects of the coating process, which is performed by the addition of a chitosan solution into previously prepared nanoparticles or during nanoparticle formation, was reviewed, as well as the techniques employed to confirm an efficient coating process, such as determinations of particle size and zeta potential. Special attention is given to physicochemical and biological advantages brought by the chitosan-coating, such as increase in physicochemical stability, controlled release, improvement of tissue/cells interaction, and increase in the bioavailability of drugs (or active substances) and drug efficacy. We also pointed out safety concerns regarding chitosan-coated nanoparticles based on the results presented so far in the literature.
•Chitosan used as a coating has numerous advantages•Chitosan coated nanoparticles can be prepared by different techniques•Different characterization techniques can be used to prove the coating.
An innovative nanocapsule formulation for parenteral administration using selected vegetable oils (mango, jojoba, pequi, oat, annatto, calendula, and chamomile) was developed that has the potential ...to encapsulate various drugs. The vegetable oil-loaded nanocapsules were prepared by interfacial deposition and compared with capric/caprylic triglyceride-loaded lipid core nanocapsules. The major objective was to investigate the effect of vegetable oils on particle size distribution and physical stability and to determine the hemolytic potential of the nanocapsules, considering their applicability for intravenous administration. Taking into account the importance of accurately determining particle size for the selected route of administration, different size characterization techniques were employed, such as Laser Diffraction, Dynamic Light Scattering, Multiple Light Scattering, Nanoparticle Tracking Analysis, and Transmission Electronic Microscopy. Laser diffraction studies indicated that the mean particle size of all nanocapsules was below 300 nm. For smaller particles, the laser diffraction and multiple light scattering data were in agreement (D3,2-130 nm). Dynamic light scattering and nanoparticle tracking analysis, two powerful techniques that complement each other, exhibited size values between 180 and 259 nm for all nanoparticles. Stability studies demonstrated a tendency of particle creaming for jojoba-nanocapsules and sedimentation for the other nanoparticles; however, no size variation occurred over 30 days. The hemolysis test proved the hemocompatibility of all nanosystems, irrespective of the type of oil. Although all developed nanocapsules presented the potential for parenteral administration, jojoba oil-loaded nanocapsules were selected as the most promising nanoformulation due to their low average size and high particle size homogeneity.
Abstract Background and aim Patients with systemic lupus erythematosus (SLE) have a higher prevalence of subclinical atherosclerosis and higher risk of cardiovascular (CV) events compared to the ...general population. The relative contribution of CV-, immune- and disease-related risk factors to accelerated atherogenesis in SLE is unclear. Methods and results Fifty SLE patients with long-lasting disease (mean age 44 ± 10 years, 86% female) and 50 sex- and age-matched control subjects were studied. Common carotid artery intima-media thickness (CCA-IMT) was used as a surrogate marker of atherosclerosis. We evaluated traditional and immune- and disease-related factors, assessed multiple T-cell subsets by 10-parameter-eight-colour polychromatic flow cytometry and addressed the effect of pharmacological therapies on CCA-IMT. In SLE patients, among several cardiometabolic risk factors, only high-density lipoprotein levels (HDL) and their adenosine triphosphate-binding cassette transporter 1 (ABCA-1)-dependent cholesterol efflux capacity were markedly reduced ( p < 0.01), whereas the CCA-IMT was significantly increased ( p = 0.03) compared to controls. CCA-IMT correlated with systolic blood pressure, low-density lipoprotein (LDL) cholesterol and body mass index (BMI), but not with disease activity and duration. The activated CD4+ HLA-DR+ and CCR5+ T-cell subsets were expanded in SLE patients. Patients under hydroxychloroquine (HCQ) therapy showed lower CCA-IMT (0.62 ± 0.08 vs. 0.68 ± 0.10 mm; p = 0.03) and better risk-factor profile and presented reduced circulating pro-atherogenic effector memory T-cell subsets and a parallel increased percentage of naïve T-cell subsets. Conclusion HDL represents the main metabolic parameter altered in SLE patients. The increased CCA-IMT in SLE patients may represent the net result of a process in which ‘classic’ CV risk factors give a continuous contribution, together with immunological factors (CD4+ HLA-DR+ T cells) which, on the contrary, could contribute through flares of activity of various degrees over time. Patients under HCQ therapy present a modified metabolic profile, a reduced T-cell activation associated with decreased subclinical atherosclerosis.
To evaluate the effect of cationic coating of polymeric nanocapsules in sunscreen formulations on the in vitro skin penetration of benzophenone-3.
Benzophenone-3-loaded nanocapsules were prepared by ...the interfacial deposition of poly(ε-caprolactone) and coated by using a chitosan solution. The nanoparticles were characterized and incorporated in hydrogels. The presence of nanoparticles in hydroxyethyl cellulose gels was observed by transmission electron microscopy and photon correlation spectroscopy. Penetration studies were carried out using Franz cells with porcine skin membranes.
Benzophenone-3-loaded chitosan-coated nanocapsules presented a mean size of 202 ± 7 nm and positive zeta potential (+21 ± 1 mV), while these values for the uncoated nanocapsules were 175 ± 1 nm and -8 ± 1 mV. Penetration profiles showed that a higher amount of benzophenone-3 remained at the skin surface and a lower amount was found in the receptor compartment after the application of the formulation containing chitosan-coated nanocapsules compared to a formulation containing its free form.
Hydrogel containing benzophenone-3 chitosan-coated nanocapsules represents an innovative formulation to overcome limitations of sunscreen daily use.
This paper looks at hydraulic modeling as a tool to examine failure modes of a central plant chilled-water system. The program is capable of solving for balanced flows and pressures throughout the ...system and includes detailed models of all pumps, heat exchangers, valves, pipes, and fittings. It allows individual pipelines to be easily shut off, simulating failure modes, and also allows redundant pumps and chillers to be turned on in response to failures. The procedures and results are demonstrated for a theoretical data center with a 5 MW IT load and 12°F (6.6°C) water-side delta t. The results are visualized by creating 2-D plots of the control valve pressure drops in the distribution grid.
This paper looks at hydraulic modeling as a tool to optimize energy savings from part-load pumping strategies, taking advantage of the fact that redundant pumps and other equipment are typically ...installed in data centers. The commercially available hydraulic analysis package used for analysis is capable of solving for balanced flows and pressures throughout the system, and includes detailed models of all pumps, heat exchangers, valves, pipes and fittings. It allows individual pipelines to be easily shut off, simulating failure modes, and also allows pump speeds to be reduced, allowing for simulation of VFD operation. The procedures and results are demonstrated for a theoretical data center with a 5.5 MWIT Load and 12°F (6.6°C) water-side delta t. Pumping energy savings of over 30% were obtained by making optimal use of redundant equipment. On the other hand, pumping penalties of up to 20% were also noted through careless selection and use of redundant pumps.
Performance of second generation BABAR resistive plate chambers Anulli, F.; Baldini, R.; Calcaterra, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2005, Letnik:
552, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The BABAR detector has operated nearly 200 Resistive Plate Chambers (RPCs), constructed as part of an upgrade of the forward endcap muon detector, for the past two years. The RPCs experience widely ...different background and luminosity-driven singles rates (0.01–10
Hz/cm
2) depending on position within the endcap. Some regions have integrated over 0.3
C/cm
2. RPC efficiency measured with cosmic rays is high and stable. The average efficiency measured with beam is also high. However, a few of the highest rate RPCs have suffered efficiency losses of 5–15%. Although constructed with improved techniques and minimal use of linseed oil, many of the RPCs, which are operated in streamer mode, have shown increased dark currents and noise rates that are correlated with the direction of the gas flow and the integrated current. Studies of the above aging effects are presented and correlated with detector operating conditions.
The nature of b-quark jet hadronisation has been investigated using data taken at the Z peak by the DELPHI detector at LEP. Two complementary methods are used to reconstruct the energy of weakly ...decaying b-hadrons,
. The average value of
is measured to be 0.699±0.011. The resulting
distribution is then analysed in the framework of two choices for the perturbative contribution (parton shower and Next to Leading Log QCD calculation) in order to extract measurements of the non-perturbative contribution to be used in studies of b-hadron production in other experimental environments than LEP. In the parton shower framework, data favour the Lund model ansatz and corresponding values of its parameters have been determined within PYTHIA 6.156 from DELPHI data:
with a correlation factor
ρ
=92.2%.
Combining the data on the b-quark fragmentation distributions with those obtained at the Z peak by ALEPH, OPAL and SLD, the average value of
is found to be 0.7092±0.0025 and the non-perturbative fragmentation component is extracted. Using the combined distribution, a better determination of the Lund parameters is also obtained:
with a correlation factor
ρ
=92.6%.
Capsaicin, a topical analgesic used in the treatment of chronic pain, has irritant properties that frequently interrupt its use. In this work, the effect of nanoencapsulation of the main ...capsaicinoids (capsaicin and dihydrocapsaicin) on skin irritation was tested in humans. Skin tolerance of a novel vehicle composed of chitosan hydrogel containing nonloaded nanocapsules (CH-NC) was also evaluated. The chitosan hydrogel containing nanoencapsulated capsaicinoids (CH-NC-CP) did not cause skin irritation, as measured by an erythema probe and on a visual scale, while a formulation containing free capsaicinoids (chitosan gel with hydroalcoholic solution CH-ET-CP) and a commercially available capsaicinoids formulation caused skin irritation. Thirty-one percent of volunteers reported slight irritation one hour after application of CH-NC-CP, while moderate (46% CH-ET-CP and 23% commercial product) and severe (8% CH-ET-CP and 69% commercial product) irritation were described for the formulations containing free capsaicinoids. When CH-NC was applied to the skin, erythema was not observed and only 8% of volunteers felt slight irritation, which demonstrates the utility of the novel vehicle. A complementary in vitro skin permeation study showed that permeation of capsaicinoids through an epidermal human membrane was reduced but not prevented by nanoencapsulation.
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