Investigating an organ-targeting platform based on hydroxyapatite nanoparticles using a novel in situ method of radioactive 125Iodine labeling

In this study, we have investigated the synthesis of nanoparticles of hydroxyapatite (HAp) and hydroxyapatite coated with chitosan (HAp/Ch) and the chitosan-poly-d,l-lactide-co-glycolide polymer blend (HAp/Ch-PLGA) as an organ-targeting system. We have examined and defined the final destination, as well as the dynamics and the pathways of the synthesized particles following intravenous administration in vivo.\ud \ud The XRD, ZP, FT-IR and SEM analyses have confirmed that the hydroxyapatite nanoparticles with d50 = 72 nm are coated with polymers. Radioactive 125-Iodine (125I), a low energy gamma emitter, was used to develop a novel in situ method for the radiolabeling of particles and investigation of their biodistribution. 125I-labeled particles exhibited high stability in saline and serum over the second day, which justified their use in the following in vivo studies.\ud \ud The biodistribution of 125I-labeled particles after intravenous injection in rats differed significantly: HAp particles mostly targeted the liver, HAp/Ch the spleen and the liver, while HAp/Ch-PLGA targeted the lungs. Twenty-four hours post injection, HAp particles were excreted completely, while both 125I-HAp/Ch and 125I-HAp/Ch-PLGA were retained in the body for a prolonged period of time with more than 20% of radioactivity still found in different organs

The success rate of hydroxyapatite nanoparticles coated with bioresorbable polymers in a biological environment

Hydroxyapatite (HAp) nanoparticles coated with bioresorbable polymers have been successfully used as filler, carriers of antibiotics, vitamins and stem cells in bone tissue engineering. Interactions in the microenvironment of nanoparticulate hydroxyapatites and tissues are of a particular interest and present a challenge in regenerative medicine. The phenomena that influence the success of targeting and controlled operation or therapeutic nanosystems are numerous and complex: size, shape, surface charge, functional groups of nanoparticles, electrical double-layer formation, zeta potential, partial molar free energy, sorption molar free energy, isoelectric point of solid–liquid interface; receptor–ligand binding interactions of nano-bio interface etc. In our studies we present the synthesis, characterization, in vitro and in vivo research of nanoparticulate form of HAp-coated polymers systems. Synthesized nanoparticulate HAp coated with different types of bioresorbable polymers: poly(D,L-lactide-co-glycolide), chitozan and other similar by the solvent/non-solvent method. The physical and chemical analyses have confirmed that HAp particles are coated with bioresorbable polymers. Results of spectroscopic analysis suggests formation of hydrogen bonds between the surface groups of HAp and =O and –H groups in the polymer chain from bioresorbable polymers. By adding nanoparticulate HAp in the polymer matrix was achieved the changes in the partial molar free energy and sorption molar free energy of the system. In vitro results showed satisfactory biocompatibility of nanoparticulate HAp-coated polymers systems. The use of these systems in the form of filler was achieved a high quality osteogenesis in reconstruction of bone tissue, in vivo.The biodistribution of 125I-labeled HAp particles after intravenous injection in rats showed the potential use of these materials as a organ-targeting system: uncoated-HAp mostly targeted the liver, coated-HAp spleen and lungs

Routes and pathways to small particles based on hydroxyapatite

Nanoparticles based on hydroxyapatite (NPs) have many useful physicochemical and biological\ud properties, such as easy preparation and modification, as well as biocompatibility, which make them suitable for transport and unloading of various pharmaceuticals. Hydroxyapatite\ud nanoparticles coated with bioresorbable polymers have been successfully used as carriers of\ud antibiotics and vitamins in bone tissue engineering. In this study, we have investigated the synthesis of nanoparticles of hydroxyapatite and hydroxyapatite coated with chitosan and the chitosan-poly-D,L-lactide-co-glycolide polymer blend. The influence of the processing technique on the structure and characteristics of the obtained particles was studied by X-ray diffraction (XRD), particle size distribution analysis (PSD), Fourier transform infrared spectroscopy (FTIR), zeta potential analysis (ZP) and scanning electronic microscopy (SEM). In applied research, an appropriate radioisotope (Iodine-125) was selected and it was used to label particles. The in vivo biodistribution of 125I-labeled particles were studied in healthy Wistar rats following intravenous administration. The XRD, FT-IR and ZP analyses have confirmed that the hydroxyapatite particles with d50=72 nm are coated with chitosan and the chitosan-poly-D,L-lactide-co-glycolide polymer blend. 125I-labeled particles showed completely different behaviour in vivo: hydroxyapatite particles have the highest liver accumulation 10 min after injection but rapid excretion from the body without residual radioactivity 24 hours after injection; chitozan coated hydroxyapatite particles have the highest accumulation in the liver 10 min after injection with considerable amount (almost 50 %) retained 24 hours later; hydroxyapatite particles coated with the chitosanpoly-D,L-lactide-co-glycolide polymer blend have the highest uptake in the lungs 10 minutes after injection and moderate retention in the same organ 24 hours later

Measurement of the production cross section of prompt j/psi mesons in association with a W (+/-) boson in pp collisions root s=7 TeV with the ATLAS detector

The process pp - GT W (+/-) J/psi provides a powerful probe of the production mechanism of charmonium in hadronic collisions, and is also sensitive to multiple parton interactions in the colliding protons. Using the 2011 ATLAS dataset of 4.5 fb(-1) of root s= 7 TeV pp collisions at the LHC, the first observation is made of the production of W (+/-) + prompt J/psi events in hadronic collisions, using W (+/-) - GT mu nu(mu) and J/psi - GT mu(+)mu(-) center dot A yield of W (+/-) + prompt J/psi events is observed, with a statistical significance of 5.1 sigma. The production rate as a ratio to the inclusive W (+/-) boson production rate is measured, and the double parton scattering contribution to the cross section is estimated

Search for W - GT t(b)over-bar in the lepton plus jets final state in proton-proton collisions at a centre-of-mass energy of root s=8 TeV with the ATLAS detector

A search for new charged massive gauge bosons, called W, is performed with the ATLAS detector at the LHC, in proton-proton collisions at a centre-of-mass energy of root s = 8 TeV, using a dataset corresponding to an integrated luminosity of 20.3 fb(-1). This analysis searches for W bosons in the W - GT t (b) over tilde decay channel in final states with electrons or muons, using a multivariate method based on boosted decision trees. The search covers masses between 0.5 and 3.0 TeV, for right-handed or left-handed W bosons. No significant deviation from the Standard Model expectation is observed and limits are set on the W - GT t (b) over bar cross-section times branching ratio and on the W-boson effective couplings as a function of the W-boson mass using the CLs procedure. For a left-handed (right-handed) W boson, masses below 1.70 (1.92) TeV are excluded at 95% confidence level. Published by Elsevier B.V

Search for dark matter in events with heavy quarks and missing transverse momentum in pp collisions with the ATLAS detector

This article reports on a search for dark matter pair production in association with bottom or top quarks in 20.3 fb(-1) of pp collisions collected at root s = 8 TeV by the ATLAS detector at the LHC. Events with large missing transverse momentum are selected when produced in association with high-momentum jets of which one or more are identified as jets containing b-quarks. Final states with top quarks are selected by requiring a high jet multiplicity and in some cases a single lepton. The data are found to be consistent with the Standard Model expectations and limits are set on the mass scale of effective field theories that describe scalar and tensor interactions between dark matter and Standard Model particles. Limits on the dark-matter-nucleon cross-section for spin-independent and spin-dependent interactions are also provided. These limits are particularly strong for low-mass dark matter. Using a simplified model, constraints are set on the mass of dark matter and of a coloured mediator suitable to explain a possible signal of annihilating dark matter

Search for new phenomena in events with a photon and missing transverse momentum in pp collisions at root s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in events with an energetic photon and large missing transverse momentum with the ATLAS experiment at the LHC are reported. Data were collected in proton-proton collisions at a center-of-mass energy of 8 TeVand correspond to an integrated luminosity of 20.3 fb(-1). The observed data are well described by the expected Standard Model backgrounds. The expected (observed) upper limit on the fiducial cross section for the production of events with a photon and large missing transverse momentum is 6.1 (5.3) fb at 95% confidence level. Exclusion limits are presented on models of new phenomena with large extra spatial dimensions, supersymmetric quarks, and direct pair production of dark-matter candidates

Search for new phenomena in events with three charged leptons at root s=7 TeV with the ATLAS detector

A generic search for anomalous production of events with at least three charged leptons is presented. The search uses a pp-collision data sample at a center-of-mass energy of root s = 7 TeV corresponding to 4.6 fb(-1) of integrated luminosity collected in 2011 by the ATLAS detector at the CERN Large Hadron Collider. Events are required to contain at least two electrons or muons, while the third lepton may either be an additional electron or muon, or a hadronically decaying tau lepton. Events are categorized by the presence or absence of a reconstructed tau-lepton or Z-boson candidate decaying to leptons. No significant excess above backgrounds expected from Standard Model processes is observed. Results are presented as upper limits on event yields from non-Standard-Model processes producing at least three prompt, isolated leptons, given as functions of lower bounds on several kinematic variables. Fiducial efficiencies for model testing are also provided. The use of the results is illustrated by setting upper limits on the production of doubly charged Higgs bosons decaying to same-sign lepton pairs. DOI: 10.1103/PhysRevD.87.05200

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to b (b) over bar final states, and pp collision data at root s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of W gamma and Z gamma production in pp collisions at root s=7 TeV with the ATLAS detector at the LHC

The integrated and differential fiducial cross sections for the production of a W or Z boson in association with a high-energy photon are measured using pp collisions at root s = 7 TeV. The analyses use a data sample with an integrated luminosity of 4.6 fb(-1) collected by the ATLAS detector during the 2011 LHC data-taking period. Events are selected using leptonic decays of the W and Z bosons [W(e nu, mu nu) and Z(e(+)e(-), mu(+)mu(-), nu(nu) over bar)] with the requirement of an associated isolated photon. The data are used to test the electroweak sector of the Standard Model and search for evidence for new phenomena. The measurements are used to probe the anomalous WW gamma, ZZ gamma, and Z gamma gamma triple-gauge-boson couplings and to search for the production of vector resonances decaying to Z gamma and W gamma. No deviations from Standard Model predictions are observed and limits are placed on anomalous triple-gauge-boson couplings and on the production of new vector meson resonances