Purification of biomimetic apatite-based hybrid colloids intended for biomedical applications: a dialysis study

The field of nanobiotechnology has lately attracted much attention both from therapeutic and diagnosis viewpoints. Of particular relevance is the development of colloidal formulations of biocompatible nanoparticles capable of interacting with selected cells or tissues. In this context, the purification of such nanoparticle suspensions appears as a critical step as residues of unreacted species may jeopardize biological and medical outcomes, and sample purity is thus increasingly taken into account by regulatory committees. In the present work, we have investigated from a physico-chemical point of view the purification by dialysis of recently developed hybrid colloids based on biomimetic nanocrystalline apatites intended for interacting with cells. Both Eu-doped (2 mol.% relative to Ca) and Eu-free suspensions were studied. The follow-up of the dialysis process was carried out by way of FTIR, TEM, XRD, pH and conductivity measurements. Mathematical modelling of conductivity data was reported. The effects of a change in temperature (25 and 45 ◦C), dialysis medium, and starting colloid composition were evaluated and discussed. We show that the dialysis method is a well-adapted and cheap technique to purify such mineral–organic hybrid suspensions in view of biomedical applications, and we point out some of the characterization techniques that may prove helpful for following the evolution of the purification process with time

Novel contributions on luminescent apatite-based colloids intended for medical imaging

The setup of colloidal hybrid nanosystems based on biomimetic calcium phosphate apatites doped with europium ions has recently raised great interest in the pharmacological community, especially due to their bio-inspired character. This is especially relevant in relation with medical imaging for cancer diagnosis. Questions however remain in relation to a number of applicability aspects, some of which have been examined in this contribution. In a first part of this work, we explored further the luminescence properties of such colloidal nanoparticles. We pointed out, upon excitation of europium, the existence of some non-radiative de-excitation via the vibration of O-H oscillators located at the vicinity of the Eu3þ luminescent centers. The replacement of Eu3þ by Tb3þ ions, less prone to non-radiative de-excitation, was then tested in a preliminary way and can be seen as a promising alternative. In a second part of this work, we inspected the possibility to store these colloids in a dry state while retaining a re-suspension ability preserving the nanometer size of the initial nanoparticles, and we propose a functional protocol involving the addition of glucose prior to freeze-drying. We finally showed for the first time, based on titrations of intracellular Ca2þ and Eu3þ ions, that folic acid-functionalized biomimetic apatite nanoparticles were able to target cancer cells that overexpress folate receptors on their membrane, which we point out here in the case of T-47-D breast carcinoma cells, as opposed to ZR-75-1 cells that do not express folate receptors. This contribution thus opens new exciting perspectives in the field of targeted cancer diagnosis, thus confirming the promise of biomimetic apatites-based colloidal formulations

Biomimetic nanocrystalline apatites: Emerging perspectives in cancer diagnosis and treatment

Nanocrystalline calcium phosphate apatites constitute the mineral part of hard tissues, and the synthesis of biomimetic analogs is now wellmastered at the labscale. Recent advances in the fine physicochemical characterization of these phases enable one to envision original applications in the medical field along with a better understanding of the underlying chemistry and related pharmacological features. In this contribution, we specifically focused on applications of biomimetic apatites in the field of cancer diagnosis or treatment. We first report on the production and first biological evaluations (cytotoxicity, proinflammatory potential, internalization by ZR751 breast cancer cells) of individualized luminescent nanoparticles based on Eudoped apatites, eventually associated with folic acid, for medical imaging purposes. We then detail, in a first approach, the preparation of tridimensional constructs associating nanocrystalline apatite aqueous gels and drugloaded pectin microspheres. Sustained releases of a fluorescein analog (erythrosin) used as model molecule were obtained over 7 days, in comparison with the ceramic or microsphere reference compounds. Such systems could constitute original bonefilling materials for in situ delivery of anticancer drug

A three-dimensional discontinuous galerkin time-domain finite element method for electromagnetic modeling of wireless power transfer coils

ABSTRACT: Inductive coupling based wireless power transfer (WPT) is a popular short-range power delivery mechanism for many industrial, biomedical, and home electronic appliances applications. A numerical methodology is needed for the analysis of the electromagnetic propagation, radiation, scattering and coupling of highly efficient WPT systems. This study is based on the discontinuous Galerkin time-domain (DGTD) finite element method. A brief survey of the DGTD method is given, which is a finite element method using discontinuous piecewise polynomials as basis functions and numerical fluxes based on up-winding for stability. DGTD method is characterized by the fact that no continuity is enforced between the elements, then it is easy to parallelize and results in fast solvers. Even though the finite element method is used by a few researchers to study WPT problems, we found no study using the DGTD method to study WPT problems, which is surprising given that this discretization technique seems particularly well suited for these problems. A design of two coils at the frequency of 3 MHz is introduced, and the effects of the distance and misalignment between two coils on the mutual coupling are studied. The numerical results are validated by experimental and analytical results

Colossal and frequency stable permittivity of barium titanate nanoceramics derived from mechanical activation and SPS sintering

Highly dense barium titanate nanoceramics have been successfully prepared via a mechanical activation synthesis method and Spark Plasma sintering. Attractive electrical properties have been evidenced in these materials: a colossal permittivity, (3.5. 105) and low loss (0.07) at room temperature and 1 kHz, that are stable over a wide frequency range (from 40 Hz to 40 kHz). Surprisingly, the ferroelectric transition is still observed, for the first time to our knowledge, in these colossal permittivity materials

Elaboration and characterization of barium titanate powders obtained by the mechanical activation of barium nitrate and titanate oxide, and electrical properties of the ceramics sintered by SPS

The current work aims to reduce the energy required to obtain a high quality barium titanate nanocrystals via solid-state reaction. In order to achieve this challenge, Ba(NO3)2 and TiO2 were mechanically activated by high-energy ball milling, and then heat treated at moderate temperature (600 oC). When stoichiometric mixture was used, the formation of BT and minor BaCO3 and TiO2 impurities was observed. The use of Ba(NO3)2 excess leads to the formation of BT and a minor BaCO3 impurity. A simple acid wash treatment was used to remove the carbonate impurity and to provide a high purity BT. The powders were characterized by XRD, BET, Raman spectroscopy, and SEM-FEG. Spark Plasma Sintering (SPS) technique was used to get the dense nanoceramics. These materials show, at room temperature and at 1 kHz, colossal permittivity (ε = 105) associated with low dielectric loss (tg δ = 0.07)

Imaging Oxygen Distribution in Marine Sediments. The Importance of Bioturbation and Sediment Heterogeneity

The influence of sediment oxygen heterogeneity, due to bioturbation, on diffusive oxygen flux was investigated. Laboratory experiments were carried out with 3 macrobenthic species presenting different bioturbation behaviour patterns:the polychaetes Nereis diversicolor and Nereis virens, both constructing ventilated galleries in the sediment column, and the gastropod Cyclope neritea, a burrowing species which does not build any structure. Oxygen two-dimensional distribution in sediments was quantified by means of the optical planar optode technique. Diffusive oxygen fluxes (mean and integrated) and a variability index were calculated on the captured oxygen images. All species increased sediment oxygen heterogeneity compared to the controls without animals. This was particularly noticeable with the polychaetes because of the construction of more or less complex burrows. Integrated diffusive oxygen flux increased with oxygen heterogeneity due to the production of interface available for solute exchanges between overlying water and sediments. This work shows that sediment heterogeneity is an important feature of the control of oxygen exchanges at the sediment–water interface

Short interpregnancy interval and low birth weight: a role of parity

Związek pomiędzy krótkim interwałem międzyurodzeniowym a niską masą urodzeniową niemowląt ma większe znaczenie w przypadku matek wieloródekObjectives: Short interpregnancy intervals (IPI) and high parity may be synergistically associated with the risk of unfavorable pregnancy outcomes. This study tests if the effect of short IPI on the odds ratio for low birth weight (LBW, <2,500 g) differs across parity status. Methods: The study was carried out on the birth registry sample of almost 40,000 singleton, live-born infants who were delivered between the years 1995 and 2009 to multiparous mothers whose residence at the time of infant’s birth was the city of Krakow. Multiple logistic regression analyses were used for testing the effect of IPI on the odds ratio (OR) for LBW, after controlling for employment, educational and marital status, parity, sex of the child, maternal and gestational age. Stratified analyses (according to parity) and tests for interaction were performed. Results: Very short IPI (0–5 months) was associated with an increased OR for LBW, but only among high parity mothers with three or more births (OR = 2.64; 95% CI 1.45–4.80). The test for interaction between very short IPI and parity on the OR for LBW was statistically significant after adjustment for multiple comparisons (P = 0.04). Among low parity mothers (two births) no statistically significant associations were found between IPI and LBW after standardization. Conclusion: Parity may modify the association between short birth spacing and LBW. Women with very short IPI and high parity may have a higher risk of having LBW infants than those with very short IPI but low parity.This study was carried out within the Framework of a Project No N N404 055 136, financed by the Ministry of Science and Higher Educatio

Mycoplasma hominis brain abscess following uterus curettage: a case report

<p>Abstract</p> <p>Introduction</p> <p><it>Mycoplasma hominis </it>is mostly known for causing urogenital infections. However, it has rarely been described as an agent of brain abscess.</p> <p>Case presentation</p> <p>We describe a case of <it>M. hominis </it>brain abscess in a 41-year-old Caucasian woman following uterus curettage. The diagnosis was obtained by 16S rDNA amplification, cloning and sequencing from the abscess pus, and confirmed by a specifically designed real-time polymerase chain reaction assay.</p> <p>Conclusions</p> <p>Findings from our patient's case suggest that <it>M. hominis </it>should be considered as a potential agent of brain abscess, especially following uterine manipulation.</p