The cellular interactions of PEGylated gold nanoparticles : effect of PEGylation on cellular uptake and cytotoxicity

Poly(ethylene glycol) (PEG) is frequently used to coat various medical nanoparticles (NPs). As PEG is known to minimize NP interactions with biological specimens, the question remains whether PEGylated NPs are intrinsically less toxic or whether this is caused by reduced NP uptake. In the present work, the effect of gold NP PEGylation on uptake by three cell types is compared and evaluated the effect on cell viability, oxidative stress, cell morphology, and functionality using a multiparametric methodology. The data reveal that PEGylation affects cellular NP uptake in a cell-type-dependent manner and influences toxicity by different mechanisms. At similar intracellular NP numbers, PEGylated NPs are found to yield higher levels of cell death, mostly by induction of oxidative stress. These findings reveal that PEGylation significantly reduces NP uptake, but that at similar functional (= cell-associated) NP levels, non-PEGylated NPs are better tolerated by the cells

Comparison of Physical-chemical and Mechanical Properties of Chlorapatite and Hydroxyapatite Plasma Sprayed Coatings

Chlorapatite can be considered a potential biomaterial for orthopaedic applications. Its use as plasma-sprayed coating could be of interest considering its thermal properties and particularly its ability to melt without decomposition unlike hydroxyapatite. Chlorapatite (ClA) was synthesized by a high-temperature ion exchange reaction starting from commercial stoichiometric hydroxyapatites (HA). The ClA powder showed similar characteristics as the original industrial HA powder, and was obtained in the monoclinic form. The HA and ClA powders were plasma-sprayed using a low-energy plasma spraying system with identical processing parameters. The coatings were characterized by physical-chemical methods, i.e. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, including distribution mapping of the main phases detected such as amorphous calcium phosphate (ACP), oxyapatite (OA), and HA or ClA. The unexpected formation of oxyapatite in ClA coatings was assigned to a side reaction with contaminating oxygenated species (O2, H2O). ClA coatings exhibited characteristics different from HA, showing a lower content of oxyapatite and amorphous phase. Although their adhesion strength was found to be lower than that of HA coatings, their application could be an interesting alternative, offering, in particular, a larger range of spraying conditions without formation of massive impurities.This study was carried out under a MNT ERA-Net Project named NANOMED. The authors gratefully thank the Midi-Pyrénées region (MNT ERA Net Midi-Pyrénées Région, NANOMED2 project) and the Institute National Polytechnique de Toulouse (BQR INPT 2011, BIOREVE project) for supporting this research work, especially the financial support for research carried out in the CIRIMAT and the LGP laboratories (France), and the Basque government and Tratamientos Superficiales Iontech, S.A. for their financial and technical support under the IG-2007/0000381 grant for the development of the LEPS device and deposition of the coatings carried out in Inasmet-Tecnalia. The French industrial collaborators (TEKNIMED SA and 2PS SA) were financed by the OSEO programs

Copper and tin isotopic analysis of ancient bronzes for archaeological investigation: development and validation of a suitable analytical methodology

Although in many cases Pb isotopic analysis can be relied on for provenance determination of ancient bronzes, sometimes the use of “non-traditional” isotopic systems, such as those of Cu and Sn, is required. The work reported on in this paper aimed at revising the methodology for Cu and Sn isotope ratio measurements in archaeological bronzes via optimization of the analytical procedures in terms of sample pre-treatment, measurement protocol, precision, and analytical uncertainty. For Cu isotopic analysis, both Zn and Ni were investigated for their merit as internal standard (IS) relied on for mass bias correction. The use of Ni as IS seems to be the most robust approach as Ni is less prone to contamination, has a lower abundance in bronzes and an ionization potential similar to that of Cu, and provides slightly better reproducibility values when applied to NIST SRM 976 Cu isotopic reference material. The possibility of carrying out direct isotopic analysis without prior Cu isolation (with AG-MP-1 anion exchange resin) was investigated by analysis of CRM IARM 91D bronze reference material, synthetic solutions, and archaeological bronzes. Both procedures (Cu isolation/no Cu isolation) provide similar δ 65Cu results with similar uncertainty budgets in all cases (±0.02–0.04 per mil in delta units, k = 2, n = 4). Direct isotopic analysis of Cu therefore seems feasible, without evidence of spectral interference or matrix-induced effect on the extent of mass bias. For Sn, a separation protocol relying on TRU-Spec anion exchange resin was optimized, providing a recovery close to 100 % without on-column fractionation. Cu was recovered quantitatively together with the bronze matrix with this isolation protocol. Isotopic analysis of this Cu fraction provides δ 65Cu results similar to those obtained upon isolation using AG-MP-1 resin. This means that Cu and Sn isotopic analysis of bronze alloys can therefore be carried out after a single chromatographic separation using TRU-Spec resin. Tin isotopic analysis was performed relying on Sb as an internal standard used for mass bias correction. The reproducibility over a period of 1 month (n = 42) for the mass bias-corrected Sn isotope ratios is in the range of 0.06–0.16 per mil (2 s), for all the ratios monitored

A generic approach for uncertainty quantification in stereovision DIC

Digital image correlation (DIC) is a wide-spread technique for measuring shape, motion and deformation in the field of experimental techniques. The complex optical-numerical nature of the technique however prohibits a straightforward and generic definition of error bars. Much uncertainty quantification has been done for 2D DIC, both experimental as numerical. Stereo-DIC is however much less investigated since the measurement chain becomes even more non-linear with the stereo-matching and the calibration stage. The novelty of this work lies in the introduction of an FE-based synthetic image generator, which is able to generate images as if they were obtained during a real experiment. Ground truth data becomes available by synthetically generating the images and individual experimental error sources can be extracted from the process. The validity and success of this technique is proven by the adoption by the stereo-DIC challenge, which is conducted under the auspices of the Society of Experimental Mechanics (SEM). Different sets of calibration and test images are generated for providing the DIC community a set of images for software testing, verification, benchmarking,... The target of this work thus is bringing more insight into stereo-DIC uncertainty quantification by programming a synthetic image generator and by investigating as many error sources as possible. This is reflected in the following contributions: • Development of a generic stereo-DIC image generator • Investigation of the calibration uncertainty with a Monte-Carlo approach • Uncertainty quantification of stereo-DIC by synthetic images • Investigation of relative camera motion, compensation methods and error estimationstatus: publishe

Closed-Loop Optimization of DIC Speckle Patterns Based on Simulated Experiments

Stereo digital image correlation (DIC) spreads widely in the last years as one of the most flexible and accurate full-field displacement-strain measurement techniques. The development of novel applications based on DIC makes the design of 3-D setups a challenging task, given the complex and nonlinear nature of stereophotogrammetric methods. The present literature allows the design and optimization of DIC experimental setup only with approximated uncertainty models or upon image quality metrics that are linked loosely with the actual value of uncertainty. In this paper, a closed-loop optimization method based on 3-D experiment simulation is presented. The approach may be used to optimize several parameters (from the camera setup to the DIC processing parameters). This paper features a case study on the problem of optimizing a regular speckle pattern for different measurement tasks. The whole approach is validated experimentally in Section V

An Experimental Investigation on Uncertainty in Measuring Vibration Deflection Shapes with Digital Image Correlation

3-D digital image correlation (DIC) is a widespread full-field displacement measurement technique based on stereo vision. It was formulated to deal with static problems in experimental mechanics in the early seventies, and since then, the applicability of the technique increased due to increasing frame rates and dropping prices of machine vision cameras. As a consequence, DIC became a feasible solution for general-purpose vibration testing. This paper, however, does not offer a comprehensive analysis of DIC accuracy when applied to vibration testing, and therefore, this paper offers a 'Type A' evaluation of uncertainty when measuring vibration deflection shapes with DIC. Uncertainty is evaluated for different experimental conditions on a stepped sine test. Data show that the average value of uncertainty normally lies below 0.02 mm, but in resonant conditions, it can increase up to 0.05 mm (considering a field of view of about half a meter). This demonstrates a strong correlation between the deflection amplitude and the random uncertainty due to motion blur