PEBBLES is a user-friendly software program which implements an accurate, unbiased, and fast method to measure the morphology of a population of nanoparticles (NPs) from TEM micrographs. The morphological parameters of the projected NP shape are obtained by fitting intensity models to the TEM micrograph. PEBBLES can be used either in automatic mode, where both fitting and validation are reliably carried out with minimal human intervention, and in manual mode, where the user has full control on the fitting and validation steps. Accuracy in diameter measurement has been shown to be ≲1%. When operated in automatic mode, PEBBLES can be very fast. The effective speed of 1 NP s⁻¹ has been achieved in favorable cases (packed monolayer of NPs). Since PEBBLES is based on a local modeling procedure, it successfully treats cases such as low contrast NPs, NPs with significant diffraction scattering, and inhomogeneous background which often make conventional thresholding procedures fail. PEBBLES is accompanied by PEBBLEJUGGLER, a software program for the statistical analysis of the sets of best-fit NP models created by PEBBLES. Effort has been devoted to make PEBBLES and PEBBLEJUGGLER the most user-friendly and the least user-tedious we could. PEBBLES and PEBBLEJUGGLER are available at http://pebbles.istm.cnr.it.

Charge order in underdoped and optimally doped high-$T_{\mathrm{c}}$ superconductors ${\mathrm{Bi}}_2{\mathrm{Sr}}_{2-x}{\mathrm{La}}_x{\mathrm{CuO}}_{6+\delta }$ (Bi2201) is investigated by Cu $L_3$ edge resonant inelastic x-ray scattering. We have directly observed charge density modulation in the optimally doped Bi2201 at momentum transfer $Q_{\parallel }\simeq 0.23$ reciprocal lattice units, with smaller intensity and correlation length with respect to the underdoped sample. This demonstrates the short-range charge order in Bi2201 persists up to optimal doping, as in other hole-doped cuprates. We explored the nodal (diagonal) direction and found no charge order peak, confirming that charge density modulates only along the Cu-O bond directions. We measured the out-of-plane dependence of charge order, finding a flat response and no maxima at half integer L values. This suggests there is no out-of-plane phase correlation in single layer Bi2201, at variance from ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6+x}$ and ${\mathrm{La}}_{2-x}{(\text{Ba},\text{Sr})}_x{\mathrm{CuO}}_4$. Combining our results with data from the literature we assess that charge order in Bi2201 exists in a large doping range across the phase diagram, i.e., $0.07\lesssim p\lesssim 0.16$, demonstrating thereby that it is intimately entangled with the antiferromagnetic background, the pseudogap, and superconductivity.

Nanoparticles (NPs) have received much attention in recent years for their diverse potential biomedical applications. However, the synthesis of NPs with desired biodistribution and pharmacokinetics is still a major challenge, with NP size and surface chemistry being the main factors determining the behavior of NPs in vivo. Here we report on the surface chemistry and in vitro cellular uptake of magnetic iron oxide NPs coated with zwitterionic dopamine sulfonate (ZDS). ZDS-coated NPs were compared to similar iron oxide NPs coated with PEG-like 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (MEEA) to investigate how surface chemistry affects their in vitro behavior. ZDS-coated NPs had a very dense coating, guaranteeing high colloidal stability in several aqueous media and negligible interaction with proteins. Treatment of HepG2 cells with increasing doses (2.5–100 μg Fe/mL) of ZDS-coated iron oxide NPs had no effect on cell viability and resulted in a low, dose-dependent NP uptake, inferior than most reported data for the internalization of iron oxide NPs by HepG2 cells. MEEA-coated NPs were scarcely stable and formed micrometer-sized aggregates in aqueous media. They decreased cell viability for dose ≥50 μg Fe/mL, and were more efficiently internalized than ZDS-coated NPs. In conclusion, our data indicate that the ZDS layer prevented both aggregation and sedimentation of iron oxide NPs and formed a biocompatible coating that did not display any biocorona effect. The very low cellular uptake of ZDS-coated iron NPs can be useful to achieve highly selective targeting upon specific functionalization.

The development of new molecules able to efficiently act as long‐circulating computed tomography (CT) contrast agents is one of the most crucial topics in the biomedical field. In the last years, the chance to manipulate materials at the nano‐size level gave new boost to this research, with the specific aim to design innovative nanoprobes. Gold nanoparticles (AuNPs) have showed unique X‐rays attenuation properties which, combined with their easy surface functionalization, makes them ideal candidates for the next generation of contrast agents. In this paper, we present a rational and facile approach to synthesize engineered and water‐stable AuNPs, achieving concentrated colloidal solution with high Hounsfield Units (HU). An accurate control of reagents ratio allowed us to design AuNPs with different shapes, from symmetrical to anisotropic morphology, in a convenient ‘one‐pot’ fashion. Their activity as efficient and reliable CT contrast agents has been evaluated and compared. Moreover, glucosamine‐functionalized gold nanoparticles have been developed ([Au] = 31.20 mg/mL; HU = 2453), in order to obtain a CT contrast agent able to combine spatial resolution with metabolic information. Copyright © 2016 John Wiley & Sons, Ltd.