Preparation and analysis of a two-components breath figure at the nanoscale

International audienceSolid/liquid two-components Ga-Pb structures in isolated nanometer sized particles have been produced and studied by electron microscopy. Production is based on the breath figure technique and we investigate the way the two components are distributed. We clearly identify two growth regimes associated with the two different ways a Pb atom incorporates into a Ga nanodrop. Using TEM and SEM, the shape and microstructure of the nanoparticles are studied and the results obtained are in good agreement with the proposed model. The experimental technique used appears to be appropriate to produce Pb nanocrystals in liquid Ga nano-containers

Three-dimensional optical data storage through multi-photon confocal microscopy and imaging

Three dimensional optical data storage is one of the most promising tools to respond to the always growing demand for high data storage capacity. Here, we focused a femtosecond laser source by means of a confocal microscope onto different transparent recording media. The purpose of the study is to probe the capability of the system to independently address different data layers within the storage medium achieving thus three dimensional data storage. We demonstrated the possibility to write superposed independent layers of data due to either multiphoton excitation or to local optical breakdown and the performances observed in the different types of media used are compared

The prognostic value of basal DNA damage level in peripheral blood lymphocytes of patients affected by bladder cancer

Bladder cancer (BC) is one of the most aggressive malignancies of the urinary tract, with the highest lifetime treatment costs per patient of all cancers, due to the high rate of recurrences requiring continuous surveillance. An early diagnosis is essential to improve survival of patients with BC. Noninvasive and sensitive molecular biomarkers are needed to improve current strategies for the detection and monitoring of BC. Previous studies suggested that elevated DNA damage levels and suboptimal nucleotide excision DNA repair (NER) may be associated with BC

Dual Drug Loaded Nanotheranostic Platforms as a Novel Synergistic Approach to Improve Pancreatic Cancer Treatment

This study focuses on the development of theranostic, dual drug-loaded nanocarriers to propose a proof-of-principle therapeutic approach in the treatment of pancreatic ductal adenocarcinoma (PDAC). The nanoconstructs consist of a core of zinc oxide nanocrystals doped with gadolinium, useful as a potential contrast agent in magnetic resonance imaging applications. After functionalizing their surface with amino-propyl groups, the physical adsorption of two hydrophobic drugs is performed: Vismodegib and Sorafenib. Their synergistic use might improve PDAC treatment and stroma depletion when co-delivered in the tumor microenvironment for future in vivo applications. To enhance the nanoconstructs’ biostability, the ensemble is coated by a lipid bilayer and a tumor targeting peptide is incorporated on the outer shell surface. As a first proof of concept, the resulting nanoconstructs are tested against two pancreatic cancer cell lines, showing a modest increase in treatment efficacy compared to the free drug counterparts and proving to spare healthy pancreatic cells. In a second testing set, the dual-drug loaded nanoconstructs are tested on both cell lines previously sensitized to a firstline chemotherapeutic drug, Gemcitabine, showing an improved treatment response. From these preliminary results, the nanotheranostic platforms might constitute a good starting point for future PDAC therapy and diagnosis studies

Localized formation and size tuning of CdS nanocrystals upon irradiation of metal precursors embedded in polymer matrices

We present a method of spatial and dimensional controlled formation of CdS quantum dots into polymer matrices by light irradiation. The initial samples consist of Cd thiolate precursors doped in TOPAS polymer matrix. Under pulsed UV laser irradiation the precursors are photolysed driving to the nucleation of CdS nanocrystals, with increasing size and concentration, related to the number of UV pulses. The formed quantum dots are localized in the irradiated area, while the host polymer remains macroscopically unaffected by the UV irradiation. In this study we investigate how the formation of the nanocrystals (size, dimensions, and concentration) is affected by the use of different irradiation conditions (wavelength, number of pulses), revealing information about the different pathways followed during the formation. The change of the size of the dots results in the change of the peak of their emission due to the quantum size effect, which is studied by fluorescence measurements. The results are reinforced by TEM microscopy and by XRD measurements. The main advantages of the presented method are the size tuning of the produced dots and their spatial confinement inside the host matrix, not possible by the other methods used until now (thermal annealing, mixing etc.)

Rod-shaped nanostructures based on superparamagnetic nanocrystals as viscosity sensors in liquid

The following article appeared in Journal of Applied Physics 110.6 (2011): 064907 and may be found at http://scitation.aip.org/content/aip/journal/jap/110/6/10.1063/1.3638695Superparamagnetic nanostructures are becoming increasingly important as tools for biological and medical applications. We report the study of the movement of rod-shaped assemblies of superparamagnetic nanocrystals under the action of a rotating magnetic field. The dynamic was characterized by means of light scattering detection at different frequencies and for different values of the intensity of the applied external field. The possibility to correlate the motion to the viscosity of the medium is used to monitor viscosity changes inside the liquid. We propose this technique as a valuable tool to monitor viscosity at microscale for application in biological studies.This work was partially supported by the European project Magnifyco (Contract NMP4-SL-2009-228622)

Optical data storage in photochromic compounds

The future of optical data storage and the search for next generation high-density technologies have become a topic of lively debate. Three dimensional (3D) optical data storage, a relatively new technique which enables hundreds-layer data recording in a hard memory, seems a viable candidate for this role. In this work, we report on 3D optical data storage in photochromic compounds. The recording medium used in the experiments was a photochromic diarylethenes derivative embedded in different host polymers. Multi-photon processes capability of triggering photochemical reactions and physical changes with micrometer-sized resolution in three dimensions offers a well-suited means to achieve volumetric storage densities. A commercial microscope coupled to pulsed NIR and CW lasers have been used to write, read and erase data in our prototype memories. Information was recorded within the volume of the media via a multi-photon process achieving high localized photoconversion and the fluorescence emission from the photoconverted molecules when excited by a 405 nm laser diode was the readout signal. It is also shown that data recorded in such a medium can be selectively erased by irradiating with 514 nm CW laser light giving the chance to write new data in the formerly used memory space. These storage media, thus, have good potentials to achieve volumetric storage of data although they certainly deserve further optimization work to achieve high number of superposed layers and to assure durability of the written data under readout conditions

The structure of DNA by direct imaging

The structure of DNA was determined in 1953 by x-ray fiber diffraction. Several attempts have been made to obtain a direct image of DNA with alternative techniques. The direct image is intended to allow a quantitative evaluation of all relevant characteristic lengths present in a molecule. A direct image of DNA, which is different from diffraction in the reciprocal space, is difficult to obtain for two main reasons: the intrinsic very low contrast of the elements that form the molecule and the difficulty of preparing the sample while preserving its pristine shape and size. We show that through a preparation procedure compatible with the DNA physiological conditions, a direct image of a single suspended DNA molecule can be obtained. In the image, all relevant lengths of A-form DNA are measurable. A high-resolution transmission electron microscope that operates at 80 keV with an ultimate resolution of 1.5 Å was used for this experiment. Direct imaging of a single molecule can be used as a method to address biological problems that require knowledge at the single-molecule level, given that the average information obtained by x-ray diffraction of crystals or fibers is not sufficient for detailed structure determination, or when crystals cannot be obtained from biological molecules or are not sufficient in understanding multiple protein configurations