Search

Drug delivery monitoring and tracking in the human body are two of the biggest challenges in targeted therapy to be addressed by nanomedicine. The ability of imaging drugs and micro-/nanoengineered drug carriers and of visualizing their interactions at the cellular interface in a label- free manner is crucial in providing the ability of tracking their cellular pathways and will help understand their biological impact, allowing thus to improve the therapeutic efficacy. We present a fast, label-free technique to achieve high-resolution imaging at the mid-infrared (MIR) spectrum that provides chemical information. Using our custom-made benchtop infrared microscope using a high-repetition-rate pulsed laser (80 MHz, 40 ps), we were able to acquire images with subwavelength resolution (0.8 × λ) at very high speeds. As a proof-of-concept, we embarked on the investigation of nanoengineered polyelectrolyte capsules (NPCs) containing the anticancer drug, docetaxel. These NPCs were synthesized using a layer-by-layer approach built upon a calcium carbonate (CaCO3) core, which was then removed away with ethylenediaminetetraacetic acid. The obtained MIR images show that NPCs are attached to the cell membrane, which is a good step toward an efficient drug delivery. This has been confirmed by both three-dimensional confocal fluorescence and stimulated emission depletion microscopy. Coupled with additional instrumentation and data processing advancements, this setup is capable of video-rate imaging speeds and will be significantly complementing current super-resolution microscopy techniques while providing an unperturbed view into living cells

MSb2O4 constitutes a relatively unexplored class of multinary oxides that is traditionally synthesized by high-temperature solid-state methods. Here, we report a facile synthesis of CoSb2O4 under hydrothermal conditions (T = 135–300 °C, 256 bar). Using in situ synchrotron powder X-ray diffraction (PXRD), the formation and growth of CoSb2O4 nanoparticles are followed in real time using different precursor stoichiometries. Phase-pure CoSb2O4 can be formed at 135 °C, although the formation mechanism changes with precursor stoichiometry. The crystallite size can be fine-tuned between 14 and 17.5 nm under nonstoichiometric conditions, but crystallites twice as large are found in the stoichiometric case. An activation energy of 65(12) kJ/mol is obtained for the crystallization from a nonstoichiometric precursor. Modeling of atomic displacement parameters obtained from Rietveld refinement of multi-temperature high-resolution synchrotron PXRD data gives a Debye temperature of 331(11) K. The thermal expansion coef...

Thermal self-assembly of C-60 on (1 x 2)-Pt(110) following room-temperature deposition has been studied by means of scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and density functional theory (DFT) calculations. Two distinct C-60 chemisorption phases have been identified and characterized as a function of the annealing temperature. After a thermal treatment at 700 K, islands of a C-60 quasi-hexagonal lattice form. These islands are characterized by the highest surface density so far reported for a two-dimensional surface-supported fullerene phase (the surface area per molecule is 87.0 angstrom(2)), with intermolecular nearest-neighbor distances equal to 9.6 +/- 0.1 angstrom. Embedded nanowires of fullerene dumbbell dimers (with an intermolecular distance equal to 9.2 +/- 0.1 A) occasionally nucleate within this high-density phase following a "molecular zip" mechanism. Highly site selective chemisorption driven by the particularly strong overlayer-substrate bonding is proposed to be responsible for the first reported example of surface-templated chemical bond formation between fullerene molecules. After annealing at 850 K, an oblique C-60 chemisorption phase forms. This is characterized by a tetramolecular basis associated to each lattice point of the two-dimensional superstructure and by a peculiar bright-dim contrast in STM images acquired at positive sample bias values. The combination of high-resolution STM images with LEED data and DFT calculations leads to the conclusion that the (1 x 2) substrate reconstruction is lifted at the fullerene-platinum interface and also provides a detailed description of the molecular bonding sites and orientations found within the phase. It is proposed that the main factor ruling the interconversion of chemisorption phases is the variation of substrate atom mobility as a function of temperature.

The changes in the surface composition of a Pt(50)Rh(50)(100) alloy due to an ongoing 2H(2) + O(2)--2H(2)O chemical reaction have been studied in situ. Exploiting the high-energy resolution and surface sensitivity of synchrotron radiation core-level spectroscopy it was possible to monitor the population of the two transitions metals atoms at the gas-surface interface. Sequences of fast high-resolution core-level spectra of the Rh3d(5/2), Pt4f(7/2), and O1s core levels showed a continuous exchange of atoms between the first and subsurface layers. An unexpected Pt surface enrichement was found under slightly oxidizing conditions, opposite to what found in a highly oxidizing atmosphere.