Search

The authors regret the following minor errors in the published article: In Section 2.1 (Materials), two chemicals, lead iodide and ethanol, were accidentally omitted from the list. The revised text should read:

Three dimensional epitaxially-fused colloidal quantum dot (QD) superlattices (epi-SLs) feature exceptional electronic coupling and spatial order and are promising systems for studying the emergence of delocalized states and mini-band charge transport in self-assembled solids. However, energy disorder arising from structural defects and aperiodicity has so far resulted in charge carrier localization and slow hopping transport. Detailed 3D structural characterization is critical for rationally improving epi-SL structural perfection to trigger the formation of mini-bands. Here, we analyze the 3D structure of a 120 × 38 nm disc-shaped region of a PbSe QD epi-SL using full-tilt high-angle annular dark-field electron tomography. The high spatial resolution of the tomographic reconstruction (0.65 nm) enables determination of the center-of-mass coordinates of all 1846 QDs in the sample as well as the size and shape of the thousands of epitaxial connections (necks) between the QDs. The tomogram reveals the detailed crystallography and internal positional disorder of the three SL grains that constitute this sample. A map of the neck network is used to quantify relationships between neck number (the number of necks each QD possesses), average neck diameter, QD location in the film, and the nearest neighbor inter-QD distance and distance distribution. We find a strong positive correlation between neck number and local spatial order, suggesting that future improvements in neck connectivity are likely to simultaneously enhance the overall structural perfection of the epi-SLs. A kinetic Monte Carlo model is employed to estimate the electron mobility of the tomography sample and assess the impact of grain boundaries on charge transport. Our electron tomography study establishes a baseline for the quantitative statistical analysis of structural defects in 3D QD epi-SLs.

Introduction: HBc particles have potential as drug delivery vehicles for cancer therapy. They are hollow nano-particles of 30-34 nm diameter and 7 nm thick envelopes, consisting of 180-240 units of 21 kDa core monomers. They possess the capacity to assemble/disassemble in a controlled manner, allowing encapsidation of various drugs and other biomolecules. Furthermore, other functional motifs, like receptor binding sequences, can be expressed. Objectives: This study focuses on the development of genetically modified HBc particles for in vivo nuclear imaging to specifically target HER- 2-expressing tumours, for future cancer diagnosis and therapy. Materials and Methods: The non-specific binding capacity of wild type HBc particles was reduced by genetic deletion of the sequence encoding argininerich domains. ZHER-2 affibodies were expressed on the HBc particles surface to achieve a specific HER-2-targeting. HIS-tag was introduced at the N-terminal of HBc monomers to allow the radiolabelling of HBc particles with 99mTc. SPECT/CT imaging and quantitative gamma counting were performed to characterise the organ biodistribution profile of the HER-2 specific-targeting HBc particles in tumour-bearing mice. Results: 97.2% and 98.0% radiolabelling efficiency was achieved for ΔHBc and ZHER-2-ΔHBc particles, respectively. 99mTc-ΔHBc and 99mTc-ZHER-2-ΔHBc was purified from free [99mTc(CO)3]+ and exhibited 100% radiolabelling efficiency. Both types of HBc particles exhibited 100% stability in serum and PBS. In vivo studies confirmed positive uptake of ZHER-2- ΔHBc particles in HER-2-expressing tumours, compared to non-targeted ΔHBc particles in intraperitoneal tumourbearing mice models. Conclusion: The present results highlight the potential of these nanocarriers in targeting HER-2-positive metastatic abdominal cancer following intra-peritoneal administration. [ABSTRACT FROM AUTHOR]

Triple-modal imaging magnetic nanocapsules, encapsulating hydrophobic superparamagnetic iron oxide nanoparticles, are formulated and used to magnetically target solid tumours after intravenous administration in tumour-bearing mice. The engineered magnetic polymeric nanocapsules m-NCs are ~200 nm in size with negative Zeta potential and shown to be spherical in shape. The loading efficiency of superparamagnetic iron oxide nanoparticles in the m-NC was ~100%. Up to ~3- and ~2.2-fold increase in tumour uptake at 1 and 24 h was achieved, when a static magnetic field was applied to the tumour for 1 hour. m-NCs, with multiple imaging probes (e.g. indocyanine green, superparamagnetic iron oxide nanoparticles and indium-111), were capable of triple-modal imaging (fluorescence/magnetic resonance/nuclear imaging) in vivo. Using triple-modal imaging is to overcome the intrinsic limitations of single modality imaging and provides complementary information on the spatial distribution of the nanocarrier within the tumour. The significant findings of this study could open up new research perspectives in using novel magnetically-responsive nanomaterials in magnetic-drug targeting combined with multi-modal imaging.