While the chemical composition of semiconducting metal halide perovskites can be precisely controlled in thin films for photovoltaic devices, the synthesis of perovskite nanostructures with tunable dimensions and composition has not been realized. Here, we describe the templated synthesis of uniform perovskite nanowires with controlled diameter (50-200 nm). Importantly, by providing three examples (CH3NH3PbI3, CH3NH3PbBr3, and Cs2SnI6), we show that this process is composition general and results in oriented nanowire arrays on transparent conductive substrates.
Anisotropic gold nanoparticles often
exhibit superior optical properties
compared to spherical ones, in part due to intense electric field
localization near sharp geometric features and a broadly tunable localized
surface plasmon resonance. As a result, anisotropic nanoparticles
are attractive building blocks for surface-enhanced Raman spectroscopy
(SERS) substrates. To unlock the full potential of such substrates,
one should be able to (1) generate a sufficient number of SERS hotspots
with structures of controlled shape and size and (2) remove ligands
so that analytes can easily access nanoparticle surface sites. Here,
we develop a synthetic strategy for the shape- and size-controlled
anisotropic growth of gold nanoparticles (concave rhombic dodecahedra
and concave cubes, 70–135 nm characteristic length) from spherical
seeds anchored on a structurally complex surface (common filter paper)
and subsequently combine electrodynamics and electronic structure
calculations with experiment to systematically characterize these
substrates using SERS. Furthermore, we explore the generalizable functionality
of these substrate-stabilized nanoparticles by using a continuous
extraction method to partially remove surface ligands that were necessary
for anisotropic growth, enabling the specific SERS detection of serotonin,
a molecular neurotransmitter with a weak affinity for gold.
We report a template-based technique for the preparation of solution-dispersible nanorings composed of Au, Ag, Pt, Ni, and Pd with control over outer diameter (60-400 nm), inner diameter (25-230 nm), and height (40 nm to a few microns). Systematic and independent control of these parameters enables fine-tuning of the three characteristic localized surface plasmon resonance modes of Au nanorings and the resulting solution-based extinction spectra from the visible to the near-infrared. This synthetic approach provides a new pathway for solution-based investigations of surfaces with negative curvature.
Bone is a specialized form of connective tissue that forms the skeleton of the body and is built at the nano and microscale levels as a multi-component composite material consisting of a hard inorganic phase (minerals) in an elastic, dense organic network. Mimicking bone structure and its properties present an important frontier in the fields of nanotechnology, materials science and bone tissue engineering, given the complex morphology of this tissue. There has been a growing interest in developing artificial bone-mimetic nanomaterials with controllable mineral content, nanostructure, chemistry for bone, cartilage tissue engineering and substitutes. This review describes recent advances in bionanomaterials for bone tissue engineering including developments in soft tissue engineering. The significance and basic process of bone tissue engineering along with different bionanomaterial bone scaffolds made of nanocomposites and nanostructured biopolymers/bioceramics and the prerequisite biomechanical functions are described. It also covers latest developments in soft-tissue reconstruction and replacement. Finally, perspectives on the future direction in nanotechnology-enabled bone tissue engineering are presented.
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