There has been an increasing interest in the past few years in the synthesis of ferroelectric nanocrystals because of their scientific importance and widespread applications in electronics, sensing, catalysis, and nonlinear optics. 1 BaTiO 3 is a perovskite-type ceramic with unique mechanical, ferroelectric, electro-optic, pyroelectric, dielectric, and elastic properties that find use in multilayered capacitors, random access memories, thermistors, photonic crystals, pressure transducers, and waveguide modulators. 2 It is well-known that perovskite nanocrystals possess structural and physical properties that are strongly dependent on their size, shape, crystallinity, and surface composition. For example, in nanoscale BaTiO 3 , the transition temperature from the ferroelectric (tetragonal) to the paraelectric (cubic) phase decreases progressively with the size of the particles as a result of a less distorted coordination environment of the Ti 4þ ions within the TiO 6 octahedra. However, there is no clear consensus as to the critical size at which ferroelectricity is suppressed, and consequently, the values reported extend over a wide range, typically from 120 to 4.2 nm. 3 Despite the increasing number

Increasing biomedical applications of iron oxide nanoparticles (IONPs) in academic and commercial settings have alarmed the scientific community about the safety and assessment of toxicity profiles of IONPs. The great amount of diversity found in the cytotoxic measurements of IONPs points toward the necessity of careful characterization and quantification of IONPs. The present document discusses the major developments related to in vitro and in vivo toxicity assessment of IONPs and its relationship with the physicochemical parameters of IONPs. Major discussion is included on the current spectrophotometric and imaging based techniques used for quantifying, and studying the clearance and biodistribution of IONPs. Several invasive and non-invasive quantification techniques along with the pitfalls are discussed in detail. Finally, critical guidelines are provided to optimize the design of IONPs to minimize the toxicity.

No abstract

Methods have been developed for the shape-selective synthesis of ferroelectric LiNbO 3 nanoparticles. Decomposition of the single-source precursor, LiNb(O-Et) 6 , in the absence of surfactants, can reproducibly lead to either cube-or sphere-like nanoparticles. X-Ray diffraction shows that the LiNbO 3 nanoparticles are rhombohedral (R3c). Sample properties were examined by piezoresponse force microscopy (PFM) and Raman where both sets of nanoparticles exhibit ferroelectricity. The longitudinal piezoelectric coefficients, d 33 , varied with shape where the largest value was exhibited in the nanocubes (17 pm V 21 for the cubes versus 12 pm V 21 for spheres).