Colloidal inorganic nanocrystals stand out as an important class of advanced nanomaterials owing to the flexibility with which their physical-chemical properties can be controlled through size, shape, and compositional engineering in the synthesis stage and the versatility with which they can be implemented into technological applications in fields as diverse as optoelectronics, energy conversion/production, catalysis, and biomedicine. The use of microwave irradiation as a non-classical energy source has become increasingly popular in the preparation of nanocrystals (which generally involves complex and time-consuming processing of molecular precursors in the presence of solvents, ligands and/or surfactants at elevated temperatures). Similar to its now widespread use in organic chemistry, the efficiency of "microwave flash heating" in dramatically reducing overall processing times is one of the main advantages associated with this technique. This Review illustrates microwave-assisted methods that have been developed to synthesize colloidal inorganic nanocrystals and critically evaluates the specific roles that microwave irradiation may play in the formation of these nanomaterials.

Microwave-assisted synthesis of colloidal inorganic nanocrystals.

Better safe than sorry: Understanding the toxicological properties of inorganic nanoparticles manufactured for biomedical applications.

Polymeric nanoparticles: Promising platform for drug delivery.

Nanoprecipitation process: From encapsulation to drug delivery

The therapeutic effects of curcumin in treating Alzheimer’s disease (AD) depend on the ability to penetrate the blood–brain barrier. The latest nanoparticle technology can help to improve the bioavailability of curcumin, which is affected by the final particle size and stability. We developed a stable curcumin nanoparticle formulation to test in vitro and in AD model Tg2576 mice. Flash nanoprecipitation of curcumin, polyethylene glycol-polylactic acid co-block polymer, and polyvinylpyrrolidone in a multi-inlet vortex mixer, followed by freeze drying with β-cyclodextrin, produced dry nanocurcumin with mean particle size <80 nm. Nanocurcumin powder, unformulated curcumin, or placebo was orally administered to Tg2576 mice for 3 months. Before and after treatment, memory was measured by radial arm maze and contextual fear conditioning tests. Nanocurcumin produced significantly (p = 0.04) better cue memory in the contextual fear conditioning test than placebo and tendencies toward better working memory in the radial arm maze test than ordinary curcumin (p = 0.14) or placebo (p = 0.12). Amyloid plaque density, pharmacokinetics, and Madin–Darby canine kidney cell monolayer penetration were measured to further understand in vivo and in vitro mechanisms. Nanocurcumin produced significantly higher curcumin concentration in plasma and six times higher area under the curve and mean residence time in brain than ordinary curcumin. The Papp of curcumin and tetrahydrocurcumin were 1.8 × 10−6 and 1.6 × 10−5 cm/s, respectively, for nanocurcumin. Our novel nanocurcumin formulation produced highly stabilized nanoparticles with positive treatment effects in Tg2576 mice.

Highly Stabilized Curcumin Nanoparticles Tested in an In Vitro Blood–Brain Barrier Model and in Alzheimer’s Disease Tg2576 Mice

In recent years there has been a growing interest in production on an industrial scale of particles with size in the sub-micron range (40-200 nm). This can be done by controlling particle formation in order to nucleate very small particles and by tailoring the particle surface in order to avoid particle aggregation and produce stable suspensions. In this work we focus on the role of turbulent mixing on particle formation in confined impinging jet reactors. In particular, we show how computational fluid dynamics and simple precipitation models could be used to derive scale-up criteria for the production of nanoparticles. © 2006 American Institute of Chemical Engineers AIChE J, 2006

Design and scale‐up of chemical reactors for nanoparticle precipitation

Predictive design of nano-particle production via precipitation requires that the different steps through which particle formation occurs are deeply understood in order to control the final product properties and quality. In this work nano-particle precipitation in a confined impinging jet reactor (CIJR) is studied from the modelling point of view. The mathematical model, based on computational fluid dynamics (CFD), includes a micro-mixing model, the interchange by exchange with the mean (IEM) model coupled with the direct quadrature method of moments (DQMOM) approach, and solves the population balance equation (PBE) with the quadrature method of moments (QMOM). Eventually CFD predictions are compared with experimental data and good agreement is found.

Liliana Rivautella

Papers

Design and scale‐up of chemical reactors for nanoparticle precipitation

CFD Modelling of Nano-Particle Precipitation in Confined Impinging Jet Reactors

CFD modeling of precipitation of nano-particles in confined impinging jet reactor

Formation of nanocapsules by emulsion-diffusion: prediction of the emulsion size