Enhanced Nanoparticle Size Control by Extending LaMer’s Mechanism

Abstract

The synthesis of well-defined nanoparticle materials has been an area of intense investigation, but size control in nanoparticle syntheses is largely empirical. Here, we introduce a general method for fine size control in the synthesis of nanoparticles by establishing steady state growth conditions through the continuous, controlled addition of precursor, leading to a uniform rate of particle growth. This approach, which we term the "Extended LaMer Mechanism" allows for reproducibility in particle size from batch to batch, as well as the ability to predict nanoparticle size by monitoring the early stages of growth. We have demonstrated this method by applying it to a challenging synthetic system: magnetite nanoparticles. To facilitate this reaction, we have developed a reproducible method for synthesizing an iron oleate precursor that can be used without purification. We then show how such fine size control affects the performance of magnetite nanoparticles in magnetic hyperthermia.

The relaxation wall: experimental limits to improving MPI spatial resolution by increasing nanoparticle core size

“…The core is single crystalline magnetite ( Fe 3 O 4 ) for all core sizes. This is experimentally confirmed by prior work (Vreeland et al 2015) with high resolution transmission electron microscopy (HRTEM) and X-ray diffraction. A representative data sample is found in the supplementary information of this reference.…”

“…The precise mass of iron in the sample was determined using a colorimetric assay as described previously (Vreeland et al 2015). Magnetization curves were recorded from −4000 kA/m to +4000 kA/m at 293K.…”

“…3b. The exact synthesis and more characterization of the nanoparticles can be found in detail in the main article and supplementary information of (Vreeland et al 2015). The MPI performance of the SPIOs was also measured using a magnetic particle spectrometer/relaxometer described in (Tay, Patrick Goodwill, et al 2016) as well as the x-space MPI scanner described in (L.…”

Fast nucleation for silica nanoparticle synthesis using a sol–gel method

“…21 This has accelerated the nanoparticle formation in our case as evident from our findings where we were able to synthesize particles within minutes at specific ethanol-water ratio in the reaction medium (Figure 1; Supplementary Note 1). Considering the consumption behavior of TEOS and hydroxyl (OH − ) in solution (Supplementary Table 1 & 2) our findings were in agreement with the theory of burst nucleation mechanism 16,30 . As evident, the hydroxyl ionconcentration substantially decreased within first 20 min.…”

Continuous Growth of Metal Oxide Nanocrystals: Enhanced Control of Nanocrystal Size and Radial Dopant Distribution

“…Several groups have recently acknowledged the importance of more generalizable synthetic methods for assembling complex nanomaterials, 21 Recently, several synthetic approaches have been reported that employ slow addition of precursor to extend the growth of nanocrystals and demonstrate some of the potential benefits of continuous growth process. [25][26][27] We previously showed that slow addition of metal oleates into hot oleyl alcohol produced monodispersed nanocrystals for a variety of binary oxides. 28 The catalytic esterification reactions that lead to nanocrystal formation seemed ideal to examine whether these syntheses could be used to carry out continuous growth of binary oxide 4 nanocrystals and, potentially, to control the radial placement of dopant atoms in the oxide matrix.…”