Enhanced Nanoparticle Size Control by Extending LaMer’s Mechanism

TLDR

Nanoparticle synthesis has been intensely studied, yet size control remains largely empirical. The authors propose a general method for fine size control by establishing steady‑state growth through continuous, controlled precursor addition. They achieve this by continuously adding precursor to maintain steady‑state growth and by developing a reproducible, purification‑free iron oleate precursor synthesis. The extended LaMer approach yields reproducible, predictable magnetite nanoparticle sizes and improves their magnetic hyperthermia performance.

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.