Controlling nanoparticle aggregation in colloidal microwave absorbers via interface chemistry

Brian A. Larsen; Michael A Haag; Michael H. B. Stowell; David C. Walther; Albert P. Pisano; Conrad R. Stoldt

doi:10.1117/12.715911

27 April 2007 Controlling nanoparticle aggregation in colloidal microwave absorbers via interface chemistry

Brian A. Larsen, Michael A Haag, Michael H. B. Stowell, David C. Walther, Albert P. Pisano, Conrad R. Stoldt

Proceedings Volume 6525, Active and Passive Smart Structures and Integrated Systems 2007; 652519 (2007) https://doi.org/10.1117/12.715911
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2007, San Diego, California, United States

Abstract

Interface chemistry can be implemented to modulate the aggregation and dispersion of nanoparticles in a colloidal solution. In this experimental study, we demonstrate the controlled aggregation of superparamagnetic magnetite nanoparticles in organic and aqueous solutions. With decrease in solution pH, individual nanoparticles (12-14 nm) reproducibly cluster to form ~52 nm monodisperse aggregates in toluene. Spin-spin (T2) proton relaxation measurements of the micellated clusters before and after aggregation show a change in the molar relaxation rate from 303 sec^-1mol^-1 to 368 sec^-1mol^-1 for individual and clustered nanoparticles, respectively. DNA-mediated aggregation of micellated nanoparticles in the colloidal solution is also demonstrated where the number of single-stranded DNA per particle determines the ultimate size of the nanoparticle aggregate.

Citation Download Citation

Brian A. Larsen, Michael A Haag, Michael H. B. Stowell, David C. Walther, Albert P. Pisano, and Conrad R. Stoldt "Controlling nanoparticle aggregation in colloidal microwave absorbers via interface chemistry", Proc. SPIE 6525, Active and Passive Smart Structures and Integrated Systems 2007, 652519 (27 April 2007); https://doi.org/10.1117/12.715911

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