Controlling Nanoparticle Aggregation in Colloidal Microwave Absorbers via Interface Chemistry
نویسندگان
چکیده
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 secmol to 368 secmol 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.
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