Reversible aggregation between nanoparticles induced by acid–base interactions

• Published in: Chemical physics letters Vol. 546; pp. 133 - 135
• Main Authors: Ionita, Gabriela, Ghica, Corneliu, Turcu, Ioana, Ionita, Petre
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 12.09.2012
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2012.08.009

Mixture of carboxyl-terminated gold nanoparticles with amino-terminated silica nanoparticles lead to aggregation; by pH change, the aggregates reversible dissolute. [Display omitted] ► Amino-silica and carboxyl-gold protected nanoparticles aggregate by acid–base interactions. ► Processes studied by ESR, fluorescence, and TEM. ► Acid–base interactions are reversible, aggregates re-dissolute by pH change. Acid–base interactions between amino-silica and carboxyl-gold protected nanoparticles, functionalized or not with free stable radicals or fluorescent moieties, were studied by ESR, fluorescence, and TEM. While those nanoparticles are stable in solution, mixing them induces aggregation, due to acid–base interactions; addition of a base or an acid redissolves them. By ESR, strong spin–spin interactions were noticed; by fluorescence, only small differences may be observed, while by TEM, it was noticed that gold nanoparticles are distributed evenly on the surface of the silica nanoparticles.