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  • Electrostatic repulsion-controlled formation of polydopamine-gold Janus particles.

Electrostatic repulsion-controlled formation of polydopamine-gold Janus particles.

Langmuir : the ACS journal of surfaces and colloids (2012-08-22)
Haolan Xu, Xiaokong Liu, Ge Su, Bin Zhang, Dayang Wang
ABSTRACT

Polydopamine (PDA)-Au Janus particles were obtained by simply adding HAuCl(4) to a PDA particle suspension, prepared via self-polymerization of dopamine in basic solution at room temperature. The structures of the PDA-Au particles are readily controlled by electrostatic repulsion between the constituent particles, which can be realized simply via adjusting the environmental pH. PDA-Au Janus particles are formed only in a narrow pH range of 2.5-3.0 due to the properly enhanced electrostatic repulsion between the Au particles growing on as-prepared PDA particles and between the Au and PDA particles. The obtained PDA-Au Janus particles can become interfacially active and self-assemble at oil/water interfaces as a result of spatially well-separated hydrophilic (PDA) and hydrophobic (Au) domains on the surfaces, reminiscent of amphiphilic molecules.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Gold(III) chloride solution, 99.99% trace metals basis, 30 wt. % in dilute HCl
Sigma-Aldrich
Sodium tetrachloroaurate(III) dihydrate, 99%
Sigma-Aldrich
Potassium gold(III) chloride, 98%
Sigma-Aldrich
Potassium gold(III) chloride, 99.995% trace metals basis