科研之友
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摘要
Gold nanoparticles protected by carboxylated alkane thiols were coupled with a BrO3--SO32-/HSO3- pH oscillator which had large-amplitude and long-period oscillations. Reversible, repetitive, and sustainable pH-responsive switching between the assembled and disassembled states of the gold nanoparticles was achieved and examined via simultaneous in situ pH and optical absorption measurements. Spectral changes caused by the assembly/disassembly process revealed that the switch included at least three processes: (1) a rapid assembling process with gradual red-shifts in the localized surface plasmon resonance (LSPR), (2) a rapid disassembling process with gradual blue-shifts in the LSPR, and (3) a slow disassembling process with an isosbestic point at the middle wavelength, whose origins were closely related to the pH change dynamics of each process. The disassembly processes were found to have a delayed response to the pH change to propagate the disassembling process from the periphery to the inside of the assembly, whereas assembly proceeded in a well-synchronized manner with the pH change. These new findings indicate the importance of the pH oscillation rate as a controlling factor for the assembly/disassembly dynamics of pH-responsive materials.
- 出版日期2012-3-15
