Журнал наномедицины и нанотехнологий

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Probing Ionic Diffusion Dynamics through the Modulation of Polymer Shell Using Surface-Enhanced Raman Spectroscopy

Song X, Phua Z, Xu W and Liu

Gold nanoparticle (AuNP) encapsulated with a di-block copolymer, polystyrene-block-poly(acrylic acid) (PSPAA), is a type of core-shell nanoparticle (AuNP@PSPAA). We demonstrate the use of surface-enhanced Raman spectroscopy (SERS) to investigate the ionic diffusion of cyanide across the polymer shell. We modulate the PS blocks by using THF, incubation in water, aniline and its oligomers and lastly cholesterol, so as to increase the porosity of the polymer shell and promote the diffusion of cyanide to etch the AuNPs. Our results show that an increase in porosity will promote the etching rate and can be monitored in situ by observing the decrease in SERS intensities as the surface-active Raman molecules detaches from the AuNPs surface. Ionic diffusion of the cyanide ions is most prominent when THF is used as an organic solvent to swell the polymer shell. This new method provides us with a platform to probe ionic diffusion across hydrophobic membranes.