A simple procedure has been developed for aggregation of polyvinylpyrrolidone (PVP) capped gold nanoparticles by controlling the pH of the solution. PVP-capped gold nanoparticles were synthesized via wet chemical method. Transmission electron microscopy (TEM) and UV-vis spectroscopy
techniques were employed for determining the morphological features and surface plasmon resonance (SPR) of the gold nanoparticles. When the pH of the solution containing PVP-capped gold nanoparticles was changed from 6.7 to 1.0, the color of the solution changed from deep red to blue due to
SPR weakening by particle aggregate formation. The color of the solution returned to its original red when the pH of the solution was brought back to 6.7. Furthermore, citrate protection of the gold nanoparticles was found to inhibit the reverse action. This reversible/irreversible-selectable
structural control of gold nanoparticles with drastic changes in their optical absorption characteristics may find various nanophotonic applications including contactless pH detection.
Materials Express is a peer-reviewed multidisciplinary journal reporting emerging researches on materials science, engineering, technology and biology. Cutting-edge researches on the synthesis, characterization, properties, and applications of a very wide range of materials are covered for broad readership; from physical sciences to life sciences. In particular, the journal aims to report advanced materials with interesting electronic, magnetic, optical, mechanical and catalytic properties for industrial applications.