Surfactant-free coating of thiols on gold nanoparticles using sonochemistry: a study of competing processes.
A method for the surfactant-free coating of gold nanoparticles with thiols using sonochemistry is presented. The gold nanoparticles were prepared by a modified Zsigmondy method, affording good control over the particle-size distribution, and the thiol coating was performed by the sonication of a biphasic system consisting of a nanoparticle suspension in water and thiols in toluene. The effects of two important reaction parameters on the particle morphology, viz. sonication time and thiol concentration, were investigated in detail using transmission electron microscopy. The effect of the thiol chain length was also studied. We show that the morphology of the coated particles is determined through a competition between two opposing effects: particle fusion, due to the sonication conditions, and digestive ripening, due to the action of the thiols. Additionally, we illustrate the utility of our technique for various applications, including surface-enhanced Raman scattering from bound molecules, and further functionalization using a thiol-exchange reaction. Our technique paves the way for an efficient synthesis of thiol-coated AuNPs of different shapes and sizes, suitable for a range of diverse applications.
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
Anuradha
A
Pallipurath
Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK.
Olivia
O
Nicoletti
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
Jonathan M
JM
Skelton
Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
Sumeet
S
Mahajan
Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK.
Paul A
PA
Midgley
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. Electronic address: sre1@cam.ac.uk.
Stephen R
SR
Elliott
D001894:Borohydrides; D006046:Gold / Q000737:chemistry*; D007202:Indicators and Reagents; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000528:radiation effects*; D055616:Microtechnology / Q000379:methods*; D010316:Particle Size; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D013438:Sulfhydryl Compounds / Q000737:chemistry* / Q000528:radiation effects*; D014465:Ultrasonics / Q000379:methods*
D001894:Borohydrides; D007202:Indicators and Reagents; D013438:Sulfhydryl Compounds; D006046:Gold; C025364:sodium borohydride
Digestive ripening; Gold nanoparticles; Sonochemistry; Surface-enhanced Raman scattering; Thiol coating