Monodisperse PolymerStabilised Water Soluble Gold Nanoparticles Nicolas SCHAEFFER The University of Liverpool Department of Chemistry Crown street Liverpool L69 7ZD U.K. n.schaeffer@liverpool.ac.uk
Stabilization Van der Waals attraction
Stabilization Electrostatic repulsion Van der Waals attraction Electrostatic stabilization + + + + + + +
Stabilization Steric repulsion Van der Waals attraction Electrostatic stabilization Steric stabilization + + + + + + +
Polymeric stabilization
What makes a suitable stabilizer?
What makes a suitable stabilizer? Binding site Hydrophobic end Hydrophilic tail J. Am. Chem. Soc.; 2004; 126; 10076
Chain transfer polymerization R' Initiation 2 + N 2 N Initiator Chain transfert agent Monomers R S R' J. Macrmol. Sc. Part A; 1999, 36, 51
Chain transfer polymerization Chain transfer R S R' J. Macrmol. Sc. Part A; 1999, 36, 51
Chain transfer polymerization Chain transfer Initiation R S R' Propagation R S R' J. Macrmol. Sc. Part A; 1999, 36, 51
Chain transfer polymerization Initiation R S R' Propagation R S R S R' R' R' J. Macrmol. Sc. Part A; 1999, 36, 51
Chain transfer polymerization Initiation R S R' Propagation R S etc R' R' J. Macrmol. Sc. Part A; 1999, 36, 51
Gold nanoparticles synthesis R 9 S n' + HAuCl 4 NaBH 4 ( agent (reducing a) b) c) d) J. Am. Chem. Soc.; 2005; 127; 16398 & Langmuir; 2007;23; 885
Endgroup contribution PMAAODT PMAADDT R PMAAHT SH R n' PMAAPentT SH PMAAPropT O R n' HO SHS n' PMAAMAT Langmuir; 2007;23; 885
Endgroup contribution Endgroup hydrophobicity C polymer C Au increasing PMAAODT M n =2980, M w =3480 PMAADDT Mn=2550, Mw=3491 PMAAHT Mn=2180, Mw=2550 PMAAPent Mn=2300, Mw=2670 PMAAProp Mn=1960, Mw=2340 PMAAMAT Mn=1780, Mw=2060 J. Am. Chem. Soc.; 2005; 127; 16398 & J. Langmuir; 2007;23; 885
Endgroup contribution Endgroup hydrophobicity C polymer C Au increasing PMAAODT M n =2980, M w =3480 PMAADDT Mn=2550, Mw=3491 PMAAHT Mn=2180, Mw=2550 PMAAPent Mn=2300, Mw=2670 PMAAProp Mn=1960, Mw=2340 PMAAMAT Mn=1780, Mw=2060 J. Am. Chem. Soc.; 2005; 127; 16398 & J. Langmuir; 2007;23; 885
Endgroup contribution Endgroup hydrophobicity C polymer C Au increasing PMAAODT M n =2980, M w =3480 PMAADDT Mn=2550, Mw=3491 PMAAHT Mn=2180, Mw=2550 PMAAPent Mn=2300, Mw=2670 PMAAProp Mn=1960, Mw=2340 PMAAMAT Mn=1780, Mw=2060 Langmuir; 2007;23; 885
Endgroup contribution Endgroup hydrophobicity C polymer C Au increasing PMAAODT M n =2980, M w =3480 PMAADDT Mn=2550, Mw=3491 PMAAHT Mn=2180, Mw=2550 PMAAPent Mn=2300, Mw=2670 PMAAProp Mn=1960, Mw=2340 PMAAMAT Mn=1780, Mw=2060 Langmuir; 2007;23; 885
Endgroup contribution Endgroup hydrophobicity C polymer C Au increasing PMAAODT M n =2980, M w =3480 PMAADDT Mn=2550, Mw=3491 PMAAHT Mn=2180, Mw=2550 PMAAPent Mn=2300, Mw=2670 PMAAProp Mn=1960, Mw=2340 PMAAMAT Mn=1780, Mw=2060 Langmuir; 2007;23; 885
Endgroup contribution Endgroup hydrophobicity C polymer C Au increasing PMAAODT M n =2980, M w =3480 PMAADDT Mn=2550, Mw=3491 PMAAHT Mn=2180, Mw=2550 PMAAPent Mn=2300, Mw=2670 PMAAProp Mn=1960, Mw=2340 PMAAMAT Mn=1780, Mw=2060 Langmuir; 2007;23; 885
Endgroup contribution Endgroup hydrophobicity C polymer C Au increasing PMAAODT M n =2980, M w =3480 PMAADDT Mn=2550, Mw=3491 PMAAHT Mn=2180, Mw=2550 PMAAPent Mn=2300, Mw=2670 PMAAProp Mn=1960, Mw=2340 PMAAMAT Mn=1780, Mw=2060 Langmuir; 2007;23; 885
What about thiol(s) containing endgroups? HS SH HS O SH O O O O O O HS O SH Langmuir; 2007;23; 885
What about thiol(s) containing endgroups? 20nm HS HOOC O S n O 50nm O O O O O HS O SH Langmuir; 2007;23; 885
«Small is beautiful» C polymer C Au increasing 4.5 4.0 3.5 Absorbance 3.0 2.5 2.0 1.5 1.0 0.5 0.0 300 400 500 600 700 Wavelength (nm)
«Small is beautiful» C polymer C Au increasing 1.7 nm
«Small is beautiful» C polymer C Au increasing 1.1 nm 1.7 nm
«Small is beautiful» C polymer C Au increasing 1.1 nm 1.1 nm 1.7 nm
«Small is beautiful» C polymer C Au increasing 1.1 nm 1.1 nm 1.1 nm 1.7 nm
«Small is beautiful» C polymer C Au increasing 1.1 nm 1.1 nm 1.1 nm 1.7 nm
Wavelength (nm) Wavelength (nm) Photophysical properties C polymer C Au increasing Excitation Emission Polymer concentration (mm) Intensity (a.u.) Intensity (a.u.) Polymer concentration (mm)
Are they really fluorescent? J. Am. Chem. Soc.; 2002; 125; 7780 & J. Am. Chem. Soc.; 2004; 126; 8358
Are they really fluorescent? The polymer is not fluorescent The polymer, after oxidation, is not fluorescent The polymer, after reduction, is not fluorescent The polymer, in the presence of HAuCl 4, is not fluorescent 200 Purification/control by size exclusion chromatography Concentration (ppm) Emission intensity (a.u.) 150 100 50 0 0 0 10 20 30 40 S Au Retention time (min)
Occurenc es Core/shell structure 20 Core (HRTEM) 15 10 5 0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 Size (nm) Shell (???) 10 μm
Occurenc es Core/shell structure 20 Core (HRTEM) 15 10 5 0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 Size (nm) Shell (Fluorescence recovery after photobleaching)
Building a model
Conclusion A simple protocol for the preparation of nearmonodisperse gold nanoparticles in the small size regime below 5 nm has been developed. Polymer structures have been optimized to control the growth of gold nanoparticles, leading to a narrow size distribution. By varying systematically the polymer to gold ratio, the size of the nanoparticles can be finely tuned and a transition from nonfluorescent to fluorescent nanoparticles is observed. A combination of characterization techniques allow us to propose a theoratical model of the most fluorescent nanoparticle solution
Acknowledgements Supervision: Pr. Andrew I. Cooper Dr. Raphaël Lévy EP/C511794/1 n.schaeffer@liverpool.ac.uk n.schaeffer@liverpool.ac.uk
Acknowledgements