I am interested to form gold nanoparticles layers on porous beads but they tend to detach. Which is most suitable method, excluding heating, to make gold nanoparticles stabilize (join/bind/aggregate) on beads surface. Gold layers should also be insoluble in organic solvents such as acetone and chloroform.
Thanking you in advance for your expert advices.
Sir,
If you could say what method you have adopted to coat Au nanoparticles over the bead, then it would be more clearer to suggest you modifications of other methods.
Simply, I incubated porous beads with gold nanoparticles solution and it forms homogenous layer on beads. But we need to heat it to 600C to stabilize gold nanoparticles. I want to avoid this heating step.
Oh... Actually you need to adapt an bottom-up method, where you prepare the gold nanoparticles from gold atoms with the presence of beads. This would make the bead surfaces act like a nucleation spot and the gold atoms will be deposited over them.. By controlling the amount of time for reaction/exposure of beads in solution, concentration of the gold precursors, you could control the thickness and amount of gold nanoparticles being formed over the beads.
Another easier method you could try i s the gold sputtering method, wherein you could deposit very thin layers of gold over your beads.
Another possible way is to find some coupler or linker or binding groups over the beads and then incubate them with your solution, so that the interaction is stronger.
Thank you Arun Kumar Rajendran, your answer has definitely given me a direction.
The route to supported catalysts - bottom-up - may answer this question or suggest a direction - absorb a gold solution (chloroauric acid usually) on an appropriate support e.g. silica. Reduce at room temperature with say hydrazine hydrate solution (5%) or hydrogen gas. I made 10 - 100 nm supported gold catalysts (5% total metal loading) in this manner.
Thanks all. Actually my research group has previously prepared porous polymeric beads that were coated with gold nanoparticles. After heating to 600C, polymer was burnt into smoke and gold nanoparticles combine (probably after melting) to form a highly porous gold nanostructures. http://onlinelibrary.wiley.com/doi/10.1002/adma.200306153/pdf
I wanted to see how can I prepare such particles without heating step. In this case, I will need another step to staiblize gold nanoparticles.
I think bottom up method will work nicely for this purpose.
Nanoparticles will form solid bridges even at room temperature if they're allowed to contact one another or surfaces. The systems must be either sterically (geometric) stabilized (as I indicated for the supported Au catalysts) or prepared in colloidal suspension and kept wet - electrostatic (charge) stabilization or steric (polymers such as 50K Da polyacrylamide) can be used to keep the particles apart. In the later case the polymer chain could form a significant part of the particle's diameter and may need to removed in subsequent processing steps. In terms of stabilization, see for example:
21. 11th Nov 2008. Dispersion and nanotechnology
http://www.brainshark.com/brainshark/vu/view.asp?pi=106756756&text=M021507
I am researching on inkjet printing technologies for bio-sensor fabrication. Gold nano ink can be used on the thin film. You may consider this for your purpose.
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