Monolayer-Protected Gold Nanoparticles: Ultra-Fast Synthesis & Ultra-Simple 2D Self-Assembly

[MANSI110390]

ohk , could u b presise in terms of gene delievery ..........

well how will u check their applications in terms of immunomodulatory / antiinflamatory ??

[MANSI110390]

what are the applications nabh4 synthesisesed AuNP

[EahLab]

@MANSI110390 1) Basic science study of their size-dependent optical properties, 2) fabrication of ultra-sensitive Raman sensors, 3) might be useful for the next-generation memory devices, 4) biological applications such as gene delivery, 5) catalysis with AuNPs smaller than 2 nm in diameter, and many others.

[MrAltamashqureshi]

thanks.. this is really helpful.

[garljr]

Is it possible to make gold nanoparticles from gold salt, water and soy beans, then inject or somehow put it with plants to make them glow in the dark?low

[ProxySpam]

I would also like to thank you for your help and support. If it wasn't for your group and your find i would be still be refluxing my glycol overnight in NaOH. Brilliant method.

thanks ;)

[EahLab]

@ProxySpam You are very welcome! I am really glad that our result is useful to someone.

[ProxySpam]

I have 2 challenging questions: I deposit my particles on YSZ. Are 1-dodecanethiol protected particles catalytically active(are there enough reaction sites?) If not, what is the minimum calcination temperature to deprotect the particles while minimizing agglomeration. Also, is there a compound to prevent particle growth during calcination? Some inhibitor? My problem is that at 300C the particles increase in size after deprotection and the YSZ powder turns blue instead of red.

1000 thanks

[EahLab]

@ProxySpam They are very good and open questions. I hope that someone including myself can answer them in the very near future!

[MsMystery2009]

@EahLab there is an ambiguity in the data diven in this video and the research paper, could you please tell me the exact concentrations and volumes of the solutions you put in?

[EahLab]

@MsMystery2009 All the numbers are in the Langmuir-2010 paper. I will repeat them here. In the two stock solutions, [HAuCl4]=[HCl]=[NaBO4]=[NaOH]=­50 mM. For a typical synthesis, we prepare 10-0.1-0.1*X mL of DI water in a glass vial. Then, add 100 uL of the HAuCl4-HCl stock solution and X*100 uL of the NaBH4-NaOH (X=3-7). Therefore, [HAuCl4]=[HCl]=0.50 mM and [NaBH4]=[NaOH]=0.50*X mM in the 10 mL reaction vial.

[EahLab]

How to make the two aqueous stock solutions of HAuCl4-HCl and NaBH4-NaOH?

1) Put a glass vial on a scale and zero it. Total weight = 0 mg.

2) Add HAuCl4-3H20 powder, e.g. 500 mg (= 1000 mg / 393.83 g/mol = 1270

umol). Total weight = 500 mg.

3) Add 1270 uL of 1.0 N HCl aqueous solution. Total weight = 500+1270 mg.

4) Add 25,400-(500+1270) uL of DI water. Total weight = 25,400 mg.

(1270:5=25400:100)

[ProxySpam]

@EahLab rofl that's exactly how I do it. We must have the same vials..

[ProxySpam]

Just wanted to say thanks for the help, I figured it out 5/5, deposited on YSZ, it's all good man. Just one critic, once the reactants are in place it's easy but making the 1M NaOH, HCl and the 50mM dual solutions, you need to have a pHD in analytical chemistry and proceidures ^.^

[ProxySpam]

o Wow I think that's it....the volume of NaBH4/NaOH you add is so small...it's like, 0.5mL for 10mL of diluted HAuCl4, I was adding equal volumes...man it's not clear :(

[ProxySpam]

I didn't read the paper though, I got ADD, I only read stuff when I got no choice. I guess I will now lol.

[ProxySpam]

Whap happends is, the solution goes red for a brief moment then immediatly turns blue-violet. When small volumes are used, the solution turns violet instantly.

I tried titrimetric addition but even when I add 1 single drop of HAuCl4, that drop turns violet and not red. I tried stirring at 100RPM, nothing works.

[ProxySpam]

Ok I made a NaBH4/NaOH solution about 1M, and HCl/HAuCl4 1M too. I tested with phenolphthalein and pH papers that when equal volumes are added together, the pH would be 7-8. I CANNOT get a red solution sir. I am missing something. I can obtain a red solution when no HCl/NaOH is added, but I can't. I think the volumes you add are not the same...I can't figure it out. When I add 200mL of diluted HAuCl4 to 12.5ml of 0.053M plain NaBH4 I get red solution.

What am I doing wrong?

[ProxySpam]

I tried 0.05M NaBH4 + diluted HAuCl4 and it worked. Can you still give us the concentration values for NaBH4 and HAuCl4 to obtain smallest size? Thanks!

Also, I noticed that 0.05M NaBH4 in water is bubbly...I was afraid to close the container to avoid hydrogen pressure buildup, how do you store NaBH4(aq)? Thanks again

[EahLab]

@ProxySpam It seems that you didn't read the Langmuir-2010 paper carefully or we were not explicit enough. Add NaOH and HCl to the NaBH4 and HAuCl4 solutions respectively. Then, the amount of H2 bubbles go down significantly, since there are much less H+. In any case, just leave the 0.05M NaBH4/NaOH container open. Get the smallest size at just above (300%) the low boundary (between 250 and 300%) of the sweet zone (300-1200%) for [HAuCl4, HCl]=0.5mM in the reaction vial.

[ProxySpam]

@EahLab Ok you mean setting HAuCl4 to 0.5mM and setting the NaBH4 to 275% of that value meaning 1.4mM?

[EahLab]

@ProxySpam Yes and No! An easier way is to pour X uL of NaBH4/NaOH for 100 uL of HAuCl4/HCl (X=100-1200%). Can hardly believe why other groups missed this simple trick of NaOH and HCl :)

[ProxySpam]

@EahLab I see you use microliters as unit. It wouldn't work if I do it in a bucket? I did it in a 200mL flask and it worked but from a 500mL flask to a bucket there's a long way lol I don't wana waste 10g of gold.

[ProxySpam]

@EahLab Great trick with the NaOH HCl, I skipped that lol. I can hardly believe you came with this by yourself, this stuff is genious.

[EahLab]

@ProxySpam We buy all our chemicals from Sigma-Aldrich with just a few exceptions.

[ProxySpam]

Hmm, I saw a colorless 2nm colloid sold by a company, they said it's colorless because the particles are too small to reflect light. You mean it can go from colorless to brown as the size goes under 2nm?

[EahLab]

@ProxySpam The company is simply wrong! A solution of atomic gold ions is of yellow color. Even the smallest gold nanoparticles below 1 nm are of brown color in a solution.

[ProxySpam]

@EahLab Yes but that's a chloride, not a gold nanoparticle. Bleach is also yellow, due to chlorine atoms. We can't consider that because HAuCl4 is yellow that 0.2nm gold colloid is also yellow, because the yellow color might be given by the chlorine atoms.

[EahLab]

@ProxySpam The smallest reproducible diameter by the method in this video is 3.2 nm! My group has been working on how to reproducibly synthesize gold nanoparticles smaller than this lower limit of 3.2 nm. After publication of the results, perhaps we will upload another video. It may take a few months.

[ProxySpam]

@EahLab You probably won't want to answer this but, when the size is lower than 3.2nm, what's the color of the colloid? transmitted and reflected ^_^

[EahLab]

@ProxySpam The color by human eyes changes from brown (d<2 nm), orange (d<3 nm), and red (d=3-10 nm). Interestingly, human eyes cannot tell the color difference for the diameters of 3, 4, and 5 nm. However, UV-Vis spectra are strongly size-dependent for the diameter range of 3 to 5 nm!

[ProxySpam]

thanks for everything btw :)

[ProxySpam]

I'll just take dodecane, add sulfuric acid and see what happends...its gona be dode-SO3H...can't be that different.

[ProxySpam]

Why would a regular surfactant not work and if it does work would it be anionic or cationic? I just don't have the reactant that's why I ask for alternative.

[EahLab]

@ProxySpam Because 1) we don't want to use surfactant molecules which are difficult to clean out after the synthesis and 2) dodecanethiol is great for coating gold nanoparticles efficiently. Note that the amount of dodecanethiol molecules is only 10% of the total gold atoms and therefore there is no need for post-synthesis cleaning. Also, we lose the special property for ultra-simple 2D self-assembly if other ligands are used.

[ProxySpam]

@EahLab Can I bubble H2S with a catalyst to convert regular surfactant into 1-dodecanthiol? How would you synthetize it from scratch. I got dodecane, H2S, NaH, LDA, LiAlH4 and so on

[EahLab]

@ProxySpam We simply buy dodecanethiol from Sigma-Aldrich! No, we didn't try to use diethyl ether! The main goal was to synthesize gold nanoparticles as easy as possibly by using the most basic (and perhaps safest) solvents like water, acetone, and hexane. In addition, we wanted to remove any post-synthesis cleaning processes.

[ProxySpam]

Also have you tried dissolving HAuCl4 into diethyl ether, then dissolving LiAlH4 into another portion of diethyl ether and mixing both?

[ChemKid13]

We are having some reproducibility problems at Texas Tech. Our solution does not turn such a vibrant purple/red as yours does, in fact, most of our solutions look grey.

[SchrondingersCat]

Awesome! :)

[AMonteverdi]

ok now i know how it will be my next mod of my cellphone...