Talk:Colloidal gold

Units
There seems to be a mini edit-war breaking out over the use of micron versus micrometre and M versus mol. Am I right in thinking that the latter in each case is technically more correct that the former? Specifically, micron is an old and deprecated (although common) alternative for micrometre, and M actually refers to the molarity of a solution rather than one mole. -- ALoan (Talk) 11:09, 11 Aug 2004 (UTC)

NanoProf (talk) 18:17, 8 October 2013 (UTC)
 * M is not the same as mol; the first is a concentration (mols/L) and the second a number of molecules (in mols). Micron and micrometre are interchangeable.

Re: Units
M vs. mol - good point, my bad. I'm a physicist, not chemist, so sometimes make stupid mistakes like that.

micron vs. micrometer - technically, the latter is correct, but the former is easier to write and means exactly the same thing: μm = 1/1 000 000 of a meter.


 * Well, I am an astronomer - fortnuately, someone who knowns some chemistry wrote articles about moles and molarity.


 * OK - so mol is right, yes? I can't get excited about the difference between micron and micrometre, but we don't need a host of reverts - what is the consensus?


 * And I think you'll find it is &micro;m (&amp;micro;m) not &mu;m (&amp;mu;m) :) -- ALoan (Talk) 15:15, 12 Aug 2004 (UTC)


 * The Wikipedia article for mole provides useful input for this debate. As does the official SI definition and symbol for mole.


 * The SI website also says that the term micron was officially dropped in 1968. Current use might be characterised as 'colloquial' as with the officially obsolete term Centigrade. The term 'micron' is typically seen in particular domains and regions, but is not universal in either. The SI format [prefix]+[unit name] indicates the size and the measure as in microgram, microvolt, microwatt, microfarad. The format also applies in symbols. The constant repetition of this consistent format is useful for transfer of knowledge when encountering terms that may be unfamiliar such as femtometre, kilocoulomb or GJ.


 * The micron does not fit into this format. It requires unique knowledge of size and what it is measuring. Many online references to micron often provide a definition in the text because of this problem. The US NIST and the IAU say micron is non-preferred.


 * I know that a lot of people still use it, just as a lot of people still use Centigrade. So we can't stop such terms cropping up in original material or in quotes. Wikipedia links to micron simply redirect to the micrometre article. At the very least, such redirect should be avoided. I made the original correction but had forgotten about it. I merely happened to come across the term on that page again. The history of edit summaries indicated something other than reversion, so I assumed it had appeared in added text. I did not check the details of each edit until you guys started discussing it. It is a small surprise to learn that it was a reversion rather than new text but it isn't a big deal.


 * I hope that is useful context
 * Bobblewik 19:42, 12 Aug 2004 (UTC)


 * Thanks for your clarification - I had assumed it was reversion as the terms swapped back and forth a couple of times, but I'm glad we have (I think; I hope) resolved the issue. -- ALoan (Talk) 19:51, 12 Aug 2004 (UTC)

"Health benefits"
Removed section again as it is not sourced to a reliable peer reviewed source, rather to A Meridian Institute website. Wiki is not for the promotion of quackery. --Vsmith 12:50, 3 January 2007 (UTC)

I would like to see some content on the page about the purported health benefits and any studies regarding those claims, one way or the other. While I believe that it may well be "quackery," it is certainly a phenomenon that is worth discussing as products meant for ingestion are being marketed heavily in the health product industry. Herbanreleaf 01:20, 25 January 2007 (UTC)


 * I think lack of such studies is part of the problem. "Nutritional supplements" don't require that they be studied before they are marketed. eaolson 01:23, 25 January 2007 (UTC)

If there are no studies then the claims should be part of the article as well as the fact that they are unproven. Herbanreleaf 19:37, 25 January 2007 (UTC)

I would have to agree that there should be some discussion of claimed health benefits in this article, whether they're true or not. The phenomenon is so large, at least in the United States, that their absence from this article is very conspicuous and smells of censure, so I'm going ahead and adding some mention of it. Yosemite1967 19:20, 27 August 2007 (UTC)


 * Followup: I've gone ahead and added a section for this and contributed quite a few government and medical-journal sources for all of the information that I added.  No quackery here (as if the government never participates in such--LOL).  Yosemite1967 23:10, 27 August 2007 (UTC)

Cancer Ward
I remember that in the novel Cancer Ward by Solzhenitsyn, one of the patients needs colloidal gold for some test or treatment. What could it be? Sergivs-en 08:25, 2 May 2007 (UTC)

Dubious
We need a reference that nanoparticle gold is the same as colloidal gold, preferrably in the reference itself, or it might be WP:SYN. As it stands, there's clearly (although this is WP:OR on my part) a difference between chelated gold (sometimes also called colloidal gold, although there's only one gold atom per structure) and structures containg a few to a few hundred gold atoms coated with some sort of ionic substance. &mdash; Arthur Rubin | (talk) 19:21, 23 September 2007 (UTC)
 * There's a link to colloid in the lead graf. Isn't that enough? I've never heard chelated gold referred to as colloidal. They're very definitely distinct things. Also, any coating on the surface of a particle is optional for a colloid. Some have one, and it makes it more stable and functionalizable, but it's not a defining characteristic. eaolson 23:22, 23 September 2007 (UTC)

Valid question but the nanoparticle article is clear about it: a nanoparticle is any particle with diameter less than 100 nm and the particles found in colloidal gold are gold nanoparticles. I do not see an immediate need for two separate articles on nanogold and colloidal gold V8rik 21:11, 24 September 2007 (UTC)


 * OK, withdrawing. &mdash; Arthur Rubin |  (talk) 21:13, 24 September 2007 (UTC)

Purple of Cassius
Are gold colloids/nanoparticles the "active" ingredient in the ancient pigment Purple of Cassius? If so, should Purple of Cassius redirect to this page? —Preceding unsigned comment added by Chem web7 (talk • contribs) 03:02, 23 January 2009 (UTC)

Purple of Cassius is a Colloid of gold nanoparticles on zincoxide. In the german wikipedia there are two distinct articles about these (though one is kind of a stub).Buriaku (talk) 08:58, 5 July 2010 (UTC)

A simple method for the production of colloidal gold
sodium hypochlorite (concentration 15% - bleach sodium) + hydrochloric acid (concentration 5% - muriatic acid) + gold dust (filings of gold) --- 48-56 h ---> Gold chloride (yellow-gold solution) HAZARD! Chlorine gas !!!!

Gold chloride (yellow-gold solution) + sodium bicarbonate ---> precipitated eventual copper carbonate (blue - green), Gold chloride remains in solution (yellow-gold), sodium bicarbonate acts as pH Buffer System and reduce acidity (strong effervescence !)

Gold chloride solution + saccharose (sucrose) or glucose --- 24-48h ---> Colloidal Gold (purple shades) or "purple of Cassius"

try it! —Preceding unsigned comment added by 82.50.35.58 (talk) 16:50, 4 April 2009 (UTC)

References for Method
There are no reference to the method of making the colloidal gold. There is a paper from 1951 I would hope someone could find it. --Saxophonemn (talk) 18:44, 16 July 2009 (UTC)

Hello, I ve added the references for the Burst and the Turkevich and the Frens Papers. Hope that helps. -- 132.252.242.146 (talk) 15:51, 3 September 2009 (UTC)

Peacock Tags
On 22-May-2009 two peacock tags were added to the following text:


 * "Known since ancient times, the synthesis of colloidal gold was originally used as a method of staining glass. Modern scientific evaluation of colloidal gold did not begin until Michael Faraday's work of the 1850s. Due to the unique optical, electronic, and molecular-recognition properties of gold nanoparticles, they are the subject of substantial research, with applications in a wide variety of areas, including electronics, nanotechnology, and the synthesis of novel materials with unique properties."

I disagree with these tags and pending discussion will remove them after a reasonable amount of time. My disagreement is as follows:

1. The word "novel" is a precise term that means "of recent origin or introduction" and "of a kind not seen before". This is not a peacock term, and in fact I would go so far as to say that a synonymous but more verbose phrase like "previously unknown" would be.

2. The phrase "unique properties" is also a precise term meaning "alone", "sole", and "unlike others". I might agree to this needing a citation to affirm the uniqueness quality but it is again not a peacock term.

66.102.199.179 (talk) 03:49, 17 October 2009 (UTC)

Colloidal gold colour
The Wiki article noted somewhere that the colour of the gold sol is relative to the concentration of the gold sol in solution, it should be noted that the colour of the sol is more reliant on the size of the gold sol particles than the concentration of the sol. —Preceding unsigned comment added by 134.148.4.14 (talk) 01:25, 9 August 2010 (UTC)

edit: It notes this in the first line of the history section. —Preceding unsigned comment added by 134.148.4.20 (talk) 01:52, 9 August 2010 (UTC)

Therapeutic processes
I'm a simple college student. I'm editing this page to work towards my final paper. Though, before I do add anything to this, I wanted to ask if there is any talk on the page about the therapeutic processes for gold particles. From what I have read, there isn't a paragraph or any little snippet about it. Is it alright if I add some of the stuff I have found? PMcShurley (talk) 19:34, 12 November 2009 (UTC)


 * Please read WP:OR. It can be added if it has already been published in a reliable, peer-reviewed journal or book or other reliable source, although adding it yourself may be risky (see WP:COI). If this is your own ongoing, unpublished research, it should not be added here until it has been first published elsewhere.&mdash;Tetracube (talk) 19:54, 12 November 2009 (UTC)

"Current Research"
This whole section is extremely esoteric, minutia, relevant only because very current at the time of posting. I'm axing it. —Preceding unsigned comment added by 207.237.243.185 (talk) 06:59, 15 February 2010 (UTC)

The main thing it's used for!
In science the main thing colloidal gold is used for is as a contrast agent in biological electron microscopy! This was already true when I took undergrad cell-biology in 1986. Your article was badly incomplete without mentioning this, as it mentions much less-important uses of colloidal gold. I have begun a section on colloidal gold in biological electron microscopy for you with three references (one from 1977 and two from the Procedings of the National Academy of Science) but there's loads of examples and derivatives of colloidal gold used to label particular tissues and organelles for electron microscopy.

UPDATE: added more references —Preceding unsigned comment added by 207.237.243.185 (talk) 04:49, 18 February 2010 (UTC)

FURTHER UPDATE: Added reference to the product catalog of Sigma-Aldrich which sells colloidal gold pre-conjugated to antibodies, superantigens, other probe-molecules. I hope that's ok, if not, delete it; it's note number 29. —Preceding unsigned comment added by 207.237.243.185 (talk) 01:36, 23 February 2010 (UTC)


 * With new innovations that is going to be an outdated use. :) John Riemann Soong (talk) 14:32, 8 February 2011 (UTC)

Nanogold
A clearly COI editor remove "nanogold" from the lede, as being trademarked. That might be a valid reason for deletion, except the redirect from Nanogold would also need to be deleted, and reference 30 refers to "nanogold", without any evidence that it's a trademark, at least in the abstract. — Arthur Rubin (talk) 19:25, 6 October 2010 (UTC)
 * Even if 'nanogold' is trademarked, that is no reason to remove it's mention... Trademarking does not make it illegal to refer to the product in an article, we don't even need to add ™ (per MOS:TM). For examples see any company page (e.g. Nike)  Jebus989 ✰ 11:39, 2 May 2011 (UTC)

Laser Ablation
Anybody else came across this before??

Previous work has been done in our laboratory with regards to the creation of AuNP's in solution using Nd:YAG laser ablation

It's a very simple method of creation, with surface plasmon resonance (SPR) being seen even after 5mins of ablating at low powers using fundamental 1064nm output further ablation with 532nm output (which is very close to the SPR of 520ish nm) results in a very uniform spread of AuNP's with diameter of 1-5nm

I can dig up a reference for discussion here if warranted

Usherly (talk) 11:11, 2 May 2011 (UTC)

Colloidal gold in something else.
The first sentence talks about "usually water" as the working fluid. Well, to provide a sense of completeness I can provide something else: colloidal gold can be dissolved in various molten glasses to form a brilliant scarlet glaze (on pottery). I even have some images of this.

But is this enough of a referenced source? All of this information is from my friend who runs a pottery business and buys a commercial glaze that arrives in a bottle labelled "Colloidal Gold Glaze". Now is that enough of a reference, or is that OR? Old_Wombat (talk) 06:51, 24 July 2011 (UTC)


 * Interesting and the stuff does exist, so the addition with images would be good - but your friend and the bottle label wouldn't be WP:RS, so would need to find a non-commercial source to support. Vsmith (talk) 14:45, 24 July 2011 (UTC)
 * Quick google search provided and  book links which should work (the books as refs not the google search links). Vsmith (talk) 14:49, 24 July 2011 (UTC)

Gold "beads" study
I removed the part as well as the following ref link http://www.ncbi.nlm.nih.gov/sites/entrez?Cmd=ShowDetailView&TermToSearch=17381835 which was about "veterinary acupuncturists" implanting gold BEADS in dogs. This form of gold is NOT colloidal, the study precisely states beads and not any solution containing colloidal gold in any manner, nor any gold salt, only BEADS. A bead being a macro sized sphere of gold, measurable in tenths of inches or millimiters. This kind of alternate medicine link should be rather put in the wikipedia article about GOLD in general, not in the Colloidal Gold article. 89.82.152.110 (talk) 01:52, 9 January 2012 (UTC)
 * Seems like some people have trouble reading or understanding here. Edits by 89.82.152.110 have been reverted, why?? Colloidal gold is not "gold beads" as referred to in the journal (see link). 89.82.152.110 is right when he says that colloidal gold and macro sized gold should not be on this colloidal gold wikipedia page. Arthur Rubin, who erased edits by 89.82.152.110, should read more about differences between colloidal metals and their solid human-scale counterpart : silver salts reduce to elemental colloidal metal in human teeth in the affection called argyrism for example, while implanting a solid piece of pure silver under the skin would not lead to have blue-grey teeth.In the case of gold, colloidal gold forming after injection of gold salts leads to renal failure (due to formation of colloidal gold) but elemental gold in non-microscopic sizes does not react with body fluids if implanted. Hypothetic health "benefits" from such sized pieces of gold implanted under the skin have nothing to do with colloidal gold and or gold salts effects. 82.240.163.245 (talk) 19:51, 11 January 2012 (UTC)
 * I didn't say gold beads were colloidal gold; I said they were related to colloidal gold. And you seem to be saying that the gold bead study is wrong.  Absurd, isn't it.  — Arthur Rubin  (talk) 20:17, 12 January 2012 (UTC)
 * Let's face it, your purpose is to confuse people by putting a ref about MACRO SIZED GOLD BEADS in the COLLOIDAL GOLD article. Why you insist is a mystery, perhaps you are yourself a "veterinary acupuncturist" ! The wikipedia article is not about "health effects of gold" it's about the health effects of COLLOIDAL GOLD (and related salts that would eventually be reduced to colloidal gold in vivo). If you have any ref pertaining to the -claimed- effects of gold beads in an obscure and isolated research paper, then post it in the wikipedia article about GOLD, not COLLOIDAL GOLD. To show you how wrong your point of view is, simply imagine SILICA and SILICA FUME. THe first will not react with body fluids while the second, if inhaled for example, will clog your lungs and eventually initiate tumors like many nano sized particles would . Silica powder coats the intestines while a macrosized silica sphere would only pass through unmodified. Gold isn't glass but my point is you cannot talk about the effects of "macroscopic" sized material in the colloidal dedicated article, unless you compare both aspects meticulously by pointing out the differences (when it's neutral and when it starts being reactive to the human body (or animals, plants ...) . In regards to these considerations, your veterinary acupuncture ref about macro sized gold beads is abolutely NOT valid (even though you consider beads "micro" sized, due to their dimeter of approximately 2mm, which is ABSOLUTELY NOT related to colloidal gold. In one word, "micro" in the mouth of an acupuncturist is worth nil).82.240.163.245 (talk) 14:37, 14 January 2012 (UTC)

Health and medical applications
Correct me if I'm wrong, but not a single one of the studies on the health risks actually mentions colloidal gold, they're all talking about gold salts. Why would they be included in this article? It's very misleading. --108.160.47.85 (talk) 23:36, 10 November 2012 (UTC)
 * You are right. I deleted the section.Desoto10 (talk) 04:13, 7 June 2013 (UTC)
 * Actually, I transferred the entire section, with a few tweaks, over to the Gold salts article where it fits.Desoto10 (talk) 18:34, 7 June 2013 (UTC)

Health and medical applications Part II
The 3-4 topics in this section are all in the preliminary animal study stage. Maybe a better heading would be Medical Research or something similar. Desoto10 (talk) 03:14, 14 August 2013 (UTC)

Synthesis Methods
Several synthesis methods are listed with their own paragraphs. They are cited correctly, but their merit relative to the Frens and Brust methods has been challenged by several users. Guidelines could be useful in this regard. A study in chemistry could be considered useful if cited at least 50-100 times in ~5 years. If few citations happen, the method may not work or does not improve on prior art. If the method is actively cited, it should be considered as worthy of listing. Also, the absolute number of citations is not a valid comparison for a new study vs. one that is decades old. NanoProf (talk) 18:17, 8 October 2013 (UTC)

Totally missing in the synthesis section are templated methods where nanoparticles are made inside a host cage or a nanoscale box (e.g. http://pubs.acs.org/doi/abs/10.1021/ja412606t or http://www.sciencemag.org/content/346/6210/1258361.short). Maybe they are not that popular, but conceptually interesting because they allow for good control over size and shape of the particles. Omenthegreat (talk) 11:07, 14 August 2015 (UTC)

I found this paper http://pubs.acs.org/doi/abs/10.1021/ja906506j on mechanism of AuNP formation in Turkevich method, which proposed a different process by which AuNPs cluster forms. I think this needs to be mentioned. --1986md (talk) 12:02, 30 July 2017 (UTC)

Brust's method - Cites
Hi... In the second paragraph the cite n° 21 is not the first cite about TOABr capped AuNP. The first report (1998) of that synthesis is also from the Schiffrin's group. Here is the citation entry:

best regards

Julio

Green chemistry based methods
The section on green chemistry based methods is disproportionate and comes across merely as green POV. The idea that colloidal gold can be made with Darjeeling tea leaves is briefly amusing, but scientifically risible, and is never going to run in any serious scientific or industrial manufacturing context. (If I am wrong and green, tea-based methods are the way to go, please provide details and a citable source). Apart from gold chloride, colloidal gold is often made from completely edible and environmentally safe reducing agents, such as citric acid, ascorbic acid (vitamin C) and distilled water as the solvent. There is therefore no case for using a less toxic solvent, and the case for using chemically undefined "green" ingredients is therefore obscure. I suggest deletion of this section. Plant surfer 12:18, 26 March 2015 (UTC)


 * Two years, and not a peep from anyone about this, for or against. To repeat, no case is made here to support the need for a "green" technology for gold nanoparticle production. This section is occupying space for no good reason. Unless a case for its retention is made then it is Going, going, go .  . . .  Plant surfer  11:55, 21 February 2017 (UTC)

External links modified
Hello fellow Wikipedians,

I have just modified 3 external links on Colloidal gold. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20120218052041/http://www.ansci.wisc.edu/facstaff/Faculty/pages/albrecht/albrecht_web/Programs/microscopy/colloid.html to http://www.ansci.wisc.edu/facstaff/Faculty/pages/albrecht/albrecht_web/Programs/microscopy/colloid.html
 * Added archive https://web.archive.org/web/20041028230241/http://uninews.unimelb.edu.au/articleid_791.html to http://uninews.unimelb.edu.au/articleid_791.html
 * Added archive https://web.archive.org/web/20150109003814/http://www.stevenperrault.com/lab-methods/ to http://www.stevenperrault.com/lab-methods/

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

Cheers.— InternetArchiveBot  (Report bug) 19:10, 10 August 2017 (UTC)

Colloidal gold vs. gold nanoparticle
There's been some discussion at WT:CHEMICALS about splitting this article into Colloidal gold and Gold nanoparticle articles. The two are overlapping but are not the same: one could have a colloid that is not composed of nanoparticles (because the particles are too large), and one can have nanoparticles that are not a colloid (because they are not in suspension, for example if they are in powder form).

As written it seems that the History and Physical properties sections are mostly about colloids while the rest is mostly about nanoparticles. But the whole article has such problems with using primary sources, may of which are outdated—especially since a significant portion of the article falls under WP:MEDRS—that it might be better to just start over with a new Gold nanoparticle article. John P. Sadowski (NIOSH) (talk) 03:37, 30 August 2017 (UTC)

CAS report: about 1-2 papers per day on "colloidal gold"
Chemical Abstracts has 14,298 references on "colloidal gold", since 2014, there are 3188, including 63 reviews. If the concept of colloidal gold is searched, one retrieves 503,459 references. Half a million.--Smokefoot (talk) 18:47, 17 July 2019 (UTC)