Using UV Light to Increase Silver Ion Production in Silver Nanoparticles to Enhance its Bactericidal Effects

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aitoshamu
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Using UV Light to Increase Silver Ion Production in Silver Nanoparticles to Enhance its Bactericidal Effects

Post by aitoshamu »

Hello,

For my project, I plan to use ultraviolet lights to cause silver nanoparticles to release silver ions, which have bactericidal effects, and determine if it has a significant difference on the population of bacteria. I plan to achieve this by culturing E. coli on petri dishes, and exposing them to silver nanoparticles. Then, the controls will not receive any UV light, while the testing subjects will be exposed to UV light. Also, a group will exist in which the bacteria is just exposed to UV light, without the silver nanoparticles. Could I have some feedback on this idea, and any problems that might be present?

Thank you.
SciB
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Re: Using UV Light to Increase Silver Ion Production in Silver Nanoparticles to Enhance its Bactericidal Effects

Post by SciB »

Hi,

That's quite an unusual and advanced science project you have chosen. Could you give us more information so we can better help you in doing it?

First off--what is your hypothesis? It has already been proven that silver ions can kill bacteria like E coli. What is the purpose of using nanoparticles that require UV to release the silver? Why not just use a solution of a silver salt that contains ions or silver nanoparticles that release silver ions spontaneously? What is gained by having to use UV to trigger the release?

What is your source of photoactivatable silver-loaded nanoparticles? Are you making them yourself? How do you know they will release silver ions upon exposure to UV? There are regulations on the use and disposal of nanoparticles into the environment. Will you be performing these experiments in a research lab under supervision with proper handling of potentially biohazardous waste?

What wavelength and intensity of UV is required to release the silver from the nanoparticles? UVC for example, from a germicidal lamp, would effectively kill most of the bacteria and is also harmful to humans. UVB is less energetic but still can be harmful. Do you have a UV light source where you can use it safely and control the intensity?

Repost with more details about your proposed project and we will try to guide you in doing it effectively.

Sybee
aitoshamu
Posts: 4
Joined: Sat Sep 12, 2015 3:35 pm
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Re: Using UV Light to Increase Silver Ion Production in Silver Nanoparticles to Enhance its Bactericidal Effects

Post by aitoshamu »

Hello,

I am sorry. I don't think I made the experiment very clear in the previous post. First off, my experiment is attempting to cause the silver nanoparticles to release the silver ions faster, not create a new nanoparticle that only emits silver ions when under UV light. Also, It is already known that when under UV light, the silver atom's electrons get excited, and escape the atom, thus creating a silver ion. I plan to apply this knowledge to test if exposure of UV light can stimulate the faster production of silver ions, thus having more effective bactericidal properties. Thus, my hypothesis is that if silver nanoparticles are exposed to UV light, then their antimicrobial properties will be enhanced. As for the UV light, I am planning to use a long wave UV light, with little harms.

Thank you very much.
SciB
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Re: Using UV Light to Increase Silver Ion Production in Silver Nanoparticles to Enhance its Bactericidal Effects

Post by SciB »

Hi and thanks for the clarification of your project.

I think there may be some confusion over the word 'nanoparticle'. I thought you were referring to a synthetic nanoparticle polymer complex that contains silver ions. What is it that you will be exposing to UV? Long-wave UV, UVA, is not very energetic. I would think that you would have to use UVB radiation to get an effect.

You said UV will ionize silver. How do you know this? Do you have a reference that you can give us? What form of silver are you referring to? The metal? Do you have silver metal in the form of nanoparticles? How small are they? I did a search for this and found an article on using copper and silver electrodes in water to produce silver and copper ions when a current was applied to the electrodes: http://www.lenntech.com/processes/disin ... zation.htm

Since UV is harmful to bacteria, I would think that you would want to UV irradiate the silver nanoparticles first and then add them to the bacterial culture.

Please answer the additional questions and we will be able to help you better with your project.

Sybee
aitoshamu
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Joined: Sat Sep 12, 2015 3:35 pm
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Re: Using UV Light to Increase Silver Ion Production in Silver Nanoparticles to Enhance its Bactericidal Effects

Post by aitoshamu »

Hello,

Thank you for all your suggestions and the article you included. I plan to use actual particles of silver, from which UV rays can cause silver ions to detach from the surface. The nanoparticles themselves will be less that 100 micrometers, and probably be around 40-50 micrometers. Here is an article that explains a study similar to the one that I am researching. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3218584/ In this study, the researchers also used UV light to enhance the effect of silver nanoparticles, and I plan to test the effectiveness on bacteria, rather than parasites. Also, I will have to do further research on the types of UV lights that would be necessary for this experiment.

Thank you very much.
SciB
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Re: Using UV Light to Increase Silver Ion Production in Silver Nanoparticles to Enhance its Bactericidal Effects

Post by SciB »

You are most welcome! I am glad my advice was helpful.

Let me ask you one thing first, however. You said that your silver particles will be 40-50 MICROmeters--is that really what you mean? If so then they are not NANOparticles. One micrometer [also known as a 'micron' or 'um'] is equal to 1000 nanometers [abbreviated 'nm']. By definition, a nanoparticle to be effective has to be around 100 nm in diameter: https://en.wikipedia.org/wiki/Nanoparticle

I quickly read through the paper you sent and now I understand better what you are trying to do. Are you planning to make your Ag-NPs the same way as the authors did in this paper? I think that would be a good idea, but you would still need to measure their size somehow to prove that they had the correct size to be NPs.

Another thing I am concerned about is that I could not find a control in which the authors UV irradiated the Ag-NPs alone and then added them to the parasite cultures. If you are saying that the UV radiation is affecting the Ag-NPs, then this pretreatment with UV should activate them. When the authors did their experiments, as far as I could tell, they UV-irradiated the parasites as well as the Ag-NPs. That complicates the conclusion because UV can alter amino acids and DNA.

The authors suggest that UV may cause silver ions to be formed from silver metal but they do not prove that by an experiment, or if they did I did not see it in the Results section. There definitely seems to be a synergy between UV and Ag-NPs, but be careful of concluding that the UV is acting on the silver without good evidence for that.

Keep posting your questions and letting us know how you are progressing with this intriguing project.

Sybee
aitoshamu
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Joined: Sat Sep 12, 2015 3:35 pm
Occupation: Student

Re: Using UV Light to Increase Silver Ion Production in Silver Nanoparticles to Enhance its Bactericidal Effects

Post by aitoshamu »

Hello,

Thank you for correcting me on the size of the particles. Yes, I did mean nano instead of micro, and I plan to buy these particles already synthesized, instead of create them myself. Also, to take into consideration the fact that UV lights can kill bacteria as well and also to follow one of your previous suggestions, I plan to irradiate the silver nanoparticles in water separately first, then pour the water over the streaked bacteria on an agar plate.

Thank you very much for your feedback and all of your help.
SciB
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Re: Using UV Light to Increase Silver Ion Production in Silver Nanoparticles to Enhance its Bactericidal Effects

Post by SciB »

Hi,

You are welcome! Happy to help.

Have you determined what wavelength and intensity of UV is needed to ionize the silver? In reading the paper you sent I did not see a mention of this but they did give a Philips lamp part #, so I guess you could find out that way. The other question is how long should you UV irradiate the Ag-NPs. In addition to that, you really need a way to measure Ag ions so if someone asks you how you know UV ionizes metallic silver, you can show them the evidence. Showing scientific proof is the only way that you can make a convincing statement.

I remember from chemistry class that adding a dilute solution of sodium chloride to a solution containing silver ions causes a white precipitate of AgCl to form. You could use this to see when you have given enough UV to create Ag+ but it does not tell you the concentration of Ag+.

Keep posting your questions and we will keep helping you to do this interesting project.

Sybee
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