Feasibility of nanoparticle + algae project

[forayin2stem]

Hello!

I was considering doing a project about nanoparticle toxicity on algae. Specifically, I wanted to analyze the difference between aggregated and nonaggregated nanoparticles (deciding between ZnO and TiO2. Maybe I'll do both!).

Some sources I have read indicate that nanoparticle aggregation can increase toxicity, while others say that aggregation makes NPs less toxic.
I also found a source that says that when daphnia consume nanoparticles, they are released in aggregated form. This inspired me to test the difference between artificially aggregated, naturally aggregated, and un-aggregated (?) nanoparticles.

To naturally aggregate the nanoparticles I would feed them to a creature like daphnia and somehow collect what they release... and I'm unsure if I can buy nanoparticles in aggregated and un-aggregated form, or if I would have to find a way to manually aggregate them and observe the difference under a microscope? (Or even if NP are naturally not aggregated when they are initially sold?)

Then I would give the three groups of NP to algae and measure their health somehow.

My questions are:

1. Is there already a scientific consensus on the aggregated nanoparticle issue? As in, does everybody already know whether aggregation is good or bad, and it's not a relevant issue to experiment? (Please direct me to where I could find sources on this, if there is a consensus.)
2. Could you give me advice on how I would "aggregate" the nanoparticles? Is my plan feasible, or is aggregation something we can't really control?
+ 2.5. How would I collect the NPs that Daphnia aggregated? Also, what happens if the particles are not aggregated after consumption? Also, I will use a marine algae, and Daphnia live in freshwater, so I wanted to use a marine creature like Acartia instead of Daphnia (more realistic, as they would be in the same environment). However, I haven't found any sources about Acartia aggregating nanoparticles in a similar fashion. So I don't know if I would have to just use daphnia.
3. How would I measure the health of the algae? I've read about people measuring their oxygen production, pH levels, even RGB color... I have no idea what method would be best/ most reasonable to quantify my dependent variable. One might measure color change in a paint-swirling experiment, temperature in a liquid-freezing experiment, but in a nanoparticle x algae experiment... "???"
4. What special tools I would need to make my research better? I'm assuming I probably need a microscope, but I'm not sure what kind, and also if I'd be able to have access to it. I want to work at a college lab but getting access to one is its own challenge...

Thank you for your time reading this, I tried my best to make sense. As a final question, is what I'm doing even a good (feasible, founded on science) idea? I've never done a STEM experiment or been able to talk to an expert in this field, so it feels like I'm taking wild stabs at the dark sometimes. Your website is a godsend!!

[ctactawong]

Hello, it could be difficult to control aggregation without changing the salt condition. One alternative is to study different sizes of nano-particle as a proxy.

One way to measure health of algae is to monitor the growth rate, which is related to how opaque the solution becomes.

[forayin2stem]

Thank you for your reply!

1. Could you explain how the salt condition relates to aggregation?
2. Thank you for the suggestion! What tool should I use to measure water opacity if I use that method?

[ctactawong]

Hello!

Nanoparticles are usually charged. The interactions among them depend on the amount and the valance of salt called the Debye screening effect.

One simple way to measure optical density is Secchi Stick.