I have some questions that need answering for an upcoming research project that I'm proposing. My chemistry knowledge is fairly limited, but from what I've read so far, there are no papers that directly address my concerns, so I thought I'd try here...

Basically I'm going to be doing bacteriological assays using media incorporating heavy metals and antibiotics together. My questions relate to the mechanics of heavy metal precipitation and interaction with other molecules, particularly organic compounds.

100fg to whoever can help a brotha out - I'll PM you

http://forums.d2jsp.org/user.php?i=88328

I'm happy to try and answer questions but I haven't got anything beyond secondary school chemistry (I did ace it, though)
Consider browing the sticky posts. Plenty of people hold a degree in chemistry, but it'll take some looking around to find a user with a degree that's still active. I'm sure you'll find one.
Lastly, please consider using the donor forum to find somebody with a degree. I'm sure you'll find one there, if not here.

100fg seems like a low offer for graduate advice.
1000fg still seems low too, though.
might get better responses by not including a price tag.

BS in chem here

Masters in chemistry here

Sounds interesting and I'll do it for free just because I like things like this

Your biggest concern is chelating since it's an entropically driven process. It can vastly change the availability of the antibiotic to the cell.

This post was edited by Thor123422 on Aug 6 2017 06:22pm

I see, so how can chelation be prevented? I've read that lowering pH can reduce the amount of chelation, although I'm not sure how tenable that would be since I'm working with bacteria...

What I'm thinking right now is a minimal media, something like low phosphate media, to reduce the amount of organics that the metal ions can interact with. I have no ideas about how to get around metals binding to antibiotics though...

I will hopefully be able to standardise any chelation by centrifuging an aliquot to condense organics, then using spectrophotometry to compare the metal content of the supernatant with the original concentration

Thanks!

What's the exact protocol? What heavy metal compounds are you proposing to use? What's your assay?

The best way to plan a project like this is literature review: https://www.ncbi.nlm.nih.gov/pubmed
Find publications with similar assays and read their method sections.

If you have specific questions, feel free to send a message.

It depends on the structure of your antibiotic. If there's a lot of groups that can bind metals (amines, carboxylic acids, alcohols) then they will chelate metals if the sizes are right.

You can lower the pH below the pKa of your carboxylic acids to reduce the affinity, but ultimately there's no way to prevent it if it's going to happen.

You can try to choose antibiotics that don't chelate metals, I'm sure there's data out there about affinities for metals since our bodies have iron, magnesium, nickel, etc. etc. in decent quantity.

I'd opt for clinical appraisal before assuming method sections. You don't want to copy mistakes