[kmlchicago]

Hello, everyone:

My end of the quarter project involves designing a biosensor to detect vitamin D concentration in a human serum sample. We are tasked simply with writing a proposal, not actually carrying out an experiment. I have been searching quite a bit of journal articles and other online resources, but I'm coming up dry. I wonder if the community might have some ideas.

In terms of direction, I want to be able to oxidize vitamin D itself or some kind of companion molecule (maybe an antibody that will bind to it?). The oxidation would produce hydrogen peroxide in solution, which, along with horseradish peroxidase, could trigger an indicator molecule like ABTS or 4CN. The insoluble product could provide a visual indicator of the concentration of vitamin D. This second part of the experiment is no problem; we have even done it before in lab. I need some guidance with the first part, namely, oxidizing vitamin D or something tagged to it.

Your thoughts would be appreciated. I am willing to do the work on this, but some direction to resources (e.g., journal articles, textbook chapters, etc.) would also be welcome.

Thanks very much!

[Babcock_Hall]

Have you studied how HRP could be conjugated (covalently linked) to other molecules?

[opsomath]

Have you explored the availability of vitamin D antibodies?

[kmlchicago]

Thanks for the replies so far!

@opsomath, I would like to see if a purely chemical coupled reaction exists first. We are instructed to minimize complexity, so purchasing something like an anti-Vitamin D antibody would be a secondary option. Can vitamin D itself be oxidized? All I need is to convert some proportion of the solution's water molecules into H202 for the second (indicator) reaction.

@Babcock_Hall, same as above. There is an ELISA kit that facilities binding between anti-vitamin D antibody and biotin, and biotin is subsequently conjugated to HRP. While I understand that real-world chemical reactions are complicated in this way, I want to see if something more basic (i.e., for a continuing studies general chemistry class) exists first.

[Corribus]

Keep in mind there are a few forms of vitamin D.  They are structurally similar but antibodies are often sensitive to this kind of thing.  (In fact, any sensing methodology could be - so this is something you need to plan for up front.)

[Babcock_Hall]

Plasma is complicated stuff, with lots of proteins, and this may limit your options.  On the other hand, you have already thought about ELISAs, which is where I was going with my question.