Does anybody know of a good and simple protocol for binding proteins to the surface of bare photodiodes (=silicon oxide)?

naknik said:

Does anybody know of a good and simple protocol for binding proteins to the surface of bare photodiodes (=silicon oxide)?

Does it have to be bare, or could you make an avidin/strepavidin thin film on the photdiode?

Alternatively, you might be able to functionalize one terminal of your protein to bind specifically silicon oxide. To do that, I would would looking at marine organisms that direct crystal growth. A professor at MIT also uses viral proteins to bind to inorganic substrates. Check out Angela Belcher or her spin off company, Cambrios, I think it's called.

Bettye

Thanks for the response.

The problem is that silicon oxide is highly hydrophilic so there is no spontaneous binding of protein. There is a published method from the 80's involving treatment of the surface with silan compound. This will make the surface hydrophobic and thereby provide protein binding.

Avidins will not bind to untreated silicon oxide. So, they are not a solution.

We used APTES to bind DNA to mica. It gives the surface a (+) charge.

The proteins that I referred to that are from marine organisms actually aggregate silicon to make shells (like diatoms). They are really only peptides that are highly functionalized, and it's thought that the functionalization facitliated binding to silica. Kroger and Sumpter studied these peptides (Silaffins) extensively, hence my thoughts about functionalizing your proteins to facilitate binding. It may not be possible though. I'm not sure what you are trying to do.

Certainly an interesting suggestion.

If the simple (and cheap) silan approach will fail I will try those silicon modifying proteins.

I think it is clear what I want to do: just bind protein (e.g. albumin, Ig) to the surface of bare photodiode chips.

naknik said:

I think it is clear what I want to do: just bind protein (e.g. albumin, Ig) to the surface of bare photodiode chips.

Yes, but do you want to bind specifically, or non-specifically? Are you trying to orient the proteins on the surface or just get a layer? If you just want a thin layer, then it's simpler than trying to orient the proteins...