A very important material assembly approach based onbiomolecular recognition is provided by use of a pair of speciesnamed biotin and streptavidin. Biotin is a small molecule thatbinds very strongly, and specifically, to four recognition siteslocated on opposite faces of the protein streptavidin.
a) Write down the molecular structure of the biotin molecule,and determine the mass of one molecule in g (grams).
Suppose that a self-assembled monolayer (SAM) is prepared on aplanar gold surface, and that a fraction of the molecules in theSAM contain a biotin. Likewise, a set of gold nanoparticles areprepared with surfaces similarly functionalized (i.e., with a SAMhaving a small fraction of biotin exposed). Describe what happensin the following two scenarios:
a) The planar surface is exposed to a solution of streptavidin.Following reaction of streptavidin with the biotins on the surface,all unbound streptavidin is rinsed away, and then the surface is exposed to the biotinylated nanoparticles.
b) A solution containing the biotinylated nanoparticles andstreptavidin is initially prepared, and this solution is put incontact with the surface.