Can graphene quench the light from FITC?

I found that when I try to excite an FITC-tag protein linked to graphene with blue light, it seems graphene quench the light every time. No matter how many times I tried, it still became the darkest one on the screen. In order to find the answers, I've searched the literature and only found these two.

http://link.aip.org/link/JCPSA6/v130/i8/p086101/s1
http://link.aip.org/link/JCPSA6/v129/i5/p054703/s1

I also repeated this experiment with almost identical condition simply by replacing graphene with CNT.
The results is quite different from graphene, it emitted green light normally.
But I think this may be due to some of CNTs are semiconductor which would not quench the light so effectly whereas the metallic one would do.
Maybe graphene behaves just like a metal, since the metal marks in the surrounding area were able to quench all the light as well.
But, what would happen if we put the FITC-tag protein on the top of the GO?
GO should have a band gap due the disruption of the π network, but it seems to depend on some specially distributed oxidized sites to open the "gap". I  believe that one day the GO will be a band gap controllable materials in the future, but now, still long way to go.