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In this feature article , we introduce recent progress in nanobiosensor development by exploiting the optical , electrical and catalytic properties of a range of nanomaterials , with a focus on gold nanoparticles , carbon nanotubes , graphene and carbon dots .
 carbon, graphene, carbon
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 carbon, graphene, carbon