19793
The unique rough naked surface , the facile synthesis , together with the ability to control the nanoparticle size and to vary the LSPR frequency in the red region , would make the substrate - supported porous icosahedral Au NPs promising on multiple levels in the applications of catalysis , ultrasensitive biosensors , and in surface - enhanced Raman scattering ( SERS ) .
 Au
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Au