8440
In this case , different nanoparticle suspensions including citrate reduced gold , silver , and HGNs were illuminated by a continuous laser at 785 nm excitation wavelength and the absorption efficiency of HGNs with a LSPR of 775 nm was calculated to be 0 . 81 % which is more than 5 times higher than the absorption efficiency of citrate reduced gold nanoparticles under similar conditions .
 citrate, silver, citrate
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 citrate, silver, citrate