27908
Layer - by - layer ( LbL ) structures of polyHis - polyAsp on gold substrates were compared with those of precipitate - forming polyHis - polyGlu by monitoring with iSPR and QCM - D .
 polyHis, polyAsp, polyHis, polyGlu
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 polyHis, polyAsp, polyHis, polyGlu