19325
Drug - initiated ring - opening polymerization of O - carboxyanhydrides for the preparation of anticancer drug - poly ( O - carboxyanhydride ) nanoconjugates .
 O - carboxyanhydrides, poly ( O - carboxyanhydride )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 O - carboxyanhydrides, poly ( O - carboxyanhydride )