8509
Herein we describe a process for making hydrogels composed of hydroxyphenyl propionic acid ( HPA ) conjugated , branched poly ( ethylene glycol ) ( PEG ) via an enzyme mediated , oxidative cross - linking method .
 Chemical: hydroxyphenyl propionic acid; Chemical: HPA; Chemical: poly ( ethylene glycol ); Chemical: PEG
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: hydroxyphenyl propionic acid; Chemical: HPA; Chemical: poly ( ethylene glycol ); Chemical: PEG