17666
The construction strategy for PEG / ligand coimmobilized surfaces is an important point in the preparation of a high - performance assays because the physiological condition of the ligand depends strongly on its interaction with the PEG chain .
 Chemical: PEG; 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: PEG; Chemical: PEG