23211
Previously it has been shown that these reactions can be caused by activation of the complement ( C ) system by a negative charge on the anchor molecule of PEG at the liposomal surface .
 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