9958
Compared with free PEI and the GO - PEI conjugate without PEGylation , NGO - PEG - PEI shows superior gene transfection efficiency without serum interference , as well as reduced cytotoxicity .
 Chemical: PEI; Chemical: PEI; Chemical: PEG; Chemical: PEI
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: PEI; Chemical: PEI; Chemical: PEG; Chemical: PEI