29641
The colloidal sphere pre - adsorbed with PEI chains was chosen to mimic the PEI / DNA polyplex .
 Chemical: PEI; 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