6909
Starting with initial SWNT orientation parallel to the bilayer surface , SWNTs wrapped with lysophospholipids and PEG ( M ( w ) = 550 ) - grafted lipids insert into the hydrophobic region of the bilayer , while SWNTs wrapped with phospholipids and longer PEG ( M ( w ) = 2000 ) - grafted lipids do not .
 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