23343
Silicone sheets are first plasma treated and then functionalized by grafting sequentially under stretching poly ( ethylene glycol ) ( PEG ) chains and biotin or arginine - glycine - aspartic acid ( RGD ) peptides .
 Chemical: poly ( ethylene glycol ); Chemical: PEG; Chemical: biotin; Chemical: arginine; Chemical: glycine; Chemical: aspartic acid
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: poly ( ethylene glycol ); Chemical: PEG; Chemical: biotin; Chemical: arginine; Chemical: glycine; Chemical: aspartic acid