17667
In this report , we investigate the interaction between thrombin and a thrombin - binding aptamer ( TBA ) on a PEG / TBA coimmobilized surface by using a shear horizontal surface acoustic wave ( SAW ) sensor .
 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