19161
The probes were tested in biological model systems , demonstrating effective imaging of unstimulated , endogenous H ( 2 ) O ( 2 ) levels in RAW 264 . 7 cells and murine brain tissue .
 Chemical: H ( 2 ) O ( 2 )
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: H ( 2 ) O ( 2 )