22822
In the present study we analyze the photobiological properties of 2 , 7 , 12 - tris ( alpha - pyridinio - p - tolyl ) - 17 - ( p - ( methoxymethyl ) phenyl ) porphycene ( Py3MeO - TBPo ) in Hela cells , in order to assess its potential as a new photosensitizer for photodynamic therapy of cultured tumor cells .
 2 , 7 , 12 - tris ( alpha - pyridinio - p - tolyl ) - 17 - ( p - ( methoxymethyl ) phenyl ) porphycene, Py3MeO - TBPo
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 2 , 7 , 12 - tris ( alpha - pyridinio - p - tolyl ) - 17 - ( p - ( methoxymethyl ) phenyl ) porphycene, Py3MeO - TBPo