22683
This critical role of the cross - linker ' s inflexibility was related to the difference of the degree of hydrophobic association between polymer cross - linkers , as confirmed with pyrene probes added in pregel solutions .
 Chemical: pyrene
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: pyrene