17998
The polyplexes are stable until a pH of 6 . 5 - 6 . 0 , and also up to 50 mM of imidazole .
 Chemical: imidazole
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: imidazole