11821
In vivo biocompatibility studies revealed that the in situ formed gels in the subcutaneous layer last for ~ 21 days , and H & E staining study suggested acceptable biocompatibility of our materials in vivo .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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