15653
Surprisingly , these nanogel - drug conjugates were relatively stable in gastric conditions and able to actively penetrate through the gastrointestinal barrier based on permeability studies in Caco - 2 cell model .
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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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