17871
The new materials provided potent antimicrobial activities against Staphylococcus aureus ( S . aureus , Gram - positive bacteria ) and Pseudomonas aeruginosa ( P . aeruginosa , Gram - negative bacteria ) , and inhibited the formation of bacterial biofilms .
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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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