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Silver nanoclusters capped by hyperbranched polyethylenimine ( PEI ) have been developed as a highly sensitive fluorescent and colorimetric pH sensor .
 Chemical: Silver; Chemical: polyethylenimine; Chemical: PEI
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: Silver; Chemical: polyethylenimine; Chemical: PEI