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Nanosized drug carriers functionalized with moieties specifically targeting tumor cells are promising tools in cancer therapy , due to their ability to circulate in the bloodstream for longer periods and their selectivity for tumor cells , enabling the sparing of healthy tissues .
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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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