10144
Endocytosed PEI - NPs trigger an oxidative stress on cells by inducing the production of reactive oxygen species ( ROS ) , which cause DNA damage without apparently affecting cell viability .
 Chemical: PEI; Chemical: oxygen
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: PEI; Chemical: oxygen