2293
While several crosslinked PEI systems in the literature have demonstrated the effect of the disulfide moiety , this work demonstrates that disulfide - mediated unpackaging may not be as important as conventionally thought for some PEI systems .
 Chemical: PEI; Chemical: disulfide; Chemical: disulfide; Chemical: PEI
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: PEI, disulfide, disulfide, PEI 
Answer:
 Chemical: PEI; Chemical: disulfide; Chemical: disulfide; Chemical: PEI