29640
In this work , we present the results of using total internal reflection microscopy ( TIRM ) to measure the interaction forces between a Brownian colloidal sphere and a flat glass plate in the presence of overdosed free PEI cationic chains , when both surfaces were saturated adsorbed with the PEI chains .
 Chemical: PEI; 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: PEI; Chemical: PEI