16214
These studies demonstrated that particles with higher negative charge ( COOH quantum dots ) were taken up to a greater extent by Daphnia ( 259 . 17 +/- 17 . 70 RFU / 20 Daphnia ) than either the NH2 ( 150 . 01 +/- 18 . 91 ) or PEG quantum dots ( 95 . 17 +/- 9 . 78 ) , however this is likely related to the functional groups attached to the nanoparticles as there were no real differences in zeta potential .
 Chemical: COOH; Chemical: NH2; Chemical: PEG
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: COOH; Chemical: NH2; Chemical: PEG