12019
The alkyl - capping ligands consist of a hydrophobic , aliphatic chain and different functional terminal groups ( e . g . , carboxyl , amine , hydroxyl , and thiol groups ) that can serve as reactive sites to chemically couple with other materials .
 carboxyl, amine, hydroxyl, thiol
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 carboxyl, amine, hydroxyl, thiol