14516
A highly luminescent and photostable quantum dot - silica monolith ( QD - SM ) substance was prepared by preliminary surface exchange of the QDs and base - catalyzed sol - gel condensation of silica .
 silica
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 silica