16888
The interaction of human telomeric G - quadruplex DNA ( HTG21 ) with the designed ligands was explored by fluorescence analysis , absorption spectroscopy , continuous variation , circular dichroism spectroscopy , fluorescence resonance energy transfer ( FRET ) melting assay , polymerase chain reaction ( PCR ) stop assay , telomerase repeat amplification protocol ( TRAP ) , and visual studies .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None