15210
DNA - based aptamers that contain 2 ' - O , 4 ' - C - methylene - bridged / linked bicyclic ribonucleotides ( B / L nucleotides ) over the entire length were successfully obtained using a capillary electrophoresis systematic evolution of ligands by exponential enrichment ( CE - SELEX ) method .
 Chemical: 2 ' - O , 4 ' - C - methylene - bridged / linked bicyclic ribonucleotides; Chemical: nucleotides
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
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Answer:
 Chemical: 2 ' - O , 4 ' - C - methylene - bridged / linked bicyclic ribonucleotides; Chemical: nucleotides