23348
We report a scaffold - free approach in which four - and six - helix DNA bundle units , assembled from a small number of single stranded DNA oligonucleotides precisely arranged in networks of contiguous and semicrossover strands , are connected into DNA nano rings .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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