for the self - assembling process , a solution containing 10 nm scaffold strand , 50 nm of each staple strand ( reverse - phase cartridge purified , bioneer inc . ) , 5 mm tris + 1 mm edta ( ph 7.9 at 20 c ) , 16 mm mgcl2 was heated to 80 c for 4 min , cooled down to 60c over the course of 80 min , and cooled further down to 24 c over the course of 72 h. the folded objects were electrophoresed on a 1.5% agarose gel containing 45 mm tris borate + 1 mm edta and 11 mm mgcl2 at 70 v for 3 h. to prevent the origami structures from denaturation during electrophoresis , the gel - box was cooled in an ice - water bath .
the gel - band containing the structures was physically extracted from the gel and run through spin columns ( freezensqueeze spin columns , biorad ) at 5000 rcf .
the dna tensegrity objects were then imaged with tem after negative staining with uranyl formate on a fei tecnai t12 biotwin at 80 kv .
a 12-helix  bundle kite with four springs of equal length ( 300 nt ) was designed such that the restriction site for ecori is located in one of the 300-nt  spring regions . the assembled kites with a double - stranded region at the ecorri restriction site ( gaattc + 10 bases or more overhang on both sides of the sequence )
were incubated for one hour with the enzymes ( 20 l of 10 nm scaffold , 80 nm each staple , 1xneb - buffer 2 , 20 units of enzyme , new england biolabs , inc . ) . uncut and cut tensegrity kites were electrophoresed on a 1.5% agarose gel .
the gel - bands were physically extracted and imaged with tem after negative staining with uranyl formate .
for the self - assembling process , a solution containing 10 nm scaffold strand , 50 nm of each staple strand ( reverse - phase cartridge purified , bioneer inc . ) , 5 mm tris + 1 mm edta ( ph 7.9 at 20 c ) , 16 mm mgcl2 was heated to 80 c for 4 min , cooled down to 60c over the course of 80 min , and cooled further down to 24 c over the course of 72 h. the folded objects were electrophoresed on a 1.5% agarose gel containing 45 mm tris borate + 1 mm edta and 11 mm mgcl2 at 70 v for 3 h. to prevent the origami structures from denaturation during electrophoresis , the gel - box was cooled in an ice - water bath .
the gel - band containing the structures was physically extracted from the gel and run through spin columns ( freezensqueeze spin columns , biorad ) at 5000 rcf .
the dna tensegrity objects were then imaged with tem after negative staining with uranyl formate on a fei tecnai t12 biotwin at 80 kv .
a 12-helix  bundle kite with four springs of equal length ( 300 nt ) was designed such that the restriction site for ecori is located in one of the 300-nt  spring regions .
the assembled kites with a double - stranded region at the ecorri restriction site ( gaattc + 10 bases or more overhang on both sides of the sequence ) were incubated for one hour with the enzymes ( 20 l of 10 nm scaffold , 80 nm each staple , 1xneb - buffer 2 , 20 units of enzyme , new england biolabs , inc . ) .
the gel - bands were physically extracted and imaged with tem after negative staining with uranyl formate .
 tensegrity or tensional integrity is a property of a structure that relies on a balance between components that are either in pure compression or in pure tension for its stability [ 1,2 ] . 
 tensegrity structures exhibit extremely high strength - to - weight ratios and great resilience , and are therefore widely used in engineering , robotics and architecture [ 3,4 ] . here 
 we report nanoscale , prestressed , three - dimensional tensegrity structures in which rigid bundles of dna double helices resist compressive forces exerted by segments of single - stranded dna that act as tension - bearing cables . 
 our dna tensegrity structures can self - assemble against forces up to 14 pn , which is twice the stall force of powerful molecular motors such as kinesin or myosin [ 5,6 ] . 
 the forces generated by this molecular prestressing mechanism can be employed to bend the dna bundles or to actuate the entire structure through enzymatic cleavage at specific sites . 
 in addition to being building blocks for nanostructures , tensile structural elements made of single - stranded dna could be used to study molecular forces , cellular mechanotransduction , and other fundamental biological processes . 
Methods
Folding and purification of Prestressed DNA Tensegrity structures
Ligand-induced mechanical actuation of the 12-helix-bundle kite
Supplementary Material