THE first microscopic 鈥渒not laboratory鈥� has been created inside a liquid crystal 鈥� and yes, it could help solve some knotty problems.
For instance, we know that enzymes unravel double-stranded DNA before proteins can be made. 鈥淏ut it鈥檚 still not very clear how this actually works,鈥� says Uro拧 Tkalec of the Jo啪ef Stefan Institute in Ljubljana, Slovenia. To investigate microscopic knots, Tkalec and colleagues turned to liquid crystals, which flow like fluids but whose constituent molecules line up in the same direction, like a solid crystal.
The team added silica particles coated with a surfactant to a liquid crystal, which disrupted its highly ordered structure. The disordered liquid crystal molecules adjacent to a silica particle formed a 3D Saturn鈥檚 ring around the particle.
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When two rings were brought close together using lasers, they immediately joined up to form a bigger, twisted loop around both the particles. A similar thing happened with three particles. By bringing just the right combination of twisted loops into contact, these arrays were made to unknot and reknot, forming interlocking hoops and a Star of David, as well as other shapes (Science, ).
鈥淸With 16 particles] you can achieve up to 80 topologically different structures,鈥� says Tkalec.
The miniature knot lab could help show how DNA is unravelled by enzymes to produce proteins, and could also allow mathematicians to study the nature of knots.