The tightest knot ever is also one of the tiniest. Made of strings of molecules braided together, the knot is only 20 nanometres long, and its properties are as yet unknown. But researchers hope that these tied-up molecules could lead to lighter body armour or more flexible surgical sutures. Molecular knots like this are probably more analogous with the knots in mathematics, which are closed loops twisted into different shapes, than with the knots in your phone charger's cord. The first molecular knot – one of the most mathematically simple kinds called a trefoil knot – was tied in 1989.
January 17, 2017 --Knots have been around for thousands of years. But now, a team of researchers from the University of Manchester has added a new twist to one of the most basic technologies known to humans. Using cutting-edge chemical techniques, the researchers have created the tightest knot ever made, woven on a molecular level. The new knot is a circular triple helix only 20 nanometers long, containing only 192 atoms, the researchers report in a paper published in the Jan. 13 issue of Science magazine. While scientists have known for decades that molecular knots like this one are theoretically possible, it has proven difficult to create knots of such complexity, with previous molecular knots using only two strands woven together in very basic patterns.
Chemists have tied the tightest knot yet, a nano-sized structure with eight crossings and just 192 atoms. The advance could help researchers learn how to manipulate materials at the atom level to develop stronger, more flexible, and lighter-weight cloth or construction materials. The knot, described in today's issue of the journal Science, measures 20 nanometers in length, about 100,000 times smaller than the head of a pin. Why make a knot that's so small? I'll give you a two-part answer.
Knots may ultimately prove just as versatile and useful at the nanoscale as at the macroscale. However, the lack of synthetic routes to all but the simplest molecular knots currently prevents systematic investigation of the influence of knotting at the molecular level. We found that it is possible to assemble four building blocks into three braided ligand strands. Octahedral iron(II) ions control the relative positions of the three strands at each crossing point in a circular triple helicate, while structural constraints on the ligands determine the braiding connections. This approach enables two-step assembly of a molecular 819 knot featuring eight nonalternating crossings in a 192-atom closed loop 20 nanometers in length.
A new vegan sustainable film could replace single-use plastics in many consumer products, scientists say. The film, created at the University of Cambridge, is inspired by spider silk, one of the strongest materials known to nature. It has the strength of human-made synthetic polymers in plastic bags and film wraps, but fully decomposes naturally, without harming the environment. The new product will be commercialised by Xampla, a University of Cambridge spin-out company developing replacements for single-use plastic and microplastics. Xampla will introduce a range of single-use sachets and capsules later this year, which can replace the plastic used in everyday products like dishwasher tablets and laundry detergent capsules – many of which still come in individual plastic wrappers.