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.
Trying to knot tiny molecules together is a task that is exactly as difficult as it sounds. However, manipulating molecules into ever tighter knots is a goal that many researchers eagerly pursue, and not just for the daunting challenge it provides. Scientists believe that making different types of molecular knots can be used as a method to probe how knotting affects strength and elasticity of materials. This, in turn, can lead to the creation of polymer strands that can be used to build stronger and more flexible materials. A team of researchers from the University of Manchester has now created a record-breaking knot.
The use of Crispr as a technology for genome editing has been around for a few years and burst into prominence in 2015, after the American Association for the Advancement of Science chose it as the breakthrough technology of the year. And as if genome editing wasn't already a precision task, researchers from Massachusetts Institute of Technology (MIT) have added a light-based layer of control to the system. According to a statement published on the MIT website Thursday, the method its researchers have developed allows Crispr to be used only when ultraviolet light is shone on the target cells, effectively making the light a switch. Sangeeta Bhatia, a professor at MIT and senior author of a research paper that describes the new technique, said in the statement: "The advantage of adding switches of any kind is to give precise control over activation in space or time." It could enable scientists to study the timing of cellular and genetic events that affect various bodily functions, from embryonic development to progression of diseases.
Scientists have developed a neural network using DNA, which can correctly identify numbers encoded in molecules using machine learning, an advance that may pave the way for biological machines with artificial intelligence. Artificial neural networks are mathematical models inspired by the human brain. Despite being much simplified compared to their biological counterparts, artificial neural networks function like networks of neurons and are capable of processing complex information. The ultimate goal for this work is to programme intelligent behaviours (the ability to compute, make choices, and more) with artificial neural networks made out of DNA. "In this work, we have designed and created biochemical circuits that function like a small network of neurons to classify molecular information substantially more complex than previously possible," said Lulu Qian, assistant professor at California Institute of Technology in the US.
The reconfigurable DNA relay arrays were constructed by using both origami and single-strand–brick approaches. In one-pot assembly, we observed that the arrays built from antijunction units exhibited a spectrum of shapes to accommodate different combinations of antijunction conformations. With the incorporation of set strands, we could lock the arrays into prescribed conformations. The more set strands were added, the greater the assembly shifted toward the corresponding array conformation. Other factors, including the size and aspect ratio of an array, the connecting pattern of an array, DNA sequences of an array, cation concentration, and temperature, have been shown to affect the result of one-pot assembly.