November 01, 2016 at 12:30AM

Today I Learned: 1) ...a few things about Salem, Massachussets. It was named after "salam", as in "peace". It was once the capital of the Massachussetts Bay Colony, until a governor's son drowned in the river near the city, and the governor decided to move the capital to Boston to avoid memories of his son's death. Salem also used to be one of the more wealthy, thriving ports in New England. Much of modern-day Salem occupies what used to be ocean, which was filled in with at least one New Hampshire mountain. List continues. 2) A joint iGEM team from Ludwig-Maximillian University and the Technical University of Munich just presented a new technology for 3D printing tissues. Current standard organ-printing technology involves printing alternating layers of hydrogel scaffolding and cells. The scaffolding provides structure for the cells until they're nicely adhered. Then the hydrogel is blasted or chemically washed away, which is fairly destructive. The Munich team built several cell lines that display biotin on their outer membranes. They print by injecting those cells (free-floating!) into a media containing tetrameric avidin variants*. The biotin on the cells sticks to the avidin in the media, and the avidin (being tetrameric --> having four binding sites for biotin) acts as a chemical bridge that causes the cells to stick together. They clump up almost immediately, and form vaguely rigid structures, or at least as rigid as a pile of cells is going to get. They can print pretty nice-looking 2D shapes, and they've demonstrated the ability to print two layers, with cells sticking in their printed layer quite well. The printer the team used was a modified Ultimaker 2. They modified it with a special printing head and a custom bed for holding petri dishes, both of which can be printed by the vanilla version of the Ultimaker for a conversion cost of about $50. * For those who don't remember from previous TILs, avidin and biotin are notable proteins mostly because they bind together really really strongly. 3) Chinese medicine has a regulation problem in China. Chinese medicinal substances occupy a weird liminal space between food and medicine, and as such somehow don't fall under the regulatory purview of any Chinese regulatory agencies. That's bad, because they are, in fact, taken as both food *and* medicine, and it turns out that it's not enormously uncommon for Chinese medicine to be contaminated with heavy metals or Aspargillus (which excretes some pretty nasty toxins).