Pearls to order

2019-03-08 06:02:15

OYSTERS have finally met their match. For the first time, German chemists have made pearls in the lab. Left to itself, calcium carbonate forms clear calcite crystals. But living creatures make complex solids as varied as bones, teeth, pearls or seashells by assembling carbonates on proteins. Wolfgang Tremel and his colleagues at the University of Mainz mimicked this process by crystallising calcium carbonate on layers of sulphanyl phenol surrounding gold particles just 5 nanometres wide. Instead of forming calcite crystals, the molecules aligned themselves in the radiating pattern typical of pearl (Angewandte Chemie International Edition, vol 37,