When we think of the most expensive items in the world, our minds often wander to priceless jewels, rare metals, or perhaps extravagant real estate. However, there’s a substance so rare and costly that it takes the top spot on the list of the world’s most expensive materials. This isn’t a diamond or a piece of art; it’s a molecule known as Nitrogen Atom-Based Endohedral Fullerenes. Priced at a staggering £110 million ($140 million) per gram, thi…