Nanotechnology refers to all types of technologies that use, explore or manipulate materials at the nanoscale. Nanoparticles are one of the most commonly used nanomaterials in industry and consumer products. These particles can be made out of metals, metal oxides, lipids as well as polymers and can be defined as any object within 1 and 1000 nm in size. At the nanoscale, typically between 5 and 200 nm in size, materials start showing different characteristics than their bulk counterparts which can be exploited for various applications. The color of gold nanoparticles, for example, is dependent on their size and aggregation state. The red-colored nanogold is used in pregnancy tests. In these tests, the presence of a specific hormone, human choriongonadortropine, is detected by a specific antibody that carries nanogold and is thus visualized and can even be quantified. Unique properties like the red color of nanogold (in physics this observed effect is explained by surface plasmon resonance) make nanomaterials widely applicable in various industries and products.