So, we've formally defined nanoparticles as any particle of the size range 1-100 nm (where 1 nm = 0.000000001 m). And this is the scale at which nanotechnology operates.However, I was thinking about nanomachines in nature. Nanorobots that have come alive through the process of evolution.
I'm talking about viruses. Yes, those pesky little things that make you sick. Viruses pose a problem, however. We don't know whether to classify them as alive or dead. Before we make an attempt to do that, we need to understand what the term "life" means and define what a living thing is.
The Nobel laureate physicist Erwin Schrodinger defined life this way: "Living things avoid decay into disorder and equilibrium". And that's a pretty good definition. Also, it means that viruses are very much alive. Viruses replicate, have DNA/RNA as genetic information, a boundary of proteins that separates it from the environment and are subject to evolution.
I like to think of viruses as nanorobots as plenty of viruses fit in the formal definition of a nanoparticle. The smallest dsDNA viruses are the hepadnaviruses such as Hepatitis B, at 42 nm; parvoviruses have smaller capsids, at 18-26 nm. As a whole the viral family geminiviridae is only about 30 nm in length. However, the two capsids making up the virus are fused, divided the capsids would be 15 nm. (Source: click here)
So, while we began thinking about nanoparticles in the early 1960s, nature was already engineering its own nanorobots for millions (perhaps billions) of years.
