Prey, By Michael Crichton
Michael Crichton was one of my heroes growing up. RIP. He was a visionary in speculative sci-fi. It's no surprise with books like Jurassic Park, Andromeda Strain, and Timeline. With his habit of researching science and technology before writing, his book Prey (3.8 on Goodreads) is despite ratings, one of the best fiction books focused on nanites.
Before Prey, Nanotech wasn't a mainstay of mainstream fiction. Since then, TV script and novel writers have increasingly relied on nanotech, appearing in works like Revolution and Apple's Foundation series. That's not to say there weren't great works before Crichton, because there absolutely were, but he made it accessible and plausible for readers who aren't die-hard sci-fi fans.
Warning: the plot isn't all that amazing, but that's part of what made it an easy read for many who wouldn't have picked up a book with nano-bots in it. It's an easy-to-read, who-done-it murder mystery set in Nevada. I won't give away the plot, but it makes for a great airplane or beach read.
He focused on a single type of nanotech as many books do, but the applications are many. Crichton thought so much of the subject that he was working on another book, Micro (Only 3.5 on Goodreads) that was finished posthumously.
For those haters out there:
There are quite a few readers who didn't like this book, but let's face a few truths. Crichton was far more meticulous and research-oriented than most authors before or since. And many of his reviews were written as a comparison to Jurassic Park, which was both a novel success (12+ million copies sold in the US) and a box office success ($1+ billion). And note that Jurassic Park only receives 4.06 stars on Goodreads.
He wasn't ahead of his time like Stanislaw Lem, who wrote The Invincible in 1964, (4.1 on Goodreads), but perfectly timed for non-sci-fi readers.