Greg Egan is a science-fiction writer that holds a B.S. in Mathematics (and a paper with John Baez). He often manages to insert some advanced maths, physics and computer science content in his novels (for instance, listing only mathematics, fiber bundles in Diaspora, Einstein's equation for general relativity in Incandescence, Cantor sets and commutative diagrams in two short stories whose title I have forgotten).
On the top of my head, I find it difficult to name a novel of his that does not feature a scientist among the protagonists.
ADDED by AK: His story "Dark Integers" deserves special mention.
