I see. I was not talking about Drexler's classical nanotech, though quantum effects are indeed irrelevant on the scale of, say, blood cells, save for essentially quantum-random ion channel gating and similar transitions. It may well be possible to design nanotech starting with, say, quantum dots, or custom fullerene molecules. Our technology is not there yet, but it's going in the right direction. It's not inconceivable that artificial prion-like structures which are not viruses can be used to modify the DNA in a living organism. Whether this requires a superintelligence or just human intelligence is a separate question.