Do single nucleotides spontaneously bind to ss DNA?
I am no expert on the topic, but single stranded DNA is commonly found during DNA replication, when DNA helicase splits apart the DNA strands so that the DNA can be replicated. When this occurs, the two DNA strands naturally have a high affinity for each other, bearing complementary base pair sequences, and another molecule must be present in order to prevent the two DNA strands from re-binding. These are single-stranded binding proteins, and they bind to ssDNA to prevent re-binding from occurring. As this prevents the DNA from binding to the antiparallel strand, I would imagine it has a role in preventing single DNA nucleotides from binding to the DNA strand as well.