Oligonucleotide libraries--variatio delectat.

In vitro selection of combinatorial nucleic acid libraries leads to specific target-binding molecules--RNA, single stranded DNA, modified RNA or modified DNA, commonly designated as aptamers--and to novel catalytic nucleic acids. The current state of aptamer and ribozyme technology is such that it establishes itself as a means of obtaining useful tools for molecular biology, diagnostics, molecular medicine and bio-organic chemistry.