A survey is given on recent work in the authors＇ laboratories dealing with the preparation and application of functional polymers, which are to be used (a) as supports for nucleic acid synthesis and (b) as carriers mediating the interaction of the immobilized nucleic acid chains with dissolved macromolecules. Two systems are spotlighted, which require loading capacities (1) as high as possible, or (2) as low as possible. These are (1) libraries of oligonucleotides bound either to particles or to a polypropylene tape. Ad (2) the possibility of loading a carrier with a single DNA molecule for exonucleolytic sequence analysis is discussed. The requirements for appropriate functional polymers for both applications are in the focus of this article. (C) 2000 Elsevier Science B.V. All rights reserved.