Abstract: Methods are provided for the production of nucleic acid ligands against target molecules using a procedure known as Transcription-free Systematic Evolution of Ligands by EXponential enrichment (Transcription-free SELEX). The Transcription-free SELEX method assembles nucleic acid ligands from fragments of synthetic nucleic acids by annealing those fragments to a complementary template, and then ligating the fragments together.

Abstract: Oligomers which have substituents on the 2' position are resistant to oligonucleases and furthermore can be derivatized to deliver reagents or drugs, to carry label, or to provide other properties.

Abstract: Pseudonucleosides and pseudonucleotides are useful in the synthesis of oligomers which contain these components as a means to derivatize the resulting oligonucleotide to useful substituents such as chelators, intercalators, or lipophilic compounds. In general, these pseudonucleotide components are of the formula: ##STR1## wherein each Y is independently O or S; each X is independently H, PO.sub.3.sup.-2, an activated nucleotide synthesis coupling moiety, a protecting group, a nucleoside, a nucleotide or a nucleotide sequence, or comprises a solid support;F is a functional group capable of linking an additional moiety or said group already reacted to effect the binding of said additional moiety;.quadrature.

Abstract: Oligonucleotides having tandem sequences of inverted polarity, i.e., oligonucleotides comprising regions of the formula: ##STR1## wherein --C-- symbolizes any method of coupling the nucleotide sequence of opposite polarity,are useful for forming an extended triple helix with a double-helical nucleotide duplex. The inverted polarity also stabilizes the single-strand oligonucleotides to exonuclease degradation.

Abstract: Oligonucleotide analogs wherein one or more phosphodiester linkages between adjacent nucleotides are replaced by an formacetal/ketal type linkage are resistant to nucleases and do not need to exhibit the diastereomerism characteristic of many other oligonucleotide analogs, and thus are capable of strong hybridization to target RNA or DNA. These oligonucleotide analogs are useful in therapies which modulate gene expression using "antisense" or other specifically binding oligomers.

Abstract: The present invention describes methods for the production of oligonucleotides under conditions which exploit the desirable characteristics, such as the property of sustaining high degrees of substitution, of functionalized organic polymeric supports while avoiding the sluggish kinetics and low rates of conversion which normally plague syntheses involving such solid supports. By employing the methods and materials disclosed, functionalized support, substituted to a degree of about 250 .mu.mol/g, can be utilized at greater than 98% conversion levels for each sequential nucleotide coupling cycle, to provide unprecedented amounts of isolated oligonucleotide per gram of solid support.