Large-Scale Oligonucleotide Synthesis Using the Solid-Phase Approach

Synthetic DNA of defined sequences are commonly termed "oligonucleotides," which are primarily composed of four different types of nucleosides linked through well-defined deoxyribose phosphate. Over the past ten years, because of refinement in synthesis chemistries (1a–1e) and automation of synthesis steps (2a,2b), oligonucleotide syntheses of defined sequences are common practices in nonchemists' laboratories. Oligonucleotides are routinely used as DNA sequencing primers (3a–3c), probes (4a, 4b), linkers, adaptors, and gene synthesis (5). In addition to these applications, biophysical studies (6a,6b) (NMR, X-ray crystallography) for structural information of synthetic oligonucleotide using milligram quantities have been carried out. Newer applications of oligonucleotides are also emerging in the field of clinical diagnosis (7a–7c), forensic testing, and disease treatment (8a–8e). Investigations are being carried out in many laboratories for potential use of oligonucleotides as therapeutic agents broadly referred to as "use as antisense DNA." Inhibition of viral replication in diseases, such as AIDS, herpes, and human pepiloma virus, and regulation of oncogene expression with oligonucleotides or their analogs are two major potential applications of synthetic DNA. Presently, these studies are moving out of research laboratories and into practical medical applications (9).