antisense antisensedna biochemistry biopharmaceutics chemicalreactions chemicalsynthesis chemistry combinatorialchemistry complementary design dna drugdiscovery drugs evolution genelibraries genelibrary geneticengineering geneticrecombination genetictechniques laboratorymanuals methods microbialmutation molecular molecularbiology molecularevolution molecularstructure pharmaceutical pharmaceuticalchemistry qu25g3262003 quantitativestructure-activityrelationship qv744 research rs419 rs420 smallmoleculelibraries synthesis technique trends