Characteristics of DNA-tagged liposomes allowing their use in capillary-migration, sandwich-hybridization assays.
Liposomes that have been labeled externally with a DNA oligomer are used in a capillary-migration, sandwich-hybridization assay for specific DNA target sequences. The liposomes are used in a DNA detection scheme that produces visually observable results in 10 min. The preparation and covalent attachment of a thiol-activated 22-base oligomer to the external surface of dye-containing liposomes is described, and the specificity of the assay toward perfectly complementary target DNA is demonstrated. Several characteristics of DNA-tagged liposomes that allow the use of increased stringency during hybridization are evaluated. These include the effect of temperature, formamide, and salt concentration on both the sandwich-hybridization assay and the liposomes themselves. The effects of several components of a common hybridization solution are determined with regard to both assay performance and liposome stability. Using a solution of 0.02% sodium dodecyl sulfate in 3X standard saline citrate, a visual detection limit of 200 amol of target DNA was obtained.
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Analytical Chemistry Laboratories, Cornell University, Geneva, New York 14456-0462, USA.
Montagna
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Durst
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D002021:Buffers; D004279:DNA, Viral / Q000737:chemistry*; D005559:Formamides; D007242:Herpesvirus 1, Bovine / Q000235:genetics; D008081:Liposomes; D009693:Nucleic Acid Hybridization / Q000379:methods*; D017422:Sequence Analysis, DNA / Q000379:methods*
D002021:Buffers; D004279:DNA, Viral; D005559:Formamides; D008081:Liposomes; C031066:formamide