The direct capture procedure involves the immobilization of double-stranded PCR products onto the beads. These are easily converted to single-stranded bead-bound templates which are then used to capture specific RNA or DNA molecules directly from solution.
An alternative indirect capture approach will offer faster reaction kinetics in some cases. This indirect capture procedure allows the target sequence to be captured prior to being immobilized onto the magnetic beads. First, a biotinylated capture-sequence (single-stranded DNA) is incubated with the sample and allowed to hybridize to the targeted RNA or DNA molecules in solution. Streptavidin-coated Dynabeads are then added to the mixture and the hybridized sequences are immobilized onto the Dynabeads via the streptavidin-biotin bond.
The 1 µm Dynabeads MyOne Streptavidin C1 present a very high surface area per mg of beads, enabling high enrichment of low-abundance RNA or DNA. When the goal is to capture nucleic acid from more viscous samples such as cerebrospinal fluid, the larger 2.8 µm sized Dynabeads M-270 Streptavidin are recommended. These Dynabeads (MyOne Streptavidin C1 and M-270 Streptavidin) are optimally designed to have slightly negatively charged surfaces which ensure negligible non-specific binding of non-target nucleic acid sequences.
Examples of applications include: isolation of RNA/DNA infectious agent (1,2,3,4), subtractive hybridization (5,6,7), cDNA selection and enrichment, detection and isolation of mutated sequences (8,9,10), isolation of cell specific transcripts, and mRNA differential display.
Learn more about Nucleic Acid Capture Assays