The label is covalently attached to the primer before amplification begins. When the primer anneals to its complementary template, DNA polymerase extends that primer, so the biotin-containing primer becomes part of the newly generated product. This places biotin on the amplified material itself rather than requiring a separate labeling step after amplification.
Biotin binds strongly to streptavidin or avidin, creating a selective connection between the amplified nucleic acid and a capture reagent. If streptavidin is associated with magnetic beads or a surface, the product can be separated, immobilized, or presented for detection. The interaction therefore converts a molecular label into a practical handling and signal-generation tool.
Both primers direct template-specific amplification through annealing and polymerase extension, but the biotinylated version adds a controllable capture feature to the resulting product. An unlabeled product does not gain that biotin-dependent route for binding streptavidin or avidin. Consequently, labeling supports downstream purification, immobilization, hybridization, or detection beyond amplification itself.
First, the labeled primer is used in a primer-directed amplification reaction so the target product incorporates biotin. The amplified material is then exposed to streptavidin- or avidin-associated magnetic beads or another capture surface. Binding enables selective retention or immobilization, allowing the labeled product to be handled separately from material that lacks the biotin-linked interaction.
These products support several workflows that require selective nucleic acid handling. The overview identifies nucleic acid purification, hybridization assays, sequencing workflows, probe-based detection, and immobilization on surfaces as applications. In each case, the incorporated label provides a means to capture, retain, position, or detect amplified DNA or RNA through avidin or streptavidin binding.
After amplification, the biotin on the product can bind streptavidin or avidin linked to a capture surface, magnetic bead, probe-based system, or signal-generating component. Immobilizing the product in this way can support hybridization assays and detection workflows. The approach connects sequence-specific amplification with selective positioning and observation of the resulting nucleic acid.