FIGURE 1.

Representation of one cycle of the solid phase amplification process. The solution is first heated to break the molecule into its two complementary fragments (a). The solution is then cooled down to allow the template to bind to the complementary grafted primers (b). Finally the solution is reheated to allow the polymerase to add nucleotides at the end of the primers and eventually make a complete complementary copy of the template (c). The solution is then reheated and a new thermal cycle is started (d). Those three steps are respectively called denaturation, annealing, and extension. SPA results in a spatially located ssDNA colony. Note that since a molecule always generates its complementary sequence in a thermal cycle, the two complementary branches will be present in the colony and two different types of primers have to be attached to the surface.