Supplementary Figure S1: Improved SARS-COV-2 PCR detection and genotyping with double-bubble primers

Depiction of anticipated stem-loop and homo-dimer Double- Bubble (D-B) primer configurations transition, as related to concentration and temperature changes. (A) At lower concentration, the primer is primarily in a stem-loop configuration since the molecular distance favors the stem-loop over the homo- dimer configuration. (B) As the primer concentration increases, the homo-dimer configuration is predominant since it is more thermodynamically-stable than that of the stem-loop configuration. (C) At lower temperature, both stem-loop and homo-dimer configurations could coexist. (D) Upon temperature elevation, primers at the stem-loop configuration are anticipated to melt and re-anneal to form the more thermodynamically-stable configuration of homo-dimer, and some primers are anticipated to assume a melted random-coiled linear mono-primer. Other intermediate possibilities like melted linear mono-primer could exist depending on concentrations and temperatures but are not shown in panels A-C for simplification reasons. For the 4 regions of the D-B primers consult Figure 1 A-C.