Nucleic acid test

However, the mutants which form the genetic basis for a variety of human diseases are usually slightly different from the normal nucleic acids.

In this case, imperfect probe-target binding can easily occur, resulting in false-positive outcomes such as mistaking a strain that is commensal for one that is pathogenic.

Nucleic acid (DNA and RNA) strands with corresponding sequences stick together in pairwise chains, zipping up like Velcro tumbled in a clothes dryer.

When the correct target(X) reacts with the toehold exchange probe(PC), P is released and hybridized product XC is formed.

On the other hand, if the toehold exchange probe(PC) reacts with spurious target(S), the reaction forwards, but the standard free energy increases to be less thermodynamically favorable.

In 2015, David's group achieved extremely high (1,000+) selectivity of single-nucleotide variants (SNVs) by introducing the system called ‘competitive compositions’.

[6] In this system, they constructed a kinetic reaction model of the underlying hybridization processes to predict the optimal parameter values, which vary based on the sequences of SNV and wildtype (WT), on the design architecture of the probe and sink, and on the reagent concentrations and assay conditions.

Their model succeeded in a median 890-fold selectivity for 44 cancer-related DNA SNVs, with a minimum of 200, which represents at least a 30-fold improvement over previous hybridization-based assays.