Fig. 7.

Schematic representation for Gold Nanoparticles Enabled Ligase Chain Reaction.

A) Perfect match; At 50 °C, the two capture probes (CPs) (numbered as 3 & 4 and are colored/shaded differently) that are coated on non-aggregated gold nanoparticles (AuNPs) (indicated by unfilled circle) hybridize adjacently on target DNA (colored in black) leaving a nick that is sealed (indicated by small black box) with ampligase enzyme producing aggregated and coloured NPs (Black filled circle). Following denaturation at 90 °C and second hybridization, more aggregated NPs are produced from sealing the nick at the junction between target DNA and the CP coated AuNPs and also the nick at the junction between ligated CPs (with a small black box) coated AuNPs and partial probes (numbered as 1 & 2 and colored/shaded differently). Denaturation is then repeated with subsequent hybridization and ligation leading to exponential amplification of ligated CP coated AuNPs with a colour change from red to purple/grey. B) Mismatch; The two CPs (numbered as 3 & 4 and colored/shaded differently) coated AuNPs do not hybridize with target DNA (colored in black) and hence neither ligation nor aggregation of CPs coated AuNPs occur with no colour change.