Fig. 2

Validation of the amplification steps. Simulation of the structure and thermodynamics parameters of H1 (A) and H2 (B). C 12% PAGE of the product of the first amplification step. Ladder: 20 bp DNA marker, H1: hairpin 1, H2: hairpin 2, T: mRNA target, C: negative control, lanes 1–3: 3 separate products of the first amplification step. D LFAs data of all components in first amplification step [H1, H2, H1 + H2(Control) and H1 + H2 + T(Sample)]. E TEM of gold nanoparticles. F TEM of gold signal probes. G Photographs and corresponding grayscale map of the second amplification step, (1): AuNPs labelled strips of AP1 (created by 0 nM and 0.1 nM mRNA) without gold enhancement; (2): AuNPs labelled strips of AP1 (created by 0 nM and 0.1 nM mRNA) with gold enhancement. [Amplification step reagents: 0.1% (w/w) HAuCl₄ and 10 mM NH₂OH·HCl (1:10), reaction time: 5 min]