DNA-mediated gold nanoparticle signal transducers for combinatorial logic operations and heavy metal ions sensing

• Different DNA structures were used as signal regulator for logic gates construction.
• Combinatorial logic gate was realized for simultaneous detection for Hg2+ and Ag+.
• This work developed an easy-making, cost-effective and rapid-readout logic system.

Herein, the structure of two DNA strands which are complementary except fourteen T–T and C–C mismatches was programmed for the design of the combinatorial logic operation by utilizing the different protective capacities of single chain DNA, part-hybridized DNA and completed-hybridized DNA on unmodified gold nanoparticles. In the presence of either Hg2+ or Ag+, the T–Hg2+–T or C–Ag+–C coordination chemistry could lead to the formation of part-hybridized DNA which keeps gold nanoparticles from clumping after the addition of 40 μL 0.2 M NaClO4 solution, but the protection would be screened by 120 μL 0.2 M NaClO4 solution. While the coexistence of Hg2+, Ag+ caused the formation of completed-hybridized DNA and the protection for gold nanoparticles lost in either 40 μL or 120 μL NaClO4 solutions. Benefiting from sharing of the same inputs of Hg2+ and Ag+, OR and AND logic gates were easily integrated into a simple colorimetric combinatorial logic operation in one system, which make it possible to execute logic gates in parallel to mimic arithmetic calculations on a binary digit. Furthermore, two other logic gates including INHIBIT1 and INHIBIT2 were realized to integrated with OR logic gate both for simultaneous qualitative discrimination and quantitative determination of Hg2+ and Ag+. Results indicate that the developed logic system based on the different protective capacities of DNA structure on gold nanoparticles provides a new pathway for the design of the combinatorial logic operation in one system and presents a useful strategy for development of advanced sensors, which may have potential applications in multiplex chemical analysis and molecular-scale computer design.