Optical Logic Gates And Biosensor Based On Cationic Conjugated Polymer/DNA Superamolecular Systems

A novel supramolecular optical-logic system based on cationic conjugated polymer/DNA/intercalating dyes assembly has been constructed to create reversible logic gates capable of multiple logic operations and enable label-free detection of conformational conversion of DNA i-motif structure.The C-rich DNA sequences could form i-motif structures, wich often participate in important biological processes. We described our strategy based on cationic conjugated polymer/DNA assembly,which gives rise to a new method for label-free detection of conformational conversion of DNA i-motif structure by working in a simple"mix-and-detect"manner, which provides some inspirations for the investigation of other biomolecular conformational conversions upon environmental changes or binding to their targets. The study to find connections between the conformational conversion of DNA secondary structure, and the photophysics and supramolecular properties of water-soluble conjugated polymers and intercalating dyes, constituted the basis of these logic systems. AND+INH,INH and NOR logic gates were obtained.Multiple logic gates operating in parallel were simulated by taking advantage of the pH-driven conformational conversion of DNA i-motif structure and the two-step fluorescence resonance energy transfer (FRET) process in this assembly. This logic system capable of INH and NINH does not require any chemical modification or oligonucleotide labeling, which offers the advantages of simplicity and cost efficiency; and it can be switched back and forth by additions of H+ and OH– , which makes the logic gates operate easily and feasible to realize system reset.