A universal lateral flow biosensor for proteins and DNAs based on the conformational change of hairpin oligonucleotide and its use for logic gate operations.

A universal lateral flow biosensor for proteins and DNAs was designed on the base of target-induced conformational changes of hairpin oligonucleotide (HO). CEA (carcinoembryonic antigen) protein and c-DNA were detected both with the naked eye and a strip reader. The scheme of detecting proteins and DNAs were based on the unique molecular recognition properties of HO to the targets to form different quantities of "active" biotin groups on the surface of gold nanoparticles (AuNPs). The output of the strip is the color of the test line, which inspired us to combine strip biosensor with logic gate. Two strip logic gates ("OR" and "INH") were designed in our paper and the combinatorial logic gates in our paper could be used to make high-throughput judgment about what targets were present in the input samples according to the output results. The biosensor facilitates a portable analysis at ambient temperature as it is simple to be conducted and no requirement of training is needed. The strip logic system is proved an excellent selection and can operate effectively as well as in human serum samples. Therefore, we indicate that such logic strips a foreseeable promise in application of intelligent point-of-care and in-field diagnostics.