Constructing dual-readout logic operations based on the silk fibroin sol-gel transition.

Inspired by an H2O2-induced chemical gelation of silk fibroin (SF) and biochemical computing, we demonstrated for the first time that the phase transformation of SF can serve as a visual output signal for constructing multiple Boolean logic operations. In our biological logic gates, three common enzymes, β-galactosidase (β-Gal), glucose oxidase (GOx) and catalase (CAT), were used as inputs and the SF state (sol or gel) was defined as an output. The designed logic gates could be observed by the naked eye and UV-Vis absorption change. Since a distinctive advantage of biocomputing is that different enzymatic reactions can take place smoothly when they work together, our logic system could be further scaled up to generate a multi-input logic network without any "crosstalk" and interference between them. We hope that such a constructed system might help us understand complex physiological processes in living systems, and have potential applications in digital bio-diagnosis.