Bioinspired Nanozymes with pH-Independent and Metal Ions-Controllable Activity: Field-Programmable Logic Conversion of Sole Logic Gate System

In nature, different environmental factors make organisms to be programmed into different forms. However, it is difficult and significant to realize the field-programmable logic conversion of sole logic system for molecular logic gates. Here, the concept of pH-programmable logic conversion on the single logic gate based on the peculiar enzyme-mimicking activity is presented. Inspired by natural enzymes with high pH-stability and metal ions-stimulated activity, pH-independent and metal ions-controllable catalase mimics (Co3O4 nanozymes) are designed by protein-directed method. Although pH cannot directly change the activity of nanozymes, pH can change the existence state of metal ions and then the electron transfer rate on nanozymes. So, versatile roles of metal ions for catalase-like and electrocatalytic activities are discovered on the premise of pH-independency. For the proof-of-concept, OR/INHIBIT- and INHIBIT/AND-switchable logic gates are facilely constructed using pH as the environmental stimulus and metal ions as inputs. Hence, the transformation of logic gate functions is realized without the change of logic gate elements and input molecules. This contribution may not only broaden the species and application area of nanozymes, but also open novel avenues for the molecular logic conversion and the metal ions sensor.