Development of dual enzyme responsive molecular AND logic gate

Molecular logic gates are information processing devices that can respond to environmental signals and produce a readable output in response through Boolean logic operations. Molecules with these properties have been used to build smart sensors and therapeutic agents. In this work, dual enzyme-responsive molecular AND logic gate is developed with the intention to discriminate various combinations of enzyme level and/or activity. A resorufin-based sensor is substituted with self-immolative tyrosinase recognition site, 3-hydroxy benzyl group. The Hydroxyl group is protected with acetyl moiety which decreases the affinity of the enzyme. When both tyrosinase and esterase are present in the solution, the acetyl group is removed by the latter enzyme, allowing the former to recognise the ligand. Oxidation of the ligand by tyrosinase triggers self-immolative cleavage of the substitution, leading to almost 70 fold enhancement in fluorescence. When single enzyme is applied, there is no significant change in the emission intensity overall, an AND logic gate is constructed. Selectivity and Michaelis-Menten kinetics of the sensor is analysed. Smart molecular probes can contribute to the research on the development of biosensors that can discriminate diseases having characteristic combinations of enzyme activities.