A chemoenzymatic reaction-diffusion system with local inhibition and distal activation

Spatiotemporal gating in signal transduction and corresponding activation or inhibition of a biochemical pathway is the hallmark of biological functionality. Herein, through both experimental and computational approaches, we developed a synthetic system to mimic one of the key biological signaling events - local inhibition and distal (long-range) activation (LIDA). The basis of our system lies in the differential diffusivity of – (i) injected dormant activator or pro-activator (Pro-A, urea, fast to diffuse due to non-binding with nanoparticle (NP) in gel matrix) that converts to activator (A, ammonium bicarbonate) via an enzyme (urease) embedded in the hydrogel) and (ii) inhibitor (IN, adenosine triphosphate (ATP), diffusion restricted due to interaction with NP). Here A and IN act as the activator and inhibitor of a base-catalyzed proton transfer reaction in the gel matrix, respectively. The indispensability of ProA to A conversion during diffusion for efficient time-regulated LIDA effect has also been demonstrated. The ability to input spatial gating of pH and reaction activation can potentially be extrapolated to develop neuromorphic self-assembled systems with distal programmability. Achieving spatiotemporal gating of signals is desirable for mimicking of biological processes, but is challenging to achieve in synthetic systems. Here, the authors report a multicomponent chemoenzymatic system to realize local inhibition and long-range activation, by exploiting variations in molecular diffusivity.