Enzyme-Based Logic Analysis of Biomarkers at Physiological Concentrations: AND Gate with Double-Sigmoid "Filter" Response

TL;DR

This paper demonstrates a biomolecular AND gate with a double-sigmoid response that accurately detects liver injury biomarkers at physiological concentrations, effectively filtering noise and functioning reliably in biological conditions.

Contribution

It introduces the first enzyme-based AND gate with a double-sigmoid response and a simple filtering mechanism to improve noise robustness in biomolecular logic systems.

Findings

Successful realization of a biomolecular AND gate with double-sigmoid response

Effective noise filtering through a biocatalytic process

Theoretical analysis confirms robust gate performance

Abstract

We report the first realization of a biomolecular AND gate function with double-sigmoid response (sigmoid in both inputs). Two enzyme biomarker inputs activate the gate output signal which can then be used as indicating liver injury, but only when both of these inputs have elevated pathophysiological concentrations, effectively corresponding to logic-1 of the binary gate functioning. At lower, normal physiological concentrations, defined as logic-0 inputs, the liver-injury output levels are not obtained. High-quality gate functioning in handling of various sources of noise, on time scales of relevance to potential applications is enabled by utilizing "filtering" effected by a simple added biocatalytic process. The resulting gate response is sigmoid in both inputs when proper system parameters are chosen, and the gate properties are theoretically analyzed within a model devised to evaluate its noise-handling properties.