Interfacing Electrochemistry with Synthetic Gene Circuits

Synthetic biology enables modular engineering and arrangement of functional nucleic acids and proteins to act cooperatively in response to a biorecognition event by initiating logic dictated specific biochemical reaction circuit. In other words, orthogonal biomolecules, implemented as LEGO bricks, are arranged into a cascade to deliver sequence encoded functions. Such engineering approaches are on-track to introduce a new paradigm for modern medicine and biotechnology, such as gene-circuit based chassis for regenerative medicine, nucleic acid computers capable of performing complex logic, gene-circuit based biosensors able to detect broad ranges of biomolecules. Specifically, highlighted by the current COVID-19 pandemic, cell-free synthetic gene circuit has significantly promoted the development of biosensing systems with high specificity, high sensitivity, and low interference, bringing in a powerful design approach for point-of-care system. However, synthetic biology only leverages the information processing capability of biological machineries to tackle molecular recognition and cascading reactions. Comparing with electrical system, synthetic gene circuit does not have the capability to extract processed information for display or memory storage, emphasizing the necessity of a physical interface to curate and translate the downstream biomolecular output into a readable and digital processable signal. Herein, I will discuss engineering strategies to interface electrochemistry with synthetic biology for the development of universal biosensing systems capable of detecting nucleic acids and proteins, translating biomolecular information directly into electrical current. I will first discuss our efforts in designing and developing the first electrochemistry based CRISPR biosensor (E-CRISPR), in which we constituted an electrochemical surface to probe the trans-cleavage activity of Cas12a. I will further introduce the design of a multi-function heterogeneous biochemical circuit and the utilization of electrochemistry to probe the circuit output. Overall, these two examples demonstrate the robust capability of the unique combination of electrochemistry and synthetic biology for the development of next-generation bioanalytical system.