UV-Resistant Cell-Free Reactions with Synthetic Melanin Additives

<i>Escherichia coli</i> lysate-based cell-free systems have gained traction for a variety of point-of-use biological applications. Lysate-based cell-free reactions can be freeze-dried, deployed without requiring cold chain, and have a high ease of use through simple rehydration. To maximize their potential, it is of interest to stabilize these reactions to withstand a variety of conditions for long-term storage and use, including stabilization to UV exposure. To address this issue and aid in point-of-use applications, we investigate the use of synthetic melanin nanoparticles as UV-protective additives that are compatible with cell-free reactions. These particles have broadband absorption properties and radical scavenging activity that allow for protection from free radical generation during prolonged UV exposure. Stabilizing cell-free reactions in this way may prolong the stability for use in the field where exposure to sunlight is inevitable.