Exponential Amplification Using Photoredox Autocatalysis

• Main Authors: Kim, Seunghyeon (Author), Martínez Dibildox, Alejandra (Author), Aguirre-Soto, Alan (Author), Sikes Johnson, Hadley (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Chemical Engineering (Contributor)
• Format: Article
• Language: English
• Published: American Chemical Society (ACS), 2021-08-09T22:46:52Z.
• Subjects: Article
• Online Access: Get fulltext

 Exponential molecular amplification such as the polymerase chain reaction is a powerful tool that allows ultrasensitive biodetection. Here, we report a new exponential amplification strategy based on photoredox autocatalysis, where eosin Y, a photocatalyst, amplifies itself by activating a nonfluorescent eosin Y derivative (EYH³⁻) under green light. The deactivated photocatalyst is stable and rapidly activated under low-intensity light, making the eosin Y amplification suitable for resource-limited settings. Through steady-state kinetic studies and reaction modeling, we found that EYH³⁻ is either oxidized to eosin Y via one-electron oxidation by triplet eosin Y and subsequent 1e⁻/H⁺ transfer, or activated by singlet oxygen with the risk of degradation. By reducing the rate of the EYH³⁻ degradation, we successfully improved EYH³⁻-to-eosin Y recovery, achieving efficient autocatalytic eosin Y amplification. Additionally, to demonstrate its flexibility in output signals, we coupled the eosin Y amplification with photoinduced chromogenic polymerization, enabling sensitive visual detection of analytes. Finally, we applied the exponential amplification methods in developing bioassays for detection of biomarkers including SARS-CoV-2 nucleocapsid protein, an antigen used in the diagnosis of COVID-19.