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Exponential Amplification Using Photoredox Autocatalysis

submitted on 23.04.2021, 01:49 and posted on 23.04.2021, 10:50 by Seunghyeon Kim, Alejandra Martinez Dibildox, Alan Aguirre-Soto, Hadley Sikes
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 non-fluorescent eosin Y derivative (EYH2) 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 EYH2 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 EYH2 degradation, we successfully improved EYH2- 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 photo-induced 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


Singapore National Research Foundation

MISTI Mexico

Kwanjeong Educational Foundation

CONACYT Postdoctoral Research Award (263622)


Email Address of Submitting Author


Massachusetts Institute of Technology



ORCID For Submitting Author


Declaration of Conflict of Interest

no conflict of interest

Version Notes

Version One