Additions and corrections

Photoinduced formation of reversible dye radicals and their impact on super-resolution imaging

Sebastian van de Linde, Ivan Krstić, Thomas Prisner, Sören Doose, Mike Heilemann and Markus Sauer

Photochem. Photobiol. Sci., 2011, 10, 499–506, DOI: 10.1039/C0PP00317D. Amendment published 21st May 2012.

The units on the x scale of Fig. 1d were incorrect. The correct version of Fig. 1 is below:

	Fig. 1 Reaction scheme, absorption, and EPR spectra of stable rhodamine radicals. (A) The dye is excited with rate kexc, fluoresces with kfl, or enters the triplet state (3F) dependent on its intersystem crossing rate kisc. The triplet state of the fluorophore can react with oxygen (k′isc(O2)) to repopulate the singlet ground state F0 and produce singlet oxygen 1O2, or react with the thiol with rate k1red(RSH/RS-) to form the semireduced dye radical (F˙) and the thiyl radical (RS˙). The semireduced dye radical can react with oxygen to repopulate the fluorescent singlet state with rate kox(O2). (B) Absorption spectra of an aqueous Alexa Fluor 488 solution containing 100 mM MEA, pH 9.3 before and after irradiation at 488 nm for 5 min. The radical anion exhibits an absorption maximum at 396 nm with an extinction coefficient of ε = 5.1 × 104 l mol-1 cm-1. (C) Absorption spectra of Alexa Fluor 488 measured in a sealed cuvette with time after photoreduction. The lifetime of the radical anion was determined to be about seven hours. (D, E) EPR spectra and time dependent behavior of the signal of a 10-4 M aqueous solution of Alexa Fluor 488 in the presence of 100 mM MEA, pH 9.3 after irradiation at 488 nm for several minutes. The exponential decay of the EPR signal reveals a radical lifetime of 100 min in non-sealed EPR capillary tubes. The pH of the solution was increased to 9.3 to facilitate photoreduction. The radical anion disappears immediately upon purging of the capillary with air.

The Royal Society of Chemistry apologises for this error and any consequent inconvenience to authors and readers.

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