Molecules 2012, 17(6), 6605-6624; doi:10.3390/molecules17066605
Article

Reversible Low-Light Induced Photoswitching of Crowned Spiropyran-DO3A Complexed with Gadolinium(III) Ions

1, 2, 3, 1, 3, 2 and 1,* email
Received: 26 March 2012; in revised form: 11 May 2012 / Accepted: 25 May 2012 / Published: 31 May 2012
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Photoswitchable spiropyran has been conjugated to the crowned ring system DO3A, which improves its solubility in dipolar and polar media and stabilizes the merocyanine isomer. Adding the lanthanide ion gadolinium(III) to the macrocyclic ring system leads to a photoresponsive magnetic resonance imaging contrast agent that displays an increased spin-lattice relaxation time (T1) upon visible light stimulation. In this work, the photoresponse of this photochromic molecule to weak light illumination using blue and green light emitting diodes was investigated, simulating the emission spectra from bioluminescent enzymes. Photon emission rate of the light emitting diodes was changed, from 1.75 × 1016 photons·s−1 to 2.37 × 1012 photons·s−1. We observed a consistent visible light-induced isomerization of the merocyanine to the spiropyran form with photon fluxes as low as 2.37 × 1012 photons·s−1 resulting in a relaxivity change of the compound. This demonstrates the potential for use of the described imaging probes in low light level applications such as sensing bioluminescence enzyme activity. The isomerization behavior of gadolinium(III)-ion complexed and non-complexed spiropyran-DO3A was analyzed in water and ethanol solution in response to low light illumination and compared to the emitted photon emission rate from over-expressed Gaussia princeps luciferase.
Keywords: spiropyran; photochromic molecule; DO3A; MRI contrast agent; luciferase; light emitting diodes; rate constant; low light applications
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MDPI and ACS Style

Kruttwig, K.; Yankelevich, D.R.; Brueggemann, C.; Tu, C.; L’Etoile, N.; Knoesen, A.; Louie, A.Y. Reversible Low-Light Induced Photoswitching of Crowned Spiropyran-DO3A Complexed with Gadolinium(III) Ions. Molecules 2012, 17, 6605-6624.

AMA Style

Kruttwig K, Yankelevich DR, Brueggemann C, Tu C, L’Etoile N, Knoesen A, Louie AY. Reversible Low-Light Induced Photoswitching of Crowned Spiropyran-DO3A Complexed with Gadolinium(III) Ions. Molecules. 2012; 17(6):6605-6624.

Chicago/Turabian Style

Kruttwig, Klaus; Yankelevich, Diego R.; Brueggemann, Chantal; Tu, Chuqiao; L’Etoile, Noelle; Knoesen, André; Louie, Angelique Y. 2012. "Reversible Low-Light Induced Photoswitching of Crowned Spiropyran-DO3A Complexed with Gadolinium(III) Ions." Molecules 17, no. 6: 6605-6624.


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