Photocleavable groups (cages) are small organic molecules that can be attached to a functional group of a biomolecule and used to light-trigger its bioactivity. The presence of the cage changes the original molecular structure, conformation or charge that results in a dramatic alteration of the biological function. Upon light exposure, the photolabile group is cleaved and the bioactivity is restored. Light has important advantages as external trigger. It can be readily available and focused, allowing a precise temporal and spatial definition of the activation process. Light dose can be precisely controlled over the irradiation time and intensity, allowing precise modulation of the concentration of active molecule, a feature that is not easy to achieve with other triggering sources.
By using photoremovable cages with differential response to selected
wavelengths, the bioactivity of coexisting molecules can be
independently triggered. The independent response relies on the
different photosensitivity of the chromophores at the selected
wavelength (as given by the quantum yield of the photolytic reaction
and extinction coefficient of the chromophore at the selected
wavelength). This strategy allows individual and highly controlled
activation of multiple processes confined into the same space.
UV-Vis spectra of caging groups showing differences in extinction coefficients
|Fluorescently labelled protein micropattern. A surface modified with a photocleavable aminoterminated silane was patterned using a scanning laser and different exposure doses. Fluorescently labelled protein was coupled to the exposed fields and. The fluorescent pattern reveals different protein surface densities that correlate with the exposure dose.||Bifunctional pattern obtained after masked irradiation of a surface layer containing two photocleavable groups at two selected wavelengths.|
- Modulating surface density of proteins via caged surfaces and controlled light exposure, M. Álvarez, J. M. Alonso, O. Filevich, M. Bhagawati, R. Etchenique, J. Piehler, A. del Campo*, Langmuir, in press
- Near field lithography by two-photon induced photocleavage of organic monolayers, M. Álvarez, A. Best, A. Unger, J.M. Alonso, A. del Campo, M. Schmelzeisen, K. Koynov, M. Kreiter, Adv. Funct. Mater. 20(24), 4265-4272 (2010)
- Photoactive branched and linear surface architectures for functional and patterned immobilization of proteins and cells onto surfaces: a comparative study, P. Stegmaier, A. del Campo*, ChemPhysChem 10, 357-369 (2009)
- Photoresponsive surfaces with two independent wavelength-selective functional levels, P. Stegmaier, J. M. Alonso, A. del Campo*, Langmuir 24, 11872-11879 (2008)