Two-photon light triggered bioactive molecule/systems

The Two-photon absorption phenomenon

Two-photon absorption (2PA) is a nonlinear optical phenomenon which, over the past 40 years, has played a significant role in the study of fundamental interactions between light and matter. Over the past 20 years, there has been a remarkable increase in the extent to which key features of 2PA have been exploited in methods, tools and devices of great potential impact to our modern technologically-driven society. Applications of 2PA cover fields that range from material science to biology and medicine. One key feature of 2PA pertinent to its application is that light absorption only occurs where the incident photon flux is sufficiently large, because the amount of 2PA depends on the square of the light intensity. This constraint can be used to define very small volumes of excitation. Specifically, by using a focused laser beam, one can address volumes in the region of 1 femtoliter. This level of 3D spatial resolution is unattainable by using more “traditional” one-photon absorption. Such resolution offer significant advantages in terms of possible external triggering with spatial and temporal control,absence of chemical additives, and compatibility with a widerange of common protecting groups. -

Two-photon uncaging systems

Dr. Cueto et at engineered a series of dyads systems that combine a dissymmetrical bis-donor chromophore that acts as the 2P absorber and a dipolar PPG can lead to synergic systems with improved 2P uncaging sensitivity at 800 nm and enhanced 2PA response. The reported uncaging 2P sensitivities are still moderate due to the poor uncaging quantum yield of NV and limited FRET efficacy, this opens an interesting route for the design of more efficient dyads by replacing the PPG by more efficient ones which have much larger uncaging quantum yields