A fine-tuned azobenzene for enhanced photopharmacology in vivo

Despite the power of photopharmacology for interrogating signaling proteins, many photopharmacological systems are limited by their efficiency, speed, or spectral properties. Here, we screen a library of azobenzene photoswitches and identify a urea-substituted "azobenzene-400" core that offers bistable switching between cis and trans with improved kinetics, light sensitivity, and a red-shift. We then focus on the metabotropic glutamate receptors (mGluRs), neuromodulatory receptors that are major pharmacological targets. Synthesis of "BGAG_12,400," a photoswitchable orthogonal, remotely tethered ligand (PORTL), enables highly efficient, rapid optical agonism following conjugation to SNAP-tagged mGluR2 and permits robust optical control of mGluR1 and mGluR5 signaling. We then produce fluorophore-conjugated branched PORTLs to enable dual imaging and manipulation of mGluRs and highlight their power in ex vivo slice and in vivo behavioral experiments in the mouse prefrontal cortex. Finally, we demonstrate the generalizability of our strategy by developing an improved soluble, photoswitchable pore blocker for potassium channels.

Observation of chirped soliton dynamics at lambda = 1.55 microm in a single-mode optical fiber with frequency-resolved optical gating

We present an experimental observation of the dynamics of an initially chirped optical soliton at 1.55microm that is propagating through a single-mode optical fiber, using frequency-resolved optical gating (FROG). FROG permits observation of both the amplitude and the phase profiles of ultrashort pulses, providing complete information on the pulse evolution. The features that are detected, which include what is believed to be the first experimental observation of phase slips, are in quantitative agreement with numerical simulations that employ the nonlinear Schrödinger equation.