Staff member

The study of intact cells and their signaling circuits with light requires a stimulation strategy that is focused, deeply penetrating, and does not damage them. Implanted optic fibers, light-emitting diodes, and luminescent materials operated externally with tissue-penetrating infrared (IR) light are invasive or limited by light attenuation around the illumination point. To overcome these barriers, two-photon pharmacology takes advantage of femtosecond-pulsed IR laser light to produce deep and spatiotemporally precise cellular stimulation using specially designed photoswitchable drugs. Compounds that can be covalently tethered to the target neuroreceptor perform particularly well. However, the tethered photoswitches reported to date require mutagenesis of the target protein, which prevents the use of photopharmacology to stimulate the nervous system in wild-type animals. Here, we report the first two-photon optimized targeted covalent photoswitch (TCP2P) that combines the efficient two-photon isomerization of ortho-fluoro-substituted azobenzene with the ability to conjugate to nucleophilic residues of endogenous proteins (AMPA and kainate ionotropic glutamate receptors in neurons). TCP2P is readily obtained by click coupling of two precursor compounds prior to use, and after simple incubation, it enables controlling neuronal activity at one- and two-photon excitation up to 800 nm without genetic modifications.

JTD Keywords: Glutamate-receptor, Optical control

The limited efficacy shown by drug delivery systems so far prompts the development of new molecular approaches for releasing drugs in a controlled and selective manner. Light is a privileged stimulus for delivery because it can be applied in sharp spatiotemporal patterns and is orthogonal to most biological processes. Supramolecular polymers form molecular nanostructures whose robustness, versatility, and responsivity to different stimuli have generated wide interest in materials chemistry. However, their application as drug delivery vehicles has received little attention. We built supramolecular polymers based on discotic amphiphiles that self-assemble in linear nanostructures in water. They can integrate diverse amphiphilic bioligands and release them upon illumination, acutely producing functional effects under physiological conditions. We devised two strategies for drug incorporation into the photoswitchable nanofibers. In the co-assembly strategy, discotic monomers with and without conjugated bioligands were co-assembled in helicoidal supramolecular fibers. In the drug embedding approach, we integrated a potent agonist of muscarinic receptors into the discotic polymer by noncovalent stacking interactions. This ligand can be released on demand with light ex situ and in situ, rapidly activating the target receptor and triggering intracellular responses. These novel discotic supramolecular polymers can be light-driven drug carriers for small, planar, and amphiphilic drugs.

JTD Keywords: Delivery, Doxorubicin, Glutamate-receptor, Nanoparticles, Nanostructures, Optical control, Paclitaxe