SwissFEL Researchers Capture Atomic-Scale Footage of Light-Activated Beta Blockers Transforming Receptor Activity in Trillionths of a Second

PSI scientists use X-ray lasers to see light-switchable drugs in action. Discover how photoazolol-1 transforms in picoseconds to control heart rate.

By: AXL Media

Published: Mar 23, 2026, 7:04 AM EDT

Source: Information for this report was sourced from [Paul Scherrer Institute]

The Precision of Light-Triggered Pharmacological Intervention

Photopharmacology is emerging as a revolutionary frontier in medicine, offering the ability to activate or deactivate medications at specific locations within the body using light. Researchers at the PSI Center for Life Sciences are developing drugs that remain inert until they are irradiated with a specific wavelength of light. This localized activation could fundamentally transform how systemic conditions are treated; for instance, a blood pressure medication could be activated exclusively within the heart tissue, leaving identical receptors in other organs unaffected. This level of precision aims to virtually eliminate the off-target side effects that currently plague traditional oral medications.

Atomic Visualization of the Photoazolol-1 Transformation

The research team focused their investigation on photoazolol-1, a switchable version of a common beta blocker used for cardiac arrhythmias and hypertension. By integrating an azobenzene group into the molecular structure, the researchers created a drug that physically "flips" its shape when exposed to violet light. Using the SwissFEL X-ray free-electron laser, the team was able to capture this transformation, which occurs in a mere matter of picoseconds. These time-resolved measurements provided the first clear look at how a synthetic light switch alters the geometry of a drug while it is docked inside a biological receptor.

Receptors as Regulators Rather Than Simple Switches

A key discovery of the study is that biological receptors do not function as simple binary "on-off" switches, but rather as sophisticated regulators. When photoazolol-1 is in its straight shape, it fits perfectly into the binding pocket of $\beta$-adrenergic receptors, effectively blocking stress responses like increased heart rate. When light triggers the molecule into a bent, bulkier shape, it remains stuck in the binding pocket but loses its potency. This allows the drug to act as a dimmer switch, weakening or amplifying physiological processes without leaving the docking site, which prevents adrenaline from reattaching and restarting the stress response.