1. What is QAQ? Ammonium–azobenzene–quaternary ammonium (QAQ) A molecule devoloped at UC Berkeley Has 2 sides, cis and trans The trans side is very similar to Lidocaine and is a straight chain in structure, blocking the ion channels that send pain signals The cis side is inactive and is bent in an L-shaped form. QAQ slowly reverts to the trans side, which can be achieved much more quickly by…

2. Light Not just any old light. 500 nm will accelerate this process Ultraviolet light reactivates the neurons

3. All well and good but… What makes lidocaine effective in dentists is it can cross cell membranes. But can QAQ do the same? Rodent experiment.

4. So not quite like Lidocaine However, this lack of permeability gives QAQ the potential to be a selective anesthetic in a way Lidocaine is not. (ie numbing entire face)

5. TRPV1 An Ion channel found in nociceptive neurons Allowing QAQ to enter the nerves Activated by a chemical called Capsaicin

6. Capcaisin making the TRPV1 dilate allows entry for a bigger molecule like QAQ into the channel The absence of TRPV1 in other nerves makes it possible to selectively target the nerves sensing pain Turned on and off with a flick of a lightswitch!