Physiologically stable fluorophore and performing fluorescence probing

A process for performing fluorescence probing with a physiologically stable fluorophore

• the process comprising:
• contacting a surface extracted cellulose nanofiber substrate with the physiologically stable fluorophore;
• forming a fluorophore-substrate complex from the physiologically stable fluorophore and the substrate in response to contacting the substrate with the physiologically stable fluorophore;
• subjecting the fluorophore-substrate complex to probe radiation;
• electronically exciting the physiologically stable fluorophore in the fluorophore-substrate complex in response to subjecting the fluorophore-substrate complex to the probe radiation;
• producing fluorescence from the physiologically stable fluorophore in the fluorophore-substrate complex in response to electronically exciting the physiologically stable fluorophore in the fluorophore-substrate complex;
• and determining, from the fluorescence from the physiologically stable fluorophore, the redox state of the substrate to perform single-electron transfer fluorescence probing;
• wherein the physiologically stable fluorophore is stable from pH=1 to pH=10 such that the photophysics of the physiologically stable fluorophore is conserved from pH=2 to pH=10.