Artificial NO and Light Cooperative Nanofluidic Diode Inspired by Stomatal Closure of Guard Cells.

Gas messenger molecule (NO) plays important roles in K+ nanochannels of guard cells by binding directly to the heme-containing enzymes. Inspired by this natural phenomenon, we developed artificial K+ nanochannels modified with ferroporphyrin, where NO triggered the nanochannels to turn "ON" states from the ferroporphyrin blocked "OFF" states. The mechanism relies on the fact that NO has higher affinity with ferroporphyrin compared to carboxyl groups on the nanochannel surface. The synergistic effect of the released carboxyl groups and the conically asymmetric shape leads the ion transportation to be diode-like. However, the nanofluidic diode properties vanished after illumination with light to remove NO from the ferroporphyrin-NO complex. This NO and light cooperative nanofluidic diode possesses excellent stability and reversibility, which shows great promise for use in gas detection and remote control of mass delivery.