pH-Stimulated Response Gating for Mimic Cytochrome C Transport on Biomimetic Asymmetric Nanochannels.

Proteins are vital components in cells, biological tissues, and organs, playing a pivotal role in growth and developmental processes in living organisms. Cytochrome C (Cyt C) is a class of heme proteins found in almost all life and is involved in cellular energy metabolic processes such as respiration, mainly as electron carriers or terminal reductases. It binds cardiolipin in the inner mitochondrial membrane, leading to apoptosis. It is a challenge to design a simple and effective artificial system to mimic the complex Cyt C biological transport process. In this paper, an asymmetric biomimetic pH-driven protein gate is described by introducing arginine (Arg) at one end of an hourglass-shaped nanochannel. The nanochannel shows a sensitive protonation-driven protein gate that can be "off" at pH = 7 and "on" at pH = 2. Further studies show that differences in the binding of Arg and Cyt C at different levels of protonation lead to different switching behaviors within the nanochannels, which in turn lead to different surface charges within the nanochannels. It can be used for detecting Cyt C and as an excellent and robust gate for developing integrated circuits and nanoelectronic logic devices.