Coordination of the electrical and optical signals revealing nanochannels with an ‘onion-like’ gating mechanism and its sensing application

Artificial stimuli-responsive nanochannels that mimic the gating property of biological ion channels to control the movement of ions across the membranes have attracted much attention. However, the ionic current is also greatly influenced by many environmental factors in the reaction system. In the present study, we coordinated the ionic current and the fluorescence signal to reveal that the gatekeepers (here, oligomers) open and close the nanochannels with an ‘onion-like’ intermediate state, as confirmed by molecular dynamics simulations. The dual-signal-output nanochannels exhibited a high sensitivity and selectivity to glucose and showed a high antijamming property with regard to impurities such as ascorbic acid (Vc) and H2O2 in complicated practical environments, which could induce false signals in traditional glucose detection methods. Ten healthy individuals’ urine samples were distinguished from those of 15 diabetes patients; moreover, the urine samples of the diabetes patients could be discriminated before and after treatment with insulin. A nanochannel device with dual optical and current signals can monitor glucose levels for diabetics with better accuracy than usual. The actions of biological ion channels have inspired the development of polymer nanochannel sensors — thin channels coated with special binding agents that open or shut in response to external stimulus. Xiaoding Lou and colleagues in China have developed a coating that captures and links glucose molecules and fluorescent probes inside a nanochannel. As glucose levels increase, the trapped components fill the channel with concentric, onion-like rings. The drop in ion current as the channel squeezes shut is accompanied by a rising fluorescence signal from the immobilized probes. This dual-output signal proved effective against ascorbic acid and peroxide impurities, which affect typical glucose assays. Furthermore, clinical testing showed this method had desirable sensitivity and selectivity. In this study, we coordinated the ionic current and the fluorescence signal to reveal that the gatekeepers (here, oligomers) open and close the nanochannels with an ‘onion-like’ intermediate state, as confirmed by molecular dynamics simulations. The dual-signal-output nanochannels exhibited a high sensitivity and selectivity to glucose and showed a high antijamming property. Ten healthy individuals’ urine samples were distinguished from those of 15 diabetes patients; moreover, the urine samples of the diabetes patients could be discriminated before and after treatment with insulin.