Nanochannels with Varied Outer Surface Charges for Protein Discrimination.

Solid-state nanochannels with probe modification demonstrate effective spontaneous charge modulation and selective ionic current regulation. Outer-surface functionalization of these nanochannels enables tunable ionic current signals before and after analyte detection. To modulate local charge distributions, we designed sensing nanochannels with significant ion rectification properties for protein detection. In this work, we utilized asymmetrically charged sensing nanochannels with DNA probe modifications to generate abundant ionic current information for multianalyte recognition. During protein detection, DNA probes on the outer surfaces of the nanochannels were competitively replaced by proteins, thereby modulating the local charge distribution. This modulation influences the ionic current through ion rectification, generating cross-reactive and differentiated signals for each target. As a result, the sensing nanochannels with asymmetry of the surface charge effectively discriminate 6 proteins using only one kind of probe. Furthermore, this system successfully distinguished proteins across various concentrations and within complex environments. This work represents a significant advancement in the development of differential sensors based on outer-surface-functionalized nanochannels for multianalyte discrimination.