Synergistic Effect of Bio-Inspired Nanochannels: Hydrophilic DNA Probes at Inner Wall and Hydrophobic Coating at Outer Surface for Highly Sensitive Detection

During the past few decades, bio-inspired nanochannels have been well developed and applied in biosensing, energy transfer, separation, and so on. Here, inspired by the synergistic effect of biological nanopores, biomimetic solid-state nanochannels with hydrophilic DNA probes at the inner wall (DNA@IW_Hydrophilic) and hydrophobic coating at the outer surface (None@OS_Hydrophobic) are designed. To demonstrate their prompted sensing properties, Hg²⁺ and its specific probe are selected as target and hydrophilic DNA probes, respectively. Compared with the traditional solid-state nanochannels with hydrophilic probes distributed on both the inner wall and outer surface, the nanochannels with DNA@IW_Hydrophilic+None@OS_Hydrophobic significantly decrease the limit of detection (LOD) by 10⁵-fold. The obvious improvement of sensitivity (with LOD of 1 nM) is attributed to the synergistic effect: None@OS_Hydrophobic results in the nanochannel's effective diameter decrease and DNA@IW_Hydrophilic induces a specific sensing target. Meanwhile, nanomolar detection of Hg²⁺ in human serum and in vivo fish muscle are achieved. Through molecular dynamics simulation, the synergistic effect can be confirmed by ion fluxes increasement; the relative carbon nanotube increases from 135.64% to 135.84%. This work improves the understanding of nanochannels’ synergistic effect and provides a significant insight for nanochannels with improved sensitivity.