Ultrasensitive and Label-Free Detection of Copper Ions by GHK-Modified Asymmetric Nanochannels.

Artificial solid-state nanochannels have garnered considerable attention as promising nanofluidic tools for ion/molecular detection, DNA sequencing, and biomimicry. Recently, nanofluidic devices have emerged as cost-effective detection tools for heavy metal ions by modifying stimuli-responsive materials. In this work, high-purity glycyl-l-histidyl-l-lysine (GHK) peptide is synthesized by using 7-diphenylphosphonooxycoumarin-4-methanol (DPCM) as a protecting group and auxiliary carrier by homogeneous synthesis of photocleavable groups. Subsequently, we developed a GHK-modified asymmetric nanochannel nanofluidic diode by covalently attaching the GHK peptide to the inner surface of the nanochannels. This modification facilitated specific recognition and ultra-trace level detection of Cuions, achieving a detection limit of 10M. Due to the robust complexing ability between Cuand GHK peptide, the GHK-modified asymmetric nanochannels can form GHK-Cu complexes on the inner surface of nanochannels when Cupasses through the nanochannels. This results in changes of current-potential (-) properties, which facilitated Cudetection. Theoretical calculations confirmed the high affinity of the GHK peptide for Cu, thereby ensuring excellent Cuselectivity. To evaluate the applicability of our system for detecting Cuin real-world scenarios, we analyzed the concentration of Cuin tap water. The GHK-Cu complexes could be dissociated by adding EDTA to the solution, enabling the regeneration and reuse of this ultrasensitive and label-free Cudetection system using GHK-modified asymmetric multi-nanochannels. We anticipate that the GHK-modified asymmetric nanochannels will find future applications in the label-free detection of Cuin domestic water.