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

Abstract

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 GHKmodified 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 Cu 2+ ions, achieving a detection limit of 10 −15 M. Due to the robust complexing ability between Cu 2+ and GHK peptide, the GHK-modified asymmetric nanochannels can form GHK-Cu complexes on the inner surface of nanochannels when Cu 2+ passes through the nanochannels. This results in changes of current−potential (I−V) properties, which facilitated Cu 2+ detection. Theoretical calculations confirmed the high affinity of the GHK peptide for Cu 2+ , thereby ensuring excellent Cu 2+ selectivity. To evaluate the applicability of our system for detecting Cu 2+ in real-world scenarios, we analyzed the concentration of Cu 2+ in 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 Cu 2+ detection system using GHK-modified asymmetric multinanochannels. We anticipate that the GHK-modified asymmetric nanochannels will find future applications in the label-free detection of Cu 2+ in domestic water.

Solid-State Nanopore/Nanochannel Sensors with Enhanced Selectivity through Pore-in Modification

“…The lack of selectivity in detecting metal ions through nanopores/nanochannels can be overcome by modifying organic ligands on the channel surface to achieve specific recognition and detection of metal ions. − For example, an amidoxime-modified nanochannel can selectively adsorb UO 2 2+ and effectively monitor UO 2 2+ (Figure ). Through a classic amidation reaction, 4-amino benzamidoxime is grafted onto the channel surface of a single nanochannel in a polyimide (PI) membrane (Figure a).…”

Superassembled MXene–carboxymethyl chitosan nanochannels for the highly sensitive recognition and detection of copper ions

“…18 Asymmetric PET multi-nanochannels modified by glycyl- l -histidyl- l -lysine (GHK) peptide were adopted for the label-free detection of Cu 2+ . 19 Previous studies have opened up new avenues in developing nanopore/nanochannel sensors for Cu 2+ detection. However, most nanochannel-based devices need exquisite modification and treatment to achieve Cu 2+ recognition and detection, which not only destroy the ordered channels of nanofluidic membrane, but also induce nonspecific, low-sensitivity and unstable detection.…”