Asymmetric Nanochannel-Ionchannel Hybrid for Ultrasensitive and Label-Free Detection of Copper Ions in Blood

Nanochannel/nanopre based analysis methods have attracted increasing interest in recent years due to their exquisite ability to reveal changes in molecular volume. In this work, a highly asymmetric nanochannel-ionchannel hybrid coupled with an electrochemical technique was developed for copper ion (Cu) detection. Polyglutamic acid (PGA) was modified in a nanochannel array of porous anodic alumina (PAA). When different concentrations of Cu were introduced into the nanochannel-ionchannel hybrid in a neutral environment, a Cu-PGA chelation reaction occurs, resulting in varied current-potential (I-V) properties of the nanochannel-ionchannel hybrid. When PAA was immersed in a low pH solution, the Cu-PGA complex dissociated. On the basis of the change in ionic current, a label-free assay for Cu was achieved along with the ability to regenerate and reuse the constructed platform. Because of the unique mass transfer property of the nanochannel-ionchannel hybrid combined with the highly amplified ionic current magnitude of the nanochannel array, significantly increased assay sensitivity was achieved, as expected. To evaluate the applicability of the present methodology for detecting Cu in a real sample, the Cu content in real blood samples was analyzed. The results demonstrate that the present method shows excellent selectivity with high sensitivity toward Cu detection in real blood samples.