Dual-Signal Electrochemical Biosensor for Neutrophil Gelatinase-Associated Lipocalin Based on MXene-Polyaniline and Cu-MOF/Single-Walled Carbon Nanohorn Nanostructures

Neutrophil gelatinase-associated lipocalin (NGAL) is an important biomarker for the early diagnosis of acute kidney injury (AKI). Herein, a sensitive dual-signal sandwich-type electrochemical immunosensor was designed for NGAL detection using square wave voltammetry (SWV) and current–time (i–t) curves. Herein, MXene-loaded polyaniline (MXene/PANI) nanocomposites were fabricated and utilized as the sensing platform for anchoring gold nanoparticles (Au NPs) and immobilizing primary antibodies. Subsequently, an Au NP-loaded copper metal–organic framework decorated with a single-walled carbon nanohorn (Au/Cu-MOF/SWNH) nanocomposite was prepared by depositing Au NPs onto Cu-MOF/SWNHs. The NGAL affinity peptide (Pep) was bound to Au/Cu-MOF/SWNHs to form a Pep/Au/Cu-MOF/SWNH nanocomposite as a probe. The probe exhibited an SWV signal (signal 1) wherein electron transfer between Cu2+ and Cu+ of the Cu-MOF without the extra electron transport medium was observed. The i–t signal (signal 2) was obtained from the reduction of H2O2 by the Au/Cu-MOF/SWNH nanocomposite with high electrocatalytic activity. Au/Cu-MOF/SWNH nanomaterials exhibit optimal analytical performance in the linear range of 0.00001–10 ng·mL–1 with limits of detection of 0.0074 pg·mL–1 (SWV) and 0.0405 pg·mL–1 (i–t) for NGAL determination. The immunosensor was further used to detect NGAL in the sample, which has potential applications in AKI diagnosis.