Electrochemical Immunosensors for Sensitive Detection of Neuron-Specific Enolase Based on Small-Size Trimetallic Au@Pd^Pt Nanocubes Functionalized on Ultrathin MnO₂ Nanosheets as Signal Labels

Abstract

Medically, neuron-specific enolase (NSE) as a specific tumor marker has become an important indicator to diagnose small-cell lung carcinoma. In this study, a sandwich-type electrochemical immunosensor was designed to determine NSE sensitively. Au nanoparticle (Au NP)-embedded zinc-based metal–organic frameworks (Au@MOFs) were prepared as the substrate materials to modify the electrode and immobilize the primary antibody (Ab1). The Au@MOFs with the free amino groups on the MOF surface could effectively increase the immobilization amount of Ab1 through covalent linkage. Simultaneously, the embedding of Au NPs improved the conductivity of MOFs and accelerated interface electron transfer. Sub-30 nm trimetallic Au@Pd^Pt nanocubes (Au@Pd^Pt NCs) loaded onto ultrathin MnO2 nanosheets (MnO2 UNs/Au@Pd^Pt NCs) acted as the labels of secondary antibodies. The small-size Au@Pd^Pt NCs enhanced atomic utilization efficiency and offered more catalytic active sites. The MnO2 UNs with high external surface areas could improve the dispersion of Au@Pd^Pt NCs. The MnO2 UNs/Au@Pd^Pt NCs could catalyze the H2O2 reduction and promote the oxidation of hydroquinone to quinone effectively because of their synergistic effect; thus, the generated quinone achieved amplification of the highly reductive peak current. Furthermore, under the optimal conditions, the immunosensor exhibited a low detection limit (4.17 fg/mL) and broad linear range (10 fg/mL to 100 ng/mL). The results were satisfactory for NSE detection in human serum samples, implying that the presented method had great application potential in clinical bioanalysis.

Magnet-assisted electrochemical immunosensor based on surface-clean Pd-Au nanosheets for sensitive detection of SARS-CoV-2 spike protein

“…4 B, indicating that the electron transfer in [Fe(CN) 6 ] 3-/4− was reversible and the reaction was a diffusion controlled process [ 42 , 43 ]. The diffusion coefficient calculated by the Randles-Sevcik equation was 6.77 × 10 −6 cm 2 /s, which was comparable to the previous reports [44] , [45] , [46] . After that, the catalase activity of Pd-Au nanosheets was identified by a simple visual method (Fig.…”

Aptamer based surface plasma resonance assay for direct detection of neuron specific enolase and progastrin-releasing peptide (31-98)

“…Compared to some immunoassays, 9,37,38 this proposed aptamer-based SPR assay introduced aptamer as affinity ligand, which shows advantages in ease of synthesis and labelling, and high stability over antibody. There are still limited aptamer based detection methods for NSE and ProGRP31-98.…”

Enzyme‐free Electrochemical Detection of Hydrogen Peroxide Based on the Three‐Dimensional Flower‐like Cu‐based Metal Organic Frameworks and MXene Nanosheets†

“…In order to overcome these problems and take the advantage of MOFs, the materials with good conductivity can be introduced to improve the properties of MOFs. [ 23‐24 ] At present, noble metals with good conductivity and catalytic activity have been employed with MOFs, however, this strategy is complex and costly. [ 25‐27 ] And some researchers have utilized two‐dimensional materials such as graphene [ 28‐29 ] and black phosphorus nanosheets [ 30 ] as electrochemical materials for improving the conductivity.…”