High-density single antibody electrochemical nanoarrays

Abstract

The fabrication and electrochemical interrogation of very high density single-antibody nanoarrays is reported. Gold nanodots, 15 nm in diameter, arranged in large (cm 2 ) square arrays with a pitch of 200 nm, are used as carriers for primary antibodies (Immunoglobulin G, IgGs), further recognized by secondary redox-labeled detection antibodies. Ensemble scale interrogation of the antibody array by cyclic voltammetry, and nanoscale interrogation of individual nanodots by mediator tethered atomic-force electrochemical microscopy (Mt/AFM-SECM), enable the occupancy of nanodots by single antibody molecules to be demonstrated. Experiments involving the competitive adsorption of antibodies of different species onto the nanodots evidence the possibility of using single-antibody nanoarrays for digital electrochemical immunoassays.

Recent Developments in Single-Entity Electrochemistry

“…Recent experiments with other SPM techniques, notably SECM and electrochemical scanning tunneling microscopy (EC-STM), have also pushed the SEE field forward. Several recent reviews provide extensive details on these techniques. ,− Notable recent works on electrocatalysis − and biological processes − investigated by SECM reveal the broad applicability of the newly developed tunneling mode for SECM as well as limitations regarding single-cell oxygen consumption rate measurements, respectively. EC-STM has advanced the study of local electrocatalytic activity to identify active sites and compare local reactivity, as well as observed phase transitions between the different structures of self-assembling 5,10,15,20-tetrakis­(4-trimethylammoniophenyl)­porphyrin tetra­( p -toluenesulfonate) porphyrins …”

Single-cell Electrochemical Aptasensor Array

“…Compared to other methods, EC sensors have the merits of easy operation, high sensitivity, and portability. [10][11][12][13][14][15][16][17][18][19] For example, a recent technique using rolling circle amplification with aptamers could successfully demonstrate a limit of detection (LOD) as low as 5 CTC cells in whole blood (with 200 μL of the sample used for incubation). 20 Another approach using quantum dots as sensing probe attained a LOD of 2 cells/mL in human serum.…”

Single-Cell Electrochemical Aptasensor Array

“…One is based on the identification of molecular differences at the single-cell level, such as flow cytometry, fluorescence-activated cell sorting, next-generation proteomics, and lipidomic studies; − another is based on capturing or detecting single tumor cells from fresh or fixed primary tumors and metastatic tissues and rare circulating tumors cells (CTCs) from blood or bone marrow, for example, dielectrophoresis technique, microfluidic-based microposts chip, and electrochemical (EC) approach. Compared to other methods, EC sensors have the merits of easy operation, high sensitivity, and portability. − For example, a recent technique using rolling circle amplification with aptamers could successfully demonstrate a limit of detection (LOD) as low as 5 CTC cells in whole blood (with 200 μL of the sample used for incubation) . Another approach using quantum dots as sensing probe attained an LOD of 2 cells/mL in human serum .…”