title: Continuous nanoflow-scanning electrochemical microscopy: voltammetric characterization and application for accurate and reproducible imaging of enzyme-labeled protein microarrays.
abstract: The coupling of scanning electrochemical microscopy (SECM) to a continuous nanoflow (CNF) system is accomplished with the use of a microconcentric ring electrode/injector probe. The gold microring electrode encapsulated by a glass sheath is robust and can be beveled and polished. The CNF system, comprising a precision gas displacement pump and a rotary valve, is capable of delivering solution to the center of the SECM probe in the range of 1-150 nL/min. Major advantages of the CNF-SECM imaging mode over the conventional SECM generation/collection (G/C) mode include higher imaging resolution, immunity from interferences by species in the bulk solution or at other sites of the substrate, elimination of the feedback current that could interfere with the G/C data interpretation, and versatility of initiating surface reactions/processes via introducing different reactants into the flowing stream. Parameters such as flow rates, probe/substrate separations, and collection efficiencies are examined and optimized. Higher resolution, reproducibility, and accuracy are demonstrated through the application of CNF-SECM to horseradish peroxidase (HRP)-amplified imaging of protein microarrays. By flowing H2O2 and ferrocenemethanol through the injector and detecting the surface-generated ferriceniummethanol, human IgG spots covered with HPR-labeled antihuman IgG can be detected in the range of 13 nM-1.333 μM with a detection limit of 3.0 nM. In addition, consistent images of microarray spots for selective and high-density detection of analytes can be attained.
authors.affiliation: #College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, China.
authors.forename: Tianhan
authors.initials: T
authors.lastname: Kai
authors.affiliation: #College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Chen
authors.affiliation: †Department of Chemistry and Biochemistry, California State University, Los Angeles, Los Angeles, California 90032, United States.
authors.forename: Estuardo
authors.initials: E
authors.lastname: Monterroso
authors.affiliation: †Department of Chemistry and Biochemistry, California State University, Los Angeles, Los Angeles, California 90032, United States.
authors.forename: Feimeng
authors.initials: F
authors.lastname: Zhou
mesh_terms: D055664:Electrochemical Techniques; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000378:metabolism*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D008853:Microscopy / Q000379:methods*; D036103:Nanotechnology; D040081:Protein Array Analysis
chemical_list: D007074:Immunoglobulin G; D006046:Gold; D006735:Horseradish Peroxidase