Label-free biosensing with functionalized nanopipette probes

• Published in: Proceedings of the National Academy of Sciences - PNAS 2009-03, Vol.106 (12), p.4611-4616
• Main Authors: Umehara, Senkei, Karhanek, Miloslav, Davis, Ronald W, Pourmand, Nader
• Format: Article
• Language: English
• Subjects: Animals; Antibodies; Antigens; Binding sites; Biochemistry; Biological Sciences; Biomarkers, Tumor - metabolism; Biomolecules; Biosensing techniques; Biosensing Techniques - instrumentation; Biotin - metabolism; Biotinylation; Cattle; Electric current; Electrodes; Electrolytes; Fluorescein-5-isothiocyanate - metabolism; Fluorescence; Glass; Humans; Immunoassay; Molecular Probes - metabolism; Molecules; Nanostructures; Nanotechnology; Neoplasm Proteins - metabolism; Polymers; Proteins; Reproducibility of Results; Sensors; Serum Albumin, Bovine - metabolism; Staining and Labeling; Static Electricity; Streptavidin - metabolism; Surface Properties
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0900306106

Nanopipette technology can uniquely identify biomolecules such as proteins based on differences in size, shape, and electrical charge. These differences are determined by the detection of changes in ionic current as the proteins interact with the nanopipette tip coated with probe molecules. Here we show that electrostatic, biotin-streptavidin, and antibody-antigen interactions on the nanopipette tip surface affect ionic current flowing through a 50-nm pore. Highly charged polymers interacting with the glass surface modulated the rectification property of the nanopipette electrode. Affinity-based binding between the probes tethered to the surface and their target proteins caused a change in the ionic current due to a partial blockade or an altered surface charge. These findings suggest that nanopipettes functionalized with appropriate molecular recognition elements can be used as nanosensors in biomedical and biological research.