Effective cell capture with tetrapeptide-functionalized carbon nanotubes and dual signal amplification for cytosensing and evaluation of cell surface carbohydrate.

A novel electrochemical cytosensing strategy was designed based on the specific recognition of integrin receptors on a cell surface to arginine−glycine−aspartic acid−serine (RGDS)-functionalized single-walled carbon nanotubes (SWNTs). The covalent conjugation of the RGDS tetrapeptide to SWNTs was proved with Raman and FT-IR spectra. The conjugated RGDS showed a predominant ability to capture cells on the electrode surface by the specific combination of RGD domains with integrin receptors. With the use of BGC-823 human gastric carcinoma cells (BGC cells) as a model, the cell surface mannosyl groups could specifically bind with horseradish peroxidase labeled concanavalin A, producing an electrochemical cytosensor. On the basis of the dual signal amplification of SWNTs and enzymatic catalysis, the cytosensor could respond down to 620 cells mL−1 of BGC cells with a linear calibration range from 1.0 × 103 to 1.0 × 107 cells mL−1, showing very high sensitivity. The dual signal amplification could be further use...