Versatile bioanalytical platform based on carbon nanohorns functionalized with concanavalin A: an innovative strategy...

The synthesis of a nanohybrid is presented obtained by non-covalent functionalization of carbon nanohorns (CNHs) with concanavalin A (ConA). The analytical applications are reported of the resulting nanomaterial to design different electrochemical biosensors previous deposition at glassy carbon electrodes (GCE) (GCE/CNH-ConA). The optimum conditions for the preparation of CNH-ConA nanohybrid were 2.0 mg mL^- 1 CNHs and 1.0 mg mL^- 1 ConA sonicated for 45 min with a sonicator probe. The versatility of this GCE/CNH-ConA platform was demonstrated in two directions. One of them is focused on the anchoring of the glycoprotein avidin (Av) at the lectin that supports the CNHs to obtain a building block for the development of different custom-made biosensors just by changing the biotinylated biorecognition molecule. In this case, we used biotinylated horseradish peroxidase (bHRP) as model to obtain a sensitive hydrogen peroxide amperometric biosensor which presented a sensitivity of (1.31 ± 0.01) x 10⁵ µA M^- 1 (R² = 0.999), a detection limit of 167 nM, and a quantification limit of 500 nM. The other application of CNH-ConA was based on the development of a new strategy to build electrochemical immunosensors, by taking advantage of the glycoprotein nature of the antibodies. As proof-of-concept, we present the direct immobilization of the antibody anti-human immunoglobulin G (anti-IgG) at GCE/CNH-ConA to build an impedimetric immunosensor for human immunoglobulin G (IgG). The sensitivity of the resulting biosensor was (3.4 ± 0.3) x 10² Ω mL mg^- 1 (R² = 0.984), with a linear range between 1.0 × 10^- 6 mg mL^- 1 and 5.0 × 10^- 4 mg mL^- 1, and a quantification and detection limits of 1.0 × 10^- 6 mg mL^- 1 and 3.0 × 10^- 7 mg mL^- 1, respectively.