Three-dimensional nitrogen-doped mesoporous carbon nanomaterials derived from plant biomass: Cost-effective construction of label-free electrochemical aptasensor for sensitively detecting alpha-fetoprotein.

We synthesized three kinds of nitrogen-doped nanoporous carbon nanomaterials (represented by N-mC) through a cost-effective method, that is, pyrolysis of plant biomasses (grass, flower, and peanut shells). We further explored their potential as sensitive bioplatforms for electrochemical label-free aptasensors to facilitate the early detection of alpha-fetoprotein (AFP). Chemical structure characterizations revealed that rich functional groups coexisted in as-synthesized N-mC nanomaterials, such as C-C, C-O, C=O, C-N, and COOH. Among the three kinds of N-mC nanomaterials, the one derived from grass (N-mC) exhibited the lowest carbon defect degree, the highest I/I ratio in the Raman spectra, and the largest specific surface area (186.2 m g). Consequently, N-mC displayed excellent electrochemical activity and strong affinity toward aptamer strands, further endowing the corresponding aptasensor with sensitive detection ability for AFP. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were used to investigate the whole detection procedure for AFP. The EIS and DPV results showed that the fabricated N-mC-based aptasensor possessed an extremely low limit of detection of 60.8 and 61.8 fg·mL (s/n = 3), respectively, for detecting AFP within a wide linear range from 0.1 pg mL to 100 ng mL. Moreover, the aptasensor displayed acceptable selectivity and applicability, high reproducibility, and excellent stability in serum samples of cancer patients. Therefore, the proposed cost-effective and label-free strategy based on the nitrogen-doped nanoporous carbon derived from plant biomass is a promising approach for the early detection of various tumor markers.