Electrochemical Detection of Plant Pathogens Using Boron-Doped Carbon Nanowalls Immunosensor

This study reports the electrochemical immunosensor development for the detection of bacteria from the Pseudomonas genus – the causative of many plant infections, inclusive of canker. This firstly reported assay on carbon-based material included: boron-doped carbon nanowalls (B:CNW) electrodes fabrication, sensor manufacturing, antigen detection, and specificity tests. B:CNW was fabricated by microwave plasma-assisted chemical vapor deposition (CVD) method. Cyclic voltammetry (CV) was applied during the modification step – the electrochemical reduction of the diazonium salt. Electrochemical impedance spectroscopy (EIS) measurements confirmed the accurate sensor preparation and were used for the quantitative detection of antigen. The antibodies were utilized as the biological recognition system and immobilized on the sensor surface by covalent linkage. The optimized assay showed high sensitivity towards seven strains of Pseudomonas syringae pv. lachrymans (Psl) in the concentration range of $3.25\times 10^{-3}$ – $3.25\times 10^{5}$ CFU/ $\mu \text{l}$ (limit of detection, LOD of 0.119 CFU/ $\mu \text{l}$ ). The specificity of the assay was confirmed on four non-target bacteria: Streptococcus pneumoniae, Streptococcus pyogenes, Bordetella parapertussis, and Haemophilus influenzae. These results indicate the importance of the sensing material choice and its modification procedure as they affect successive analytical performance.