Abstract
The present work describes an impedimetric immunosensor for Pseudomonas syringae pv. lachrymans (Psl) detection. This pathogen infects many crop species causing considerable yield losses, thus fast and cheap detection method is in high demand. In the assay, the gold disc electrode was modified with 4-aminothiophenol (4-ATP), glutaraldehyde (GA), and anti-Psl antibodies, and free-sites were blocked with bovine serum albumin (BSA). Sensor development was characterized by cyclic voltammetry (CV) and antigen detection by electrochemical impedance spectroscopy (EIS) measurements. Seven analyzed strains of Psl were verified as positive by the reference method (PCR) and this immunoassay, proving sensor specificity. Label-free electrochemical detection was in the linear range 1 × 103–1.2 × 105 CFU/mL (colony-forming unit) with an R2 coefficient of 0.992 and a detection limit (LOD) of 337 CFU/mL. The sensor did not interfere with negative probes like buffers and other bacteria. The assay was proven to be fast (10 min detection) and easy in preparation. The advantage was the simplicity and availability of the verified analyte (whole bacteria) as the method does not require sample pretreatment (e.g., DNA isolation). EIS biosensing technique was chosen as one of the simplest and most sensitive with the least destructive influence on the probes compared to other electrochemical methods.
Highlights
Pseudomonas syringae species divide into 60 subtypes basing on pathogenic characters, and lachrymans is one of them [1,2]
Biosensing techniques focus mainly on antibody-based and DNA-based platforms [31]. They are willingly applied in point of care (POC) devices for bacteria detection using optical, magnetic, or electrical visualization [32]
(4‐ATP), electrode modifiedmodified with 4‐ATP; glutaraldehyde (GA), electrode electrode modified with 4-ATP and glutaraldehyde; Au/4-ATP/GA/anti-Psl, electrode modified with modified with 4‐ATP and glutaraldehyde; Au/4‐ATP/GA/anti‐Psl, electrode modified with 4‐ATP, 4-ATP, glutaraldehyde, and anti-Psl antibodies; Au/4-ATP/GA/anti-Psl, electrode modified with 4-ATP, glutaraldehyde, and anti‐Psl antibodies; Au/4‐ATP/GA/anti‐Psl, electrode modified with 4‐ATP, glutaraldehyde, and anti-Psl antibodies; Au/4-ATP/GA/anti-Psl/ bovine serum albumin (BSA), electrode glutaraldehyde, and anti‐Psl antibodies; Au/4‐ATP/GA/anti‐Psl/ bovine serum albumin (BSA), modified with 4-ATP, glutaraldehyde, anti-Psl antibodies and BSA
Summary
Pseudomonas syringae species divide into 60 subtypes (pathovars) basing on pathogenic characters, and lachrymans is one of them [1,2]. Biosensing techniques focus mainly on antibody-based and DNA-based platforms [31] They are willingly applied in point of care (POC) devices for bacteria detection using optical, magnetic, or electrical visualization [32]. Jarocka et al detected prunus necrotic ringspot virus (PNRV) in cucumber leaf extracts using the electrochemical method. The main disadvantage is that they require a DNA sample which (when it is not synthetic [40]) needs to be prepared in an amplification method, e.g., PCR. The electrochemical impedance spectroscopy method was chosen as it is not destructive for the analyte
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