A sensitive electrochemical DNA biosensor for detecting the genome of a plant growth-promoting bacteria

Felipe Zahrebelnei; Dhésmon Lima; Lucas Stori de Lara; Derik William Gryczak; Taiza Alissul Sauer do Carmo; Salomé Urrea-Valencia; Carolina Weigert Galvão; Rafael Mazer Etto; Christiana Andrade Pessôa; Karen Wohnrath

doi:10.1016/j.talanta.2024.127484

A sensitive electrochemical DNA biosensor for detecting the genome of a plant growth-promoting bacteria

Talanta. 2025 Jan 3:286:127484. doi: 10.1016/j.talanta.2024.127484. Online ahead of print.

Affiliations

¹ Department of Chemistry, State University of Ponta Grossa, Ponta Grossa, CEP 84030-900, PR, Brazil.
² Department of Chemistry and Physics, Faculty of Arts and Science, Mount Saint Vincent University, 166 Bedford Highway, B3M 2J6, Halifax, Nova Scotia, Canada.
³ Department of Physics, State University of Ponta Grossa, Ponta Grossa, CEP 84030-900, PR, Brazil.
⁴ Academic Department of Mathematic, Federal Technological University of Paraná - Campus Ponta Grossa, Ponta Grossa, 84016-210, PR, Brazil.
⁵ Microbial Molecular Biology Laboratory, State University of Ponta Grossa, Ponta Grossa, CEP 84030-900, PR, Brazil.
⁶ Department of Chemistry, State University of Ponta Grossa, Ponta Grossa, CEP 84030-900, PR, Brazil; Microbial Molecular Biology Laboratory, State University of Ponta Grossa, Ponta Grossa, CEP 84030-900, PR, Brazil.
⁷ Department of Chemistry, State University of Ponta Grossa, Ponta Grossa, CEP 84030-900, PR, Brazil. Electronic address: karen.woh@gmail.com.

PMID: 39755076
DOI: 10.1016/j.talanta.2024.127484

Abstract

The challenge of increasing food production while maintaining environmental sustainability can be addressed by using biofertilizers such as Azospirillum, which can enhance plant growth and colonize more than 100 plant species. The success of this biotechnology depends on the amount of plant growth-promoting bacteria associated with the plant during crop development. However, monitoring bacterial population dynamics after inoculation requires time-consuming, laborious, and costly procedures. To address these issues, this study describes an effective electrochemical DNA biosensor to detect Azospirillum brasilense. The biosensor comprises a glassy carbon electrode modified with a nanocomposite based on carbon nanotubes and gold nanoparticles capped with 3-n-propylpyridinium chloride silsesquioxane, followed by the immobilization of a thiolated probe oligonucleotide that binds specifically to the A. brasilense genome (AZO_genome). The nanocomposite was characterized utilizing spectroscopic and morphological methods. Its presence on the biosensor's surface enhanced electrochemical responses due to its excellent electrocatalytic properties, as observed during electrochemical impedance spectroscopy and cyclic voltammetry experiments. The biosensor enabled the detection of AZO_genome after the hybridization event, which alters the electrochemical response of the electrode and was rapidly detected by square wave voltammetry. The detection range of the bacterial genome was 1.17 pmol L^-1 to 146.8 pmol L^-1, with LOD and LOQ of 0.261 and 0.322 pmol L^-1, respectively, and sensitivity of -15.560 μA/log [AZO_genome] (pmol L^-1). The biosensor showed good selectivity and reproducibility, with a coefficient of variation of -5.69 %, in addition to satisfactory sensitivity and stability for up to seven weeks. These promising analytical features allowed the quantification of A. brasilense in low concentrations in soil metagenomic DNA samples.

Keywords: 3-n-propylpyridinium silsesquioxane chloride; Azospirillum brasilense; Carbon nanotubes; Gold nanoparticles; Soil health.