Carbon-dot pequi-nut in the development of immunosensor to detect pathogenic bacteria

• Published in: Brazilian journal of microbiology 2025-01
• Main Authors: Castelo, Rachel Menezes, de Albuquerque Oliveira, Marília, Furtado, Roselayne Ferro, de Oliveira, Bruno Peixoto, Martoni, Lucas Vinicius Leite, Machado, Terezinha Feitosa, Muniz, Celli Rodrigues, da Silva Abreu, Flávia Oliveira Monteiro, Machado, Sérgio Antônio Spinola, Melo, Airis Maria Araújo, Cheng, Huai N, Biswas, Atanu, Alves, Carlucio Roberto
• Format: Article
• Language: English
• ISSN: 1517-8382; 1678-4405; 1678-4405
• DOI: 10.1007/s42770-025-01612-1

Carbon dots in biosensing have advanced significantly, adding improvements to different detection techniques. In this study, an amperometric immunosensor for Salmonella Thyphimurium was designed using antibodies labeled with carbon dots (Cdots) from pequi almond (Caryocar brasiliensis). Cdots were synthesized by pyrolysis and characterized by FTIR, UV/fluorescence, electrochemistry, zeta potential, and transmission electron microscopy (TEM). A particle size of 6.80 ± 2.13 nm was estimated, and the zeta potential was - 47.4 mV, indicating the preponderant presence of acidic groups, as confirmed by FTIR. The impedance evaluation of the response of biosensors assembled for live (Rct = 13.4 kΩ) and dead (Rct = 499.7 Ω) Salmonella showed a significant difference in their values, in agreement with chronoamperometric analyses, which had their current values drastically reduced from - 2.2 mA (live) to 0 mA (dead). An analytical curve for Salmonella was established with the limit of detection lower than 1 CFU/mL. This electrochemical biosensor using pequi carbon dots for antibody labeling showed promising results for detecting the pathogen. Thus, carbon dots can be used as substitutes for enzymes in labeling antibodies used in the design and production of sensors.