Performance of an amperometric immunosensor assembled on carboxymethylated cashew gum for Salmonella detection

Authors: ARAUJO MELO, AIRIS - State University Of Ceará; FURTADO, ROSELAYNE - Embrapa; DE FATIMA BORGES, MARIA - Embrapa; Biswas, Atanu; Cheng, Huai; ALVES, CARLUCIO - State University Of Ceará

Submitted to: Microchemical Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2021
Publication Date: 4/28/2021
Citation: Araujo Melo, A.M., Furtado, R.F., De Fatima Borges, M., Biswas, A., Cheng, H.N., Alves, C.R. 2021. Performance of an amperometric immunosensor assembled on carboxymethylated cashew gum for Salmonella detection. Microchemical Journal. 167, Article 106268. https://doi.org/10.1016/j.microc.2021.106268.
DOI: https://doi.org/10.1016/j.microc.2021.106268

Interpretive Summary: Salmonella contamination is one of the most common causes of food poisoning. Because of its importance to public health, analysis for Salmonella in food is a requirement for the regulatory agencies of many governments. A number of tests for Salmonella are being used, but they usually take several days to obtain the result. Recently some faster tests are available, but almost all these methods include a sample pre-enrichment step that increases the analysis time by up to 24 hours. In this study, we developed a fast, specific and quantitative test, based on an electrochemical immunosensors using carboxymethylated cashew gum. The new biosensor has been evaluated for the detection of Salmonella sp. in milk and found to be superior to two of the best test methods available. The biosensor described in this work shows great potential for use in the food industry and especially for emergency response.

Technical Abstract: Electrochemical immunosensors are rapid-response bioelectronic devices with great potential for miniaturization and portability that use antibody molecules such as bioreceptor and electrochemical transducer to generate the analytical signal. The development of immunosensors requires the use of biocompatible platforms that allow the binding of metals and biomolecules simultaneously. The present study aims to develop and evaluate the analytical performance of an electrochemical immunosensor for the detection of Salmonella sp. in milk using chemically modified cashew gum (CG) as a new platform for immobilization of biomolecules. For immunosensor development, polyclonal anti-Salmonella antibodies were immobilized on the carboxymethyl CG (CMCG) film and electrodeposited on the surface of gold electrodes. Optimization studies were conducted to improve the performance of the CMCG-based immunosensor. The analytical response was obtained by means of the chronoamperometry technique in the presence of the bacterium Salmonella enterica serovar Typhimurium. The immunosensor was characterized by electrochemical, scanning electron microscopy and infrared spectroscopy. Performance parameters of the immunosensor were determined, and food applicability was tested on different milk samples. Comparisons were made with other established methods for Salmonella detection. Characterization of the CMCG-based immunosensor demonstrated that CMCG was an excellent platform for mounting the immunosensor that displayed a stable structure with a 12% coefficient of variation after 30 sweeps in PBS buffer. The chronoamperometric response was proportional to the concentration of S. Typhimurium tested and presented a linear calibration curve up to 105 CFU mL-1. A loss of sensitivity with probable system saturation was observed at higher concentrations. The calculated limit of detection was 10 CFU mL-1. When tested on immunosensor milk samples, it could distinguish three different concentrations, proving its efficacy in detecting bacteria in a complex food matrix. The GCCM-based immunosensor detected the Salmonella pathogen quickly and specifically in milk samples with a low detection limit, thereby showing great potential for use in the food industry and especially for emergency response.