In a recent article published in Biosensors, researchers presented the development of an innovative electrochemical biosensor utilizing surface-modified bacterial cellulose (BC) integrated with polypyrrole (Ppy), reduced graphene oxide (RGO), and immobilized phage particles. The aim of the study was to create a highly sensitive and efficient platform for the detection of S. typhimurium in food products.
Study: Ultrasensitive electrochemical detection of Salmonella typhimurium in food matrices using surface-modified bacterial cellulose with immobilized phage particles. Image Credit: Pattikky/Shutterstock.com
Background
Detecting foodborne pathogens like Salmonella typhimurium is critical for ensuring food safety and public health. Salmonella typhimurium is a major cause of foodborne illness worldwide, often linked to contaminated poultry, dairy, and other food products. The need for rapid detection methods has led to the exploration of biosensors, which can provide real-time pathogen monitoring.
Bacteriophages, viruses that specifically infect bacteria, have emerged as effective tools for pathogen detection due to their specificity and binding ability. Their integration into biosensors enhances sensitivity and selectivity. Additionally, using nanomaterials like Ppy and RGO improves the electrical properties of biosensors, allowing for better signal transduction. This study builds on earlier research by combining these elements to develop a novel biosensing platform.
The Current Study
The electrochemical biosensor was developed using a composite material of BC, Ppy, and RGO. The BC/Ppy/RGO composite was prepared by dissolving pyrrole in an acidic medium, adding RGO, and washing and drying the resulting material. It was characterized using field-emission scanning electron microscopy (FE-SEM) to assess morphology, and Fourier-transform infrared (FTIR) spectroscopy to confirm functional group modifications.
Salmonella typhimurium-specific bacteriophages were concentrated, purified, and immobilized onto the BC/Ppy/RGO composite via electrostatic interactions, optimizing the phage orientation to keep tail fibers accessible for bacterial binding.
Electrochemical measurements were conducted using a three-electrode system, with the modified electrode as the working electrode, platinum wire as the counter electrode, and a saturated calomel electrode as the reference. Cyclic voltammetry (CV) and amperometric techniques were employed to assess the biosensor's performance.
Detection limits were determined by analyzing the current response to varying S. typhimurium concentrations in both phosphate-buffered saline (PBS) and real food samples, including milk and chicken. The stability and reproducibility of the biosensor were evaluated through repeated measurements and recovery tests, ensuring consistent performance for practical applications.
Results and Discussion
The BC/Ppy/RGO-phage biosensor showed exceptional sensitivity, with a detection limit of 1 colony-forming unit (CFU)/mL in PBS. In real food samples, it maintained low detection limits of 5 CFU/mL in milk and 3 CFU/mL in chicken, demonstrating its potential for food safety monitoring. The immobilized phages significantly enhanced the electrochemical response, facilitating specific binding and detection of S. typhimurium.
Characterization of the composite materials revealed a uniform distribution of phage particles on the biointerface, contributing to effective signal transduction. FE-SEM images confirmed successful nanomaterial integration, while XRD and FTIR analyses provided additional evidence of the composite's structural integrity and functional group modifications.
The biosensor exhibited consistent performance over multiple tests, indicating high stability and reproducibility, which are crucial for reliable pathogen detection. Recovery tests further demonstrated the biosensor's ability to accurately detect S. typhimurium in complex food matrices, reinforcing its practical utility in real-world scenarios.
Conclusion
In summary, this study successfully developed an ultrasensitive electrochemical biosensor for detecting Salmonella typhimurium in diverse food samples. The BC/Ppy/RGO-phage composite demonstrated exceptional conductivity and efficiency, forming a biointerface that enables fast and precise pathogen detection. The findings highlight the potential of integrating nanomaterials and bacteriophages in biosensor technology to enhance food safety measures.
The low detection limits achieved underscore the biosensor's applicability for early contamination detection, which is crucial for preventing foodborne illnesses. Future research could focus on further optimizing the biosensor's design and expanding its use to other foodborne pathogens, ultimately contributing to improved public health outcomes.
Journal Reference
Hussain W., Wang H., et al. (2024). Ultrasensitive electrochemical detection of Salmonella typhimurium in food matrices using surface-modified bacterial cellulose with immobilized phage particles. Biosensors 14(500). DOI: 10.3390/bios14100500, https://www.mdpi.com/2079-6374/14/10/500