In a recent article published in the journal 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 is 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
The detection of foodborne pathogens, particularly Salmonella typhimurium, is critical for ensuring food safety and public health. Salmonella typhimurium is a significant cause of foodborne illness worldwide, often associated with 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 monitoring of pathogens.
Bacteriophages, viruses that infect bacteria, have emerged as effective tools for pathogen detection due to their specificity and ability to bind to target bacterial cells. The integration of bacteriophages into biosensor designs enhances sensitivity and selectivity. Additionally, the use of nanomaterials such as Ppy and RGO improves the electrical properties of the biosensor, facilitating better signal transduction. This study builds on previous research by combining these elements to develop a novel biosensing platform.
The Current Study
The electrochemical biosensor was developed using a composite material consisting of surface-modified bacterial cellulose (BC), polypyrrole (Ppy), and reduced graphene oxide (RGO). To prepare the BC/Ppy/RGO composite, a solution of Ppy was prepared by dissolving pyrrole in an acidic medium, followed by the addition of RGO. The resulting composite was washed, dried, and characterized using field-emission scanning electron microscopy (FE-SEM) to assess morphology, and Fourier-transform infrared (FTIR) spectroscopy to confirm functional group modifications.
For the immobilization of Salmonella typhimurium-specific bacteriophages, the phages were first concentrated and purified. The BC/Ppy/RGO composite was then incubated with the phage solution, allowing for electrostatic interactions to facilitate binding. The orientation of the phages was optimized to ensure that the tail fibers remained accessible for bacterial binding.
Electrochemical measurements were conducted using a three-electrode system, where the modified electrode served as the working electrode, a platinum wire as the counter electrode, and a saturated calomel electrode as the reference. Cyclic voltammetry (CV) and amperometric techniques were employed to evaluate the sensor's performance.
The detection limits were determined by analyzing the current response to varying concentrations of S. typhimurium in phosphate-buffered saline (PBS) and real food samples, including milk and chicken. The stability and reproducibility of the biosensor were assessed through repeated measurements and recovery tests, ensuring reliable performance in practical applications.
Results and Discussion
The results demonstrated that the developed BC/Ppy/RGO-phage biosensor exhibited exceptional sensitivity, with a detection limit as low as 1 colony-forming unit (CFU)/mL in PBS. In real food samples, the biosensor maintained low detection limits of 5 CFU/mL in milk and 3 CFU/mL in chicken, indicating its potential for practical applications in food safety monitoring. The electrochemical response of the biosensor was significantly enhanced by the presence of the immobilized phages, which facilitated the specific binding and detection of S. typhimurium.
Characterization of the composite materials revealed a uniform distribution of the phage particles on the biointerface, which contributed to the effective signal transduction observed in the electrochemical measurements. The FE-SEM images showed distinct morphological features of the BC/Ppy/RGO composite, confirming the successful integration of the nanomaterials. The XRD and FTIR analyses provided further evidence of the structural integrity and functional group variations in the composite, supporting its suitability for biosensing applications.
The study also highlighted the importance of the stability and reproducibility of the biosensor. The results indicated that the biosensor maintained consistent performance over multiple tests, which is crucial for reliable pathogen detection in food safety applications. Recovery tests 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 research successfully created an ultrasensitive electrochemical biosensor for detecting Salmonella typhimurium in diverse food samples. The novel BC/Ppy/RGO-phage composite material demonstrated exceptional conductivity and efficiency, forming a biointerface that enables fast and precise pathogen detection. The findings underscore the potential of integrating nanomaterials and bacteriophages in biosensor technology to enhance food safety measures.
The low detection limits achieved in this study highlight the biosensor's applicability for early identification of contamination, which is essential for preventing foodborne illnesses. Future research may focus on further optimizing the biosensor design and expanding its application 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