Electrochemical sensors based on laser induced graphene for food safety monitoring

Description:
Carbon nanomaterials such as graphene are being explored in various electrochemical applications due to their large surface area, high electrical conductivity, and mechanical stiffness that have the potential to significantly improve the performance of electrochemical sensors. Laser-induced graphene (LIG) has proven to be a scalable manufacturing alternative to produce high-performance electrochemical transducers for sensors that overcome the associated expenses of conventional graphene fabrication methods. Herein, we report label-free, high-sensitivity, and rapid-response-time graphene-based electrochemical sensors for quantitatively detecting foodborne pathogen Salmonella Typhimurium in chicken broth and nitrite in cured meat. We fabricate hydrophilic and hydrophobic LIG-electrodes using a CO2 laser through a single- or double-step lasing process, respectively. Next, hydrophilic LIG electrodes are converted into Salmonella Typhimurium sensors by covalently linking polyclonal antibody to electrode surface. Additionally, hydrophobic LIG solid-state ion selective electrodes (ISE) are created by drop-casting poly(vinyl) chloride-based nitrite ion-selective membrane. The resultant nitrite ion-selective sensors displayed Nernstian response behavior with a sensitivity of 59.5 mV dec^-1, a detection limit of 0.3 ± 0.1 ppm, and a broad linear sensing range from 10^-5 to 10^-1 M, that was significantly larger than currently published nitrite methods. While the resulting electrochemical immunosensor exhibited a limit of detection of 13 ± 2 CFU/10 mL and rapid response time (17 min) with a wide linear sensing range, from 1 to 10^5 CFU/mL in chicken broth. These results demonstrate the versatility of LIG platform for ion-selective-LIG sensors and immunosensors paving the way for simple, efficient, and scalable electrochemical sensing and as a promising alternative to monitor nitrite and Salmonella levels in food products ensuring compliance with the safety standards.

Speaker: Carmen Gomes - Iowa State University
Dr. Gomes's research is focused on the design of nanoscale materials using biopolymers and 2D materials for the development of functional delivery systems and biosensors. Dr. Gomes's group has key research thrusts that include new material development, primarily nanocarbon materials such as graphene and carbon quantum dots and biopolymers, in particular, stimuli-responsive polymers with application areas biosensing and delivery system for food safety and quality, soil health, water safety and quality, and human health applications.