Introduction: The improper use of nitrite ions and the widespread presence of antibiotics like kanamycin in food products pose significant risks to human health. To address these challenges, we developed two advanced electrochemical sensing platforms using laser-induced graphene (LIG) electrodes for sensitive and selective detection of these contaminants.

Methods: For nitrite detection, LIG electrodes were modified with an electrochemically deposited melanin-like film (MeLF), leveraging its redox-active catechol and o-quinone moieties. Redox capacitance spectroscopy was employed as a probe-free detection method. For kanamycin detection, LIG electrodes were functionalized with gold nanoparticles and a kanamycin-specific aptamer. Non-faradaic capacitance measurements were utilized to detect interactions between aptamer and kanamycin. Both sensors were characterized electrochemically and validated in real sample matrices.

Results: The MeLF-modified LIG sensor exhibited enhanced electron transfer kinetics, an increased electroactive surface area, and improved charge capacitance. It detected nitrite ions with a limit of detection of 2.45 μM and a dynamic range of 10 μM to 10 mM, achieving high recovery rates in water and processed meat samples. The aptamer-functionalized LIG sensor demonstrated a proportional increase in non-faradaic capacitance with kanamycin concentration, achieving a linear range from 100 fg/mL to 10 µg/mL, with successful real-time application in milk samples.

Conclusions: These novel sensing platforms demonstrate the versatility of modified LIG electrodes in electrochemical sensing. The combination of redox-active films and aptamer-based recognition elements with capacitive detection offers promising solutions for food safety monitoring and environmental analysis, providing sensitive, reliable, and practical analytical tools for real-world applications.