A novel screen-printed mast cell-based electrochemical sensor for detecting spoilage bacterial quorum signaling molecules (N-acyl-homoserine-lactones) in freshwater fish

A novel screen-printed cell-based electrochemical sensor was developed to assess bacterial quorum signaling molecules, N-acylhomoserine lactones (AHLs). Screen-printed carbon electrode (SPCE), which possesses excellent properties such as low-cost, disposable and energy-efficient, was modified with multi-walled carbon nanotubes (MWNTs) to improve electrochemical signals and enhance the sensitivity. Rat basophilic leukemia (RBL-2H3) mast cells encapsulated in alginate/graphene oxide (NaAgl/GO) hydrogel were immobilized on the MWNTs/SPCE to serve as recognition element. Electrochemical impedance spectroscopy (EIS) was employed to record the cell impedance signal as-influenced by Pseudomonas aeruginosa quorum-sensing molecule, N-3-oxododecanoyl homoserine lactone (30C(12)-HSL). Experimental results show that 30C(12)-HSL caused a significant decrease in cell viability in a dose dependent manner. The EIS value decreased with concentrations of 30C(12)-HSL in the range of 0.1-1 mu M, and the detection limit for 30C(12)-HSL was calculated to be 0.094 mu M. These results were confirmed via cell viability, SEM, TEM analysis. Next, the sensor was successfully applied to monitoring the production of AHLs by spoilage bacteria in three different freshwater fish juice samples which efficiently proved the practicability of this cell based method. Therefore, the proposed cell sensor may serve as an innovative and effective approach to the measurement of quorum signaling molecule and thus provides a new avenue for realtime monitoring the spoilage bacteria in freshwater fish production.