Nanoarchitectonic E-Tongue of Electrospun Zein/Curcumin Carbon Dots for Detecting Staphylococcus aureusin Milk

We report a nanoarchitectonic electronic tongue made with flexible electrodes coated with curcumin carbon dots and zein electrospun nanofibers, which could detect Staphylococcus aureus(S. aureus) in mil k using electrical impedance spectroscopy. Electronic tongues are based on the global select i v i t y concept in which the electrical responses of distinct sensing units are combined to provide a unique pattern , which in this case allowed the detection of S. aureus through non-specific interactions. The electronic tongue used here comprised 3 sensors w i t h electrodes coated with zein nanofibers, carbon dots, and carbon dots with zein nanofibers. The capacitance data obtained with the three sensors were processed with a multidimensional projection technique referred to as interactive document mapping (IDMAP) and analyzed using the machine learning-based concept of multidimensional calibration space (MCS). The concentration of S. aureus could be determined with the sensing units, especially with the one containing zein as the l i m i t of detection was 0.83 CFU/mL (CFU stands for colony-forming unit). This high sensit i v i t y is attributed to molecular-level interactions between the protein zein and C-H groups in S. aureus according to polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS) data. Using machine learning and IDMAP, we demonstrated the select i v i t y of the electronic tongue in distinguishing mil k samples from mastitis-infected cows from mil k collected from healthy cows, and from mil k spiked with possible interferents. Calibration of the electronic tongue can also be reached with the MCS concept employing decision tree algorithms, with an 80.1% accuracy in the diagnosis of mastitis. The low-cost electronic tongue presented here may be exploited in diagnosing mastitis at early stages, with tests performed in the farms without requiring specialized laboratories or personnel.