Fig. 2: Characterizations of E-MIP sensor for Phe detection.

a DPV scans of a PANI-based E-MIP electrode (PANI-E-MIP), a PANI-based E-NIP electrode (PANI-E-NIP), a PPY-based E-MIP electrode (PPY-E-MIP) electrode, and a gold electrode (Au) in a 10× PBS containing 200 μM Phe. b, c Comparison of the electron transfer number between different electrodes and Phe molecule within an external electric field. d, e DPV scans of the E-MIP-based Phe sensor for direct Phe detection after baseline correction (d) and corresponding peak current readouts (e). Inset, the molecular electrostatic potential surfaces of the E-MIP electrode and Phe. The error bars (n = 3 measurements) correspond to the standard deviation (SD). f Response comparison between E-MIP and E-NIP electrodes to equivalent Phe concentrations in PBS. g CV scans of different MIP electrodes based on PANI and an Au electrode in a solution containing 5 mM [Fe(CN)₆]³⁻ and 0.2 M KCl. h EIS responses of an E-MIP electrode, a MIP electrode, and an Au electrode in a PBS containing 200 μM Phe. i Selectivity of the E-MIP sensor against other AAs. The following substances were added in succession: 1 mM Glycine (Gly), 1 mM Serine (Ser), 500 μM Alanine (Ala), 500 μM Histidine (His), 200 μM Tyr, 200 μM tryptophan (Trp), and 200 μM Phe. j Selectivity of the E-MIP sensor against common sweat interferents in presence of 200 μM Phe. The following interferents were added in succession: 100 μM glucose (Glu), 5 mM Urea, 5 mM lactate (LA), and 100 μM ascorbic acid (AS). k Batch-to-batch variation of the E-MIP sensor performance in the presence of 200 μM Phe. The error bars correspond to the standard deviation (n = 3 independent sensors). The center for the error bars represents the mean value. l Influence of pH changes in peak currents and respective peak potentials. The dashed box indicates the pH range with stable DPV responses.