*4.7. Drug-Delivery Studies*

The electrochemically triggered release of MER or DMP from the films was achieved using a PalmSens EmStat 3+ potentiostat connected to a personal computer using the PSTrace 7.4 software (amperometric technique), and a three-electrode system (described above) in a biomedically relevant buffer (4 mL of PBS at pH 7.4). Prior to electrical stimulation, there was a quiet time of 20 s at a potential

of 0.1 V, after which the PPY-coated ITO working electrodes were stimulated for 30 s with a reducing potential of 0.6 V. The films were allowed to rest for 10.5 min after each stimulation, during the last 30 s of which 10 μL of the solution was taken for quantification of drug release with UV spectroscopy (at either 242 nm for DMP, or 297 nm for MER) using a Nanodrop 2000c spectrophotometer (Thermo Fisher Scientific, Loughborough, UK). The PBS was not changed between rounds of stimulation, and the data are reported as cumulative release as a percentage of the total mass of the drug in the film (films were individually weighed; DMP-doped PPY films contained 12 wt % of DMP, and MER-doped PPY films contained 4 wt % of MER). These data were compared to the passive drug release from non-stimulated films every 11 min. To determine the total amount of drug in the films, the drug-doped films were stimulated at a reducing potential of 0.6 V for 60 min, and the medium was changed every 10 min. All reported data were normalized relative to the amount of released drug from a 1-mg-drug-doped PPY film with a surface area of 100 mm2.

### *4.8. Calculating the Main Physical Descriptors of the Investigated Drugs*

Physical descriptors (constitutional and electronic) were calculated. The selected descriptors were the dipole moment, LogP (octanol/water), molecular globularity, number of H-atom donors and acceptors, and the molecular flexibility. The descriptors were calculated using the MOE software version 2014.0901 (Chemical Computing Group Inc., Montreal, QC, Canada), and the builder tool in the same software was used to generate the three-dimensional (3D) structures of the investigated drugs from their isomeric simplified molecular-input line-entry system (SMILES) obtained from The PubChem Project® (National Institutes of Health, Bethesda, MD, USA).
