**4. Conclusions**

We have successfully delivered therapeutic doses of dexamethasone by an electroactive controlled system, adjusting the initial formulation and the electrical stimulated events. Moreover, using κ-carrageenan as dispersant during the polymerization and as a doping agen<sup>t</sup> in the composite, we avoided delamination and changes in the film roughness. The chemical composition inside the conductive film was confirmed by 2D Raman and electrochemical signal in the cyclic voltammetry analysis. Concentrations of dexamethasone in the range of 100 to 1000 nM were obtained using a lower amount of dexamethasone in the initial formulation. Those concentrations are recommended to induce di fferentiation in mesenchymal cell cultures and in anti-inflammatory responses. Therefore, an adequate formulation along with a proper active electrochemical stimulation profile allowed the delivery of therapeutic doses of charged molecules without significant changes in our film roughness. Our approach may be useful in the development of diverse strategies and implant systems in the regenerative medicine field.

*Molecules* **2020**, *25*, 2139

**Supplementary Materials:** The following is available online, Figure S1: Galvanostatic curve of the electro-polymerization process from an EDOT:κC:Dx dispersion onto a bare gold electrode. Figure S2. Raman spectra of the PEDOT:κC:Dx coating (a.) before dexamethasone release process (Inset: PEDOT:κC:Dx electrode surface) and (b.) after 160 release cycles (Inset: PEDOT:κC:Dx electrode surface). Figure S3. μ-Raman spectral measurement of the dexamethasone 21-phosphate disodium salt. Figure S4. Deposited PEDOT:κC:Dx electrode after 160 cycles of electrical stimulation (left) and gold electrode without passivation as reference (right). Table S1: Gradient elution method for the mobile phase using during dexamethasone analysis. Solvents were water: 0.05% formic acid (A) and methanol: 0.05% formic acid (B). and S1: Configuration of the mass spectrometer during dexamethasone quantification.

**Author Contributions:** Conceptualization, K.R.S.; M.P., and R.S.P.; methodology, K.R.S.; A.L.-E.; A.S.-K.; E.A.-S., and R.S.P.; software, K.R.S.; A.L.-E.; A.S.-K.; E.A.-S., and R.S.P. validation, K.R.S.; A.L.-E.; A.S.-K., and R.S.P.; formal analysis, R.S.P.; investigation, K.R.S. and R.S.P.; resources, E.A.-S. and R.S.P.; data curation, K.R.S.; A.L.-E., and A.S.-K.; writing—original draft preparation, K.R.S. and R.S.P.; writing—review and editing, K.R.S.; A.L.-E.; A.S.-K.; E.A.-S.; M.P., and R.S.P; visualization, K.R.S. and R.S.P.; supervision, M.P. and R.S.P.; project administration, K.R.S. and R.S.P.; funding acquisition, E.A.-S. and R.S.P. All authors have read and agree to the published version of the manuscript.

**Funding:** This research was funded by Costa Rica Institute of Technology (ITCR), project number: 5402-1360-4401.

**Acknowledgments:** Costa Rica Institute of Technology (ITCR), project number: 5402-1360-4401. Part of this work was carried out in the frame of the COST-Action "Advanced Engineering of Aerogels for Environment and Life Sciences" (AERoGELS, ref. CA18125) funded by the European Commission. The authors would like to thank to Steven Hidalgo and Jazmín Umaña for their participation in the electrode fabrication process. RGSF-RIP.

**Conflicts of Interest:** The authors declare no conflict of interest.
