Two approaches to the model drug immobilization into conjugated polymer matrix

• Polypyrrole matrix is used to immobilize and release quercetin and ciprofloxacin.
• Two routes of drug immobilization are described: during and after polymerization.
• Both immobilization approaches exhibit different drug-loading efficiencies.
• Drugs are released in a controlled way under the influence of applied potential.

The purpose of this study is to develop biocompatible and conducting coating being carrier of biologically active compounds with the potential use in neuroprosthetics. Conducting polypyrrole matrix has been used to immobilize and release model drugs, quercetin and ciprofloxacin. Two routes of immobilization are described: drugs have been incorporated in the polymer matrix in the course of the electropolymerization process or after polymerization, in the course of polymer oxidation. Using UV/Vis spectroscopic detection we demonstrate that both immobilization approaches display different drug-loading efficiencies. In the case of ciprofloxacin, drug incorporation following synthesis is a more efficient immobilization approach (final drug concentration: 43.3 (± 9.5) μM/cm2), while for quercetin the highest loading is accomplished by drug incorporation during synthesis (final drug concentration: 29.1 (± 5.9) μM/cm2). The process of drug incorporation results in the variation of surface morphology with respect to the method of immobilization as well as the choice of drug. The results prove that electrochemical methods are efficient procedures for making multifunctional polymer matrices which might be perspective bioactive coatings for implantable neuroprosthetic devices.