Hydroxyapatite and Silicon-Modified Hydroxyapatite as Drug Carriers for 4-Aminopyridine
Laura Marincaș,
Graziella Liana Turdean,
Monica Toșa,
Zsolt Kovács,
Béla Kovács,
Réka Barabás,
Noémi-Izabella Farkas,
Liliana Bizo
Affiliations
Laura Marincaș
Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, 11 Arany János Street, 400028 Cluj-Napoca, Romania
Graziella Liana Turdean
Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, 11 Arany János Street, 400028 Cluj-Napoca, Romania
Monica Toșa
Enzymology and Applied Biocatalysis Research Centre, Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, 11 Arany János Street, 400028 Cluj-Napoca, Romania
Zsolt Kovács
Department of Biochemistry and Environmental Chemistry, Faculty of Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, Gheorghe Marinescu 38 Street, 540142 Târgu Mureș, Romania
Béla Kovács
Department of Biochemistry and Environmental Chemistry, Faculty of Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, Gheorghe Marinescu 38 Street, 540142 Târgu Mureș, Romania
Réka Barabás
Department of Chemistry and Chemical Engineering of Hungarian Line of Study, Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, 11 Arany János Street, 400028 Cluj-Napoca, Romania
Noémi-Izabella Farkas
Department of Chemical Engineering, Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, 11 Arany János Street, 400028 Cluj-Napoca, Romania
Liliana Bizo
Department of Chemical Engineering, Faculty of Chemistry and Chemical Engineering, Babeș-Bolyai University, 11 Arany János Street, 400028 Cluj-Napoca, Romania
Adsorption and desorption properties of nano-hydroxyapatite (HAP) and silicon-modified hydroxyapatite (Si–HAP) were investigated with 4-aminopyridine (fampridine-4AP). The novelty of this research is the investigation of the suitability of the previously mentioned carriers for drug-delivery of 4AP. UV-VIS spectrophotometric results showed that the presence of silicon in the carrier did not significantly affect its adsorption capacity. The success of the adsorption was confirmed by thermal analysis (TG/DTA), scanning electron microscopy (SEM)/energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRPD). Drug release experiments, performed in simulated body fluid (SBF), revealed a drug release from Si–HAP that was five times slower than HAP, explained by the good chemical bonding between the silanol groups of the carrier and the 4AP functional groups. The electrochemical measurements showed a value of the polarization resistance of the charge transfer (Rct) more than five times smaller in the case of Si–HAP coating loaded with 4AP, so the charge transfer process was hindered. The electrochemical impedance results revealed that electron transfer was inhibited in the presence of 4AP, in concordance with the previously mentioned strong bonds. The silicon substitution in HAP leads to good chemical bonding with the drug and a slow release, respectively.
