Sol-Gel Synthesis of Caffeic Acid Entrapped in Silica/Polyethylene Glycol Based Organic-Inorganic Hybrids: Drug Delivery and Biological Properties

The failure of medical devices, such as bones prosthesis, is mainly due to inflammatory and infectious phenomena. Entrapping anti-inflammatory and antimicrobial agents inside the biomaterial matrix could avoid these phenomena. In this context, inorganic/organic silica (S)/polyethylene glycol (P)/caffeic acid (A) hybrid systems were synthesized via the sol-gel method with different weight percentages of P and A. Fourier-transform infrared (FT-IR) revealed that caffeic acid undergoes an oxidizing phenomenon in the sol-gel synthesis condition. Additionally, the formation of a hydroxyapatite layer on hybrid surfaces was demonstrated by employing the Kokubo test and analyzing the samples using scanning electron microscopy, X-ray diffraction, and FT-IR. Moreover, further characterization of the antimicrobial activity of the synthesized biomaterials was carried out using the Kirby-Bauer test. Finally, UV-Vis measurement was useful to evaluate the caffeic acid kinetic release in simulated body fluid (SBF) at 37 degrees C. The kinetic study disclosed that the hybrid materials without polyethylene glycol had faster release rates than the ones obtained without the organic polymer.