Electrophoretically assembly of silk fibroin coatings from different pre‐assembled nanostructures on dental abutment to tune the release of antibiotics

Abstract

Background Constructing coatings on dental abutment surfaces via electrophoretic deposition (EPD) technique is highly appealing strategy to act as a reservoir to release therapeutic antibiotics for patients with serious periodontal disease or diabetes. Previous studies attempt to incorporate various drug delivery vehicles into EPD matrix to control drug release. However, these methods lead to formation of new substances or use of additional chemicals, which could often cause concerns on biosafety and cost. Aim/Hypothesis We hypothesize that deposition of controlled pre-assembled nanostructures of EPD matrix, instead of SF (silk fibroin) molecule solution, would provide more control over drug release. Material and Methods 2% wt SF solution was obtained by dissolving cocoons in saturated LiBr solution. 2wt% SF nanospheres were synthesized via precipitation reaction. Different EPD matrix solutions of 2 wt% were made by mixing SF molecule with SF nanospheres at different weight ratios of 0%, 25%, 50%, 75%, 100%. We coated these EPD matrixes on titanium disks by EPD technique, and they were denoted as SF0, SF25, SF50, SF75 and SF100, respectively. We characterized the surface properties of these coatings, including conformations, topography, roughness, adhesion strength, wettability, and degradation. Doxycycline was applied as a model antibiotic drug. The release kinetics of doxycycline from different coatings was monitored by means of high-performance liquid chromatography (HPLC). P. gingivalis and minimum inhibition concentration (MIC) tests were used to show antibacterial bioactivity of released doxycycline at different time points. Fibroblasts were cultured on coatings to evaluate their biocompatibility. Results Through optimization, different SF coatings with different composition of pre-assembled nanostructures were deposited on titanium disks. With increasing the weight ratio of nanospheres, the roughness of the coatings ascended, and the adhesion strength decreased. The b-sheet content of SF conformations, wettability, degradation rates and biocompatibility of the coatings were comparable among all groups. When there were more pre-assembled nanospheres inside the coatings, the release time of doxycycline could gradually change from 3 day to 3 weeks measured by HPLC, whose antibacterial bioactivity was consistent with the results of MIC. Conclusion and Clinical Implications We proposed a novel strategy to electrophoretically assembly SF coatings from different pre-assembled nanostructures. This strategy largely enhanced the control release capability of drug without formation of new substances or use of additional chemicals. This study not only constitutes a straightforward approach to control antibiotics’ release from abutment to deal with different patient's conditions, but also opens up a new insight for the development of EPD coating based drug release system.