Self-assembled mesoporous particles of Antheraea pernyi silk fibroin for encapsulation and sustained release of 5-fluorouracil

Abstract

Mesoporous particles have attracted considerable attention in drug delivery system, because they can offer fast mass transport and overcome the diffusion restriction as occurred in micro/nano- porous particles. Conventional mesoporous particles are generally dominated by inorganic compounds, little concern has been raised over biodegradable organic polymers, especially silk fibroin. Here, we show that Antheraea pernyi (A. pernyi) silk fibroin, rich in Arg-Gly-Asp (RGD) moiety, can be developed into mesoporous particles via self-assembly in a direct and eco-friendly (without any organic solvents) manner for sustained release of 5-fluorouracil (5-FU). By cultivating a mild condition at 40 ℃, a mesoporous structure was successfully achieved without any foreign organic solvents. The self-assembled mesoporous particles were quasi-spherical in shape with an average diameter of 1.58 µm. Mesopores ran through the entire particles to construct a divergent structure with external pore diameters ranging from 30 to 60 nm and internal pore width of 6.225 nm. The mesoporous particles were predominated by β-sheet conformation (∼45%), which effectively reduced the weight-loss ratio to 2.6%. 5-FU was encapsulated into the mesoporous particles by hydrogen bonding and van der Waals force as well as ionic interactions. Drug loading efficiency and encapsulation efficiency were found to be 26.24% and 50.36%, respectively. The mesoporous particles enabled sustained drug release, with approximately 90% release after 110 h. After a small burst release (20%) of the surface-bound 5-FU, a slower linear release dominated by Fickian-diffusion occurred. These features together with the excellent biocompatibility of A. pernyi silk indicated that the self-assembled mesoporous particles would be an ideal carrier for sustained drug release to meet critical requirements of biomaterials. Furthermore, without any foreign materials, this one-step strategy may offer new green chemistry approaches as well as options to load bioactive drugs.