Electrospun Magnetic Composite Poly-3-hydroxybutyrate/Magnetite Scaffolds for Biomedical Applications: Composition, Structure, Magnetic Properties, and Biological Performance

Abstract

Magnetically responsive composite polymer scaffolds have good potential for a variety of biomedical applications. In this work, electrospun composite scaffolds made of polyhydroxybutyrate (PHB) and magnetite (Fe 3 O 4 ) particles (MPs) were studied before and after degradation in either PBS or a lipase solution. MPs of different sizes with high saturation magnetization were synthesized by the coprecipitation method followed by coating with citric acid (CA). Nanosized MPs were prone to magnetite−maghemite phase transformation during scaffold fabrication, as revealed by Raman spectroscopy; however, for CA-functionalized nanoparticles, the main phase was found to be magnetite, with some traces of maghemite. Submicron MPs were resistant to the magnetite−maghemite phase transformation. MPs did not significantly affect the morphology and diameter of PHB fibers. The scaffolds containing CA-coated MPs lost 0.3 or 0.2% of mass in the lipase solution and PBS, respectively, whereas scaffolds doped with unmodified MPs showed no mass changes after 1 month of incubation in either medium. In all electrospun scaffolds, no alterations of the fiber morphology were observed. Possible mechanisms of the crystalline-lamellar-structure changes in hybrid PHB/Fe 3 O 4 scaffolds during hydrolytic and enzymatic degradation are proposed. It was revealed that particle size and particle surface functionalization affect the mechanical properties of the hybrid scaffolds. The addition of unmodified MPs increased scaffolds' ultimate strength but reduced elongation at break after the biodegradation, whereas simultaneous increases in both parameters were observed for composite scaffolds doped with CA-coated MPs. The highest saturation magnetization�higher than that published in the literature�was registered for composite PHB scaffolds doped with submicron MPs. All PHB scaffolds proved to be biocompatible, and the ones doped with nanosized MPs yielded faster proliferation of rat mesenchymal stem cells. In addition, all electrospun scaffolds were able to support angiogenesis in vivo at 30 days after implantation in Wistar rats.

Poly(3-hydroxybutyrate) 3D-Scaffold–Conduit for Guided Tissue Sprouting

“…The microstructures of the scaffolds were studied by performing WLM and SEM using a stereomicroscope Nikon SMZ1500 (Nikon, Tokyo, Japan) and a scanning electron microscope JSM-6380LA (JEOL, Tokyo, Japan), respectively. The scaffolds with attached MSCs and 3T3 cells were also examined using SEM with the special pretreatment of specimens as previously reported [ 16 ].…”

“…The 3T3 cells (Biolot, Sankt-Peterburg, Russia) were maintained in DMEM, supplemented with 10% FBS and 50 U/mL penicillin/streptomycin. The bone marrow MSCs were isolated from the femurs of young (3–8 days old) Wistar rats as previously described [ 16 , 43 ]. The isolated MSCs were cultured for 2 weeks in -MEM (PanEco, Moscow, Russia) supplemented with 10% fetal calf serum (FCS, Biological Industries, Beit Haemek, Israel), 50 U/mL penicillin/streptomycin.…”

“…The scaffold was subcutaneously placed and the wounds were sutured. After 7, 14, 28, and 60 days, the animals were sacrificed, with a fragment of the soft tissue with the tested area being extracted and preserved in 10% formalin solution for histological examination [ 16 ].…”

“…Following euthanasia, the polymer scaffolds (4 specimens for each tested material at each experimental time) were removed together with a surrounding soft tissue capsule. The explants were immersed in 4% formaldehyde in phosphate buffered saline (pH 7.4) and fixed for 24 h. Then, the specimens were prepared for histological examination as previously described [ 16 ]. The slices were stained using hematoxylin-eosin and analyzed under a light microscope Leica DM 2500 (Leica Microsystems, Germany).…”

“…[ 14 ]. PHB is also often used as a basic compound of composite materials [ 15 , 16 , 17 , 18 ]. PHB has a number of unique biological properties: complete biodegradability to non-toxic products, biocompatibility, non-carcinogenicity, and special diffusion properties that provide sustained drug release [ 19 , 20 , 21 , 22 ].…”