Effect Of Core-shell Structure Research Articles

Fabrication, mechanical property and in vitro evaluation of poly (L-lactic acid-co-ε-caprolactone) core-shell nanofiber scaffold for tissue engineering

Coaxial electrospinning, in which Poly (L-lactic acid-co-ε-caprolactone) (PLC) with different Lactic acid (LA) to caprolactone (CL) ratio (75:25 and 50:50) were employed to electrospin core-shell nanofibers which could mimic the native extracellular matrix for tissue engineering applications. Core-shell nanofibrous scaffolds of PLC (50:50)/BSA (426 ± 157 nm) and PLC (75:25)/BSA (427 ± 197 nm) were fabricated and model drug bovine serum albumin (BSA) was entrapped in the core layer. The morphology, core-shell structure and sustained release behaviors were evaluated by Scanning electron microscopy (SEM), transmission electron microscopy (TEM), inverted fluorescence microscopy, water contact angle test and in vitro release test, respectively. The effect of core-shell structure and shell layer materials on the variation tendency of mechanical characterization in dry and wet situation were also investigated by tensile testing. The in vitro biocompatibility of scaffolds were investigated by growing human mesenchymal stem cells (hMSCs) on scaffolds surface and the proliferation of cells were evaluated with Alamar Blue tests. In vitro cultivations of hMSCs showed that PLC (50:50)/BSA scaffolds supported a significantly higher proliferation rate of seeded cells than scaffolds prepared by polymer PLC (75:25)/BSA. Overall, the PLC core-shell nanofibers possessed potentially regulable mechanical properties useful for tissue engineering as well as sustained release potential for medical applications.

Effect of core-shell structure on optical properties of Au-Cu2O nanoparticles

Solid Au-Cu2O core-shell nanoparticles were synthesized using gold nanoparticles of 16.6nm in size as the core. The core-shell structure of the synthesized particles was confirmed and characterized by TEM and HRTEM images. Due to their similar crystal structure, the (111) planes of Cu2O are nucleated and grown epitaxially on the {111} facets of Au nanoparticles with the lattice mismatch of about 4.3% resulting in a polycrystallized Cu2O shell covering the Au nanocore. Due to the quantum confinement effect, the band gap energy Eg of the synthesized Cu2O shells is blue-shifted from 2.35 to 2.70eV as the shell thickness decreases from of 24.6±3.6 to 9.0±1.7nm. The localized SPR (Surface Plasmon Resonance) peak of the Au nanocore undergoes a large red shift of the order of a hundred of nm due to both the high refractive index and the increase of the thickness of Cu2O shell. Theoretical models within the Drude framework significantly underestimate the experimental data and predict a wrong rate of change of the SPR peak position with respect to the shell thickness.

Core-shell 구조를 지니는 하모닉 분말의 성형거동 분석

Abstract In this study, effect of core-shell structure on compaction behavior of harmonic powder is investigated.Harmonic powders are made by electroless plating method on Fe powders. Softer Cu shell encloses harder Fe core, andthe average size of Fe core and thickness of Cu shell are 34.3 µm and 3.2 µm, respectively. The powder compactionprocedure is processed with pressure of 600 MPa in a cylindrical die. Due to the low strength of Cu shell regions, theharmonic powders show better densification behavior compared with pure Fe powders. Finite element method (FEM) isperformed to understand the roll of core-shell structure. Based on stress and strain distributions of FEM results, it isconcluded that the early stage of powder compaction of harmonic powders mainly occurs at the shell region. FEMresults also well predict porosity of compacted materials. Keywords: Harmonic powder, Finite element method, Shell compaction region, Compaction behavior ······························································································································· ·································································································