Surface potential of biomaterials is a key factor regulating cell responses, driving their adhesion and signaling in tissue regeneration. In this study we compared the surface and zeta potential of ...smooth and porous electrospun polycaprolactone (PCL) fibers, as well as PCL films, to evaluate their significance in bone regeneration. The ’ surface potential of the fibers was controlled by applying positive and negative voltage polarities during the electrospinning. The surface properties of the different PCL fibers and films were measured using X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM), and the zeta potential was measured using the electrokinetic technique. The effect of surface potential on the morphology of bone cells was examined using advanced microcopy, including 3D reconstruction based on a scanning electron microscope with a focused ion beam (FIB-SEM). Initial cell adhesion and collagen formation were studied using fluorescence microscopy and Sirius Red assay respectively, while calcium mineralization was confirmed with energy-dispersive x-ray (EDX) and Alzarin Red staining. These studies revealed that cell adhesion is driven by both the surface potential and morphology of PCL fibers. Furthermore, the ability to tune the surface potential of electrospun PCL scaffolds provides an essential electrostatic handle to enhance cell-material interaction and cellular activity, leading to controllable morphological changes.
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•Applied voltage polarity in electrospinning tailors surface chemistry and potential of PCL fibers.•Surface potential was analyzed by KPFM and compared with zeta potential in liquid.•Cell adhesion, collagen formation and mineralization are controlled with surface potential.•Surface potential on PCL fibers can enhance the bone regeneration process.
This study represents the unique analysis of the electrospun scaffolds with the controlled and stable surface potential without any additional biochemical modifications for bone tissue regeneration. ...We controlled surface potential of polyvinylidene fluoride (PVDF) fibers with applied positive and negative voltage polarities during electrospinning, to obtain two types of scaffolds PVDF(+) and, PVDF(−). The cells’ attachments to PVDF scaffolds were imaged in great details with advanced scanning electron microscopy (SEM) and 3D tomography based on focus ion beam (FIB-SEM). We presented the distinct variations in cells shapes and in filopodia and lamellipodia formation according to the surface potential of PVDF fibers that was verified with Kelvin probe force microscopy (KPFM). Notable, cells usually reach their maximum spread area through increased proliferation, suggesting the stronger adhesion, which was indeed double for PVDF(−) scaffolds having surface potential of −95 mV. Moreover, by tuning the surface potential of PVDF fibers, we were able to enhance collagen mineralization for possible use in bone regeneration. The scaffolds built of PVDF(−) fibers demonstrated the greater potential for bone regeneration than PVDF(+), showing after 7 days in osteoblasts culture produce well-mineralized osteoid required for bone nodules. The collagen mineralization was confirmed with energy dispersive X-ray spectroscopy (EDX) and Sirius Red staining, additionally the cells proliferation with fluorescence microscopy and Alamar Blue assays. The scaffolds made of PVDF fibers with the similar surface potential to the cell membranes promoting bone growth for next-generation tissue scaffolds, which are on a high demand in bone regenerative medicine.
This article presents the results of an analysis regarding the microstructure, mechanical strength, and microhardness of two kinds of samples built through selective laser melting with Inconel 718, ...the most frequently used alloy in metal additive manufacturing due to its excellent mechanical properties. The sample geometry was made up of two types of lattice structures with spherical and hyperbolical stiffness elements. The goals of these studies are to determine how homogenization heat treatment influences the microhardness and the mechanical properties of the specimens and to identify the structure with the best mechanical properties. The analysis showed that heat treatment was beneficial because the regular dendritic structure disappears, the δ phase precipitates at the grain boundaries, and both the γ and γ″ phases dissolve. It has also been shown that the structures with hyperbolical stiffness elements have better compressive strength than the structures with the elliptical structures, with a 47.6% increase for the as-fabricated structures and an approximate 50% increase for the heat-treated structure.
Hybrid materials combining organic and inorganic compounds used as scaffolds are highly beneficial in bone regeneration. In this study, we successfully produced by blend electrospinning ...poly(3-hydroxybutyric acid-co-3-hydrovaleric acid) (PHBV) scaffolds enriched with hydroxyapatite (HA) particles to biomimic bone tissue for improved and faster regeneration processes. The morphology, fiber diameters, and composition of the scaffolds were investigated by scanning electron microscopy (SEM) techniques followed by focused ion beam (FIB) sectioning to verify HA particles integration with PHBV fibers.
cell culture was performed for 7 days and followed with the cell proliferation test (CellTiter-Blue
Assay). Additionally, cell integration with the scaffold was visualized by confocal and SEM imaging. We developed a simple way of obtaining hybrid scaffolds by electrospinning PHBV solution with HA particles without any post-processing. The PHBV + HA scaffold enhanced cell proliferation and filopodia formation responsible for cell anchoring within the created 3D environment. The obtained results show the great potential in the development of hybrid scaffolds stimulating bone tissue regeneration.
The main goal of this study was to obtain, for the first time, highly efficient water barrier and oxygen-scavenging multilayered electrospun biopaper coatings of biodegradable polymers over ...conventional cellulose paper, using the electrospinning coating technique. In order to do so, poly(3-hydroxybutyrate) (PHB) and polycaprolactone (PCL) polymer-containing palladium nanoparticles (PdNPs) were electrospun over paper, and the morphology, thermal properties, water vapor barrier, and oxygen absorption properties of nanocomposites and multilayers were investigated. In order to reduce the porosity, and to enhance the barrier properties and interlayer adhesion, the biopapers were annealed after electrospinning. A previous study showed that electrospun PHB-containing PdNP did show significant oxygen scavenging capacity, but this was strongly reduced after annealing, a process that is necessary to form a continuous film with the water barrier. The results in the current work indicate that the PdNP were better dispersed and distributed in the PCL matrix, as suggested by focus ion beam-scanning electron microscopy (FIB-SEM) experiments, and that the Pd enhanced, to some extent, the onset of PCL degradation. More importantly, the PCL/PdNP nanobiopaper exhibited much higher oxygen scavenging capacity than the homologous PHB/PdNP, due to most likely, the higher oxygen permeability of the PCL polymer and the somewhat higher dispersion of the Pd. The passive and active multilayered biopapers developed here may be of significant relevance to put forward the next generation of fully biodegradable barrier papers of interest in, for instance, food packaging.
The effect of creep deformation on the microstructure of the PWA 1497 single crystal Ni-base superalloy developed for turbine blade applications was investigated. The aim of the present study was to ...characterize quantitatively a superalloy microstructure and subsequent development of rafted γ′ precipitates in the PWA 1497 during creep deformation at 982°C and 248MPa up to rupture. The PWA1497 microstructure was characterized by scanning electron microscopy and FIB–SEM electron tomography. The 3D reconstruction of the PWA1497 microstructure is presented and discussed.
•The microstructure of PWA1497 superalloy was examined using FIB–SEM tomography.•In case of modern single crystal superalloys, measurements of AA are adequate for VV.•During creep the γ channel width increases from 65 to 193nm for ruptured specimen.•Tomography is a useful technique for quantitative studies of material microstructure.
Melting temperature is one of the principal parameters of phase equilibria thermodynamics and its value affects the majority of materials properties. Despite previous studies, the fundamental ...mechanisms of interphase interactions at melting in two-component nanomaterials are under consideration. We address these issues in a comprehensive experimental study of phase transformations in nanosized Ag-Ge eutectic system by means of in situ TEM techniques. The Ge/Ag/Ge and Ag/Ge layered films with thin Ag layer (1–50 nm) on top or in-between amorphous Ge films have been used as a model of a binary system of variable size. Morphology, crystalline structure and composition of Ag-Ge films have been examined in situ and ex situ by advanced (S)TEM techniques, the eutectic temperature (TE) and the Ge crystallization temperature have been measured as a function of Ag film thickness. A few hundred degrees lowering of TE with the film thickness reduction has been registered. Complex changes of the Ge/Ag/Ge films morphology below the eutectic temperature driven by Ag-mediated crystallization of amorphous Ge have been observed and related to the formation of metastable (liquid and/or Ag-Ge hcp) phases at the metal-semiconductor interface at 250 °C already.
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•We examine interphase interactions in nanosized Ag-Ge films.•Eutectic temperature has been systematically measured.•Thickness of Ge layer controls Ag film morphology evolution with temperature.•Crystallization of amorphous Ge occurs through an intermediate phase.
•Microscopy characterization of Linothele megatheloides spider webs and silk fibers.•Novel approach to produce the hydrophobic webs from electrospun fibers.•Biomimetic bundles of spider silk fibers ...with electrospun wrinkled PVDF fibers.•Similar contact angle for water and roughness on spider webs and electrospun fibers.•Just geometry approach, no chemical modification, to create hydrophobic surfaces.
In this study, we showed a simple approach to biomimic the wetting properties of spider webs, which can be mainly attributed to the geometry of fibers. We created biomimetic fibers using electrospun polyvinylidene fluoride (PVDF) with a wrinkled surface similar to the morphology of spider silk bundles produced by Linothele megatheloides. Without any chemical modification and copying the silk bundles geometry, we successfully translated the similar hydrophobic properties to an electrospun network of fibers. The novelty of this approach lays in obtaining similar macroscale roughness parameters, responsible here for wetting contact angles, due to the substitution of spider silk bundles with individual wrinkled electrospun fibers. The presented methods open new creative solutions for manufacturing anti-wetting surfaces.
A single‐step electrospinning approach enables controlling surface potential of fibers by changing voltage polarities during scaffolds production to enhance cells biointegration. This innovative and ...facile way of fibers production regulates the interfacial properties to enhance cells adhesion and filopodia formation on fibrous tissue scaffolds for possible bone regeneration. Tuning surface chemistry of polycaprolactone (PCL) by altering voltage polarity during electrospinning allows to double the surface potential on fibers up to 145 mV, which is directly measured using Kelvin probe force microscopy. The obtained surface potential on PCL fibers is directly correlated with surface chemistry analyzed at the grazing angle by X‐ray photoelectron spectroscopy, showing lower oxygen content at PCL fiber surfaces, produced with negative voltage polarity, PCL (−). These fibers create well‐engineered scaffolds that are able to increase significantly cell proliferation that is visualized with fluorescence microscopy, and filopodia formation on positively charged fibers, investigated with high‐resolution scanning electron microscopy. This work introduces electrospun PCL fibers without a need for chemical modification to tune electrostatic interactions between cells and fibrous scaffolds for biomaterials used in regenerative medicine.
This study shows an innovative way of a single‐step electrospinning approach enabling to control surface potential of the fibers by alternating voltage polarities during scaffolds production. The produced polycaprolactone scaffolds with negative voltage polarities increase twice their surface potential measured directly with Kelvin probe force microscopy and enhance cells proliferation, adhesion, and filopodia formation on electrospun fiber surfaces for bone regeneration.
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