Magnetic Scaffolds Research Articles

Magnetic biodegradable Fe3O4/CS/PVA nanofibrous membranes for bone regeneration

In recent years, interest in magnetic biomimetic scaffolds for tissue engineering has increased considerably. The aim of this study is to develop magnetic biodegradable fibrous materials with potential use in bone regeneration. Magnetic biodegradable Fe3O4/chitosan (CS)/poly vinyl alcohol (PVA) nanofibrous membranes were achieved by electrospinning with average fiber diameters ranging from 230 to 380 nm and porosity of 83.9–85.1%. The influences of polymer concentration, applied voltage and Fe3O4 nanoparticles loading on the fabrication of nanofibers were investigated. The polymer concentration of 4.5 wt%, applied voltage of 20 kV and Fe3O4 nanoparticles loading of lower than 5 wt% could produce homogeneous, smooth and continuous Fe3O4/CS/PVA nanofibrous membranes. X-ray diffraction (XRD) data confirmed that the crystalline structure of the Fe3O4, CS and PVA were maintained during electrospinning process. Fourier transform infrared spectroscopy (FT-IR) demonstrated that the Fe3O4 loading up to 5 wt% did not change the functional groups of CS/PVA greatly. Transmission electron microscopy (TEM) showed islets of Fe3O4 nanoparticles evenly distributed in the fibers. Weak ferrimagnetic behaviors of membranes were revealed by vibrating sample magnetometer (VSM) test. Tensile test exhibited Young's modulus of membranes that were gradually enhanced with the increase of Fe3O4 nanoparticles loading, while ultimate tensile stress and ultimate strain were slightly reduced by Fe3O4 nanoparticles loading of 5%. Additionally, MG63 human osteoblast-like cells were seeded on the magnetic nanofibrous membranes to evaluate their bone biocompatibility. Cell growth dynamics according to MTT assay and scanning electron microscopy (SEM) observation exhibited good cell adhesion and proliferation, suggesting that this magnetic biodegradable Fe3O4/CS/PVA nanofibrous membranes can be one of promising biomaterials for facilitation of osteogenesis.

A basic approach toward the development of nanocomposite magnetic scaffolds for advanced bone tissue engineering

AbstractMagnetic scaffolds for bone tissue engineering based on a poly(ε‐caprolactone) (PCL) matrix and iron oxide (Fe3O4) magnetic nanoparticles were designed and developed through a three‐dimensional (3D) fiber‐deposition technique. PCL/Fe3O4 scaffolds were characterized by a 90/10 w/w composition. Tensile and magnetic measurements were carried out, and nondestructive 3D imaging was performed through microcomputed tomography (Micro‐CT). Furthermore, confocal analysis was undertaken to investigate human mesenchymal stem cell adhesion and spreading on the PCL/Fe3O4 nanocomposite fibers. The results suggest that nanoparticles mechanically reinforced the PCL matrix; the elastic modulus and the maximum stress increased about 10 and 30%, respectively. However, the maximum strain decreased about 50%; this suggested an enhanced brittleness. Magnetic results evidenced a superparamagnetic behavior for these nanocomposite scaffolds. Micro‐CT suggested an almost uniform distribution of nanoparticles. Confocal analysis highlighted interesting results in terms of cell adhesion and spreading. All of these results show that a magnetic feature could be incorporated into a polymeric matrix that could be processed to manufacture scaffolds for advanced bone tissue engineering and, thus, provide new opportunity in terms of scaffold fixation and functionalization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Microspheres Containing Cibacron Blue F3G-A and Incorporated Iron Oxide Nanoparticles as Biomarker Harvesting Platforms

In this work, magnetic functionality was introduced to cross-linked acrylamide-based particles via the in situ coprecipitation of iron oxide nanoparticles within the hydrogel particle interior. Cibacron Blue F3G-A was then incorporated onto the magnetic hydrogel scaffold to facilitate the harvest of targeted protein species. The dye-loaded magnetic particles were physically characterized, and their protein sequestration performance was investigated. The results of these studies indicated that dye-loaded magnetic particles sequestered a greater amount of lower molecular weight proteins from the test solution than was achieved using reference particles, dye-loaded cross-linked N-isopropylacrylamide-based core-shell particles. This difference in protein harvesting ability may reflect the higher degree of dye-loading in the magnetic particles relative to the dye-loaded core-shell particles.

Multifunctional magnetic mesoporous bioactive glass scaffolds with a hierarchical pore structure

Hyperthermia and local drug delivery have been proposed as potential therapeutic approaches for bone defects resulting from malignant bone tumors. The development of bioactive materials with magnetic and drug delivery properties may potentially meet this target. The aim of this study was to develop a multifunctional mesoporous bioactive glass (MBG) scaffold system for both hyperthermic and local drug delivery applications. To this end iron (Fe)-containing MBG (Fe-MBG) scaffolds with a hierarchical large pores structure (300–500 μm) and fingerprint-like mesopores (4.5 nm) have been prepared. The effects of Fe on the mesopore structure and physiochemical, magnetic, drug delivery and biological properties of MBG scaffolds have been systematically investigated. The results show that the morphology of the mesopores varied from straight channels to curved fingerprint-like channels after incorporation of Fe into MBG scaffolds. The magnetism of MBG scaffolds can be tailored by controlling the Fe content. Furthermore, the incorporation of Fe into mesoporous MBG glass scaffolds enhanced the mitochondrial activity and the expression of bone-related genes (ALP and OCN) in human bone marrow mesenchymal stem cells (BMSC) attached to the scaffolds. The Fe-MBG scaffolds obtained also possessed high specific surface areas and demonstrated sustained drug delivery. Thus Fe-MBG scaffolds are magnetic, degradable and bioactive. The multifunctionality of Fe-MBG scaffolds suggests that there is great potential for their use in the treatment and regeneration of large-bone defects caused by malignant bone tumors through a combination of hyperthermia, local drug delivery and osteoconductivity.

Surface-Engineered Magnetic Nanoparticle Platforms for Cancer Imaging and Therapy

Enormous efforts have been made toward the translation of nanotechnology into medical practice, including cancer management. Generally the applications have fallen into two categories: diagnosis and therapy. Because the targets are often the same, the development of separate approaches can miss opportunities to improve efficiency and effectiveness. The unique physical properties of nanomaterials enable them to serve as the basis for superior imaging probes to locate and report cancerous lesions and as vehicles to deliver therapeutics preferentially to those lesions. These technologies for probes and vehicles have converged in the current efforts to develop nanotheranostics, nanoplatforms with both imaging and therapeutic functionalities. These new multimodal platforms are highly versatile and valuable components of the emerging trend toward personalized medicine, which emphasizes tailoring treatments to the biology of individual patients to optimize outcomes. The close coupling of imaging and treatment within a theranostic agent and the data about the evolving course of an illness that these agents provide can facilitate informed decisions about modifications to treatment. Magnetic nanoparticles, especially superparamagnetic iron oxide nanoparticles (IONPs), have long been studied as contrast agents for magnetic resonance imaging (MRI). Owing to recent progress in synthesis and surface modification, many new avenues have opened for this class of biomaterials. Such nanoparticles are not merely tiny magnetic crystals, but potential platforms with large surface-to-volume ratios. By taking advantage of the well-developed surface chemistry of these materials, researchers can load a wide range of functionalities, such as targeting, imaging and therapeutic features, onto their surfaces. This versatility makes magnetic nanoparticles excellent scaffolds for the construction of theranostic agents, and many efforts have been launched toward this goal. In this Account, we introduce the surface engineering techniques that we and others have developed, with an emphasis on how these techniques affect the role of nanoparticles as imaging or therapeutic agents. We and others have developed a set of chemical methods to prepare magnetic nanoparticles that possess accurate sizes, shapes, compositions, magnetizations, relaxivities, and surface charges. These features, in turn, can be harnessed to adjust the toxicity and stability of the nanoparticles and, further, to load functionalities, via various mechanisms, onto the nanoparticle surfaces.

Poly(caprolactone) based magnetic scaffolds for bone tissue engineering

Synthetic scaffolds for tissue engineering coupled to stem cells represent a promising approach aiming to promote the regeneration of large defects of damaged tissues or organs. Magnetic nanocomposites formed by a biodegradable poly(caprolactone) (PCL) matrix and superparamagnetic iron doped hydroxyapatite (FeHA) nanoparticles at different PCL/FeHA compositions have been successfully prototyped, layer on layer, through 3D bioplotting. Magnetic measurements, mechanical testing, and imaging were carried out to calibrate both model and technological processing in the magnetized scaffold prototyping. An amount of 10% w/w of magnetic FeHA nanoparticles represents a reinforcement for PCL matrix, however, a reduction of strain at failure is also observed. Energy loss (absorption) measurements under a radio-frequency applied magnetic field were performed in the resulting magnetic scaffolds and very promising heating properties were observed, making them very useful for potential biomedical applications.

A conceptually new type of bio-hybrid scaffold for bone regeneration

Magnetic bio-hybrid porous scaffolds have been synthesized, nucleating nano-apatitein situ on self-assembling collagen, in the presence of magnetite nano-particles. Themagnetic phase acted as a sort of cross-linking agent for the collagen, inducing achemico-physical-mechanical stabilization of the material and allowing us to control theporosity network of the scaffold. Gradients of bio-mineralization and magnetization werealso developed for osteochondral application.The good potentiality of the material as a biomedical device, able to offer assistance tobone regeneration through scaffold reloading with specific factors guided by an externalmagnetic field, has been preliminarily investigated. Up to now the proof of this concept hasbeen realized through in vitro assessments.

A novel route in bone tissue engineering: Magnetic biomimetic scaffolds

In recent years, interest in tissue engineering and its solutions has increased considerably. In particular, scaffolds have become fundamental tools in bone graft substitution and are used in combination with a variety of bio-agents. However, a long-standing problem in the use of these conventional scaffolds lies in the impossibility of re-loading the scaffold with the bio-agents after implantation. This work introduces the magnetic scaffold as a conceptually new solution. The magnetic scaffold is able, via magnetic driving, to attract and take up in vivo growth factors, stem cells or other bio-agents bound to magnetic particles. The authors succeeded in developing a simple and inexpensive technique able to transform standard commercial scaffolds made of hydroxyapatite and collagen in magnetic scaffolds. This innovative process involves dip-coating of the scaffolds in aqueous ferrofluids containing iron oxide nanoparticles coated with various biopolymers. After dip-coating, the nanoparticles are integrated into the structure of the scaffolds, providing the latter with magnetization values as high as 15 emu g(-)(1) at 10 kOe. These values are suitable for generating magnetic gradients, enabling magnetic guiding in the vicinity and inside the scaffold. The magnetic scaffolds do not suffer from any structural damage during the process, maintaining their specific porosity and shape. Moreover, they do not release magnetic particles under a constant flow of simulated body fluids over a period of 8 days. Finally, preliminary studies indicate the ability of the magnetic scaffolds to support adhesion and proliferation of human bone marrow stem cells in vitro. Hence, this new type of scaffold is a valuable candidate for tissue engineering applications, featuring a novel magnetic guiding option.

ChemInform Abstract: Imidazoline Nitroxide Radicals: Molecular Paramagnetic Components for Construction of Magnetic Scaffolds

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.