Incorporation of Superparamagnetic Iron Oxide Nanoparticles into Collagen Formulation for 3D Electrospun Scaffolds

Nanomaterial-functionalized electrospun scaffolds for tissue engineering

Tissue engineering has emerged as a biological alternative aimed at sustaining, rehabilitating, or enhancing the functionality of tissues that have experienced partial or complete loss of their operational capabilities. The distinctive characteristics of electrospun nanofibrous structures, such as their elevated surface-area-to-volume ratio, specific pore sizes, and fine fiber diameters, make them suitable as effective scaffolds in tissue engineering, capable of mimicking the functions of the targeted tissue. However, electrospun nanofibers, whether derived from natural or synthetic polymers or their combinations, often fall short of replicating the multifunctional attributes of the extracellular matrix (ECM). To address this, nanomaterials (NMs) are integrated into the electrospun polymeric matrix through various functionalization techniques to enhance their multifunctional properties. Incorporation of NMs into electrospun nanofibrous scaffolds imparts unique features, including a high surface area, superior mechanical properties, compositional variety, structural adaptability, exceptional porosity, and enhanced capabilities for promoting cell migration and proliferation. This review provides a comprehensive overview of the various types of NMs, the methodologies used for their integration into electrospun nanofibrous scaffolds, and the recent advancements in NM-functionalized electrospun nanofibrous scaffolds aimed at regenerating bone, cardiac, cartilage, nerve, and vascular tissues. Moreover, the main challenges, limitations, and prospects in electrospun nanofibrous scaffolds are elaborated.

Magnetic colloidal nanoformulations to remotely trigger mechanotransduction for osteogenic differentiation

Nowadays, diseases associated with an ageing population, such as osteoporosis, require the development of new biomedical approaches to bone regeneration. In this regard, mechanotransduction has emerged as a discipline within the field of bone tissue engineering. Herein, we have tested the efficacy of superparamagnetic iron oxide nanoparticles (SPIONs), obtained by the thermal decomposition method, with an average size of 13 nm, when exposed to the application of an external magnetic field for mechanotransduction in human bone marrow-derived mesenchymal stem cells (hBM-MSCs). The SPIONs were functionalized with an Arg-Gly-Asp (RGD) peptide as ligand to target integrin receptors on cell membrane and used in colloidal state. Then, a comprehensive and comparative bioanalytical characterization of non-targeted versus targeted SPIONs was performed in terms of biocompatibility, cell uptake pathways and mechanotransduction effect, demonstrating the osteogenic differentiation of hBM-MSCs. A key conclusion derived from this research is that when the magnetic stimulus is applied in the first 30 min of the in vitro assay, i.e., when the nanoparticles come into contact with the cell membrane surface to initiate endocytic pathways, a successful mechanotransduction effect is observed. Thus, under the application of a magnetic field, there was a significant increase in runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP) gene expression as well as ALP activity, when cells were exposed to RGD-functionalized SPIONs, demonstrating osteogenic differentiation. These findings open new expectations for the use of remotely activated mechanotransduction using targeted magnetic colloidal nanoformulations for osteogenic differentiation by drug-free cell therapy using minimally invasive techniques in cases of bone loss.

Development of Super-Paramagnetic Iron Oxide Nanoparticle-Coated Melt Electrowritten Scaffolds for Biomedical Applications

Polycaprolactone (PCL) is usually the material chosen for melt electrowriting (MEW) due to its biocompatibility, mechanical strength, and melt processability. This work first investigates the effect of different processing parameters to obtain optimum PCL-MEW scaffolds. Secondly, to increase PCL`s hydrophilicity and cell affinity, and to enable coating with superparamagnetic iron oxide nanoparticles (SPIONs) and silica-coated-SPIONs (Si-SPIONs), the scaffolds are modified with alkaline surface treatment. Finally, SPIONs and Si-SPIONs are successfully coated on MEW scaffolds. Results show that reproducible scaffolds are fabricated. Additionally, the alkaline treatment does not change the three-dimensional morphology of scaffolds while reducing fiber diameter. Furthermore, SEM images and ATR-FTIR results confirmed that SPIONs and Si-SPIONs-were coated on scaffolds. A cytocompatibility assay showed a non-toxic effect on MG-63 osteoblast-like cells in all scaffolds. Additionally, higher MC3T3-E1 pre-osteoblastic cell adhesion efficiency and proliferation are achieved for the alkaline-treated scaffolds and SPIONs/Si-SPIONs-coated scaffolds. All samples demonstrated the ability to generate heat, useful for hyperthermia-treatment, when subjected to an alternating magnetic field. Overall, the findings suggest that the strategy of coating PCL-MEW scaffolds with SPIONs/Si-SPIONs has the potential to improve scaffold performance for biomedical applications, especially for producing magnetically responsive MEW scaffolds.

Investigation of background, novelty and recent advance of iron (II,III) oxide- loaded on 3D polymer based scaffolds as regenerative implant for bone tissue engineering: A review

Bone tissue engineering had crucial role in the bone defects regeneration, particularly when allograft and autograft procedures have limitations. In this regard, different types of scaffolds are used in tissue regeneration as fundamental tools. In recent years, magnetic scaffolds show promising applications in different biomedical applications (in vitro and in vivo). As superparamagnetic materials are widely considered to be among the most attractive biomaterials in tissue engineering, due to long-range stability and superior bioactivity, therefore, magnetic implants shows angiogenesis, osteoconduction, and osteoinduction features when they are combined with biomaterials. Furthermore, these scaffolds can be coupled with a magnetic field to enhance their regenerative potential. In addition, magnetic scaffolds can be composed of various combinations of magnetic biomaterials and polymers using different methods to improve the magnetic, biocompatibility, thermal, and mechanical properties of the scaffolds. This review article aims to explain the use of magnetic biomaterials such as iron (II,III) oxide (Fe2O3 and Fe3O4) in detail. So it will cover the research background of magnetic scaffolds, the novelty of using these magnetic implants in tissue engineering, and provides a future perspective on regenerative implants.

ADSCs labeled with SPIONs tracked in corpus cavernosum of rat and miniature pig by MR imaging and histological examination

Adipose tissue-derived stem cells (ADSCs) have been shown to improve erectile function in animal models of erectile dysfunction. However, few studies have been carried out using a reliable in vivo imaging method to trace transplanted cells in real time, which is necessary for systematic investigation of cell therapy. The study aims to explore the feasibility of non-invasively monitoring intracavernous injection of ADSCs in rat and miniature pig corpus cavernosum using in vivo magnetic resonance (MR) imaging. Thirty-six male Sprague Dawley rats (10 weeks old) and six healthy, sexually mature male miniature pigs (20 kg weight) were obtained. ADSCs were isolated from paratesticular fat of donor rats and cultured. Then ADSCs were labeled with superparamagnetic iron oxide nanoparticles (SPIONs), a type of MR imaging contrast agent, before transplantation into rats and pigs. After intracavernous injection, all rats and pigs underwent and were analyzed by MR imaging at the day of ADSC transplantation and follow-up at 1, 2 and 4 weeks after transplantation. In addition, penile histological examination was performed on all rats and pigs before (n = 6) and at 1 day (n = 6), 1 week (n = 6), 2 weeks (n = 6) or 4 weeks (n = 12) after ADSC transplantation. SPION-labeled ADSCs demonstrated a strong decreased signal intensity compared with distilled water, unlabeled ADSCs or agarose gel. SPION-labeled ADSCs showed a hypointense signal at all concentrations, and the greatest hypointense signal was observed at the concentration of 1 × 106. MR images of the corpus cavernosum showed a hypointense signal located at the injection site. T2*-weighted signal intensity increased over the course of 1 week after ADSCs transplantation, and demonstrated a similar MR signal with that before ADSCs transplantation. After SPION-labeled ADSC injection, T2*-weighted MR imaging clearly demonstrated a marked hypointense signal in pig corpus cavernosum. The T2*-weighted signal faded over time, similar to the MR imaging results in rats. Obvious acute inflammatory exudation was induced by intracavernous injection, and the T2*-weighted signal intensity of these exudation was higher than that of the injection site. The presence of iron was detected by Prussian blue staining, which demonstrated ADSC retention in rat corpus cavernosum. Lack of cellular infiltrations were demonstrated by H&E staining before and 4 weeks after transplantation, which indicated no negative immune response by rats. Prussian blue staining was positive for iron oxide nanoparticles at 2 weeks after transplantation. SPION-labeled ADSCs showed a clear hypointense signal on T2-weight MRI in vitro and in vivo. The MR signal intensity in the corpus cavernosum of the rats and miniature pigs faded and disappeared over time after ADSC transplantation. These findings suggested that MR imaging could trace transplanted ADSCs in the short term in the corpus cavernosum of animals.

Ultra-thin electrospun nanocomposite scaffold of poly (3-hydroxybutyrate)-chitosan/magnetic mesoporous bioactive glasses for bone tissue engineering applications

Bioglass is widely used in skeletal tissue engineering due to its outstanding bioactive properties. In the present study, magnetic mesoporous bioglass (MMBG) synthesized through the sol-gel method was incorporated into poly(3-hydroxybutyrate)-chitosan (PHB-Cs) solution and the resulting electrospun nanocomposite scaffolds were investigated and compared with MMBG free scaffold. The addition of 10 wt% MMBG has an outstanding effect on producing ultra-thin electrospun nanocomposite fibers due to its magnetic content (diameter of ≃128 nm). This improvement led to better mechanical properties, including an increase in both tensile modulus (up to ≃229 MPa) and tensile strength (to ≃4.95 MPa). Although the inclusion of MMBG slightly decreased the surface roughness of the nanofibrous scaffold (RMS from ≃197 to 154 nm), it could improve the wettability (WCA from ≃54 to 44°). This achievement has the potential to bring an enhancement in biomineralization and biological response. These outputs, combined with the observed increase in human osteoblast MG-63 cell viability (≃53 % improvement) as measured by MTT assay, DAPI, and SEM indicate prefer cell behavior of this nanocomposite structure. Additionally, the qualitative improvement in Alizarin Red staining and the quantitative enhancement of ALP secretion, serve as further evidence of the PHB-Cs/MMBG ultrathin nanofibers potential in bone tissue engineering.

Effect of Highly Hydrophilic Superparamagnetic Iron Oxide Nanoparticles on Macrophage Function and Survival

Superparamagnetic iron oxide nanoparticles (SPIONs) have garnered significant attention in the medical sector due to their exceptional superparamagnetic properties and reliable tracking capabilities. In this study, we investigated the immunotoxicity of SPIONs with a modified surface to enhance hydrophilicity and prevent aggregate formation. The synthesized SPIONs exhibited a remarkably small size (~4 nm) and underwent surface modification using a novel "haircut" reaction strategy. Experiments were conducted in vitro using a human monocytic cell line (THP-1). SPIONs induced dose-dependent toxicity to THP-1 cells, potentially by generating ROS and initiating the apoptotic pathway in the cells. Concentrations up to 10 μg/mL did not affect the expression of Nrf2, HO-1, NF-κB, or TLR-4 proteins. The results of the present study demonstrated that highly hydrophilic SPIONs were highly toxic to immune cells; however, they did not activate pathways of inflammation and immune response. Further investigation into the mechanisms of cytotoxicity is warranted to develop a synthetic approach for producing effective, highly hydrophilic SPIONs with little to no side effects.

Synthesis of Iron Oxides and Influence on Final Sizes and Distribution in Bacterial Cellulose Applications

Iron oxide nanoparticles have been investigated due to their suitable characteristics for diverse applications in the fields of biomedicine, electronics, water or wastewater treatment and sensors. Maghemite, magnetite and hematite are the most widely studied iron oxide particles and have ferrimagnetic characteristics. When very small, however, these particles have superparamagnetic properties and are called superparamagnetic iron oxide nanoparticles (SPIONs). Several methods are used for the production of these particles, such as coprecipitation, thermal decomposition and microemulsion. However, the variables of the different types of synthesis must be assessed to achieve greater control over the particles produced. In some studies, it is possible to compare the influence of variations in the factors for production with each of these methods. Thus, researchers use different adaptations of synthesis based on each objective and type of application. With coprecipitation, it is possible to obtain smaller, more uniform particles with adjustments in temperature, pH and the types of reagents used in the process. With thermal decomposition, greater control is needed over the time, temperature and proportion of surfactants and organic and aqueous phases in order to produce smaller particles and a narrower size distribution. With the microemulsion process, the control of the confinement of the micelles formed during synthesis through the proportions of surfactant and oil makes the final particles smaller and less dispersed. These nanoparticles can be used as additives for the creation of new materials, such as magnetic bacterial cellulose, which has different innovative applications. Composites that have SPIONs, which are produced with greater rigour with regards to their size and distribution, have superparamagnetic properties and can be used in medical applications, whereas materials containing larger particles have ferromagnetic applications. To arrive at a particular particle with specific characteristics, researchers must be attentive to both the mechanism selected and the production variables to ensure greater quality and control of the materials produced.

Magnetic Bone Tissue Engineering: Reviewing the Effects of Magnetic Stimulation on Bone Regeneration and Angiogenesis

Bone tissue engineering emerged as a solution to treat critical bone defects, aiding in tissue regeneration and implant integration. Mainly, this field is based on the development of scaffolds and coatings that stimulate cells to proliferate and differentiate in order to create a biologically active bone substitute. In terms of materials, several polymeric and ceramic scaffolds have been developed and their properties tailored with the objective to promote bone regeneration. These scaffolds usually provide physical support for cells to adhere, while giving chemical and physical stimuli for cell proliferation and differentiation. Among the different cells that compose the bone tissue, osteoblasts, osteoclasts, stem cells, and endothelial cells are the most relevant in bone remodeling and regeneration, being the most studied in terms of scaffold-cell interactions. Besides the intrinsic properties of bone substitutes, magnetic stimulation has been recently described as an aid in bone regeneration. External magnetic stimulation induced additional physical stimulation in cells, which in combination with different scaffolds, can lead to a faster regeneration. This can be achieved by external magnetic fields alone, or by their combination with magnetic materials such as nanoparticles, biocomposites, and coatings. Thus, this review is designed to summarize the studies on magnetic stimulation for bone regeneration. While providing information regarding the effects of magnetic fields on cells involved in bone tissue, this review discusses the advances made regarding the combination of magnetic fields with magnetic nanoparticles, magnetic scaffolds, and coatings and their subsequent influence on cells to reach optimal bone regeneration. In conclusion, several research works suggest that magnetic fields may play a role in regulating the growth of blood vessels, which are critical for tissue healing and regeneration. While more research is needed to fully understand the relationship between magnetism, bone cells, and angiogenesis, these findings promise to develop new therapies and treatments for various conditions, from bone fractures to osteoporosis.

Biological Scaffolds Assembled with Magnetic Nanoparticles for Bone Tissue Engineering: A Review

Superparamagnetic iron oxide nanoparticles (SPION) are widely used in bone tissue engineering because of their unique physical and chemical properties and their excellent biocompatibility. Under the action of a magnetic field, SPIONs loaded in a biological scaffold can effectively promote osteoblast proliferation, differentiation, angiogenesis, and so on. SPIONs have very broad application prospects in bone repair, bone reconstruction, bone regeneration, and other fields. In this paper, several methods for forming biological scaffolds via the biological assembly of SPIONs are reviewed, and the specific applications of these biological scaffolds in bone tissue engineering are discussed.

Electrospun Collagen Scaffold Bio-Functionalized with Recombinant ICOS-Fc: An Advanced Approach to Promote Bone Remodelling

The treatment of osteoporotic fractures is a severe clinical issue, especially in cases where low support is provided, e.g., pelvis. New treatments aim to stimulate bone formation in compromised scenarios by using multifunctional biomaterials combined with biofabrication techniques to produce 3D structures (scaffolds) that can support bone formation. Bone’s extracellular matrix (ECM) is mainly composed of type I collagen, making this material highly desirable in bone tissue engineering applications, and its bioactivity can be improved by incorporating specific biomolecules. In this work, type I collagen membranes were produced by electrospinning showing a fibre diameter below 200 nm. An optimized one-step strategy allowed to simultaneously crosslink the electrospun membranes and bind ICOS-Fc, a biomolecule able to reversibly inhibit osteoclast activity. The post-treatment did not alter the ECM-like nanostructure of the meshes and the physicochemical properties of collagen. UV-Vis and TGA analyses confirmed both crosslinking and grafting of ICOS-Fc onto the collagen fibres. The preservation of the biological activity of grafted ICOS-Fc was evidenced by the ability to affect the migratory activity of ICOSL-positive cells. The combination of ICOS-Fc with electrospun collagen represents a promising strategy to design multifunctional devices able to boost bone regeneration in osteoporotic fractures.

Hope for bone regeneration: The versatility of iron oxide nanoparticles

Although bone tissue has the ability to heal itself, beyond a certain point, bone defects cannot rebuild themselves, and the challenge is how to promote bone tissue regeneration. Iron oxide nanoparticles (IONPs) are a magnetic material because of their excellent properties, which enable them to play an active role in bone regeneration. This paper reviews the application of IONPs in bone tissue regeneration in recent years, and outlines the mechanisms of IONPs in bone tissue regeneration in detail based on the physicochemical properties, structural characteristics and safety of IONPs. In addition, a bibliometric approach has been used to analyze the hot spots and trends in the field in order to identify future directions. The results demonstrate that IONPs are increasingly being investigated in bone regeneration, from the initial use as magnetic resonance imaging (MRI) contrast agents to later drug delivery vehicles, cell labeling, and now in combination with stem cells (SCs) composite scaffolds. In conclusion, based on the current research and development trends, it is more inclined to be used in bone tissue engineering, scaffolds, and composite scaffolds.

Nanoparticles for Bio-Medical Applications

The Special Issue of Nanomaterials "Nanoparticles for Biomedical Applications" highlights the use of different types of nanoparticles for biomedical applications, including magnetic nanoparticles, mesoporous carbon nanoparticles, mesoporous bioactive glass nanoparticles, and mesoporous silica nanoparticles [...].