Magnetic Scaffolds Research Articles

Magnetic hydrogel scaffold based on hyaluronic acid/chitosan and gelatin natural polymers.

Owing to their native extracellular matrix-like features, magnetic hydrogels have been proven to be promising biomaterials as tissue engineering templates In the present work, magnetic hydrogels scaffold based on chitosan, gelatin, hyaluronic acid, containing Fe3O4 as magnetic nanoparticles (IONPs) were prepared. The prepared hydrogels were loaded with ciprofloxacin hydrochloride as a model drug. The magnetic hydrogel was prepared using different volumes of chitosan, 1%, gelatin, 10%, and hyaluronic acid, 1% in glutaraldehyde as the crosslinking agent and Fe3O4 as magnetic nanoparticles. The hydrogel scaffold and magnetic scaffold hydrogel samples were characterized by scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and Fourier-transform infrared spectroscopy (FTIR). The porosity, mechanical properties, swelling degree, and antibacterial activity of the hydrogel scaffold were also determined as well as the drug release profiles of the hydrogels. SEM imaging revealed that the magnetic hydrogel scaffold showed a relatively rough morphology with an irregular surface. The data obtained indicated that the hydrogel surface has three-dimensional porous microstructures and the porosity varied depending on the hydrogel formulation. The breaking load of the hydrogel scaffold increased from 1.361 Kgf to 4.98 Kgf by increasing the glutaraldehyde concentration from 0.2 mL to 0.8 mL. Swelling degree values in water were from 250 to 2000% after 24h. The antibacterial activity of the hydrogel scaffold ranged from 54% to about 97% for Gram-positive bacteria (S. aureus) and from about 26-92% for Gram-negative bacteria (E. coli). The ciprofloxacin hydrochloride loaded hydrogel has a sustained release of ciprofloxacin hydrochloride over 10h. The presence of IONPs gave a faster release of ciprofloxacin hydrochloride.

Determination of the Optimum Architecture of Additively Manufactured Magnetic Bioactive Glass Scaffolds for Bone Tissue Engineering and Drug-Delivery Applications.

For better bone regeneration, precise control over the architecture of the scaffolds is necessary. Because the shape of the pore may affect the bone regeneration, therefore, additive manufacturing has been used in this study to fabricate magnetic bioactive glass (MBG) scaffolds with three different architectures, namely, grid, gyroid, and Schwarz D surface with 15 × 15 × 15 mm3 dimensions and 70% porosity. These scaffolds have been fabricated using an in-house-developed material-extrusion-based additive manufacturing system. The composition of bioactive glass was selected as 45% SiO2, 20% Na2O, 23% CaO, 6% P2O5, 2.5% B2O3, 1% ZnO, 2% MgO, and 0.5% CaF2 (wt %), and additionally 0.4 wt % of iron carbide nanoparticles were incorporated. Afterward, MBG powder was mixed with a 25% (w/v) Pluronic F-127 solution to prepare a slurry for fabricating scaffolds at 23% relative humidity. The morphological characterization using microcomputed tomography revealed the appropriate pore size distribution and interconnectivity of the scaffolds. The compressive strengths of the fabricated grid, gyroid, and Schwarz D scaffolds were found to be 14.01 ± 1.01, 10.78 ± 1.5, and 12.57 ± 1.2 MPa, respectively. The in vitro study was done by immersing the MBG scaffolds in simulated body fluid for 1, 3, 7, and 14 days. Darcy's law, which describes the flow through porous media, was used to evaluate the permeability of the scaffolds. Furthermore, an anticancer drug (Mitomycin C) was loaded onto these scaffolds, wherein these scaffolds depicted good release behavior. Overall, gyroid-structured scaffolds were found to be the most suitable among the three scaffolds considered in this study for bone tissue engineering and drug-delivery applications.

Osteogenic Potential and Long-Term Enzymatic Biodegradation of PHB-based Scaffolds with Composite Magnetic Nanofillers in a Magnetic Field.

Millions of people worldwide suffer from musculoskeletal damage, thus using the largest proportion of rehabilitation services. The limited self-regenerative capacity of bone and cartilage tissues necessitates the development of functional biomaterials. Magnetoactive materials are a promising solution due to clinical safety and deep tissue penetration of magnetic fields (MFs) without attenuation and tissue heating. Herein, electrospun microfibrous scaffolds were developed based on piezoelectric poly(3-hydroxybutyrate) (PHB) and composite magnetic nanofillers [magnetite with graphene oxide (GO) or reduced GO]. The scaffolds' morphology, structure, mechanical properties, surface potential, and piezoelectric response were systematically investigated. Furthermore, a complex mechanism of enzymatic biodegradation of these scaffolds is proposed that involves (i) a release of polymer crystallites, (ii) crystallization of the amorphous phase, and (iii) dissolution of the amorphous phase. Incorporation of Fe3O4, Fe3O4-GO, or Fe3O4-rGO accelerated the biodegradation of PHB scaffolds owing to pores on the surface of composite fibers and the enlarged content of polymer amorphous phase in the composite scaffolds. Six-month biodegradation caused a reduction in surface potential (1.5-fold) and in a vertical piezoresponse (3.5-fold) of the Fe3O4-GO scaffold because of a decrease in the PHB β-phase content. In vitro assays in the absence of an MF showed a significantly more pronounced mesenchymal stem cell proliferation on composite magnetic scaffolds compared to the neat scaffold, whereas in an MF (68 mT, 0.67 Hz), cell proliferation was not statistically significantly different when all the studied scaffolds were compared. The PHB/Fe3O4-GO scaffold was implanted into femur bone defects in rats, resulting in successful bone repair after nonperiodic magnetic stimulation (200 mT, 0.04 Hz) owing to a synergetic influence of increased surface roughness, the presence of hydrophilic groups near the surface, and magnetoelectric and magnetomechanical effects of the material.

Development of Scaffolds with Chitosan Magnetically Activated with Cobalt Nanoferrite: A Study on Physical-Chemical, Mechanical, Cytotoxic and Antimicrobial Behavior.

Background/Objectives: This study investigates the development of 3D chitosan-x-cobalt ferrite scaffolds (x = 5, 7.5, and 10 wt%) with interconnected porosity for potential biomedical applications. The objective was to evaluate the effects of magnetic particle incorporation on the scaffolds' structural, mechanical, magnetic, and biological properties, specifically focusing on their biocompatibility and antimicrobial performance. Methods: Scaffolds were synthesized using freeze-drying, while cobalt ferrite nanoparticles were produced via a pilot-scale combustion reaction. The scaffolds were characterized for their physical and chemical properties, including porosity, swelling, and mechanical strength. Hydrophilicity was assessed through contact angle measurements. Antimicrobial efficacy was evaluated using time kill kinetics and agar diffusion assays, and biocompatibility was confirmed through cytotoxicity tests. Results: The incorporation of cobalt ferrite increased magnetic responsiveness, altered porosity profiles, and influenced swelling, biodegradation, and compressive strength, with a maximum value of 87 kPa at 7.5 wt% ferrite content. The scaffolds maintained non-toxicity and demonstrated bactericidal activity. The optimal concentration for achieving a balance between structural integrity and biological performance was found at 7.5 wt% cobalt ferrite. Conclusions: These findings suggest that magnetic chitosan-cobalt ferrite scaffolds possess significant potential for use in biomedical applications, including tissue regeneration and advanced healing therapies. The incorporation of magnetic properties enhances both the structural and biological functionalities, presenting promising opportunities for innovative therapeutic approaches in reconstructive procedures.

Preparation of magnetic scaffolds via supercritical carbon dioxide foaming process using iron oxide nanoparticles coated with CO2‐philic materials as nucleating agents

AbstractThe iron oxide nanoparticles (IONs), coated with different materials, are synthesized and utilized as nucleating agents to prepare magnetic multi‐modal porous scaffolds of poly (lactic‐co‐glycolic acid)/IONs using the supercritical carbon dioxide (ScCO2) foaming process. The effects of the modification materials, including citric acid, polycaprolactone, and polyvinyl acetate, on the foaming process and properties of the magnetic scaffolds are systematically investigated. The results indicate that the solubility and diffusion ability of CO2 in the foaming materials played a vital role in the foaming process. The use of CO2‐philic materials and high pressure proves beneficial in generating micropores. The scaffolds with multi‐modal porous structures can be obtained at relatively low pressure for the ScCO2 foaming systems evaluated in this study. Furthermore, the prepared scaffolds exhibit high porosity and a good compressive modulus (higher than 0.4 MPa), satisfying the requirements of tissue engineering for soft tissue scaffolds.

Magnetical scafford with ROS-scavenging for bone regeneration under static magnetic field

Excessive reactive oxygen species (ROS) and bacterial infection significantly disrupt the microenvironment of tissue regeneration. Magnetic nanoparticles in combination with magnetic fields are emerging strategies to regulate tissue regeneration. In this work, ZnFe2O4 (ZFO) nanoparticles were prepared and subsequently decorated with polydopamine (PDA) and RGD peptide. The modified ZFO nanoparticles were loaded into polylactic-glycolic acid/polycaprolactone (PLGA/PCL) scaffolds as PP-ZFO/PDA-RGD magnetic scaffolds. Physicochemical, anti-ROS, antibacterial and osteogenic properties were evaluated in vitro. Under 30 mT static magnetic field, the PP-ZFO/PDA-RGD scaffold significantly enhanced the expression of ALP, RUNX2, BMP2 and mineralized nodules. It indicated that the magnetic system could promote the attachment, proliferation, differentiation and mineralization of MC3T3-E1 cells. The scaffold showed excellent ROS scavenging ability via the additive effect of ZFO, PDA and RGD. The remarkable antibacterial properties of Zn²⁺ and Fe³⁺ endowed the scaffolds with excellent antibacterial activity against E. coli and S. aureus. These results demonstrate that the PP-ZFO/PDA-RGD based magnetic system is a promising approach for bone regeneration under complex microenvironment.

Evaluation of magnetic hyperthermia, drug delivery and biocompatibility (bone cell adhesion and zebrafish assays) of trace element co-doped hydroxyapatite combined with Mn-Zn ferrite for bone tissue applications.

The treatment and regeneration of bone defects, especially tumor-induced defects, is an issue in clinical practice and remains a major challenge for bone substitute material invention. In this research, a composite material of biomimetic bone-like apatite based on trace element co-doped apatite (Ca10-δ M δ (PO4)5.5(CO3)0.5(OH)2; M = trace elements of Mg, Fe, Zn, Mn, Cu, Ni, Mo, Sr and BO3 3-; THA)-integrated-biocompatible magnetic Mn-Zn ferrite ((Mn, Zn)Fe2O4 nanoparticles, BioMags) called THAiBioMags was prepared via a co-precipitation method. Its characteristics, i.e., physical properties, hyperthermia performance, ion/drug delivery, were investigated in vitro using osteoblasts (bone-forming cells) and in vivo using zebrafish. The synthesized THAiBioMags particles revealed superparamagnetic behaviour at room temperature. Under the influence of an alternating magnetic field, THAiBioMags particles demonstrated a change in temperature, indicating their potential for magnetic hyperthermia, in which THAiBioMags further exhibited a specific absorption rate (SAR) value of 9.44 W g-1 (I = 44 A, H = 6.03 kA m-1 and f = 130 kHz). In addition, the as-prepared particles demonstrated sustained ion/drug (doxorubicin (DOX)) release under physiological pH conditions. Biological assay analysis revealed that THAiBioMags exhibited no toxicity towards osteoblast cells and demonstrated excellent cell adhesion properties. In vivo studies employing an embryonic zebrafish model showed the non-toxic nature of the synthesized THAiBioMags particles, as revealed by evaluation of the survivability, hatching rate, and embryonic morphology. These results could potentially lead to the design and fabrication of magnetic scaffolds to be used in therapeutic treatment and bone regeneration.

Imparting of Nearly Superparamagnetic Properties to Cryogel Scaffolds With Mesoporous MNPs for Magneto-Sensitive Tissue Engineering Strategies.

This work reports the assembly of mesoporous iron oxide nanoparticles (meso-MNPs) with cryogel scaffolds composed of chitosan and gelatin. Meso-MNPs with a particle size ranging from 2 and 50 nm, a surface area of 140.52 m2 g-1, and a pore volume of 0.27 cm3 g-1 were synthesized on a porous SiO2 template in the presence of PEG 6000 followed by leaching of SiO2. Different ratios of meso-MNPs were successfully incorporated into chitosan:gelatin cryogels up to an amount equivalent to the entire amount of polymer. The morphological structure and physicochemical properties of the cryogels were directly affected by the amount of MNPs. VSM curves showed that all composite cryogels could be magnetized by applying a magnetic field. In the context of the safety of magnetic cryogel scaffolds for use in biomedicine, it is important to note that all values are below the exposure limit for static magnetic fields, and according to cytotoxicity data, scaffolds containing meso-MNPs showed nontoxicity with cell viability ranging from 150% to 275%. In addition, microbial analysis with gram-negative and gram-positive bacteria showed that the scaffolds exhibited activity against these bacteria.

Magnetic Substrates for Tissue Engineering—A Review

Tissue engineering is based on combining cells with suitable scaffolds and growth factors. Recently, bone tissue engineering has been especially investigated deeply due to a large number of bone-related diseases. One approach to improve scaffolds is based on using piezoelectric materials as a way to influence the growing bone tissue by mechanical stress. Another method to stimulate tissue growth is by applying an external magnetic field to composites of magnetostrictive and piezoelectric materials, as well as the possibility to prepare oriented surfaces by orienting embedded magnetic fibers or nanoparticles. In addition, magnetic scaffolds without other special properties have also been reported to show improved properties for bone tissue and other tissue engineering. Here, we provide an overview of recent research on magnetic scaffolds for tissue engineering, differentiating between bone and other tissue engineering. We show the advantages of magnetic scaffolds, especially related to cell guidance and differentiation, and report recent progress in the production and application of such magnetic substrates for different areas of tissue engineering.

Raman spectroscopic investigation of polymer based magnetic multicomponent scaffolds

Scaffolds acting as an artificial matrix for cell proliferation are one of the bone tissue engineering approaches to the treatment of bone tissue defects. In the presented study, novel multicomponent scaffolds composed of a poly(ε-caprolactone) (PCL), phenolic compounds such as tannic (TA) and gallic acids (GA), and nanocomponents such as silica-coated magnetic iron oxide nanoparticles (MNPs-c) and functionalized multi-walled carbon nanotubes (CNTs) have been produced as candidates for such artificial substitutes. Well-developed interconnected porous structures were observed using scanning electron microscopy (SEM). Raman spectra showed that the highly crystalline nature of PCL was reduced by the addition of nanoadditives. In the case of scaffolds containing MNPs-c and TA, the formation of a Fe-TA complex was concluded because characteristic bands of chelation of the Fe3+ ion by phenolic catechol oxygen appeared. It was found that the necessary conditions for the crystallization of the PCL/MNPs-c/TA are for the catechol groups to be able to penetrate the porous silica shell of MNPs-c, as during experiment with MNPs-c and TA without polymer, no such complexation was observed. Moreover, the number of catechol groups, the spatial structure and molecular size of this phenolic compound are also crucial for complexation process because GA does not form complexes. Therefore, the PCL/CNTs/MNPs-c/TA scaffolds are interesting candidates to consider for their possible medical applications.

Ultrasensitive Dual ELONA/SERS-RPA Multiplex Diagnosis of Antimicrobial Resistance.

Antimicrobial resistance (AMR) is a significant global health threat concern, necessitating healthcare practitioners to accurately prescribe the most effective antimicrobial agents with correct doses to combat resistant infections. This is necessary to improve the therapeutic outcomes for patients and prevent further increase in AMR. Consequently, there is an urgent need to implement rapid and sensitive clinical diagnostic methods to identify resistant pathogenic strains and monitor the efficacy of antimicrobials. In this study, we report a novel proof-of-concept magnetic scaffold-recombinase polymerase amplification (RPA) technique, coupled with an enzyme-linked oligonucleotide assay (ELONA) and surface-enhanced Raman scattering (SERS) detection, aimed at selectively amplifying and detecting the DNA signature of three resistant carbapenemase genes, VIM, KPC, and IMP. To achieve this, streptavidin-coated magnetic beads were functionalized with biotin-modified forward primers. RPA was conducted on the surface of the beads, resulting in an immobilized duplex amplicon featuring a single overhang tail specific to each gene. These tails were subsequently hybridized with recognition HRP probes conjugated to a complementary single-stranded oligonucleotide and detected colorimetrically. Additionally, they underwent hybridization with similar selective SERS probes and were measured using a handheld Raman spectrometer. The resulting quantification limits were at subpicomolar level for both assays, allowing the potential for early diagnosis. Moreover, we demonstrated the platform capability to conduct a multiplex RPA-SERS detection of the three genes in a single tube. Compared to similar approaches like PCR, RPA offers advantages of speed, affordability, and isothermal operation at 37 °C, eliminating the need for a thermal cycler. The whole assay was completed within <2 h. Therefore, this novel magnetic scaffold ELONA/SERS-RPA platform, for DNA detection, demonstrated excellent capability for the rapid monitoring of AMR in point-of-care applications, in terms of sensitivity, portability, and speed of analysis.

Physical, mechanical characterization, and artificial neural network modeling of biodegradable composite scaffold for biomedical applications

The performance of substitute osteoconductive scaffolds in guiding new bone formation and creating vital biological conditions in living organisms is of crucial importance. In this study, bioresorbable scaffolds were synthesized by incorporating polyvinyl alcohol (PVA) with hydroxyapatite nanoparticles (n-HAP) and Iron oxide (Fe3O4) nanoparticles (NPs) (MNPs) using a freeze-drying technique. Subsequently, the magnetic nanocomposite scaffolds were immersed in a phosphate-buffered saline (PBS) solution for 24 days to assess their degradability percentage. The physicochemical and morphological properties of the magnetic nanocomposite scaffolds were evaluated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Furthermore, the mechanical behavior was examined, while the pore dimensions and porosity were determined using immersion-based techniques. Noteworthy attributes of the magnetic nanocomposite scaffolds were observed, including a maximum swelling capacity of 176 %, a substantial porosity of 72.7%, and impressive mechanical characteristics, such as a compressive strength of 4.61 MPa and an elastic modulus of 2.13 GPa. The degradation study conducted in a PBS solution revealed that the scaffold with the highest n-HAP content (20 wt%) exhibited a degradation rate of approximately 21% after a 24-day period. The influence of environmental conditions, including time, temperature, and salt-containing environments, on the swelling behavior and bio-resorption of the scaffolds was examined. Additionally, an artificial neural network (ANN) was developed to forecast the impact of weight percentages of n-HAP and MNPs on various scaffold properties. According to the ANN predictions, increasing the weight percentages of n-HAP and MNPs resulted in a reduction in pore size, an increase in porosity, and an improvement in the mechanical properties of the scaffolds. Moreover, the incorporation of a higher number of nanoparticles led to increased absorption and swelling, facilitating bone tissue formation. Satisfactory accuracy in predicting scaffold properties was demonstrated through error analysis and linear regression plots, aiding designers in selecting appropriate weight percentages of nanoparticles for future designs. The findings indicate that the synthesized magnetic nanocomposite scaffold closely resembles the physical and mechanical characteristics of natural bone tissue. The utilization of an ANN for performance assessment demonstrated favorable efficiency and effectiveness. Therefore, the significance of the current study lies in the comprehensive investigation of the synthesis and characterization of a biodegradable magnetic nanocomposite scaffold, as well as the utilization of an ANN-based approach to predict and optimize its properties for potential bone tissue engineering applications.

Initial therapeutic evidence of a borosilicate bioactive glass (BSG) and Fe3O4 magnetic nanoparticle scaffold on implant-associated Staphylococcal aureus bone infection

Implant-associated Staphylococcus aureus (S. aureus) osteomyelitis is a severe challenge in orthopedics. While antibiotic-loaded bone cement is a standardized therapeutic approach for S. aureus osteomyelitis, it falls short in eradicating Staphylococcus abscess communities (SACs) and bacteria within osteocyte-lacuna canalicular network (OLCN) and repairing bone defects. To address limitations, we developed a borosilicate bioactive glass (BSG) combined with ferroferric oxide (Fe3O4) magnetic scaffold to enhance antibacterial efficacy and bone repair capabilities. We conducted comprehensive assessments of the osteoinductive, immunomodulatory, antibacterial properties, and thermal response of this scaffold, with or without an alternating magnetic field (AMF). Utilizing a well-established implant-related S. aureus tibial infection rabbit model, we evaluated its antibacterial performance in vivo. RNA transcriptome sequencing demonstrated that BSG + 5%Fe3O4 enhanced the immune response to bacteria and promoted osteogenic differentiation and mineralization of MSCs. Notably, BSG + 5%Fe3O4 upregulated gene expression of NOD-like receptor and TNF pathway in MSCs, alongside increased the expression of osteogenic factors (RUNX2, ALP and OCN) in vitro. Flow cytometry on macrophage exhibited a polarization effect towards M2, accompanied by upregulation of anti-inflammatory genes (TGF-β1 and IL-1Ra) and downregulation of pro-inflammatory genes (IL-6 and IL-1β) among macrophages. In vivo CT imaging revealed the absence of osteolysis and periosteal response in rabbits treated with BSG + 5%Fe3O4 + AMF at 42 days. Histological analysis indicated complete controls of SACs and bacteria within OLCN by day 42, along with new bone formation, signifying effective control of S. aureus osteomyelitis. Further investigations will focus on the in vivo biosafety and biological mechanism of this scaffold within infectious microenvironment.

Modeling of Magnetic Scaffolds as Drug Delivery Platforms for Tissue Engineering and Cancer Therapy.

Magnetic scaffolds (MagSs) are magneto-responsive devices obtained by the combination of traditional biomaterials (e.g., polymers, bioceramics, and bioglasses) and magnetic nanoparticles. This work analyzes the literature about MagSs used as drug delivery systems for tissue repair and cancer treatment. These devices can be used as innovative drugs and/or biomolecules delivery systems. Through the application of a static or dynamic stimulus, MagSs can trigger drug release in a controlled and remote way. However, most of MagSs used as drug delivery systems are not optimized and properly modeled, causing a local inhomogeneous distribution of the drug's concentration and burst release. Few physical-mathematical models have been presented to study and analyze different MagSs, with the lack of a systematic vision. In this work, we propose a modeling framework. We modeled the experimental data of drug release from different MagSs, under various magnetic field types, taken from the literature. The data were fitted to a modified Gompertz equation and to the Korsmeyer-Peppas model (KPM). The correlation coefficient (R2) and the root mean square error (RMSE) were the figures of merit used to evaluate the fitting quality. It has been found that the Gompertz model can fit most of the drug delivery cases, with an average RMSE below 0.01 and R2>0.9. This quantitative interpretation of existing experimental data can foster the design and use of MagSs for drug delivery applications.

Study of chemically deposited magnetic materials of NiTi memory alloys and their magnetothermal properties

Abstract NiTi alloy has good mechanical properties and biocompatibility, as well as unique shape memory properties. Therefore, it is commonly used to make metal stents in clinical practice. In this study, the substrate used is a NiTi memory alloy, which has been coated with CoNiFeP magnetic material through an electroless plating. The morphology, composition, and magnetic properties of the coating were analyzed using SEM, XRD, and VSM. The magneto-thermal properties were studied by high-frequency alternating magnetic field (AMF) induction equipment. The results showed that after determining a reasonable plating application process, the prepared coatings had certain soft magnetic properties and could exceed 43°C in a short time at different field intensities (Happl×fappl=M×109 Aꞏm−1ꞏs−1, M=1.0, 2.0, 3.0, 4.0, and 5.0) to reach the temperature required for tumor ablation, which can be used to prepare magnetic scaffolds for magnetothermal therapy.

Advanced Biomimetic and Biohybrid Magnetic Micro/Nano‐Machines

AbstractBiomimetic and biohybrid micro/nano‐structures involve the replication and creation of technologies, structures, and materials based on biological systems at the micrometer and nanometer scale. These strategies harness the natural biological principles to develop innovative treatment methods and advanced microstructure devices for noninvasive therapies. In this study, a detailed overview of fabrication processes, magnetically assisted locomotive techniques, and potential applications of biomimetic and biohybrid micro/nano‐machines are presented. The latest advancements in magnetically actuated biomimetic structures, such as annelid‐worm‐like microswimmers, jellyfish‐shaped microparticles, fish‐shaped microswimmers, and walnut‐shaped micromotors are explored. Additionally, the magnetic biohybrid systems, including sunflower seed‐based micro‐perforators, nanomotors extracted from the bamboo stem, sperm cell‐based micromotors, bacteria‐based robots, scaffold‐based microrobots, DNA‐based micromotors, microalgae‐based microswimmers, and red blood cell‐based microswimmers are also examined. A thorough investigation of the magnetically assisted locomotive behavior of these microstructure devices in biological Newtonian fluids, featuring cork‐screw motion, undulatory motion, surface wrinkling motion, traveling wave‐like motion, and ciliary stroke motion is discussed. Furthermore, unprecedented and innovative treatment methods developed using these minuscule devices such as cervical cancer treatment using tetrapod hybrid sperm micromotors, tissue regeneration using silk fibroin protein‐based magnetic microscale scaffolds, and doxorubicin drug delivery using mushroom‐based microrobots is extensively presented.

Nerve tissue regeneration based on magnetic and conductive bifunctional hydrogel scaffold

The growth of neurons is often influenced by magnetic and electrical physical factors, and there is more and more research focused on designing a magnetic and conductive engineering scaffolds for nerve injury repair. In this study, electrospun poly lactic-co-glycolic acid (PLGA) fibers containing Fe3O4 magnetic nanoparticles were cryo-cut into magnetic short fibers (MSFs) and subsequently incorporated into sodium alginate (SA)/carboxymethyl chitosan (CMCS) hydrogel along with the addition of multi-wall carbon nanotubes (MWCNTs). MSFs can also achieve alignment by external magnetic fields within the hydrogel to construct magnetic and conductive bifunctional MSF/MWCNT/SA/CMCS hydrogel with anisotropic structure. The magnetic-conductive bifunctional hydrogel exhibited good magnetic responsiveness, electrically activity and mechanical property, in which both conductivity and mechanical property increased with the enhancement of MWCNTs contents. Notably, appearing of aligned structure significantly promoted the mechanical property of MSF/SA/CMCS hydrogel. The MSF/SA/CMCS hydrogel with aligned structure also facilitated greater primary neuron cells proliferation than random ones. Compared with individual magnetic or conductive hydrogel, there was a significant increase in cell viability in the primary cultured cortical neurons on MSF/MWCNT/SA/CMCS hydrogel with aligned structure. Simultaneously, electrical stimulation (ES) combined with magnetic stimulation (MS) delivered via magnetic and conductive bifunctional MSF/MWCNT/SA/CMCS hydrogel with aligned structure produced a better effect on promoting neuronal growth compared with individual ES or MS. Besides, hot plate measurement indicated that MSF/MWCNT/SA/CMCS hydrogel with aligned structure and MS significantly decreased the mice licking latency after sciatic nerve injury. Animal behavior studies confirmed the protective role of synergistic MS with magnetic hydrogel. Such hydrogel scaffolds have long-term potential for nerve tissue regeneration.

DIFFERENT APPROACHES IN BONE TISSUE ENGINEERING: ADVANTAGES AND DISADVANTAGES

Human bone tissue damage arises due to defects, injury, tumors, aging, and traffic accidents. It is one of the most challenging issues that need surgical development and advanced bone implants. Biocomposite-based bone has insufficient blood supply restricting the utilization for bone regeneration. It is often overcome by including scaffold having angiogenic factor delivery, in vitro and in vivo pre-vascularization. Bone and endothelial cell development and proliferation are stimulated by magnetic responsive scaffolds containing magnetic nanoparticles. Its porous structure allows cells to communicate and develop in all directions, which improves osteointegration. Scaffolds without seeded cells might have applications in bone tissue engineering (BTE) and it is mandatory to estimate in vitro and in vivo biocompatibility and degradation behavior. Three-dimensional (3D) printing opens the door to the creation of one-of-a-kind shapes and structures with specific properties. It helps to minimize the spread of germs during synthesis stage. The gamma rays minimize the infection communicated during transplantation but also damage the graft. When it comes to choosing biomaterials for cancellous and cortical bones, an artificial neural network has the highest recognition rate. This review paper explores the different potential approaches for bone grafting. Different techniques have been developed to create hydrogels with desirable properties for BTE, including non-toxicity, biocompatibility, controllability, and performance. A cell-free framework is used to stimulate bone regeneration, which helps in the bone the self-healing processes of bone fractures. The recent approach combines TE, material science, and genetic engineering for enhanced vascularization, restoring blood flow, and preventing cell death.

Magnetic biocomposite scaffold based on decellularized tendon ECM and MNP-deposited halloysite nanotubes: physicochemical, thermal, rheological, mechanical and in vitro biological evaluations

The development of new three-dimensional biomaterials with advanced versatile properties is critical to the success of tissue engineering (TE) applications. Here, (a) bioactive decellularized tendon extracellular matrix (dECM) with a sol-gel transition feature at physiological temperature, (b) halloysite nanotubes (HNT) with known mechanical properties and bioactivity, and (c) magnetic nanoparticles (MNP) with superparamagnetic and osteogenic properties were combined to develop a new scaffold that could be used in prospective bone TE applications. Deposition of MNPs on HNTs resulted in magnetic nanostructures without agglomeration of MNPs. A completely cell-free, collagen- and glycosaminoglycan- rich dECM was obtained and characterized. dECM-based scaffolds incorporated with 1%, 2% and 4% MNP-HNT were analysed for their physical, chemical, and in vitro biological properties. Fourier-transform infrared spectroscopy, x-ray powder diffractometry and vibrating sample magnetometry analyses confirmed the presence of dECM, HNT and MNP in all scaffold types. The capacity to form apatite layer upon incubation in simulated body fluid revealed that dECM-MNP-HNT is a bioactive material. Combining dECM with MNP-HNT improved the thermal stability and compressive strength of the macroporous scaffolds upto 2% MNP-HNT. In vitro cytotoxicity and hemolysis experiments showed that the scaffolds were essentially biocompatible. Human bone marrow mesenchymal stem cells adhered and proliferated well on the macroporous constructs containing 1% and 2% MNP-HNT; and remained metabolically active for at least 21 d in vitro. Collectively, the findings support the idea that magnetic nanocomposite dECM scaffolds containing MNP-HNT could be a potential template for TE applications.

Enhanced contrast imaging with polyamide 6/Fe(OH)3 nanofibrous scaffolds: A focus on high T1 relaxivity

Nanofibers serve as widely employed tissue engineering scaffolds in diverse biomedical applications. When implanted in vivo, it is crucial for tissue engineering scaffolds to be visualizable, enabling the monitoring of their shape, position, and performance. This capability facilitates the effective assessment of implant deformations, displacements, degradations, and functionalities. However, in many biomedical imaging techniques such as magnetic resonance imaging (MRI), the contrast of tissue engineering scaffolds is often inadequate. MRI is particularly notable for its effectiveness in imaging soft tissues. Previous endeavors to enhance the contrast of tissue engineering scaffolds in MRI have involved the use of negative contrast agents (CAs). Nonetheless, negative CAs can result in artifacts, thus favoring the preference for positive CAs due to their ability to generate clearer boundaries. In this study, we successfully prepared composite polyamide 6 nanofibrous scaffolds with ultrafine dispersion Fe(OH)3 nanoparticles using electrospinning and in-situ growth techniques. The relaxation properties of the magnetic nanofibrous scaffolds confirmed the successful production of scaffolds suitable for positive imaging. In vitro cell seeding experiments demonstrated the efficient proliferation and adhesion of endothelial cells and fibroblasts. In vivo studies further revealed the biocompatibility and functionality of the scaffolds. These findings indicate that the prepared PA6/Fe(OH)3 composite nanofibrous scaffolds can enable straightforward, safe, and efficient in vivo positive contrast MRI monitoring, thereby playing a pivotal role in the integration of diagnosis and treatment within tissue engineering scaffolds.