Magnetic iron oxide nanoparticles for biomedical applications

Antimicrobial Coatings Based on Hybrid Iron Oxide Nanoparticles

This study presents the preparation of hybrid iron oxide nanocomposites through a two-step process combining microfluidic-assisted synthesis and post-synthetic surface modification. Fe3O4 nanoparticles were synthesized and simultaneously functionalized with salicylic acid using a three-dimensional vortex-type microfluidic chip, enabling rapid and uniform particle formation. The resulting Fe3O4/SA nanostructures were further modified with either silver or copper oxide to form iron oxide nanocomposites with enhanced antimicrobial functionality. These nanocomposites were subsequently integrated into silica aerogel matrices using a dip-coating approach to improve surface dispersion, structural stability, and biocompatibility. The structural and morphological properties of the samples were investigated using XRD, FT-IR, TEM with SAED analysis, and Raman microscopy. In vitro cytotoxicity and antimicrobial assays demonstrated that Fe3O4/SA-Ag and Fe3O4/SA-CuO exhibit potent antibacterial activity and cell type-dependent biocompatibility. In vivo biodistribution studies showed no accumulation in major organs and selective clearance via the spleen, validating the systemic safety of the platform. These findings highlight the potential of the synthesized nanocomposites as biocompatible, antimicrobial coatings for advanced biomedical surfaces.

Amino acid coating of Fe3O4 surfaces under dry and hydrated conditions

This study explores the adsorption behavior of two amino acids (glycine - gly and glutamic acid - glu) as coating molecules for Fe3O4 nanoparticles to improve their biocompatibility for medical applications. Amino acid adsorption on the dry and hydrated reconstructed Fe3O4 (001) surface was investigated by means of quantum mechanical methods. According to Density Functional Theory (DFT) calculations (HSE06), the deprotonated form is favored over the zwitterion for both amino acids on the dry surface (by -0.14 and -0.59 eV for gly and glu, respectively), whereas the order is reversed under hydrated conditions (by +0.07 and +0.35 eV, for gly and glu, respectively). Given the small energy difference in the case of gly, deprotonated and zwitterionic adsorption modes are expected to compete and, probably, to coexist on the magnetite surface both under dry and hydrated conditions. Density Functional Tight-Binding (DFTB) method can only provide a qualitative energy order for amino acids adsorption on the dry magnetite surface due to excessive stabilization of the deprotonated adsorbed form (-0.54 and -1.24 eV for gly and glu, respectively). This overestimation favors the deprotonated form even under hydrated conditions (by -0.41 and -0.18 eV for gly and glu, respectively), which contradicts the more accurate DFT results. The approximate DFTB method presents limitations in correctly capturing the relative stability of different protonation states.

Molecular dynamics investigation of structural, thermal, and dynamic properties of maghemite through thermal cycling

We analyzed the thermal, structural, and dynamic properties of maghemite using classical molecular dynamics, focusing on bulk and nanoparticle systems. We explored their behavior when heated to high temperatures (above the melting point) and during cooling, as well as under thermal cycles ending at intermediate temperatures. Our findings show that in the bulk system, both the tetrahedral and octahedral iron sub-lattices undergo a phase transition prior to melting. Cooling the system from above this transition, or from above the melting point, leads to the formation of different metastable maghemite structures. In contrast, this sub-lattice transition is absent in nanoparticles, where melting occurs through an interface-mediated process. At temperatures just above the transition, nanoparticles adopt an ellipsoidal shape, which is retained during cooling. In addition, the specific heat of both bulk and nanoparticle systems at temperatures above the Debye temperature is evaluated and compared with the available experimental data. Overall, our results highlight the complex thermal behavior of maghemite across a range of temperatures, which remains insufficiently explored experimentally. Further experimental investigations could also provide valuable feedback for model refinements.

Non-Debye Behavior of the Néel and Brown Relaxation in Interacting Magnetic Nanoparticle Ensembles

We used ac-susceptibility measurements to study the superspin relaxation in Fe3O4/Isopar M nanomagnetic fluids of different concentrations. Temperature-resolved data collected at different frequencies, χ″ vs. T|f, reveal magnetic events both below and above the freezing point of the carrier fluid (TF = 197 K): χ″ shows peaks at temperatures Tp1 and Tp2 around 75 K and 225 K, respectively. Below TF, the Néel mechanism is entirely responsible for the superspin relaxation (as the carrier fluid is frozen), and we found that the temperature dependence of the relaxation time, τN(Tp1), is well described by the Dorman-Bessais-Fiorani (DBF) model: τNT=τrexp⁡EB+EadkB T. Above TF, both the internal (Néel) and the Brownian superspin relaxation mechanisms are active. Yet, we found evidence that the effective relaxation times, τeff, corresponding to the Tp2 peaks observed in the denser samples do not follow the typical Debye behavior described by the Rosensweig formula 1τeff=1τN+1τB. First, τeff is 5 × 10-5 s at 225 K, almost three orders of magnitude more that its Néel counterpart, τN~8 × 10-8 s, estimated by extrapolating the above-mentioned DBF analysis. Thus, 1τN≫1τeff, which is clearly not consistent with the Rosensweig formula. Second, the observed temperature dependence of the effective relaxation time, τeff(Tp2), is excellently described by τB-1T=Tγ0exp⁡-E'kBT-T0', a model solely based on the hydrodynamic Brown relaxation, τB(T)=3ηTVHkBT, combined with an activation law for the temperature variation of the viscosity, ηT=η0exp⁡E'/kB(T-T0'. The best fit yields γ0=3ηVHkB = 1.6 × 10-5 s·K, E'/kB = 312 K, and T0' = 178 K. Finally, the higher temperature Tp2 peaks vanish in the more diluted samples (δ ≤ 0.02). This indicates that the formation of larger hydrodynamic particles via aggregation, which is responsible for the observed Brownian relaxation in dense samples, is inhibited by dilution. Our findings, corroborating previous results from Monte Carlo calculations, are important because they might lead to new strategies to synthesize functional magnetic ferrofluids for biomedical applications.

Engineering Magnetic Nanoclusters for Highly Efficient Heating in Radio-Frequency Nanowarming

Effective thawing of cryopreserved samples requires rapid and uniform heating. This is achievable through nanowarming, an approach that heats magnetic nanoparticles by using alternating magnetic fields. Here we demonstrate the synthesis and surface modification of magnetic nanoclusters for efficient nanowarming. Magnetite (Fe3O4) nanoclusters with an optimal diameter of 58 nm exhibit a high specific absorption rate of 1499 W/g Fe under an alternating magnetic field at 43 kA/m and 413 kHz, more than twice that of commercial iron oxide cores used in prior nanowarming studies. Surface modification with a permeable resorcinol-formaldehyde resin (RFR) polymer layer significantly enhances their colloidal stability in complex cryoprotective solutions, while maintaining their excellent heating capacity. The Fe3O4@RFR nanoparticles achieved a high average heating rate of 175 °C/min in cryopreserved samples at a concentration of 10 mg Fe/mL and were successfully applied in nanowarming porcine iliac arteries, highlighting their potential for enhancing the efficacy of cryopreservation.

Multifunctional Self-Assembled Block Copolymer/Iron Oxide Nanocomposite Hydrogels Formed from Wormlike Micelles

This article reports the preparation of multifunctional magnetic nanocomposite hydrogels formed from wormlike micelles. Specifically, iron oxide nanoparticles were incorporated into a temperature responsive block copolymer, poly(glycerol monomethacrylate)-b-poly(2-hydroxypropyl methacrylate) (PGMA-b-PHPMA), and graphene oxide (GO) dispersion at a low temperature (∼2 °C) through high-speed mixing and returning the mixture to room temperature, resulting in the formation of nanocomposite gels. The optimal concentrations of iron oxide and GO enhanced the gel strength of the nanocomposite gels, which exhibited a strong magnetic response when a magnetic field was applied. These materials retained the thermoresponsiveness of the PGMA-PHPMA wormlike micelles allowing for a solid-to-liquid transition to occur when the temperature was reduced. The mechanical and rheological properties and performance of the nanocomposite gels were demonstrated to be adjustable, making them suitable for a wide range of potential applications. These nanocomposite worm gels were demonstrated to be relatively adhesive and to act as strain and temperature sensors, with the measured electrical resistance of the nanocomposite gels changing with applied strain and temperature sweeps. The nanocomposite gels were found to recover efficiently after the application of high shear with approximately 100% healing efficiency within seconds. Additionally, these nanocomposite worm gels were injectable, and the addition of GO and iron oxide nanomaterials seemed to have no significant adverse impact on the biocompatibility of the copolymer gels, making them suitable not only for 3D printing in nanocomposite engineering but also for potential utilization in various biomedical applications as an injectable magnetic responsive hydrogel.

Advances in smart delivery of magnetic field-targeted drugs in cardiovascular diseases

Magnetic Drug Targeting (MDT) is of particular interest to researchers because of its good loading efficiency, targeting accuracy, and versatile use in vivo. Cardiovascular Disease (CVD) is a global chronic disease with a high mortality rate, and the development of more precise and effective treatments is imminent. A growing number of studies have begun to explore the feasibility of MDT in CVD, but an up-to-date systematic summary is still lacking. This review discusses the current research status of MDT from guiding magnetic fields, magnetic nanocarriers, delivery channels, drug release control, and safety assessment. The current application status of MDT in CVD is also critically introduced. On this basis, new insights into the existing problems and future optimization directions of MDT are further highlighted.

Green synthesis of biocompatible Fe3O4 magnetic nanoparticles using Citrus Sinensis peels extract for their biological activities and magnetic-hyperthermia applications

Green synthesis of nanoparticles (NPs) is eco-friendly, biocompatible, cost-effective, and highly stable. In the present study, Citrus sinensis peel extract was utilized to the fabrication of superparamagnetic iron oxide nanoparticles (SPIONs). The fabricated SPIONs were first characterized using UV-Visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The UV-Vis spectra analysis displayed a peak at 259 nm due to the surface plasmon resonance. The FTIR spectrum showed bands at 3306 cm-1, and 1616 cm-1 revealed the protein's involvement in the development and capping of NPs. TEM analysis indicated that green synthesized SPIONs were spherical in shape with particle size of 20-24 nm. Magnetization measurements indicate that the synthesized SPIONs exhibited superparamagnetic behavior at room temperature. The antimicrobial activity, minimum inhibitory concentration (MIC), antioxidant potential, anti-inflammatory effect, and catalytic degradation of methylene blue by SPIONs were investigated in this study. Results demonstrated that SPIONs had variable antimicrobial effect against different pathogenic multi-drug resistant bacteria. At the highest concentration (400 μg/mL), SPIONs showed inhibition zones (14.7-37.3 mm) against all the target isolates. Furthermore, the MIC of synthesized SPIONs against Staphylococcus aureus, Streptococcus mutans, Bacillus subtilis, Escherichia coli, Klebsiella pneumonia, and Candida albicans were 3, 6.5, 6.5, 12.5, 50, 25 μg/mL, respectively. SPIONs exhibited strong antioxidant, anti-inflammatory, and catalytic dye degradation activities. Interestingly, Fe3O4 SPIONs shows optimum magnetic hyperthermia (MHT) techniques under an alternating magnetic field (AMF) measured in specific absorption rate (SAR) of 164, 230, and 286 W/g at concentrations 1, 5, and 10 mg/mL, respectively. Additionally, these newly fabricated SPIONs virtually achieve significant execution under the AMF in fluid MHT and are suitable for biomedical applications.

Green synthesis of biocompatible Fe 3 O 4 magnetic nanoparticles using Citrus Sinensis peels extract for their biological activities and magnetic- hyperthermia applications.. [DOI: 10.21203/rs.3.rs-3010022/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Plants include active chemicals known as phytochemicals and biomolecules that serve as decreasing and biostability factors for nanoparticle (NP) creation. Citrus Sinensis peels are rich in phenolics, flavonoids, antioxidants, and biophysical benefits. Herein, we prepared superparamagnetic iron oxide nanoparticles (SPIONs) by co-precipitation using Citrus Sinensis peel extract as a novel green synthesis method. The antioxidant, anti-inflammatory, dye degradation activities, and antimicrobial activities of Fe3O4 MNPs were investigated. Furthermore, the produced materials were characterized using FTIR, UV, TEM, VSM, and XRD analysis. The Fe3O4 MNPs showed higher antibacterial activities against multi antibiotic resistant bacterial strains: Escherichia coli, Streptococcus mutans, Candida albicans, Staphylococcus aureus, Bacillus subtilis, and Klebsiella pneumonia. The sample has generated a lot of attention in the scientific community for magnetic hyperthermia (MHT) applications. The maximum value of the specific absorption rate (SAR) was evaluated at sample concentrations of 10mg under the magnetic field condition. Additionally, these newly fabricated SPIONs virtually achieve significant execution under the alternating magnetic field (AMF) in fluid HT and are suitable for biomedical applications.

Magnetic Nanoparticles: Current Advances in Nanomedicine, Drug Delivery and MRI

Magnetic nanoparticles (MNPs) have evolved tremendously during recent years, in part due to the rapid expansion of nanotechnology and to their active magnetic core with a high surface-to-volume ratio, while their surface functionalization opened the door to a plethora of drug, gene and bioactive molecule immobilization. Taming the high reactivity of the magnetic core was achieved by various functionalization techniques, producing MNPs tailored for the diagnosis and treatment of cardiovascular or neurological disease, tumors and cancer. Superparamagnetic iron oxide nanoparticles (SPIONs) are established at the core of drug-delivery systems and could act as efficient agents for MFH (magnetic fluid hyperthermia). Depending on the functionalization molecule and intrinsic morphological features, MNPs now cover a broad scope which the current review aims to overview. Considering the exponential expansion of the field, the current review will be limited to roughly the past three years.

Nanotheranostics for Image-Guided Cancer Treatment

Image-guided nanotheranostics have the potential to represent a new paradigm in the treatment of cancer. Recent developments in modern imaging and nanoparticle design offer an answer to many of the issues associated with conventional chemotherapy, including their indiscriminate side effects and susceptibility to drug resistance. Imaging is one of the tools best poised to enable tailoring of cancer therapies. The field of image-guided nanotheranostics has the potential to harness the precision of modern imaging techniques and use this to direct, dictate, and follow site-specific drug delivery, all of which can be used to further tailor cancer therapies on both the individual and population level. The use of image-guided drug delivery has exploded in preclinical and clinical trials although the clinical translation is incipient. This review will focus on traditional mechanisms of targeted drug delivery in cancer, including the use of molecular targeting, as well as the foundations of designing nanotheranostics, with a focus on current clinical applications of nanotheranostics in cancer. A variety of specially engineered and targeted drug carriers, along with strategies of labeling nanoparticles to endow detectability in different imaging modalities will be reviewed. It will also introduce newer concepts of image-guided drug delivery, which may circumvent many of the issues seen with other techniques. Finally, we will review the current barriers to clinical translation of image-guided nanotheranostics and how these may be overcome.

Magnetic Nanoparticles in Bone Tissue Engineering

Large bone defects with limited intrinsic regenerative potential represent a major surgical challenge and are associated with a high socio-economic burden and severe reduction in the quality of life. Tissue engineering approaches offer the possibility to induce new functional bone regeneration, with the biomimetic scaffold serving as a bridge to create a microenvironment that enables a regenerative niche at the site of damage. Magnetic nanoparticles have emerged as a potential tool in bone tissue engineering that leverages the inherent magnetism of magnetic nano particles in cellular microenvironments providing direction in enhancing the osteoinductive, osteoconductive and angiogenic properties in the design of scaffolds. There are conflicting opinions and reports on the role of MNPs on these scaffolds, such as the true role of magnetism, the application of external magnetic fields in combination with MNPs, remote delivery of biomechanical stimuli in-vivo and magnetically controlled cell retention or bioactive agent delivery in promoting osteogenesis and angiogenesis. In this review, we focus on the role of magnetic nanoparticles for bone-tissue-engineering applications in both disease modelling and treatment of injuries and disease. We highlight the materials-design pathway from implementation strategy through the selection of materials and fabrication methods to evaluation. We discuss the advances in this field and unmet needs, current challenges in the development of ideal materials for bone-tissue regeneration and emerging strategies in the field.

Charge-Modulated Synthesis of Highly Stable Iron Oxide Nanoparticles for In Vitro and In Vivo Toxicity Evaluation

The surface charge of iron oxide nanoparticles (IONPs) plays a critical role in the interactions between nanoparticles and biological components, which significantly affects their toxicity in vitro and in vivo. In this study, we synthesized three differently charged IONPs (negative, neutral, and positive) based on catechol-derived dopamine, polyethylene glycol, carboxylic acid, and amine groups, via reversible addition-fragmentation chain transfer-mediated polymerization (RAFT polymerization) and ligand exchange. The zeta potentials of the negative, neutral, and positive IONPs were -39, -0.6, and +32 mV, respectively, and all three IONPs showed long-term colloidal stability for three months in an aqueous solution without agglomeration. The cytotoxicity of the IONPs was studied by analyzing cell viability and morphological alteration in three human cell lines, A549, Huh-7, and SH-SY5Y. Neither IONP caused significant cellular damage in any of the three cell lines. Furthermore, the IONPs showed no acute toxicity in BALB/c mice, in hematological and histological analyses. These results indicate that our charged IONPs, having high colloidal stability and biocompatibility, are viable for bio-applications.