Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

Multicore iron oxide nanoparticles for magnetic hyperthermia and combination therapy against cancer cells

HYPOTHESIS

Multicore flower-like iron oxide nanoparticles (IONPs) are among the best candidates for magnetic hyperthermia applications against cancers. However, they are rarely investigated in physiological environments and their efficacy against cancer cells has been even less studied. The combination of magnetic hyperthermia, using multicore IONPs, with selected bioactive molecules should lead to an enhanced activity against cancer cells.

EXPERIMENTS

Multicore IONPs were synthesized by a seeded-growth thermal decomposition approach. Then, the cytotoxicity, cell uptake, and efficacy of the magnetic hyperthermia approach were studied with six cancer cell lines: PANC1 (pancreatic carcinoma), Mel202 (uveal melanoma), MCF7 (breast adenocarcinoma), MB231 (triple-negative breast cancer line), A549 (lung cancer), and HCT116 (colon cancer). Finally, IONPs were modified with a chemotherapeutic drug (SN38) and tumor suppressor microRNAs (miR-34a, miR-182, let-7b, and miR-137), to study their activity against cancer cells with and without combination with magnetic hyperthermia.

FINDINGS

Two types of multicore IONPs with very good heating abilities under magnetic stimulation have been prepared. Their concentration-dependent cytotoxicity and internalization have been established, showing a strong dependence on the cell line and the nanoparticle type. Magnetic hyperthermia causes significant cell death that is dramatically enhanced in combination with the bioactive molecules.

Pharmaceutical Quality by Design Approach to Develop High-Performance Nanoparticles for Magnetic Hyperthermia

Magnetic hyperthermia holds significant therapeutic potential, yet its clinical adoption faces challenges. One obstacle is the large-scale synthesis of high-quality superparamagnetic iron oxide nanoparticles (SPIONs) required for inducing hyperthermia. Robust and scalable manufacturing would ensure control over the key quality attributes of SPIONs, and facilitate clinical translation and regulatory approval. Therefore, we implemented a risk-based pharmaceutical quality by design (QbD) approach for SPION production using flame spray pyrolysis (FSP), a scalable technique with excellent batch-to-batch consistency. A design of experiments method enabled precise size control during manufacturing. Subsequent modeling linked the SPION size (6-30 nm) and composition to intrinsic loss power (ILP), a measure of hyperthermia performance. FSP successfully fine-tuned the SPION composition with dopants (Zn, Mn, Mg), at various concentrations. Hyperthermia performance showed a strong nonlinear relationship with SPION size and composition. Moreover, the ILP demonstrated a stronger correlation to coercivity and remanence than to the saturation magnetization of SPIONs. The optimal operating space identified the midsized (15-18 nm) Mn0.25Fe2.75O4 as the most promising nanoparticle for hyperthermia. The production of these nanoparticles on a pilot scale showed the feasibility of large-scale manufacturing, and cytotoxicity investigations in multiple cell lines confirmed their biocompatibility. In vitro hyperthermia studies with Caco-2 cells revealed that Mn0.25Fe2.75O4 nanoparticles induced 80% greater cell death than undoped SPIONs. The systematic QbD approach developed here incorporates process robustness, scalability, and predictability, thus, supporting the clinical translation of high-performance SPIONs for magnetic hyperthermia.

Magneto-optical nanosystems for tumor multimodal imaging and therapy in-vivo

Multimodal imaging, which combines the strengths of two or more imaging modalities to provide complementary anatomical and molecular information, has emerged as a robust technology for enhancing diagnostic sensitivity and accuracy, as well as improving treatment monitoring. Moreover, the application of multimodal imaging in guiding precision tumor treatment can prevent under- or over-treatment, thereby maximizing the benefits for tumor patients. In recent years, several intriguing magneto-optical nanosystems with both magnetic and optical properties have been developed, leading to significant breakthroughs in the field of multimodal imaging and image-guided tumor therapy. These advancements pave the way for precise tumor medicine. This review summarizes various types of magneto-optical nanosystems developed recently and describes their applications as probes for multimodal imaging and agents for image-guided therapeutic interventions. Finally, future research and development prospects of magneto-optical nanosystems are discussed along with an outlook on their further applications in the biomedical field.

Iron oxide nanoparticles for treatment and diagnosis of chronic inflammatory diseases: A systematic review

Chronic inflammatory conditions are among the most prevalent diseases worldwide. Several debilitating diseases such as atherosclerosis, inflammatory bowel disease, rheumatoid arthritis, and Alzheimer's are linked to chronic inflammation. These conditions often develop into complex and fatal conditions, making early detection and treatment of chronic inflammation crucial. Current diagnostic methods show high variability and do not account for disease heterogeneity and disease-specific proinflammatory markers, often delaying the disease detection until later stages. Furthermore, existing treatment strategies, including high-dose anti-inflammatory and immunosuppressive drugs, have significant side effects and an increased risk of infections. In recent years, superparamagnetic iron oxide nanoparticles (SPIONs) have shown tremendous biomedical potential. SPIONs can function as imaging modalities for magnetic resonance imaging, and as therapeutic agents due to their magnetic hyperthermia capability. Furthermore, the surface functionalization of SPIONs allows the detection of specific disease biomarkers and targeted drug delivery. This systematic review explores the utility of SPIONs against chronic inflammatory disorders, focusing on their dual role as diagnostic and therapeutic agents. We extracted studies indexed in the Web of Science database from the last 10 years (2013-2023), and applied systematic inclusion criteria. This resulted in a final selection of 38 articles, which were analyzed for nanoparticle characteristics, targeted diseases, in vivo and in vitro models used, and the efficacy of the therapeutic or diagnostic modalities. The results revealed that ultrasmall SPIONs are excellent for imaging arterial and neuronal inflammation. Furthermore, novel therapies using SPIONs loaded with chemotherapeutic drugs show promise in the treatment of inflammatory diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Key Insights on the Classification and Theranostic Applications of Magnetic Resonance Imaging Contrast Agents

Magnetic resonance imaging (MRI) is a non-invasive molecular imaging tool being extensively employed in clinical and biomedical research for the detection of a broad spectrum of diseases. This technique offers remarkable spatial resolution, good tissue penetration and a high soft tissue contrast. Contrast agents (CAs) have been regularly used in MRI tests to enhance the resolution of MR images and to visualize the diseased sites in the body. In the past years, considerable efforts have been devoted towards developing new theranostic MRI agents that can be tailored to integrate the targeting and therapeutic functions in a single agent. In this review, we have underlined the role of the MRI CAs in the developing field of 'theranostics' and their recent applications in the combined imaging and therapy of different types of tumors. In addition, this review also outlines the different categories of MRI CAs and their comprehensive classification based on different criteria such as chemical composition, relaxation mechanism and biodistribution with clinically relevant examples.

Targeted drug delivery systems for matrix metalloproteinase-responsive anoparticles in tumor cells: A review

Nanodrug delivery systems based on tumor microenvironment responses have shown excellent performance in tumor-targeted therapy, given their unique targeting and drug-release characteristics. Matrix metalloproteinases (MMPs) have been widely explored owing to their high specificity and expression in various tumor microenvironments. The design of an enzyme-sensitive nanodelivery system using MMPs as targeted receptors could markedly improve the performance of drug targeting. The current review focuses on the development and application of MMP-responsive drug carriers, and summarizes the classification of single- and multi-target nanocarriers based on their MMP responsiveness. The potential applications and challenges of this nanodrug delivery system are discussed to provide a reference for designing high-performance nanodrug delivery systems.

Fluorinated amphiphilic Poly(β-Amino ester) nanoparticle for highly efficient and specific delivery of nucleic acids to the Lung capillary endothelium

Endothelial cell dysfunction occurs in a variety of acute and chronic pulmonary diseases including pulmonary hypertension, viral and bacterial pneumonia, bronchopulmonary dysplasia, and congenital lung diseases such as alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV). To correct endothelial dysfunction, there is a critical need for the development of nanoparticle systems that can deliver drugs and nucleic acids to endothelial cells with high efficiency and precision. While several nanoparticle delivery systems targeting endothelial cells have been recently developed, none of them are specific to lung endothelial cells without targeting other organs in the body. In the present study, we successfully solved this problem by developing non-toxic poly(β-amino) ester (PBAE) nanoparticles with specific structure design and fluorinated modification for high efficiency and specific delivery of nucleic acids to the pulmonary endothelial cells. After intravenous administration, the PBAE nanoparticles were capable of delivering non-integrating DNA plasmids to lung microvascular endothelial cells but not to other lung cell types. IVIS whole body imaging and flow cytometry demonstrated that DNA plasmid were functional in the lung endothelial cells but not in endothelial cells of other organs. Fluorination of PBAE was required for lung endothelial cell-specific targeting. Hematologic analysis and liver and kidney metabolic panels demonstrated the lack of toxicity in experimental mice. Thus, fluorinated PBAE nanoparticles can be an ideal vehicle for gene therapy targeting lung microvascular endothelium in pulmonary vascular disorders.

Cellulase-immobilized chitosan-coated magnetic nanoparticles for saccharification of lignocellulosic biomass

Devising and consolidating cost-effective and greener technologies for sustainable energy production pertain to some of the most pressing needs of the present times. Bioconversion of abundantly available lignocellulosic materials into fermentable sugars to produce biofuels involves the cost-extensive requirement of hydrolytic enzymes called cellulases. Cellulases are highly selective and eco-friendly biocatalysts responsible for deconstruction of complex polysaccharides into simple sugars. Currently, immobilization of cellulases is being carried out on magnetic nanoparticles functionalized with suitable biopolymers such as chitosan. Chitosan, a biocompatible polymer, exhibits high surface area, chemical/thermal stability, functionality, and reusability. The chitosan-functionalized magnetic nanocomposites (Ch-MNCs) present a nanobiocatalytic system that enables easy retrieval, separation, and recycling of cellulases, thereby offering a cost-effective and sustainable approach for biomass hydrolysis. These functional nanostructures show enormous potential owing to certain physicochemical and structural features that have been discussed in a comprehensive manner in this review. It provides an insight into the synthesis, immobilization, and application of cellulase immobilized Ch-MNCs for biomass hydrolysis. This review aims to bridge the gap between sustainable utilization and economic viability of employing replenishable agro-residues for cellulosic ethanol production by incorporating the recently emerging nanocomposite immobilization approach.

Intracellular transformation and disposal mechanisms of magnetosomes in macrophages and cancer cells

Magnetosomes are magnetite nanoparticles biosynthesized by magnetotactic bacteria. Given their potential clinical applications for the diagnosis and treatment of cancer, it is essential to understand what becomes of them once they are within the body. With this aim, here we have followed the intracellular long-term fate of magnetosomes in two cell types: cancer cells (A549 cell line), because they are the actual target for the therapeutic activity of the magnetosomes, and macrophages (RAW 264.7 cell line), because of their role at capturing foreign agents. It is shown that cells dispose of magnetosomes using three mechanisms: splitting them into daughter cells, excreting them to the surrounding environment, and degrading them yielding less or non-magnetic iron products. A deeper insight into the degradation mechanisms by means of time-resolved X-ray absorption near-edge structure (XANES) spectroscopy has allowed us to follow the intracellular biotransformation of magnetosomes by identifying and quantifying the iron species occurring during the process. In both cell types there is a first oxidation of magnetite to maghemite and then, earlier in macrophages than in cancer cells, ferrihydrite starts to appear. Given that ferrihydrite is the iron mineral phase stored in the cores of ferritin proteins, this suggests that cells use the iron released from the degradation of magnetosomes to load ferritin. Comparison of both cellular types evidences that macrophages are more efficient at disposing of magnetosomes than cancer cells, attributed to their role in degrading external debris and in iron homeostasis.

Direct Polyphenol Attachment on the Surfaces of Magnetite Nanoparticles, Using Vitis vinifera, Vaccinium corymbosum, or Punica granatum

This study presents an alternative approach to directly synthesizing magnetite nanoparticles (MNPs) in the presence of Vitis vinifera, Vaccinium corymbosum, and Punica granatum derived from natural sources (grapes, blueberries, and pomegranates, respectively). A modified co-precipitation method that combines phytochemical techniques was developed to produce semispherical MNPs that range in size from 7.7 to 8.8 nm and are coated with a ~1.5 nm thick layer of polyphenols. The observed structure, composition, and surface properties of the MNPs@polyphenols demonstrated the dual functionality of the phenolic groups as both reducing agents and capping molecules that are bonding with Fe ions on the surfaces of the MNPs via -OH groups. Magnetic force microscopy images revealed the uniaxial orientation of single magnetic domains (SMDs) associated with the inverse spinel structure of the magnetite (Fe3O4). The samples' inductive heating (H0 = 28.9 kA/m, f = 764 kHz), measured via the specific loss power (SLP) of the samples, yielded values of up to 187.2 W/g and showed the influence of the average particle size. A cell viability assessment was conducted via the MTT and NRu tests to estimate the metabolic and lysosomal activities of the MNPs@polyphenols in K562 (chronic myelogenous leukemia, ATCC) cells.

Fast and reliable analysis of pH-responsive nanocarriers for drug delivery using microfluidic tools

During the last decades, there has been growing interest in the application of functionalized mesoporous nanomaterials as stimuli-responsive carriers for drug delivery. However, at present there is not a standardized methodology to evaluate their performance. The limitations of the different techniques reported in literature give rise to the necessity for new, simple, and cost-effective alternatives. This work constitutes a step forward in the development of advanced in vitro procedures for testing the behavior of nanocarriers, proposing a novel microfluidic platform. To test the capacity of the reported tool, the performance of amino-functionalized MCM-41 nanoparticles has been assessed. These materials show a pH-responsive mechanism, which prevents the drug release at acidic conditions, maximizing its distribution at neutral pH, thus, the selected release medium mimicked gastrointestinal conditions. As a first approximation, the delivery of Ru(bipy)32+ was evaluated, proving the advantages of the proposed microfluidic system: i) continuous flow of particles and media, ii) rigorous control of the residence time, temperature and pH, iii) enhanced mixing, iv) possibility to simulate different human body conditions and, v) possible integration with the continuous synthesis of nanocarriers. Finally, the microfluidic tool was used to analyze the delivery of the anti-inflammatory drug ibuprofen.

Comparing the Colloidal Stabilities of Commercial and Biogenic Iron Oxide Nanoparticles That Have Potential In Vitro/In Vivo Applications

For the potential in vitro/in vivo applications of magnetic iron oxide nanoparticles, their stability in different physiological fluids has to be ensured. This important prerequisite includes the preservation of the particles' stability during the envisaged application and, consequently, their invariance with respect to the transfer from storage conditions to cell culture media or even bodily fluids. Here, we investigate the colloidal stabilities of commercial nanoparticles with different coatings as a model system for biogenic iron oxide nanoparticles (magnetosomes) isolated from magnetotactic bacteria. We demonstrate that the stability can be evaluated and quantified by determining the intensity-weighted average of the particle sizes (Z-value) obtained from dynamic light scattering experiments as a simple quality criterion, which can also be used as an indicator for protein corona formation.

The influence of pure (ligandless) magnetite nanoparticles functionalization on blood gases and electrolytes in acute blood loss

Objective was to compare the effect of functionalization of magnetite (Fe₃O₄) nanoparticles (NPs) with sodium chloride (NaCl), or its combination with ethylmethylhydroxypyrydine succinate (EMHPS) and polyvinylpyrrolidone (PVP) on blood gases and electrolytes in acute blood loss. Ligandless magnetite NPs were synthesized by the electron beam technology and functionalized by mentioned agents. Size of NPs in colloidal solutions Fe₃O₄@NaCl, Fe₃O₄@NaCl@EMHPS, Fe₃O₄@NaCl@PVP, Fe₃O₄@NaCl@EMHPS@PVP (nanosystems 1-4) was determined by dynamic light scattering. In vivo experiments were performed on 27 Wistar rats. Acute blood loss was modeled by removal 25 % circulating blood. Nanosystems 1-4 were administered to animals intaperitoneally after the blood loss with followed determination of blood gases, pH and electrolytes. In blood loss, nanosystems Fe₃O₄@NaCl and Fe₃O₄@NaCl@PVP were able to improve the state of blood gases, pH, and the ratio of sodium/potassium in the blood. So, magnetite NPs with a certain surface modification can promote oxygen transport under hypoxic conditions.

Long-Term Stability, Biocompatibility, and Magnetization of Suspensions of Isolated Bacterial Magnetosomes

Magnetosomes are magnetic nanoparticles biosynthesized by magnetotactic bacteria. Due to a genetically strictly controlled biomineralization process, the ensuing magnetosomes have been envisioned as agents for biomedical and clinical applications. In the present work, different stability parameters of magnetosomes isolated from Magnetospirillum gryphiswaldense upon storage in suspension (HEPES buffer, 4 °C, nitrogen atmosphere) for one year in the absence of antibiotics are examined. The magnetic potency, measured by the saturation magnetization of the particle suspension, drops to one-third of its starting value within this year-about ten times slower than at ambient air and room temperature. The particle size distribution, the integrity of the surrounding magnetosome membrane, the colloidal stability, and the biocompatibility turn out to be not severely affected by long-term storage.

Core-shell micro/nanocapsules: from encapsulation to applications

Encapsulation is the way to wrap or coat one substance as a core inside another tiny substance known as a shell at micro and nano scale for protecting the active ingredients from the exterior environment. A lot of active substances, such as flavours, enzymes, drugs, pesticides, vitamins, in addition to catalysts being effectively encapsulated within capsules consisting of different natural as well as synthetic polymers comprising poly(methacrylate), poly(ethylene glycol), cellulose, poly(lactide), poly(styrene), gelatine, poly(lactide-co-glycolide)s, and acacia. The developed capsules release the enclosed substance conveniently and in time through numerous mechanisms, reliant on the ultimate use of final products. Such technology is important for several fields counting food, pharmaceutical, cosmetics, agriculture, and textile industries. The present review focuses on the most important and high-efficiency methods for manufacturing micro/nanocapsules and their several applications in our life.

Study on Doxorubicin Loading on Differently Functionalized Iron Oxide Nanoparticles: Implications for Controlled Drug-Delivery Application

Nanoplatforms applied for the loading of anticancer drugs is a cutting-edge approach for drug delivery to tumors and reduction of toxic effects on healthy cells. In this study, we describe the synthesis and compare the sorption properties of four types of potential doxorubicin-carriers, in which iron oxide nanoparticles (IONs) are functionalized with cationic (polyethylenimine, PEI), anionic (polystyrenesulfonate, PSS), and nonionic (dextran) polymers, as well as with porous carbon. The IONs are thoroughly characterized by X-ray diffraction, IR spectroscopy, high resolution TEM (HRTEM), SEM, magnetic susceptibility, and the zeta-potential measurements in the pH range of 3-10. The degree of doxorubicin loading at pH 7.4, as well as the degree of desorption at pH 5.0, distinctive to cancerous tumor environment, are measured. Particles modified with PEI were shown to exhibit the highest loading capacity, while the greatest release at pH 5 (up to 30%) occurs from the surface of magnetite decorated with PSS. Such a slow release of the drug would imply a prolonged tumor-inhibiting action on the affected tissue or organ. Assessment of the toxicity (using Neuro2A cell line) for PEI- and PSS-modified IONs showed no negative effect. In conclusion, the preliminary evaluation of the effects of IONs coated with PSS and PEI on the rate of blood clotting was carried out. The results obtained can be taken into account when developing new drug delivery platforms.

Magnetic nanocomposites for magneto-promoted osteogenesis: from simulation auxiliary design to experimental validation

Magnetically actuated mechanical stimulation, as a novel form of intelligent responsive force stimulation, has a great potential for remote spatiotemporal regulation of a variety of life processes. Hence, the optimal design of magnetic nanomaterials for generating magneto-mechanical stimuli becomes an important driving force in the development of magneto-controlled biotherapy. This study aims to clarify the general rule that the surface modification amount of magnetic nanoparticles (NPs) affects the biological behavior (e.g., cell adhesion, proliferation and differentiation) of pre-osteoblast cells. First of all, course-grained molecular dynamics simulations predict that 23.3% graft modification of the NPs can maximize the heterogeneity of the dynamics of the polymer matrix, which may generate enhanced mechanical stimuli. Then, experimentally, iron oxide (IO) NPs grafted with different amounts of poly(γ-benzyl-L-glutamate) (PBLG) were prepared to obtain homogeneous magnetic nanocomposites with improved mechanical properties. Further in vitro cell experiments demonstrate that the grafting amounts of 21.46% and 32.34% of PBLG on IO NPs are the most beneficial for the adhesion and osteogenic differentiation of cells. Simultaneously, the maximized upregulation of the Piezo1 gene indicates that the cells receive the strongest magneto-mechanical stimuli. The consistent conclusion of the experiments and simulations indicates that 20-30% PBLG grafted on the IO surface could maximize the ability of magnetic stimuli to regulate the biological behavior of the cells, which validates the feasibility of simulation auxiliary material design and is of great importance for promoting the application of magneto-controlled biotherapy in bioengineering and biomedicine.

Block Copolymer-Assisted Synthesis of Iron Oxide Nanoparticles for Effective Removal of Congo Red

Iron oxide nanoparticles (IONPs) were synthesized via a block copolymer-assisted hydrothermal method and the phase purity and the crystal structure were investigated by X-ray diffraction. The Rietveld analysis of X-ray diffractometer spectra shows the hexagonal phase symmetry of α-Fe₂O₃. Further, the vibrational study suggests Raman active modes: 2A1g + 5Eg associated with α-Fe₂O₃, which corroborates the Rietveld analysis and orbital analysis of 2PFe. The superparamagnetic behavior is confirmed by magnetic measurements performed by the physical properties measurement system. The systematic study of the Congo red (CR) interaction with IONPs using a UV-visible spectrophotometer and a liquid chromatography-tandem mass spectrometry system equipped with a triple quadrupole mass analyzer and an electrospray ionization interface shows effective adsorption. In visible light, the Fe₂O₃ nanoparticles get easily excited and generate electrons and holes. The photogenerated electrons reduce the Fe³⁺ ions to Fe²⁺ ions. The Fe²⁺/H₂O₂ oxidizes CR by the Fenton mechanism. The strong adsorption ability of prepared nanoparticles towards dyes attributes the potential candidates for wastewater treatment and other catalytic applications.

Magnetic nanoparticles: multifunctional tool for cancer therapy

INTRODUCTION

Cancer has one of the highest mortality rates globally. The traditional therapies used to treat cancer have harmful adverse effects. Considering these facts, researchers have explored new therapeutic possibilities with enhanced benefits. Nanoparticle development for cancer detection, in addition to therapy, has shown substantial progress over the past few years.

AREA COVERED

Herein, the latest research regarding cancer treatment employing magnetic nanoparticles (MNPs) in chemo-, immuno-, gene-, and radiotherapy along with hyperthermia is summarized, in addition to their physio-chemical features, advantages, and limitations for clinical translation have also been discussed.

EXPERT OPINION

MNPs are being extensively investigated and developed into effective modules for cancer therapy. They are highly functional tools aimed at cancer therapy owing to their excellent superparamagnetic, chemical, biocompatible, physical, and biodegradable properties.

Recent advances in development of functional magnetic adsorbents for selective separation of proteins/peptides

Nowadays, proteins separation has attracted great attention in proteomics research. Because the proteins separation is helpful for making an early diagnosis of many diseases. Magnetic nanoparticles are an interesting and useful functional material, and have attracted extensive research interest during the past decades. Because of the excellent properties such as easy surface functionalization, tunable biocompatibility, high saturation magnetization etc, magnetic microspheres have been widely used in isolation of proteins/peptides. Notably, with the rapid development of surface decoration strategies, more and more functional magnetic adsorbents have been designed and fabricated to meet the growing demands of biological separation. In this review, we have collected recent information about magnetic adsorbents applications in selective separation of proteins/peptides. Furthermore, we present a comprehensive prospects and challenges in the field of protein separation relying on magnetic nanoparticles.

Radiolabeled Iron Oxide Nanoparticles as Dual Modality Contrast Agents in SPECT/MRI and PET/MRI

During the last decades, the utilization of imaging modalities such as single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI) in every day clinical practice has enabled clinicians to diagnose diseases accurately at early stages. Radiolabeled iron oxide nanoparticles (RIONs) combine their intrinsic magnetic behavior with the extrinsic character of the radionuclide additive, so that they constitute a platform of multifaceted physical properties. Thus, at a practical level, RIONs serve as the physical parent of the so-called dual-modality contrast agents (DMCAs) utilized in SPECT/MRI and PET/MRI applications due to their ability to combine, at real time, the high sensitivity of SPECT or PET together with the high spatial resolution of MRI. This review focuses on the synthesis and in vivo investigation of both biodistribution and imaging efficacy of RIONs as potential SPECT/MRI or PET/MRI DMCAs.

Biosensors and Drug Delivery in Oncotheranostics Using Inorganic Synthetic and Biogenic Magnetic Nanoparticles

Magnetic nanocarriers have attracted attention in translational oncology due to their ability to be employed both for tumor diagnostics and therapy. This review summarizes data on applications of synthetic and biogenic magnetic nanoparticles (MNPs) in oncological theranostics and related areas. The basics of both types of MNPs including synthesis approaches, structure, and physicochemical properties are discussed. The properties of synthetic MNPs and biogenic MNPs are compared with regard to their antitumor therapeutic efficiency, diagnostic potential, biocompatibility, and cellular toxicity. The comparative analysis demonstrates that both synthetic and biogenic MNPs could be efficiently used for cancer theranostics, including biosensorics and drug delivery. At the same time, reduced toxicity of biogenic particles was noted, which makes them advantageous for in vivo applications, such as drug delivery, or MRI imaging of tumors. Adaptability to surface modification based on natural biochemical processes is also noted, as well as good compatibility with tumor cells and proliferation in them. Advances in the bionanotechnology field should lead to the implementation of MNPs in clinical trials.

The Effect of Trehalose Coating for Magnetite Nanoparticles on Stability of Egg White Lysozyme

In this study, the protein stability of hen egg-white lysozymes (HEWL) by Fe₃O₄ and Fe₃O₄-coated trehalose (Fe₃O₄@Tre) magnetic nanoparticles (NPs) is investigated. For this purpose, the co-precipitation method was used to synthesize magnetic NPs. The synthesized NPs were characterized by XRD, FT-IR spectroscopy, FE-SEM, and VSM analysis. In addition, the stability of HEWLs exposed to different NP concentrations in the range of 0.001–0.1 mg mL⁻¹ was investigated by circular dichroism (CD) spectroscopy, fluorescence, and UV-Vis analysis. Based on the results, in the NP concentration range of 0.001–0.04 mg mL⁻¹ the protein structure is more stable, and this range was identified as the range of kosmotropic concentration. The helicity was measured at two concentration points of 0.02 and 0.1 mg mL⁻¹. According to the results, the α-helix at 0.02 mg mL⁻¹ of Fe₃O₄ and Fe₃O₄@Tre was increased from 35.5% for native protein to 37.7% and 38.7%, respectively. The helicity decreased to 36.1% and 37.4%, respectively, with increasing the concentration of Fe₃O₄ and Fe₃O₄@Tre to 0.1 mg mL⁻¹. The formation of hydrated water shells around protein molecules occurred by using Fe₃O₄@Tre NPs. Hence, it can be concluded that the trehalose as a functional group along with magnetic NPs can improve the stability of proteins in biological environments.

Nanotechnology Advances in the Detection and Treatment of Cancer: An Overview

Over the last few years, progress has been made across the nanomedicine landscape, in particular, the invention of contemporary nanostructures for cancer diagnosis and overcoming complexities in the clinical treatment of cancerous tissues. Thanks to their small diameter and large surface-to-volume proportions, nanomaterials have special physicochemical properties that empower them to bind, absorb and transport high-efficiency substances, such as small molecular drugs, DNA, proteins, RNAs, and probes. They also have excellent durability, high carrier potential, the ability to integrate both hydrophobic and hydrophilic compounds, and compatibility with various transport routes, making them especially appealing over a wide range of oncology fields. This is also due to their configurable scale, structure, and surface properties. This review paper discusses how nanostructures can function as therapeutic vectors to enhance the therapeutic value of molecules; how nanomaterials can be used as medicinal products in gene therapy, photodynamics, and thermal treatment; and finally, the application of nanomaterials in the form of molecular imaging agents to diagnose and map tumor growth.

Fine Control of In Vivo Magnetic Hyperthermia Using Iron Oxide Nanoparticles with Different Coatings and Degree of Aggregation

The clinical implementation of magnetic hyperthermia has experienced little progress since the first clinical trial was completed in 2005. Some of the hurdles to overcome are the reliable production of magnetic nanoparticles with controlled properties and the control of the temperature at the target tissue in vivo. Here, forty samples of iron oxide superparamagnetic nanoparticles were prepared by similar methods and thoroughly characterized in terms of size, aggregation degree, and heating response. Selected samples were intratumorally administered in animals with subcutaneous xenografts of human pancreatic cancer. In vivo experiments showed that it is possible to control the rise in temperature by modulating the field intensity during in vivo magnetic hyperthermia protocols. The procedure does not require sophisticated materials and it can be easily implemented by researchers or practitioners working in magnetic hyperthermia therapies.

Magnetic nanoparticles and magnetic particle spectroscopy-based bioassays: a 15 year recap

Magnetic nanoparticles (MNPs) have unique physical and chemical properties, such as high surface area to volume ratio and size-related magnetism, which are completely different from their bulk materials. Benefiting from the facile synthesis and chemical modification strategies, MNPs have been widely studied for applications in nanomedicine. Herein, we firstly summarized the designs of MNPs from the perspectives of materials and physicochemical properties tailored for biomedical applications. Magnetic particle spectroscopy (MPS), first reported in 2006, has flourished as an independent platform for many biological and biomedical applications. It has been extensively reported as a versatile platform for a variety of bioassays along with the artificially designed MNPs, where the MNPs serve as magnetic nanoprobes to specifically probe target analytes from fluid samples. In this review, the mechanisms and theories of different MPS platforms realizing volumetric- and surface-based bioassays are discussed. Some representative works of MPS platforms for applications such as disease diagnosis, food safety and plant pathology monitoring, drug screening, thrombus maturity assessments are reviewed. At the end of this review, we commented on the rapid growth and booming of MPS-based bioassays in its first 15 years. We also prospected opportunities and challenges that portable MPS devices face in the rapidly growing demand for fast, inexpensive, and easy-to-use biometric techniques.

Magnetic Anisotropy of Individual Nanomagnets Embedded in Biological Systems Determined by Axi-asymmetric X-ray Transmission Microscopy

Over the past few years, the use of nanomagnets in biomedical applications has increased. Among others, magnetic nanostructures can be used as diagnostic and therapeutic agents in cardiovascular diseases, to locally destroy cancer cells, to deliver drugs at specific positions, and to guide (and track) stem cells to damaged body locations in regenerative medicine and tissue engineering. All these applications rely on the magnetic properties of the nanomagnets which are mostly determined by their magnetic anisotropy. Despite its importance, the magnetic anisotropy of the individual magnetic nanostructures is unknown. Currently available magnetic sensitive microscopic methods are either limited in spatial resolution or in magnetic field strength or, more relevant, do not allow one to measure magnetic signals of nanomagnets embedded in biological systems. Hence, the use of nanomagnets in biomedical applications must rely on mean values obtained after averaging samples containing thousands of dissimilar entities. Here we present a hybrid experimental/theoretical method capable of working out the magnetic anisotropy constant and the magnetic easy axis of individual magnetic nanostructures embedded in biological systems. The method combines scanning transmission X-ray microscopy using an axi-asymmetric magnetic field with theoretical simulations based on the Stoner-Wohlfarth model. The validity of the method is demonstrated by determining the magnetic anisotropy constant and magnetic easy axis direction of 15 intracellular magnetite nanoparticles (50 nm in size) biosynthesized inside a magnetotactic bacterium.

Unique Properties of Surface-Functionalized Nanoparticles for Bio-Application: Functionalization Mechanisms and Importance in Application

This review tries to summarize the purpose of steadily developing surface-functionalized nanoparticles for various bio-applications and represents a fascinating and rapidly growing field of research. Due to their unique properties—such as novel optical, biodegradable, low-toxicity, biocompatibility, size, and highly catalytic features—these materials are considered superior, and it is thus vital to study these systems in a realistic and meaningful way. However, rapid aggregation, oxidation, and other problems are encountered with functionalized nanoparticles, inhibiting their subsequent utilization. Adequate surface modification of nanoparticles with organic and inorganic compounds results in improved physicochemical properties which can overcome these barriers. This review investigates and discusses the iron oxide nanoparticles, gold nanoparticles, platinum nanoparticles, silver nanoparticles, and silica-coated nanoparticles and how their unique properties after fabrication allow for their potential use in a wide range of bio-applications such as nano-based imaging, gene delivery, drug loading, and immunoassays. The different groups of nanoparticles and the advantages of surface functionalization and their applications are highlighted here. In recent years, surface-functionalized nanoparticles have become important materials for a broad range of bio-applications.

Mechano-Nanoswitches for Ultrasound-Controlled Drug Activation

Current pharmacotherapy is challenged by side effects and drug resistance issues due to the lack of drug selectivity. Mechanochemistry-based strategies provide new avenues to overcome the related problems by improving drug selectivity. It is recently shown that sonomechanical bond scission enables the remote-controlled drug release from their inactive parent macromolecules using ultrasound (US). To further expand the scope of the US-controlled drug activation strategy, herein a mechano-responsive nanoswitch for the selective activation of doxorubicin (DOX) to inhibit cancer cell proliferation is constructed. As a proof-of-concept, the synthesis, characterization, and US-responsive drug activation evaluation of the mechano-nanoswitch, which provides a blueprint for tailoring nanosystems for force-induced pharmacotherapy is presented.

Multimodal Locomotion and Active Targeted Thermal Control of Magnetic Agents for Biomedical Applications

Magnetic microrobots can be miniaturized to a nanometric scale owing to their wireless actuation, thereby rendering them ideal for numerous biomedical applications. As a result, nowadays, there exist several mechano-electromagnetic systems for their actuation. However, magnetic actuation is not sufficient for implementation in biomedical applications, and further functionalities such as imaging and heating are required. This study proposes a multimodal electromagnetic system comprised of three pairs of Helmholtz coils, a pair of Maxwell coils, and a high-frequency solenoid to realize multimodal locomotion and heating control of magnetic microrobots. The system produces different configurations of magnetic fields that can generate magnetic forces and torques for the multimodal locomotion of magnetic microrobots, as well as generate magnetic traps that can control the locomotion of magnetic swarms. Furthermore, these magnetic fields are employed to control the magnetization of magnetic nanoparticles, affecting their magnetic relaxation mechanisms and diminishing their thermal properties. Thus, the system enables the control of the temperature increase of soft-magnetic materials and selective heating of magnetic microrobots at different positions, while suppressing the heating properties of magnetic nanoparticles located at undesired areas.

Nanoparticles for neurotrophic factor delivery in nerve guidance conduits for peripheral nerve repair

Peripheral nerve injuries are a major source of disabilities, and treatment of long nerve gap autografts is the gold standard. However, due to poor availability and donor-site morbidity, research is directed towards the development of regenerative strategies based on the use of artificial nerve guidance conduits (NGCs). Several properties and characteristics of the NGCs can be fine-tuned, such as the architecture of the conduit, the surface topography and the addition of bioactive molecules and cells to speed up nerve regeneration. In this review, US FDA-approved NGCs are described. The recent works, in which polymeric, magnetic, silica-based and lipidic NPs are employed to introduce growth factors (GFs) to NGCs, are overviewed and discussed in depth herein.

An update on the applications and characteristics of magnetic iron oxide nanoparticles for drug delivery

INTRODUCTION

In the field of drug delivery, controlling the release of therapeutic substances at localized targets has become a primary focus of medical research, especially in the field of cancer treatment. Magnetic nanoparticles are one of the most promising drug carriers thanks to their biocompatibility and (super)paramagnetic properties. These properties allow for the combination between imaging modalities and specific release of drugs at target sites using either local stimulus (i.e. pH, conjugation of biomarkers, …) or external stimulus (i.e. external magnetic field).

AREAS COVERED

This review provides an update on recent advances with the development of targeted drug delivery systems based on magnetic nanoparticles (MNPs). This overview focuses on active targeting strategies and systems combining both imaging and therapeutic modalities (i.e. theranostics). If most of the examples concern the particular case of cancer therapy, the possibility of using MNPs for other medical applications is also discussed.

EXPERT OPINION

The development of clinically relevant drug delivery systems based on magnetic nanoparticles is driven by advantages stemming from their remarkable properties (i.e. easy preparation, facile chemical functionalization, biocompatibility, low toxicity and superior magnetic responsiveness). This literature review shows that drug carriers based on magnetic nanoparticles can be efficiently used for the controlled release of drug at targeted locations mediated by various stimuli. Advances in the field should lead to the implementation of such systems into clinical trials, especially systems enabling drug tracking in the body.

Polymeric Composite of Magnetite Iron Oxide Nanoparticles and Their Application in Biomedicine: A Review

A broad spectrum of nanomaterials has been investigated for multiple purposes in recent years. Some of these studied materials are magnetics nanoparticles (MNPs). Iron oxide nanoparticles (IONPs) and superparamagnetic iron oxide nanoparticles (SPIONs) are MNPs that have received extensive attention because of their physicochemical and magnetic properties and their ease of combination with organic or inorganic compounds. Furthermore, the arresting of these MNPs into a cross-linked matrix known as hydrogel has attracted significant interest in the biomedical field. Commonly, MNPs act as a reinforcing material for the polymer matrix. In the present review, several methods, such as co-precipitation, polyol, hydrothermal, microemulsion, and sol-gel methods, are reported to synthesize magnetite nanoparticles with controllable physical and chemical properties that suit the required application. Due to the potential of magnetite-based nanocomposites, specifically in hydrogels, processing methods, including physical blending, in situ precipitation, and grafting methods, are introduced. Moreover, the most common characterization techniques employed to study MNPs and magnetic gel are discussed.

Approaches on Ferrofluid Synthesis and Applications: Current Status and Future Perspectives

Ferrofluids are colloidal suspensions of iron oxide nanoparticles (IONPs) within aqueous or nonaqueous liquids that exhibit strong magnetic properties. These magnetic properties allow ferrofluids to be manipulated and controlled when exposed to magnetic fields. This review aims to provide the current scope and research opportunities regarding the methods of synthesis of nanoparticles, surfactants, and carrier liquids for ferrofluid production, along with the rheology and applications of ferrofluids within the fields of medicine, water treatment, and mechanical engineering. A ferrofluid is composed of IONPs, a surfactant that coats the magnetic IONPs to prevent agglomeration, and a carrier liquid that suspends the IONPs. Coprecipitation and thermal decomposition are the main methods used for the synthesis of IONPs. Despite the fact that thermal decomposition provides precise control on the nanoparticle size, coprecipitation is the most used method, even when the oxidation of iron can occur. This oxidation alters the ratio of maghemite/magnetite, influencing the magnetic properties of ferrofluids. Strategies to overcome iron oxidation have been proposed, such as the use of an inert atmosphere, adjusting the Fe(II) and Fe(III) ratio to 1:2, and the exploration of other metals with the oxidation state +2. Surfactants and carrier liquids are chosen according to the ferrofluid application to ensure stability. Hence, a compatible carrier liquid (polar or nonpolar) is selected, and then, a surfactant, mainly a polymer, is embedded in the IONPs, providing a steric barrier. Due to the variety of surfactants and carrier liquids, the rheological properties of ferrofluids are an important response variable evaluated when synthesizing ferrofluids. There are many reported applications of ferrofluids, including biosensing, medical imaging, medicinal therapy, magnetic nanoemulsions, and magnetic impedance. Other applications include water treatment, energy harvesting and transfer, and vibration control. To progress from synthesis to applications, research is still ongoing to ensure control of the ferrofluids' properties.

Basic Principles and Recent Advances in Magnetic Cell Separation

Magnetic cell separation has become a key methodology for the isolation of target cell populations from biological suspensions, covering a wide spectrum of applications from diagnosis and therapy in biomedicine to environmental applications or fundamental research in biology. There now exists a great variety of commercially available separation instruments and reagents, which has permitted rapid dissemination of the technology. However, there is still an increasing demand for new tools and protocols which provide improved selectivity, yield and sensitivity of the separation process while reducing cost and providing a faster response. This review aims to introduce basic principles of magnetic cell separation for the neophyte, while giving an overview of recent research in the field, from the development of new cell labeling strategies to the design of integrated microfluidic cell sorters and of point-of-care platforms combining cell selection, capture, and downstream detection. Finally, we focus on clinical, industrial and environmental applications where magnetic cell separation strategies are amongst the most promising techniques to address the challenges of isolating rare cells.

Magnetic Gold Nanoparticles with Idealized Coating for Enhanced Point-Of-Care Sensing

Magnetic nanoparticles with hybrid sensing functions are in wide use for bioseparation, sensing, and in vivo imaging. Yet, nonspecific protein adsorption to the particle surface continues to present a technical challenge and diminishes the theoretical protein detection capabilities. Here, a magneto-plasmonic nanoparticle synthesis is developed that minimizes nonspecific protein adsorption. Building on the success of zwitterionic polymers, a highly stable and anergic nanomaterial, magnetic gold nanoparticles with idealized coating (MAGIC) is obtained with significantly lower serum protein adsorption compared to control nanoparticles coated with commonly used polymers (polyethylene glycol, polyethylenimine, or polyallylamine hydrochloride). MAGIC nanoparticles are able to sense specific bladder cancer biomarkers at low levels and in the presence of other proteins. This strategy may find wide spread applications for in vitro and in vivo sensing as well as isolations.

Synthesis of Cobalt-Nickel Nanoparticles via a Liquid-Phase Reduction Process

Cobalt-nickel nanoparticles (Co-Ni-NPs) show promising electrochemical performance in oxygen and hydrogen evolution reactions (OER and HER) due to their physicochemical properties such as electronic configuration and great electrochemical stability. Therefore, developing new economically and environmentally friendly methods of synthesizing Co-Ni-NPs has become a practical requirement. Co-Ni-NPs were produced by employing the liquid-phase reduction method. Nickel and cobalt sulfate solutions in hydrazine monohydrate with various mixing ratios were used as raw materials. Nickel plays an important role in the nucleation process via increasing the reduction reaction rate throughout the formation of Co-Ni-NPs. Furthermore, the acceleration of the Co-Ni-NPs formation process may be attributed to the partial dissolution of Ni(OH)2 in the presence of N2H4 and/or citrate-anions and the formation of the Ni-N2H4 or Ni-Cit complexes in contrast to Co(OH)2.

Emerging Application of Magnetic Nanoparticles for Diagnosis and Treatment of Cancer

Cancer is a disease that has resulted in millions of deaths worldwide. The current conventional therapies utilized for the treatment of cancer have detrimental side effects. This led scientific researchers to explore new therapeutic avenues with an improved benefit to risk profile. Researchers have found nanoparticles, particles between the 1 and 100 nm range, to be encouraging tools in the area of cancer. Magnetic nanoparticles are one of many available nanoparticles at present. Magnetic nanoparticles have increasingly been receiving a considerable amount of attention in recent years owing to their unique magnetic properties, among many others. Magnetic nanoparticles can be controlled by an external magnetic field, signifying their ability to be site specific. The most popular approaches for the synthesis of magnetic nanoparticles are co-precipitation, thermal decomposition, hydrothermal, and polyol synthesis. The functionalization of magnetic nanoparticles is essential as it significantly increases their biocompatibility. The most utilized functionalization agents are comprised of polymers. The synthesis and functionalization of magnetic nanoparticles will be further explored in this review. The biomedical applications of magnetic nanoparticles investigated in this review are drug delivery, magnetic hyperthermia, and diagnosis. The diagnosis aspect focuses on the utilization of magnetic nanoparticles as contrast agents in magnetic resonance imaging. Clinical trials and toxicology studies relating to the application of magnetic nanoparticles for the diagnosis and treatment of cancer will also be discussed in this review.

Aspects of high-performance and bio-acceptable magnetic nanoparticles for biomedical application

This review covers extensively the synthesis & surface modification, characterization, and application of magnetic nanoparticles. For biomedical applications, consideration should be given to factors such as design strategies, the synthesis process, coating, and surface passivation. The synthesis method regulates post-synthetic change and specific applications in vitro and in vivo imaging/diagnosis and pharmacotherapy/administration. Special insights have been provided on biodistribution, pharmacokinetics, and toxicity in a living system, which is imperative for their wider application in biology. These nanoparticles can be decorated with multiple contrast agents and thus can also be used as a probe for multi-mode imaging or double/triple imaging, for example, MRI-CT, MRI-PET. Similarly loading with different drug molecules/dye/fluorescent molecules and integration with other carriers have found application not only in locating these particles in vivo but simultaneously target drug delivery/hyperthermia inside the body. Studies are underway to collect the potential of these magnetically driven nanoparticles in various scientific fields such as particle interaction, heat conduction, imaging, and magnetism. Surely, this comprehensive data will help in the further development of advanced techniques for theranostics based on high-performance magnetic nanoparticles and will lead this research area in a new sustainable direction.

Simultaneous blockade of TIGIT and HIF-1α induces synergistic anti-tumor effect and decreases the growth and development of cancer cells

PURPOSE

T-cell immunoglobulin and ITIM domain (TIGIT) is an immune checkpoint that is overexpressed on both immune cells and some cancer cells. TIGIT can alter the anti-tumor responses inside the tumor microenvironment. Hypoxia-inducible factor 1-alpha (HIF-1α) plays a significant role in the TME and involves suppressing the anti-tumor responses. Under hypoxic conditions, HIF-1α can enhance the expression of different immune checkpoints. Accordingly, hypoxic TME and TIGIT overexpression cause cancer development. Thus, we decided to inhibit tumor cell expansion by inhibiting TIGIT and HIF-1α molecules and discovering the relationship between TIGIT and HIF-1α.

METHODS

In this research, we utilized superparamagnetic iron oxide-based NPs (SPIONs) combined with chitosan lactate (CL) and folic acid (FA) nanoparticles (NPs) loaded with TIGIT-siRNA and HIF-1α- siRNA for suppressing TIGIT and HIF-1α in tumor cells and evaluated the consequences of this treatment strategy on tumor growth, apoptosis, and metastasis.

RESULTS

The results showed that cancer cells treated with TIGIT and HIF-1α siRNA-loaded SPIONs-CL-FA NPs, strongly suppressed the TIGIT and HIF-1α expression, colony formation ability, angiogenesis, and the growth rate of cancer cells.

CONCLUSIONS

Present data suggest the combination treatment of TIGIT and HIF-1α as a novel treatment strategy against colorectal and breast cancer, but more researches are required to realize the complete role of TIGIT and HIF-1α inside the TME.

Influence of Coating and Size of Magnetic Nanoparticles on Cellular Uptake for In Vitro MRI

Iron oxide nanoparticles (IONPs) are suitable materials for contrast enhancement in magnetic resonance imaging (MRI). Their potential clinical applications range from diagnosis to therapy and follow-up treatments. However, a deeper understanding of the interaction between IONPs, culture media and cells is necessary for expanding the application of this technology to different types of cancer therapies. To achieve new insights of these interactions, a set of IONPs were prepared with the same inorganic core and five distinct coatings, to study their aggregation and interactions in different physiological media, as well as their cell labelling efficiency. Then, a second set of IONPs, with six different core sizes and the same coating, were used to study how the core size affects cell labelling and MRI in vitro. Here, IONPs suspended in biological media experience a partial removal of the coating and adhesion of molecules. The FBS concentration alters the labelling of all types of IONPs and hydrodynamic sizes ≥ 300 nm provide the greatest labelling using the centrifugation-mediated internalization (CMI). The best contrast for MRI results requires a core size range between 12–14 nm coated with dimercaptosuccinic acid (DMSA) producing R₂^* values of 393.7 s⁻¹ and 428.3 s⁻¹, respectively. These findings will help to bring IONPs as negative contrast agents into clinical settings.

Recent development for biomedical applications of magnetic nanoparticles

In recent decades, the use of engineered nanoparticles has been increasing in various sectors, including biomedicine, diagnosis, water treatment, and environmental remediation leading to significant public concerns. Among these nanoparticles, magnetic nanoparticles (MNPs) have gained many attentions in medicine, pharmacology, drug delivery system, molecular imaging, and bio-sensing due to their various properties. In addition, various studies have reviewed MNPs main applications in the biomedical engineering area with intense progress and recent achievements. Nanoparticles, especially the magnetic nanoparticles, have recently been confirmed with excellent antiviral activity against different viruses, including SARS-CoV-2(Covid-19) and their recent development against Covid-19 also has also been discussed. This review aims to highlight the recent development of the magnetic nanoparticles and their biomedical applications such as diagnosis of diseases, molecular imaging, hyperthermia, bio-sensing, gene therapy, drug delivery and the diagnosis of Covid-19.

Advances in Magnetic Nanoparticles Engineering for Biomedical Applications-A Review

Magnetic iron oxide nanoparticles (MNPs) have been developed and applied for a broad range of biomedical applications, such as diagnostic imaging, magnetic fluid hyperthermia, targeted drug delivery, gene therapy and tissue repair. As one key element, reproducible synthesis routes of MNPs are capable of controlling and adjusting structure, size, shape and magnetic properties are mandatory. In this review, we discuss advanced methods for engineering and utilizing MNPs, such as continuous synthesis approaches using microtechnologies and the biosynthesis of magnetosomes, biotechnological synthesized iron oxide nanoparticles from bacteria. We compare the technologies and resulting MNPs with conventional synthetic routes. Prominent biomedical applications of the MNPs such as diagnostic imaging, magnetic fluid hyperthermia, targeted drug delivery and magnetic actuation in micro/nanorobots will be presented.

Enzymatic recognition of hydrogen peroxide (H2 O2 ) in human plasma samples using HRP immobilized on the surface of poly(arginine-toluidine blue)- Fe3 O4 nanoparticles modified polydopamine; A novel biosensor

In this study, an innovative strategy was proposed for the electrocatalytical reduction and enzymatic biosensing of hydrogen peroxide (H₂ O₂ ) using chronoamperometry technique. For the first time, immobilization of horseradish peroxidase (HRP) in polydopamine-modified magnetic nanoparticles (PDA-MNPs) was successfully performed. Also, poly(l-arginine/toluidine blue) film-modified glassy carbon electrode was constructed through co-electropolymerization of l-arginine and toluidine blue on the surface of GCE using cyclic voltammetry technique. The engineered hybrid thin film provides strong functionalities for efficient grafting of PDA-MNPs which, in turn, enable the covalent immobilization of HRP. The proposed biosensor was used for the detection of H₂ O₂ in the range of 0.5-30 μM with a low limit of quantification 0.23 μM. It also was successfully applied for the investigation of hydrogen peroxide in human plasma samples.

Advanced biomedical applications of iron oxide nanostructures based ferrofluids

Ferrofluids or magnetic nanofluids are highly stable colloidal suspensions of magnetic nanoparticles (NPs) dispersed into various base fluids. These stable ferrofluids possess high thermal conductivity, improved thermo-physical properties, higher colloidal stability, good magnetic properties, and biocompatibility, which are the primary driving forces behind their excellent performance, and thus enable them to be used for a wide range of practical applications. The most studied and advanced ferrofluids are based on iron oxide nanostructures especially NPs, because of their easy and large-scale synthesis at low costs. Although in the last decade, several review articles are available on ferrofluids but mainly focused on preparations, properties, and a specific application. Hence, a collective and comprehensive review article on the recent progress of iron oxide nanostructures based ferrofluids for advanced biomedical applications is undeniably required. In this review, the state of the art of biomedical applications is presented and critically analyzed with a special focus on hyperthermia, drug delivery/nanomedicine, magnetic resonance imaging, and magnetic separation of cells. This review article provides up-to-date information related to the technological advancements and emerging trends in iron oxide nanostructures based ferrofluids research focused on advanced biomedical applications. Finally, conclusions and outlook of iron oxide nanostructures based ferrofluids research for biomedical applications are presented.