Magnetic Nanoparticles for Biomedical Applications: From the Soul of the Earth to the Deep History of Ourselves

Adsorption Dynamics of Uremic Toxins to Cyclodextrin-Coated Magnetic Nano-Adsorbents

Chronic kidney disease entails a progressive decline in kidney function, hindering the kidneys' ability to excrete fluid, electrolytes, and metabolites. This dysfunction leads to metabolite accumulation in the bloodstream, which can reach toxic concentrations. Hemodialysis is an effective means of treating patients with kidney failure, but it does not clear all toxins effectively. Engineered nano-adsorbents can potentially improve the removal of retained toxins, particularly protein-bound types. Magnetic nanoparticles coated with α-, β-, and γ-cyclodextrin were synthesized, and physicochemical properties were characterized using thermogravimetric analysis, transmission electron microscopy, dynamic light scattering, and ζ-potential for their physiochemical properties. The effect of surface chemistry and incubation time on toxin adsorption was investigated using quantitative mass spectrometry techniques. All particle types demonstrated toxin adsorption to some level. Overall, the adsorption process was independent of metabolite concentration, suggesting a dynamic interplay between surface properties and solution composition. This insight will contribute to developing innovative adsorbent films designed to remove uremic toxins effectively.

Size-dependent Curie temperature of Ni nanoparticles from spin-lattice dynamics simulations

The magnetic properties of Ni nanoparticles (NPs) with diameter D are investigated using spin-lattice dynamics (SLD) simulations. Using exchange interactions fitted to ab-initio results we obtain a Curie temperature, T c , similar, but lower, than experiments. In order to reproduce quantitatively the bulk Curie temperature and the experimental results, the exchange energy has to be increased by 25% compared to the ab-initio value. During the simulated time, Ni NPs remain ferromagnetic down to the smallest sizes investigated here, containing around 500 atoms. The average magnetic moment of the NPs is slightly smaller than that determined experimentally. By considering a core-shell model for NPs, in which the shell atoms are assigned a larger magnetic moment, this discrepancy can be removed. T c is lower for a moving lattice than for a frozen lattice, as expected, but this difference decreases with NP size because smaller NPs include higher surface disorder which dominates the transition. For NPs, T c decreases with the NP diameter D by at most 10% at D = 2  nm, in agreement with several experiments, and unlike some modeling or theoretical scaling results which predict a considerably larger decrease. The decrease of T c is well described by finite-size scaling models, with a critical exponent that depends on the SLD settings for a frozen or moving lattice, and also depends on the procedure for determining T c . Extrapolating the inverse of the magnetization as function of temperature near T c gives a lower T c than the maximum of the susceptibility.

Understanding electrocatalytic mechanisms and ultra-trace uranyl detection with Pd nanoparticles electrodeposited in deep eutectic solvents

This research paper investigates the electrocatalytic mechanisms and ultra-trace detection abilities of uranyl ions (UO22+) using palladium nanoparticles (PdNPs) electrodeposited in deep eutectic solvents (DESs). The unique properties of DESs, such as their adjustable viscosity and ionic conductivity, offer an advantageous and environmentally friendly medium for Pd nanoparticle electrodeposition, resulting in highly active and stable electrocatalysts. Various characterization techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), were used to examine the morphology, size distribution, and crystallographic structure of the Pd nanoparticles. Electrochemical tests revealed that the Pd-modified electrodes show exceptional electrocatalytic activity and current sensitivity towards uranyl ions, with detection limits as low as 3.4 nM. Density functional theory (DFT) calculations were conducted to elucidate the mechanism of the electrocatalytic reduction of UO22+ by the PdNPs, providing a plausible explanation for the high sensitivity of PdNPs in detecting uranyl ions based on the calculated structural parameters and reaction energetics. This study underscores the potential of Pd nanoparticles electrodeposited in DESs as a promising method for sensitive uranyl ion detection, contributing to advancements in environmental monitoring and nuclear safety.

Contactless magnetically responsive injectable hydrogel for aligned tissue regeneration

Cellular alignment plays a pivotal role in several human tissues, including skeletal muscle, spinal cord and tendon. Various techniques have been developed to control cellular alignment using 3D biomaterials. However, the majority of 3D-aligned scaffolds require invasive surgery for implantation. In contrast, injectable hydrogels provide a non-invasive delivery method, gaining considerable attention for the treatment of diverse conditions, including osteochondral lesions, volumetric muscle loss, and traumatic brain injury. We engineered a biomimetic hydrogel with magnetic responsiveness by combining gellan gum, hyaluronic acid, collagen, and magnetic nanoparticles (MNPs). Collagen type I was paired with MNPs to form magnetic collagen bundles (MCollB), allowing the orientation control of these bundles within the hydrogel matrix through the application of a remote low-intensity magnetic field. This resulted in the creation of an anisotropic architecture. The hydrogel mechanical properties were comparable to those of human soft tissues, such as skeletal muscle, and proof of the aligned hydrogel concept was demonstrated. In vitro findings confirmed the absence of toxicity and pro-inflammatory effects. Notably, an increased fibroblast cell proliferation and pro-regenerative activation of macrophages were observed. The in-vivo study further validated the hydrogel biocompatibility and demonstrated the feasibility of injection with rapid in situ gelation. Consequently, this magnetically controlled injectable hydrogel exhibits significant promise as a minimally invasive, rapid gelling and effective treatment for regenerating various aligned human tissues.

Magnetic nanosystem a tool for targeted delivery and diagnostic application: Current challenges and recent advancement

Over the last two decades, researchers have paid more attention to magnetic nanosystems due to their wide application in diverse fields. The metal nanomaterials' antimicrobial and biocidal properties make them an essential nanosystem for biomedical applications. Moreover, the magnetic nanosystems could have also been used for diagnosis and treatment because of their magnetic, optical, and fluorescence properties. Superparamagnetic iron oxide nanoparticles (SPIONs) and quantum dots (QDs) are the most widely used magnetic nanosystems prepared by a simple process. By surface modification, researchers have recently been working on conjugating metals like silica, copper, and gold with magnetic nanosystems. This hybridization of the nanosystems modifies the structural characteristics of the nanomaterials and helps to improve their efficacy for targeted drug and gene delivery. The hybridization of metals with various nanomaterials like micelles, cubosomes, liposomes, and polymeric nanomaterials is gaining more interest due to their nanometer size range and nontoxic, biocompatible nature. Moreover, they have good injectability and higher targeting ability by accumulation at the target site by application of an external magnetic field. The present article discussed the magnetic nanosystem in more detail regarding their structure, properties, interaction with the biological system, and diagnostic applications.

Toxicity and magnetometry evaluation of the uptake of core-shell maghemite-silica nanoparticles by neuroblastoma cells

Nanoparticle uptake by cells is a key parameter in their performance in biomedical applications. However, the use of quantitative, non-destructive techniques to obtain the amount of nanoparticles internalized by cells is still uncommon. We have studied the cellular uptake and the toxicity of core-shell maghemite-silica magnetic nanoparticles (MNPs), with a core diameter of 9 nm and a shell thickness of 3 nm. The internalization of the nanoparticles by mouse neuroblastoma 2a cells was evaluated by sensitive and non-destructive Superconducting Quantum Interference Device (SQUID) magnetometry and corroborated by graphite furnace atomic absorption spectroscopy. We were thus able to study the toxicity of the nanoparticles for well-quantified MNP uptake in terms of nanoparticle density within the cell. No significant variation in cell viability or growth rate was detected for any tested exposure. Yet, an increase in both the amount of mitochondrial superoxide and in the lysosomal activity was detected for the highest concentration (100 μg ml-1) and incubation time (24 h), suggesting the onset of a disruption in ROS homeostasis, which may lead to an impairment in antioxidant responses. Our results validate SQUID magnetometry as a sensitive technique to quantify MNP uptake and demonstrate the non-toxic nature of these core-shell MNPs under our culture conditions.

Advances in the Optimization of Fe Nanoparticles: Unlocking Antifungal Properties for Biomedical Applications

In recent years, nanotechnology has achieved a remarkable status in shaping the future of biological applications, especially in combating fungal diseases. Owing to excellence in nanotechnology, iron nanoparticles (Fe NPs) have gained enormous attention in recent years. In this review, we have provided a comprehensive overview of Fe NPs covering key synthesis approaches and underlying working principles, the factors that influence their properties, essential characterization techniques, and the optimization of their antifungal potential. In addition, the diverse kinds of Fe NP delivery platforms that command highly effective release, with fewer toxic effects on patients, are of great significance in the medical field. The issues of biocompatibility, toxicity profiles, and applications of optimized Fe NPs in the field of biomedicine have also been described because these are the most significant factors determining their inclusion in clinical use. Besides this, the difficulties and regulations that exist in the transition from laboratory to experimental clinical studies (toxicity, specific standards, and safety concerns) of Fe NPs-based antifungal agents have been also summarized.

Magnetic nanoparticles in square-wave fields for breakthrough performance in hyperthermia and magnetic particle imaging

Driving immobilized, single-domain magnetic nanoparticles at high frequency by square wave fields instead of sinusoidal waveforms leads to qualitative and quantitative improvements in their performance both as point-like heat sources for magnetic hyperthermia and as sensing elements in frequency-resolved techniques such as magnetic particle imaging and magnetic particle spectroscopy. The time evolution and the frequency spectrum of the cyclic magnetization of magnetite nanoparticles with random easy axes are obtained by means of a rate-equation method able to describe time-dependent effects for the particle sizes and frequencies of interest in most applications to biomedicine. In the presence of a high-frequency square-wave field, the rate equations are shown to admit an analytical solution and the periodic magnetization can be therefore described with accuracy, allowing one to single out effects which take place on different timescales. Magnetic hysteresis effects arising from the specific features of the square-wave driving field results in a breakthrough improvement of both the magnetic power released as heat to an environment in magnetic hyperthermia treatments and the magnitude of the third harmonic of the frequency spectrum of the magnetization, which plays a central role in magnetic particle imaging.

Nanocomposites Based on Magnetic Nanoparticles and Metal-Organic Frameworks for Therapy, Diagnosis, and Theragnostics

In the last two decades, metal-organic frameworks (MOFs) with highly tunable structure and porosity, have emerged as drug nanocarriers in the biomedical field. In particular, nanoscaled MOFs (nanoMOFs) have been widely investigated because of their potential biocompatibility, high drug loadings, and progressive release. To enhance their properties, MOFs have been combined with magnetic nanoparticles (MNPs) to form magnetic nanocomposites (MNP@MOF) with additional functionalities. Due to the magnetic properties of the MNPs, their presence in the nanosystems enables potential combinatorial magnetic targeted therapy and diagnosis. In this Review, we analyze the four main synthetic strategies currently employed for the fabrication of MNP@MOF nanocomposites, namely, mixing, in situ formation of MNPs in presynthesized MOF, in situ formation of MOFs in the presence of MNPs, and layer-by-layer methods. Additionally, we discuss the current progress in bioapplications, focusing on drug delivery systems (DDSs), magnetic resonance imaging (MRI), magnetic hyperthermia (MHT), and theragnostic systems. Overall, we provide a comprehensive overview of the recent advances in the development and bioapplications of MNP@MOF nanocomposites, highlighting their potential for future biomedical applications with a critical analysis of the challenges and limitations of these nanocomposites in terms of their synthesis, characterization, biocompatibility, and applicability.

Tannic acid- and N-acetylcysteine-chitosan-modified magnetic nanoparticles reduce hepatic oxidative stress in prediabetic rats

Magnetic nanoparticles (MNPs) modified with tannic acid (TA) have shown remarkable success as an antioxidant and antimicrobial therapeutic agent. Herein, we report a synthetic procedure for the preparation of silica-coated MNPs modified with N-acetylcysteine-modified chitosan and TA. This was achieved by free-radical grafting of NAC onto chitosan (CS), a layer-by-layer technique for modifying negatively charged MNP@SiO2 nanoparticles with positively charged CS-NAC, and crosslinking CS with TA. The antioxidant and metabolic effects of MNP@SiO2-CS-NAC and MNP@SiO2-CS-NAC-TA nanoparticles were tested in a model of prediabetic rats with hepatic steatosis, the hereditary hypertriglyceridemic rats (HHTg). The particles exhibited significant antioxidant properties in the liver, increasing the activity of the antioxidant enzymes superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GPx), decreasing the concentration of the lipoperoxidation product malondialdehyde (MDA), and improving the antioxidant status determined as the ratio of reduced to oxidized glutathione; in particular, TA increased some antioxidant parameters. MNPs carrying antioxidants such as NAC and TA could thus represent a promising therapeutic agent for the treatment of various diseases accompanied by increased oxidative stress.

Magnetic Hydroxyapatite Nanoparticles in Regenerative Medicine and Nanomedicine

This review focuses on the latest advancements in magnetic hydroxyapatite (mHA) nanoparticles and their potential applications in nanomedicine and regenerative medicine. mHA nanoparticles have gained significant interest over the last few years for their great potential, offering advanced multi-therapeutic strategies because of their biocompatibility, bioactivity, and unique physicochemical features, enabling on-demand activation and control. The most relevant synthetic methods to obtain magnetic apatite-based materials, either in the form of iron-doped HA nanoparticles showing intrinsic magnetic properties or composite/hybrid compounds between HA and superparamagnetic metal oxide nanoparticles, are described as highlighting structure-property correlations. Following this, this review discusses the application of various magnetic hydroxyapatite nanomaterials in bone regeneration and nanomedicine. Finally, novel perspectives are investigated with respect to the ability of mHA nanoparticles to improve nanocarriers with homogeneous structures to promote multifunctional biological applications, such as cell stimulation and instruction, antimicrobial activity, and drug release with on-demand triggering.

Magnetic Nanoparticles: A Review on Synthesis, Characterization, Functionalization, and Biomedical Applications

Nowadays, magnetic nanoparticles (MNPs) are applied in numerous fields, especially in biomedical applications. Since biofluidic samples and biological tissues are nonmagnetic, negligible background signals can interfere with the magnetic signals from MNPs in magnetic biosensing and imaging applications. In addition, the MNPs can be remotely controlled by magnetic fields, which make it possible for magnetic separation and targeted drug delivery. Furthermore, due to the unique dynamic magnetizations of MNPs when subjected to alternating magnetic fields, MNPs are also proposed as a key tool in cancer treatment, an example is magnetic hyperthermia therapy. Due to their distinct surface chemistry, good biocompatibility, and inducible magnetic moments, the material and morphological structure design of MNPs has attracted enormous interest from a variety of scientific domains. Herein, a thorough review of the chemical synthesis strategies of MNPs, the methodologies to modify the MNPs surface for better biocompatibility, the physicochemical characterization techniques for MNPs, as well as some representative applications of MNPs in disease diagnosis and treatment are provided. Further portions of the review go into the diagnostic and therapeutic uses of composite MNPs with core/shell structures as well as a deeper analysis of MNP properties to learn about potential biomedical applications.

Single and Multitarget Systems for Drug Delivery and Detection: Up-to-Date Strategies for Brain Disorders

This review summarizes the recent findings on the development of different types of single and multitarget nanoparticles for disease detection and drug delivery to the brain, focusing on promising active principles encapsulated and nanoparticle surface modification and functionalization. Functionalized nanoparticles have emerged as promising tools for the diagnosis and treatment of brain disorders, offering a novel approach to addressing complex neurological challenges. They can act as drug delivery vehicles, transporting one or multiple therapeutic agents across the blood-brain barrier and precisely releasing them at the site of action. In diagnostics, functionalized nanoparticles can serve as highly sensitive contrast agents for imaging techniques such as magnetic resonance imaging and computed tomography scans. By attaching targeting ligands to the nanoparticles, they can selectively accumulate in the affected areas of the brain, enhancing the accuracy of disease detection. This enables early diagnosis and monitoring of conditions like Alzheimer's or Parkinson's diseases. While the field is still evolving, functionalized nanoparticles represent a promising path for advancing our ability to diagnose and treat brain disorders with greater precision, reduced invasiveness, and improved therapeutic outcomes.

A narrative review of the synthesis, characterization, and applications of iron oxide nanoparticles

The significance of green synthesized nanomaterials with a uniform shape, reduced sizes, superior mechanical capabilities, phase microstructure, magnetic behavior, and superior performance cannot be overemphasized. Iron oxide nanoparticles (IONPs) are found within the size range of 1-100 nm in nanomaterials and have a diverse range of applications in fields such as biomedicine, wastewater purification, and environmental remediation. Nevertheless, the understanding of their fundamental material composition, chemical reactions, toxicological properties, and research methodologies is constrained and extensively elucidated during their practical implementation. The importance of producing IONPs using advanced nanofabrication techniques that exhibit strong potential for disease therapy, microbial pathogen control, and elimination of cancer cells is underscored by the adoption of the green synthesis approach. These IONPs can serve as viable alternatives for soil remediation and the elimination of environmental contaminants. Therefore, this paper presents a comprehensive analysis of the research conducted on different types of IONPs and IONP composite-based materials. It examines the synthesis methods and characterization techniques employed in these studies and also addresses the obstacles encountered in prior investigations with comparable objectives. A green engineering strategy was proposed for the synthesis, characterization, and application of IONPs and their composites with reduced environmental impact. Additionally, the influence of their phase structure, magnetic properties, biocompatibility, toxicity, milling time, nanoparticle size, and shape was also discussed. The study proposes the use of biological and physicochemical methods as a more viable alternative nanofabrication strategy that can mitigate the limitations imposed by the conventional methods of IONP synthesis.

Modified gefitinib conjugated Fe3O4 NPs for improved delivery of chemo drugs following an image-guided mechanistic study of inner vs. outer tumor uptake for the treatment of non-small cell lung cancer

Gefitinib (GEF) is an FDA-approved anti-cancer drug for the first-line treatment of patients with metastatic non-small cell lung cancer (NSCLC). However, the efficacy of anticancer drugs is limited due to their non-specificity, lower accumulation at target sites, and systemic toxicity. Herein, we successfully synthesized a modified GEF (mGEF) drug and conjugated to Iron oxide nanoparticles (Fe3O4 NPs) for the treatment of NSCLC via magnetic resonance (MR) image-guided drug delivery. A traditional EDC coupling pathway uses mGEF to directly conjugate to Fe3O4 NPs to overcom the drug leakage issues. As a result, we found in vitro drug delivery on mGEF- Fe3O4 NPs exhibits excellent anticancer effects towards the PC9 cells selectively, with an estimated IC 50 value of 2.0 μM. Additionally, in vivo MRI and PET results demonstrate that the NPs could accumulate in tumor-specific regions with localized cell growth inhibition. Results also revealed that outer tumor region exhibiting a stronger contrast than the tinner tumor region which may due necrosis in inner tumor region. In vivo biodistribution further confirms Fe3O4 NPs are more biocompatible and are excreated after the treatment. Overall, we believe that this current strategy of drug modification combined with chemical conjugation on magnetic NPs will lead to improved cancer chemotherapy as well as understanding the tumor microenvironments for better therapeutic outcomes.

mAb-Functionalized Biomimetic MamC-Mediated-Magnetoliposomes as Drug Delivery Systems for Cancer Therapy

In cancer therapy, new therapeutic nanoformulations able to mediate targeted chemotherapy are required. Recently, biomimetic magnetic nanoparticles (BMNPs) mediated by MamC, a magnetosome protein from Magnetococcus marinus MC-1, have proven, in vitro and in vivo, to be effective drug nanocarriers (following the application of an external gradient magnetic field) and to allow combination with hyperthermia. However, these nanoassemblies require further optimization to improve cytocompatibility, stability and active targeting ability. Herein, we describe the production of the magnetoliposomes (LP) embedding BMNPs functionalized (or not) with doxorubicin (DOXO), [LP(+/-DOXO-BMNPs)], and their surface modification with the DO-24 mAb, which targets the human Met/HGF receptor's ectodomain (overexpressed in many cancers). Nanoformulations were extensively characterized using TEM, DLS, FTIR and when tested in vitro, the lipid coating increased the colloidal stability and their biocompatibility, favoring the cellular uptake in cells overexpressing the cognate receptor. Indeed, the magnetoliposomes mAb-LP(+/-DOXO-BMNPs) exerted a specific active targeting ability by the presence of the mAb that preserved its immunocompetence. Both LP(BMNPs) and mAb-LP(BMNPs) were not toxic to cells, while +/-mAb-LP(DOXO-BMNPs) nanoformulations were indeed cytotoxic. Therefore, this study represents a proof of concept for the development of promising drug carriers for cancer therapy based on local chemotherapy directed by mAbs.

Size dependence of the surface spin disorder and surface anisotropy constant in ferrite nanoparticles

The magnetic properties of nanoscale magnets are greatly influenced by surface anisotropy. So far, its quantification is based on the examination of the blocking temperature shift within a series of nanoparticles of varying sizes. In this scenario, the surface anisotropy is assumed to be a particle size-independent quantity. However, there is no solid experimental proof to support this simplified picture. On the contrary, our work unravels the size-dependent magnetic morphology and surface anisotropy in highly uniform magnetic nanoparticles using small-angle polarized neutron scattering. We observed that the surface anisotropy constant does not depend on the nanoparticle's size in the range of 3-9 nm. Furthermore, our results demonstrate that the surface spins are less prone to polarization with increasing nanoparticle size. Our study thus proves the size dependence of the surface spin disorder and the surface anisotropy constant in fine nanomagnets. These findings open new routes in materials based on a controlled surface spin disorder, which is essential for future applications of nanomagnets in biomedicine and magnonics.

Preparation and PET/CT imaging of implant directed 68Ga-labeled magnetic nanoporous silica nanoparticles

BACKGROUND

Implant infections caused by biofilm forming bacteria are a major threat in orthopedic surgery. Delivering antibiotics directly to an implant affected by a bacterial biofilm via superparamagnetic nanoporous silica nanoparticles could present a promising approach. Nevertheless, short blood circulation half-life because of rapid interactions of nanoparticles with the host's immune system hinder them from being clinically used. The aim of this study was to determine the temporal in vivo resolution of magnetic nanoporous silica nanoparticle (MNPSNP) distribution and the effect of PEGylation and clodronate application using PET/CT imaging and gamma counting in an implant mouse model.

METHODS

PEGylated and non-PEGylated MNPSNPs were radiolabeled with gallium-68 (68Ga), implementing the chelator tris(hydroxypyridinone). 36 mice were included in the study, 24 mice received a magnetic implant subcutaneously on the left and a titanium implant on the right hind leg. MNPSNP pharmacokinetics and implant accumulation was analyzed in dependence on PEGylation and additional clodronate application. Subsequently gamma counting was performed for further final analysis.

RESULTS

The pharmacokinetics and biodistribution of all radiolabeled nanoparticles could clearly be visualized and followed by dynamic PET/CT imaging. Both variants of 68Ga-labeled MNPSNP accumulated mainly in liver and spleen. PEGylation of the nanoparticles already resulted in lower liver uptakes. Combination with macrophage depletion led to a highly significant effect whereas macrophage depletion alone could not reveal significant differences. Although MNPSNP accumulation around implants was low in comparison to the inner organs in PET/CT imaging, gamma counting displayed a significantly higher %I.D./g for the tissue surrounding the magnetic implants compared to the titanium control. Additional PEGylation and/or macrophage depletion revealed no significant differences regarding nanoparticle accumulation at the implantation site.

CONCLUSION

Tracking of 68Ga-labeled nanoparticles in a mouse model in the first critical hours post-injection by PET/CT imaging provided a better understanding of MNPSNP distribution, elimination and accumulation. Although PEGylation increases circulation time, nanoparticle accumulation at the implantation site was still insufficient for infection treatment and additional efforts are needed to increase local accumulation.

Endogenous and Exogenous Antioxidants as Agents Preventing the Negative Effects of Contrast Media (Contrast-Induced Nephropathy)

The use of conventional contrast media for diagnostic purposes (in particular, Gd-containing and iodinated agents) causes a large number of complications, the most common of which is contrast-induced nephropathy. It has been shown that after exposure to contrast agents, oxidative stress often occurs in patients, especially in people suffering from various diseases. Antioxidants in the human body can diminish the pathological consequences of the use of contrast media by suppressing oxidative stress. This review considers the research studies on the role of antioxidants in preventing the negative consequences of the use of contrast agents in diagnostics (mainly contrast-induced nephropathy) and the clinical trials of different antioxidant drugs against contrast-induced nephropathy. Composite antioxidant/contrast systems as theranostic agents are also considered.

Advances in Enantiomer-Dependent Nanotherapeutics

The nanoscale properties of nanomaterials, especially nanoparticles, including size, shape, and surface charge, have been extensively studied for their impact on nanomedicine. Given the inherent chiral nature of biological systems and their high enantiomeric selectivity, there is rising interest to manipulate the chirality of nanomaterials to enhance their biomolecular interactions and improve nanotherapeutics. Chiral nanostructures are currently more prevalently used in biosensing and diagnostic applications owing to their distinctive physical and optical properties, but they hold great promise for use in nanomedicine. In this Review, we first discuss stereospecific interactions between chiral nanomaterials and biomolecules before comparing the synthesis and characterization methods of chiral nanoparticles and nanoassemblies. Finally, we examine the applications of chiral nanotherapeutics in cancer, immunomodulation, and neurodegenerative diseases and propose plausible mechanisms in which chiral nanomaterials interact with cells for biological manipulation. This Review on chirality is a timely reminder of the arsenal of nanoscale modifications to boost research in nanotherapeutics.

Influence of the modifiers in polyol method on magnetically induced hyperthermia and biocompatibility of ultrafine magnetite nanoparticles

Magnetite nanoparticles (Fe₃O₄ NPs) are widely tested in various biomedical applications, including magnetically induced hyperthermia. In this study, the influence of the modifiers, i.e., urotropine, polyethylene glycol, and NH₄HCO_3, on the size, morphology, magnetically induced hyperthermia effect, and biocompatibility were tested for Fe₃O₄ NPs synthesized by polyol method. The nanoparticles were characterized by a spherical shape and similar size of around 10 nm. At the same time, their surface is functionalized by triethylene glycol or polyethylene glycol, depending on the modifiers. The Fe₃O₄ NPs synthesized in the presence of urotropine had the highest colloidal stability related to the high positive value of zeta potential (26.03 ± 0.55 mV) but were characterized by the lowest specific absorption rate (SAR) and intrinsic loss power (ILP). The highest potential in the hyperthermia applications have NPs synthesized using NH₄HCO₃, for which SAR and ILP were equal to 69.6 ± 5.2 W/g and 0.613 ± 0.051 nHm²/kg, respectively. Their application possibility was confirmed for a wide range of magnetic fields and by cytotoxicity tests. The absence of differences in toxicity to dermal fibroblasts between all studied NPs was confirmed. Additionally, no significant changes in the ultrastructure of fibroblast cells were observed apart from the gradual increase in the number of autophagous structures.

Facile Synthesis and X-ray Attenuation Properties of Ultrasmall Platinum Nanoparticles Grafted with Three Types of Hydrophilic Polymers

Ultrasmall platinum nanoparticles (Pt-NPs) grafted with three types of hydrophilic and biocompatible polymers, i.e., poly(acrylic acid), poly(acrylic acid-co-maleic acid), and poly(methyl vinyl ether-alt-maleic acid) were synthesized using a one-pot polyol method. Their physicochemical and X-ray attenuation properties were characterized. All polymer-coated Pt-NPs had an average particle diameter (davg) of 2.0 nm. Polymers grafted onto Pt-NP surfaces exhibited excellent colloidal stability (i.e., no precipitation after synthesis for >1.5 years) and low cellular toxicity. The X-ray attenuation power of the polymer-coated Pt-NPs in aqueous media was stronger than that of the commercial iodine contrast agent Ultravist at the same atomic concentration and considerably stronger at the same number density, confirming their potential as computed tomography contrast agents.

3D Printable Hybrid Gel Made of Polymer Surface-Modified Cellulose Nanofibrils Prepared by Surface-Initiated Controlled Radical Polymerization (SI-SET-LRP) and Upconversion Luminescent Nanoparticles

A cellulose nanofibril-based hybrid gel material was developed by grafting the polymerized stearyl acrylate (PSA) and upconversion nanoparticles (UCNPs) onto cellulose nanofibrils (CNFs) via Cu⁰-mediated radical polymerization (SET-LRP) to create a highly cross-linked CNF system. A two-step strategy was exploited to surface-exchange the ligand of the UCNPs from a hydrophobic ligand (oleic acid) to a hydrophilic small-molecule ligand (2-acrylamido-2-methyl-1-propanesulfonic acid, AMPS) and therefore be suitable for SET-LRP. The characteristics and properties of the hybrid material (UCNP-PSA-CNF) were monitored by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), rheology, X-ray diffraction (XRD), and microscopic analysis. Those characterization techniques prove the efficient modification of the CNF, with the presence of 1.8% UCNPs. The luminescence measurement was carried out using a homebuilt confocal microscope with a 980 nm laser source. The nanostructure of UCNPs and their incorporated CNF species were measured by small-angle X-ray scattering (SAXS). In addition, this CNF-based hybrid gel has decisive rheological properties, such as good viscoelasticity (loss tangent was below 0.35 for the UCNP-PSA-CNF gel, while the PSA-CNF gel reached the highest value of 0.42), shear-thinning behavior, and shape retention, and was successfully applied to three-dimensional (3D) gel printing throughout various 3D print models.

Magnetic Nanoparticles for Protein Separation and Purification

Proteins are essential for various functions such as brain activity and muscle contraction in humans. Even though food is a source of proteins, the bioavailability of proteins in most foods is usually limited due to matrix interaction with other biomolecules. Thus, it is essential to extract these proteins and provide them as a nutraceutical supplement to maintain protein levels and avoid protein deficiency. Hence, protein purification and extraction from natural sources are highly significant in biomedical applications. Chromatography, crude mechanical disruption, use of extractive chemicals, and electrophoresis are some of the methods applied to isolate specific proteins. Even though these methods possess several advantages, they are unable to extract specific proteins with high purity. A suitable alternative is the use of nanoparticles, which can be beneficial in protein purification and extraction. Notably, magnetic iron and iron-based nanoparticles have been employed in protein extraction processes and can be reused via demagnetization due to their magnetic property, smaller size, morphology, high surface-to-volume ratio, and surface charge-mediated property. This chapter is a summary of various magnetic nanoparticles (MNPs) that can be used for the biomolecular separation of proteins.

Different coatings on magnetic nanoparticles dictate their degradation kinetics in vivo for 15 months after intravenous administration in mice

BACKGROUND

The surface coating of iron oxide magnetic nanoparticle (MNPs) drives their intracellular trafficking and degradation in endolysosomes, as well as dictating other cellular outcomes. As such, we assessed whether MNP coatings might influence their biodistribution, their accumulation in certain organs and their turnover therein, processes that must be understood in vivo to optimize the design of nanoformulations for specific therapeutic/diagnostic needs.

RESULTS

In this study, three different MNP coatings were analyzed, each conferring the identical 12 nm iron oxide cores with different physicochemical characteristics: 3-aminopropyl-triethoxysilane (APS), dextran (DEX), and dimercaptosuccinic acid (DMSA). When the biodistribution of these MNPs was analyzed in C57BL/6 mice, they all mainly accumulated in the spleen and liver one week after administration. The coating influenced the proportion of the MNPs in each organ, with more APS-MNPs accumulating in the spleen and more DMSA-MNPs accumulating in the liver, remaining there until they were fully degraded. The changes in the physicochemical properties of the MNPs (core size and magnetic properties) was also assessed during their intracellular degradation when internalized by two murine macrophage cell lines. The decrease in the size of the MNPs iron core was influenced by their coating and the organ in which they accumulated. Finally, MNP degradation was analyzed in the liver and spleen of C57BL/6 mice from 7 days to 15 months after the last intravenous MNP administration.

CONCLUSIONS

The MNPs degraded at different rates depending on the organ and their coating, the former representing the feature that was fundamental in determining the time they persisted. In the liver, the rate of degradation was similar for all three coatings, and it was faster than in the spleen. This information regarding the influence of coatings on the in vivo degradation of MNPs will help to choose the best coating for each biomedical application depending on the specific clinical requirements.

Hyperthermia of Magnetically Soft-Soft Core-Shell Ferrite Nanoparticles

Magnetically soft-soft MnFe₂O₄-Fe₃O₄ core-shell nanoparticles were synthesized through a seed-mediated method using the organometallic decomposition of metal acetyl acetonates. Two sets of core-shell nanoparticles (S1 and S2) of similar core sizes of 5.0 nm and different shell thicknesses (4.1 nm for S1 and 5.7 nm for S2) were obtained by changing the number of nucleating sites. Magnetic measurements were conducted on the nanoparticles at low and room temperatures to study the shell thickness and temperature dependence of the magnetic properties. Interestingly, both core-shell nanoparticles showed similar saturation magnetization, revealing the ineffective role of the shell thickness. In addition, the coercivity in both samples displayed similar temperature dependencies and magnitudes. Signatures of spin glass (SG) like behavior were observed from the field-cooled temperature-dependent magnetization measurements. It was suggested to be due to interface spin freezing. We observed a slight and non-monotonic temperature-dependent exchange bias in both samples with slightly higher values for S2. The effective magnetic anisotropy constant was calculated to be slightly larger in S2 than that in S1. The magnetothermal efficiency of the chitosan-coated nanoparticles was determined by measuring the specific absorption rate (SAR) under an alternating magnetic field (AMF) at 200-350 G field strengths and frequencies (495.25-167.30 kHz). The S2 nanoparticles displayed larger SAR values than the S1 nanoparticles at all field parameters. A maximum SAR value of 356.5 W/g was obtained for S2 at 495.25 kHz and 350 G for the 1 mg/mL nanoparticle concentration of ferrogel. We attributed this behavior to the larger interface SG regions in S2, which mediated the interaction between the core and shell and thus provided indirect exchange coupling between the core and shell phases. The SAR values of the core-shell nanoparticles roughly agreed with the predictions of the linear response theory. The concentration of the nanoparticles was found to affect heat conversion to a great extent. The in vitro treatment of the MDA-MB-231 human breast cancer cell line and HT-29 human colorectal cancer cell was conducted at selected frequencies and field strengths to evaluate the efficiency of the nanoparticles in killing cancer cells. The cellular cytotoxicity was estimated using flow cytometry and an MTT assay at 0 and 24 h after treatment with the AMF. The cells subjected to a 45 min treatment of the AMF (384.50 kHz and 350 G) showed a remarkable decrease in cell viability. The enhanced SAR values of the core-shell nanoparticles compared to the seeds with the most enhancement in S2 is an indication of the potential for tailoring nanoparticle structures and hence their magnetic properties for effective heat generation.

Atomic Force Manipulation of Single Magnetic Nanoparticles for Spin-Based Electronics

Magnetic nanoparticles (MNPs) are instrumental for fabrication of tailored nanomagnetic structures, especially where top-down lithographic patterning is not feasible. Here, we demonstrate precise and controllable manipulation of individual magnetite MNPs using the tip of an atomic force microscope. We verify our approach by placing a single MNP with a diameter of 50 nm on top of a 100 nm Hall bar fabricated in a quasi-two-dimensional electron gas (q2DEG) at the oxide interface between LaAlO₃ and SrTiO₃ (LAO/STO). A hysteresis loop due to the magnetic hysteresis properties of the magnetite MNPs was observed in the Hall resistance. Further, the effective coercivity of the Hall resistance hysteresis loop could be changed upon field cooling at different angles of the cooling field with respect to the measuring field. The effect is associated with the alignment of the MNP magnetic moment along the easy axis closest to the external field direction across the Verwey transition in magnetite. Our results can facilitate experimental realization of magnetic proximity devices using single MNPs and two-dimensional materials for spin-based nanoelectronics.

Development of Core@Shell γ-Fe2O3@MnxOy@SiO2 Nanoparticles for Hyperthermia, Targeting, and Imaging Applications

Monodispersed core@shell γ-Fe₂O₃@Mn_xO_y nanoparticles have been prepared through thermolysis of iron and manganese oleate. Further, these prepared nanoparticles are coated with biocompatible substances such as silica and polyethylene glycol. These particles are highly biocompatible for different cell lines such as normal and cancer cell lines. The nanoparticles are used as hyperthermia agents, and successful hyperthermia treatment in cancer cells is carried out. As compared to γ-Fe₂O₃@SiO₂, γ-Fe₂O₃@Mn_xO_y@SiO₂ shows the enhanced killing of cancer cells through hyperthermia. In order to make them potential candidates for targeting to cancer cells, folic acid (FA) is tagged to the nanoparticles. Fluorescein isothiocyanate (FITC) is also tagged onto these nanoparticles for imaging. The developed γ-Fe₂O₃@Mn_xO_y@SiO₂ nanoparticle can act as a single entity for therapy through AC magnetic field, imaging through FITC and targeting through folic acid simultaneously. This is the first report on this material, which is highly biocompatible for hyperthermia, imaging, and targeting.

Emergent magnetism and exchange bias effect in iron oxide nanocubes with tunable phase and size

We report a systematic investigation of the magnetic properties including the exchange bias (EB) effect in an iron oxide nanocube system with tunable phase and average size (10, 15, 24, 34, and 43 nm). X-ray diffraction and Raman spectroscopy reveal the presence of Fe₃O₄, FeO, andα-Fe₂O₃phases in the nanocubes, in which the volume fraction of each phase varies depending upon particle size. While the Fe₃O₄phase is dominant in all and tends to grow with increasing particle size, the FeO phase appears to coexist with the Fe₃O₄phase in 10, 15, and 24 nm nanocubes but disappears in 34 and 43 nm nanocubes. The nanocubes exposed to air resulted in anα-Fe₂O₃oxidized surface layer whose thickness scaled with particle size resulting in a shell made ofα-Fe₂O₃phase and a core containing Fe₃O₄or a mixture of both Fe₃O₄and FeO phases. Magnetometry indicates that the nanocubes undergo Morin (of theα-Fe₂O₃phase) and Verwey (of the Fe₃O₄phase) transitions at ∼250 K and ∼120 K, respectively. For smaller nanocubes (10, 15, and 24 nm), the EB effect is observed below 200 K, of which the 15 nm nanocubes showed the most prominent EB with optimal antiferromagnetic (AFM) FeO phase. No EB is reported for larger nanocubes (34 and 43 nm). The observed EB effect is ascribed to the strong interfacial coupling between the ferrimagnetic (FiM) Fe₃O₄phase and AFM FeO phase, while its absence is related to the disappearance of the FeO phase. The Fe₃O₄/α-Fe₂O₃(FiM/AFM) interfaces are found to have negligible influence on the EB. Our findings shed light on the complexity of the EB effect in mixed-phase iron oxide nanosystems and pave the way to design exchange-coupled nanomaterials with desirable magnetic properties for biomedical and spintronic applications.

A Sensitive Fluorescent Immunoassay for Prostate Specific Antigen Detection Based on Signal Amplify Strategy of Horseradish Peroxidase and Silicon Dioxide Nanospheres

A simple, sensitive, and fluorescent immunoassay for the detection of prostate-specific antigen (PSA) based on horseradish peroxidase and silicon dioxide nanospheres as a signal amplification strategy has been described. In the design, the primary antibody (Ab₁) of PSA was first immobilized on the 96-well plates via physical adsorption between polystyrene and hydrophobic groups of the antibody molecule. The silicon dioxide nanospheres (SiO₂ NSs), with large surface area and good biocompatibility, were loaded with horseradish peroxidase (HRP) and horseradish peroxidase-labeled secondary antibodies (HRP-Ab₂) as signal amplification systems. In the presence of PSA, a sandwich-type immunocomplex composed of Ab₁-Ag-HRP-Ab₂ had been formed. Fluorescence technology was employed to obtain the response signal of the immunoassay in the L-tyrosine and H₂O₂ systems. Experiment results showed that a strong and stable fluorescent signal at 416 nm (excitation wavelength: 325 nm) was observed, and the changes in fluorescent intensity were related to the levels of PSA. Under the optimal conditions, the relative fluorescence intensity was linear with the logarithm of PSA concentration from 0.03 to 100 ng·mL^-1, with a detection limit of 0.01 ng·mL^-1 (at a signal/noise ratio of 3). In contrast to other fluorescent immunoassays, the sandwich-type immunoreaction based on the high binding ELISA plates has the advantages of being simple, stable, and easy to operate, high selectivity, small sample quantity, etc., which can be widely used in the selective detection of a variety of targets, from DNA to proteins and small molecules. Such fluorescent immunoassays should be feasible for the fields of molecular diagnosis and other life science fields in the future.

Superparamagnetic Nickel Nanocluster-Embedded MoS2 Nanosheets for Gram-Selective Bacterial Adhesion and Antibacterial Activity

Ever increasing infectious diseases caused by pathogenic bacteria are creating one of the greatest health problems. The extensive use of numerous antibiotics and antimicrobial agents has prompted the growth of multidrug-resistant bacterial strains. The ancient biomedical application of metals and the recent advancement in the field of nanotechnology have encouraged us to explore the antimicrobial activity of nanomaterials. Herein, we have synthesized a magnetically separable superparamagnetic nickel nanocluster-loaded two-dimensional molybdenum disulfide nanocomposite (Ni@2D-MoS₂). It can selectively bind with Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis over Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa. After the functionalization of Ni@2D-MoS₂ with a positively charged ligand, it showed an excellent Gram-selective antibacterial activity toward MRSA and E. faecalis. Furthermore, the superparamagnetic property of the synthesized material can be used for the simultaneous removal and killing of the microbes and recycled for further use. This study demonstrates strategies to develop hybrid antimicrobial nanomaterial systems for selective antibacterial activity with recyclability.

Silica sulfuric acid coated on SnFe2O4 MNPs: synthesis, characterization and catalytic applications in the synthesis of polyhydroquinolines

An efficient and heterogeneous novel magnetic solid sulfuric acid, immobilized on silica functionalized SnFe₂O₄, was successfully synthesized, characterized, and employed as a novel recoverable nanocatalyst for the synthesis of biologically active polyhydroquinoline derivatives. The SnFe₂O₄@SiO₂-SO₃H was easily synthesized and confirmed using various spectroscopic techniques, including FT-IR, XRD, EDX, Map, TGA, SEM and TEM analyses. The catalytic behavior of the resulting catalyst system was investigated in the Hantzsch synthesis of polyhydroquinoline derivatives. The desired products were obtained with high conversions and excellent reusability.

Smart Shape-Memory Polymeric String for the Contraction of Blood Vessels in Fetal Surgery of Sacrococcygeal Teratoma

Shape-memory polymers (SMPs) are promising materials in numerous emerging biomedical applications owing to their unique shape-memory characteristics. However, simultaneous realization of high strength, toughness, stretchability while maintaining high shape fixity (R_f ) and shape recovery ratio (R_r ) remains a challenge that hinders their practical applications. Herein, a novel shape-memory polymeric string (SMP string) that is ultra-stretchable (up to 1570%), strong (up to 345 MPa), tough (up to 237.9 MJ m^-3 ), and highly recoverable (R_f averagely above 99.5%, R_r averagely above 99.1%) through a facile approach fabricated solely by tetra-branched poly(ε-caprolactone) (PCL) is reported. Notably, the shape-memory contraction force (up to 7.97 N) of this SMP string is customizable with the manipulation of their energy storage capacity by adjusting the string thickness and stretchability. In addition, this SMP string displays a controllable shape-memory response time and demonstrates excellent shape-memory-induced contraction effect against both rigid silicone tubes and porcine carotids. This novel SMP string is envisioned to be applied in the contraction of blood vessels and resolves the difficulties in the restriction of blood flow in minimally invasive surgeries such as fetoscopic surgery of sacrococcygeal teratoma (SCT).

Hercynite silica sulfuric acid: a novel inorganic sulfurous solid acid catalyst for one-pot cascade organic transformations

Herein, we delignated the synthesis of a novel inorganic sulfurous magnetic solid acid catalyst by the immobilization of an extremely high content of sulfuric acid functionalities on the amorphous silica-modified hercynite nanomagnetic core–shell via a simple method. Silica sulfuric acid (SSA) modified hercynite nanocomposite (hercynite@SSA) combines excellent recoverability and stability characteristics of hercynite (which can be regarded as a ferro spinel with Fd3m space group and cubic crystal structure) with the strong Brønsted acid properties of –SO₃H groups. This nanomagnetic solid acid was found to be an efficient and facile strong solid acid catalyst for the synthesis of bis(pyrazolyl)methanes via two different one-pot multicomponent methodologies under green conditions. The hercynite@SSA catalyst shows excellent catalytic activity and reusability in the ethanolic medium among different solid acid materials. A plausible reaction mechanism is proposed for this synthesis.

A novel inorganic sulfurous nanomagnetic solid acid composite was synthesized and its catalytic activity was evaluated in the synthesis of bis(pyrazolyl)methane derivatives. The catalyst displayed excellent activity and recoverability under green conditions.

The Effect of Zn-Substitution on the Morphological, Magnetic, Cytotoxic, and In Vitro Hyperthermia Properties of Polyhedral Ferrite Magnetic Nanoparticles

The clinical translation of magnetic hyperthermia (MH) needs magnetic nanoparticles (MNPs) with enhanced heating properties and good biocompatibility. Many studies were devoted lately to the increase in the heating power of iron oxide MNPs by doping the magnetite structure with divalent cations. A series of MNPs with variable Zn/Fe molar ratios (between 1/10 and 1/1) were synthesized by using a high-temperature polyol method, and their physical properties were studied with different techniques (Transmission Electron Microscopy, X-ray diffraction, Fourier Transform Infrared Spectroscopy). At low Zn doping (Zn/Fe ratio 1/10), a significant increase in the saturation magnetization (90 e.m.u./g as compared to 83 e.m.u./g for their undoped counterparts) was obtained. The MNPs' hyperthermia properties were assessed in alternating magnetic fields up to 65 kA/m at a frequency of 355 kHz, revealing specific absorption rates of up to 820 W/g. The Zn ferrite MNPs showed good biocompatibility against two cell lines (A549 cancer cell line and BJ normal cell line) with a drop of only 40% in the viability at the highest dose used (500 μg/cm2). Cellular uptake experiments revealed that the MNPs enter the cells in a dose-dependent manner with an almost 50% higher capacity of cancer cells to accommodate the MNPs. In vitro hyperthermia data performed on both cell lines indicate that the cancer cells are more sensitive to MH treatment with a 90% drop in viability after 30 min of MH treatment at 30 kA/m for a dose of 250 μg/cm2. Overall, our data indicate that Zn doping of iron oxide MNPs could be a reliable method to increase their hyperthermia efficiency in cancer cells.

Nanoparticles for Magnetic Heating: When Two (or More) Is Better Than One

The increasing use of magnetic nanoparticles as heating agents in biomedicine is driven by their proven utility in hyperthermia therapeutic treatments and heat-triggered drug delivery methods. The growing demand of efficient and versatile nanoheaters has prompted the creation of novel types of magnetic nanoparticle systems exploiting the magnetic interaction (exchange or dipolar in nature) between two or more constituent magnetic elements (magnetic phases, primary nanoparticles) to enhance and tune the heating power. This process occurred in parallel with the progress in the methods for the chemical synthesis of nanostructures and in the comprehension of magnetic phenomena at the nanoscale. Therefore, complex magnetic architectures have been realized that we classify as: (a) core/shell nanoparticles; (b) multicore nanoparticles; (c) linear aggregates; (d) hybrid systems; (e) mixed nanoparticle systems. After a general introduction to the magnetic heating phenomenology, we illustrate the different classes of nanoparticle systems and the strategic novelty they represent. We review some of the research works that have significantly contributed to clarify the relationship between the compositional and structural properties, as determined by the synthetic process, the magnetic properties and the heating mechanism.