Design and synthesis of magnetic nanoparticles for biomedical diagnostics

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.

Iron acquisition and mineral transformation by cyanobacteria living in extreme environments

Iron is an essential micronutrient for most living organisms, including cyanobacteria. These microorganisms have been found in Earth's driest polar and non-polar deserts, including the Atacama Desert, Chile. Iron-containing minerals were identified in colonized rock substrates from the Atacama Desert, however, the interactions between microorganisms and iron minerals remain unclear. In the current study, we determined that colonized gypsum rocks collected from the Atacama Desert contained both magnetite and hematite phases. A cyanobacteria isolate was cultured on substrates consisting of gypsum with embedded magnetite nanoparticles. Transmission electron microscopy imaging revealed a significant reduction in the size of magnetite nanoparticles due to their dissolution, which occurred around the microbial biofilms. Concurrently, hematite was detected, likely from the oxidation of the magnetite nanoparticles. Higher cell counts and production of siderophores were observed in cultures with magnetite nanoparticles suggesting that cyanobacteria were actively acquiring iron from the magnetite nanoparticles. Magnetite dissolution and iron acquisition by the cyanobacteria was further confirmed using large bulk magnetite crystals, uncovering a survival strategy of cyanobacteria in these extreme environments.

CFD Analysis and Life Cycle Assessment of Continuous Synthesis of Magnetite Nanoparticles Using 2D and 3D Micromixers

Magnetite nanoparticles (MNPs) have attracted basic and applied research due to their immense potential to enable applications in fields as varied as drug delivery and bioremediation. Conventional synthesis schemes led to wide particle size distributions and inhomogeneous morphologies and crystalline structures. This has been attributed to the inability to control nucleation and growth processes under the conventional conditions of bulk batch processes. Here, we attempted to address these issues by scaling down the synthesis process aided by microfluidic devices, as they provide highly controlled and stable mixing patterns. Accordingly, we proposed three micromixers with different channel configurations, namely, serpentine, triangular, and a 3D arrangement with abrupt changes in fluid direction. The micromixers were first studied in silico, aided by Comsol Multiphysics^® to investigate the obtained mixing patterns, and consequently, their potential for controlled growth and the nucleation processes required to form MNPs of uniform size and crystalline structure. The devices were then manufactured using a low-cost approach based on polymethyl methacrylate (PMMA) and laser cutting. Testing the micromixers in the synthesis of MNPs revealed homogeneous morphologies and particle size distributions, and the typical crystalline structure reported previously. A life cycle assessment (LCA) analysis for the devices was conducted in comparison with conventional batch co-precipitation synthesis to investigate the potential impacts on water and energy consumption. The obtained results revealed that such consumptions are higher than those of the conventional process. However, they can be reduced by conducting the synthesis with reused micromixers, as new PMMA is not needed for their assembly prior to operation. We are certain that the proposed approach represents an advantageous alternative to co-precipitation synthesis schemes, in terms of continuous production and more homogeneous physicochemical parameters of interest such as size, morphologies, and crystalline structure. Future work should be directed towards improving the sustainability indicators of the micromixers’ manufacturing process.

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.

The Potential Application of Magnetic Nanoparticles for Liver Fibrosis Theranostics

Liver fibrosis is a major cause of morbidity and mortality worldwide due to chronic liver damage and leading to cirrhosis, liver cancer, and liver failure. To date, there is no effective and specific therapy for patients with hepatic fibrosis. As a result of their various advantages such as biocompatibility, imaging contrast ability, improved tissue penetration, and superparamagnetic properties, magnetic nanoparticles have a great potential for diagnosis and therapy in various liver diseases including fibrosis. In this review, we focus on the molecular mechanisms and important factors for hepatic fibrosis and on potential magnetic nanoparticles-based therapeutics. New strategies for the diagnosis of liver fibrosis are also discussed, with a summary of the challenges and perspectives in the translational application of magnetic nanoparticles from bench to bedside.

Synthesis and applications of surface-modified magnetic nanoparticles: progress and future prospects

The growing use of magnetic nanoparticles (MNPs) demands cost-effective methods for their synthesis that allow proper control of particle size and size distribution. The unique properties of MNPs include high specific surface area, ease of functionalization, chemical stability and superparamagnetic behavior, with applications in catalysis, data and energy storage, environmental remediation and biomedicine. This review highlights breakthroughs in the use of MNPs since their initial introduction in biomedicine to the latest challenging applications; special attention is paid to the importance of proper coating and functionalization of the particle surface, which dictates the specific properties for each application. Starting from the first report following LaMer’s theory in 1950, this review discusses and analyzes methods of synthesizing MNPs, with an emphasis on functionality and applications. However, several hurdles, such as the design of reactors with suitable geometries, appropriate control of operating conditions and, in particular, reproducibility and scalability, continue to prevent many applications from reaching the market. The most recent strategy, the use of microfluidics to achieve continuous and controlled synthesis of MNPs, is therefore thoroughly analyzed. This review is the first to survey continuous microfluidic coating or functionalization of particles, including challenging properties and applications.

Magnetite (Fe3O4) Nanoparticles in Biomedical Application: From Synthesis to Surface Functionalisation

Nanotechnology has gained much attention for its potential application in medical science. Iron oxide nanoparticles have demonstrated a promising effect in various biomedical applications. In particular, magnetite (Fe3O4) nanoparticles are widely applied due to their biocompatibility, high magnetic susceptibility, chemical stability, innocuousness, high saturation magnetisation, and inexpensiveness. Magnetite (Fe3O4) exhibits superparamagnetism as its size shrinks in the single-domain region to around 20 nm, which is an essential property for use in biomedical applications. In this review, the application of magnetite nanoparticles (MNPs) in the biomedical field based on different synthesis approaches and various surface functionalisation materials was discussed. Firstly, a brief introduction on the MNP properties, such as physical, thermal, magnetic, and optical properties, is provided. Considering that the surface chemistry of MNPs plays an important role in the practical implementation of in vitro and in vivo applications, this review then focuses on several predominant synthesis methods and variations in the synthesis parameters of MNPs. The encapsulation of MNPs with organic and inorganic materials is also discussed. Finally, the most common in vivo and in vitro applications in the biomedical world are elucidated. This review aims to deliver concise information to new researchers in this field, guide them in selecting appropriate synthesis techniques for MNPs, and to enhance the surface chemistry of MNPs for their interests.

pH Tunable Thin Film Gradients of Magnetic Polymer Colloids for MRI Diagnostics

Magnetic polymer colloids comprising of magnetite (Fe₃O₄) nanoparticles and Eudragit E100 were employed to fabricate thin film gradients and were investigated for in-vitro magnetic resonance imaging. Magnetic polymer colloids (MPC) and polyacrylic acid (PAA) with stimuli-responsive cationic and anionic functional groups respectively facilitate the formation of thin film gradients via layer by layer technique. The characteristics of films were controlled by changing the pH and level of the adsorbing solutions that lead to the development of gradient films having 5.5, 10.5 and 15.5 bilayers. Optical microscopy, scanning electron microscopy and magnetic force microscopy was carried out to determine the surface coverage of films. Surface wettability demonstrated the hydrophilicity of adsorbed colloids. The developed thin-film gradients were explored for in vitro magnetic resonance imaging that offers a point of care lab-on-chip as a dip-stick approach for ultrasensitive in-vitro molecular diagnosis of biological fluids.

Water-Nanomaterial Interaction to Escalate Twin-Mode Magnetic Resonance Imaging

Molecular imaging has gained utmost importance in the recent past in early diagnosis of diseases. In comparison to other imaging modalities, magnetic resonance imaging (MRI) has proven to extend its abilities not only for its usage of non-ionizing radiation but also for the high spatial resolution in soft tissues. A major limitation faced by MRI is the sensitivity in detecting diseased conditions until a certain stage. At present, this limitation is overcome with the use of contrast agents that show potential in altering the T1 and T2 relaxation times of the hydrogen protons. This modulation to the relaxation times leads to better contrast differences based on the type of contrast agent and the pulse sequence being engaged for acquiring images. Water molecules, as the major contributor of hydrogen protons, are proven to interact with such contrast agents. Major drawbacks noted with the marketed MRI contrast agents are their toxicity and renal clearance. To conquer these issues, magnetic nanomaterials are being researched for their abilities to match the contrast enhancement offered by traditional agents reducing their drawbacks. Furthermore, comparative diagnosis with both T1 and T2 contrast at the same time has also interested investigators. To achieve this, twin mode T1 and T2 weighted contrast agents are developed utilizing the remarkable properties extended by magnetic nanoplatforms. As a step forward, multimodal imaging agents are also being engineered based on these magnetic nanoplatforms that will generate cross-verified diagnoses using multiple imaging modalities with a unique imaging agent. This review starts by introducing the basics of MRI with major focus on the typical interactions of water molecules with a variety of magnetic nanomaterials. The review also concentrates on the clinical needs and nanomaterials available for twin T1 and T2 contrast with a minor introduction to multimodal imaging agents. In conclusion, the advent of MRI with the advantages offered by magnetic nanomaterials is summarized, leading to insights for future developments.

Gold-based Inorganic Nanohybrids for Nanomedicine Applications

Noble metal Au nanoparticles have attracted extensive interests in the past decades, due to their size and morphology dependent localized surface plasmon resonances. Their unique optical property, high chemical stability, good biocompatibility, and easy functionalization make them promising candidates for a variety of biomedical applications, including bioimaging, biosensing, and cancer therapy. With the intention of enhancing their optical response in the near infrared window and endowing them with additional magnetic properties, Au nanoparticles have been integrated with other functional nanomaterials that possess complementary attributes, such as copper chalcogenides and magnetic metal oxides. The as constructed hybrid nanostructures are expected to exhibit unconventional properties compared to their separate building units, due to nanoscale interactions between materials with different physicochemical properties, thus broadening the application scope and enhancing the overall performance of the hybrid nanostructures. In this review, we summarize some recent progresses in the design and synthesis of noble metal Au-based hybrid inorganic nanostructures for nanomedicine applications, and the potential and challenges for their clinical translations.

Application of Zero-Dimensional Nanomaterials in Biosensing

Zero-dimensional (0D) nanomaterials, including graphene quantum dots (GQDs), carbon quantum dots (CQDs), fullerenes, inorganic quantum dots (QDs), magnetic nanoparticles (MNPs), noble metal nanoparticles, upconversion nanoparticles (UCNPs) and polymer dots (Pdots), have attracted extensive research interest in the field of biosensing in recent years. Benefiting from the ultra-small size, quantum confinement effect, excellent physical and chemical properties and good biocompatibility, 0D nanomaterials have shown great potential in ion detection, biomolecular recognition, disease diagnosis and pathogen detection. Here we first introduce the structures and properties of different 0D nanomaterials. On this basis, recent progress and application examples of 0D nanomaterials in the field of biosensing are discussed. In the last part, we summarize the research status of 0D nanomaterials in the field of biosensing and anticipate the development prospects and future challenges in this field.

New Sensors for Extracellular Vesicles: Insights on Constituent and Associated Biomarkers

Extracellular vesicles (EVs) are diverse, nanoscale membrane vesicles released by cells into the circulation. As an emerging class of circulating biomarkers, EVs contain a trove of molecular information and play important roles in mediating intercellular communication. These EV molecular cargoes are differentially organized in the vesicles; they could be inherited from the parent cells or bound to the EV membrane through surface interactions. While the inherited constituents could serve as cell surrogate biomarkers, extravesicular association could reflect structural states of the bound molecules, revealing distinct subpopulations with different biophysical and/or biochemical properties. Despite the clinical potential of EVs and their diverse contents, conventional sensing technologies have limited compatibility to reveal nanoscale EV features. Complementary analytical platforms are being developed to address these technical challenges and expand the biomedical applications of EVs, to establish novel correlations and empower new diagnostics. This article provides a perspective on recent developments in sensor technologies to profile the diverse contents-different molecular types, quantities, and organizational states-in extracellular vesicles.

Pharmaceutical Applications of Iron-Oxide Magnetic Nanoparticles

Advances of nanotechnology led to the development of nanoparticulate systems with many advantages due to their unique physicochemical properties. The use of iron-oxide magnetic nanoparticles (IOMNPs) in pharmaceutical areas increased in the last few decades. This article reviews the conceptual information about iron oxides, magnetic nanoparticles, methods of IOMNP synthesis, properties useful for pharmaceutical applications, advantages and disadvantages, strategies for nanoparticle assemblies, and uses in the production of drug delivery, hyperthermia, theranostics, photodynamic therapy, and as an antimicrobial. The encapsulation, coating, or dispersion of IOMNPs with biocompatible material(s) can avoid the aggregation, biodegradation, and alterations from the original state and also enable entrapping the bioactive agent on the particle via adsorption or covalent attachment. IOMNPs show great potential for target drug delivery, improving the therapy as a consequence of a higher drug effect using lower concentrations, thus reducing side effects and toxicity. Different methodologies allow IOMNP synthesis, resulting in different structures, sizes, dispersions, and surface modifications. These advantages support their utilization in pharmaceutical applications, and getting suitable drug release control on the target tissues could be beneficial in several clinical situations, such as infections, inflammations, and cancer. However, more toxicological clinical investigations about IOMNPs are necessary.