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

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.

Eudragit S100 coated iron oxide-chitosan nanocomposites for colon targeting of 5-aminosalicylic acid ameliorate ulcerative colitis by improving intestinal barrier function and inhibiting NLRP3 inflammasome

The therapeutic effect of 5-amino salicylic acid (5-ASA), a first-line therapeutic agent for the treatment of ulcerative colitis (UC), is limited by the modest bioavailability afforded by its oral administration. In this study, a 5-ASA oral delivery system was developed using Eudragit S100-coated iron oxide-chitosan nanocomposites (ES-IOCS/5-ASA) to address this issue. According to drug release studies in vitro, ES-IOCS/5-ASA only released a small amount of drug in simulated gastric fluid with a pH of 1.2. However, in a medium with a pH of 7.5, a relatively rapid and complete release was noted. 5-ASA-loaded iron oxide-chitosan nanocomposites (IOCS/5-ASA) could be effectively taken up by NCM460 cells and performed better anti-inflammatory effects than free 5-ASA. At the same time, IOCS/5-ASA improved barrier damage in DSS-induced NCM460 cells. In vivo models of dextran sulphate sodium (DSS)-induced colitis were used to assess the therapeutic efficacy of oral administration of ES-IOCS/5-ASA. ES-IOCS/5-ASA significantly relieved DSS-induced colitis and enhanced the integrity of the intestinal epithelial barrier. ES-IOCS/5-ASA also reduced the expression of NLRP3, ASC and IL-1β. Additionally, iron oxide nanoparticles used as nanozymes could alleviate inflammation. In summary, this study indicates that ES-IOCS/5-ASA exert anti-inflammatory effects on DSS-induced colitis by improving intestinal barrier function and inhibiting NLRP3 inflammasome expression, presenting a viable therapeutic choice for the treatment of UC.

The Fluorescent Cell Line SW620-GFP Is a Valuable Model to Monitor Magnetic Hyperthermia

In this work, the cell line SW620-GFP has been used in a complete magnetic hyperthermia assay, from the preparation of the ferrofluid with folate-coated iron oxide nanoparticles to in vivo experiments. The physical and chemical characterization of the nanoparticles evidenced their superparamagnetic behaviour, an average diameter of 12 ± 4 nm, a 2 nm coat thickness, and a high-power loss density. The main innovation of the work is the exclusive capability of viable SW620-GFP cells to emit fluorescence, enabling fast analysis of both, cell viability in vitro with an epifluorescence microscope and tumour size and shape in vivo in a non-invasive manner using the iBox technology. Moreover, with this imaging technique, it was possible to demonstrate the successful tumour size reduction in mice applying magnetic hyperthermia three times a week over 3 weeks.

3,4-Dihydroxiphenylacetic Acid-Based Universal Coating Technique for Magnetic Nanoparticles Stabilization for Biomedical Applications

Magnetic nanoparticles based on iron oxide attract researchers' attention due to a wide range of possible applications in biomedicine. As synthesized, most of the magnetic nanoparticles do not form the stable colloidal solutions that are required for the evaluation of their interactions with cells or their efficacy on animal models. For further application in biomedicine, magnetic nanoparticles must be further modified with biocompatible coating. Both the size and shape of magnetic nanoparticles and the chemical composition of the coating have an effect on magnetic nanoparticles' interactions with living objects. Thus, a universal method for magnetic nanoparticles' stabilization in water solutions is needed, regardless of how magnetic nanoparticles were initially synthesized. In this paper, we propose the versatile and highly reproducible ligand exchange technique of coating with 3,4-dihydroxiphenylacetic acid (DOPAC), based on the formation of Fe-O bonds with hydroxyl groups of DOPAC leading to the hydrophilization of the magnetic nanoparticles' surfaces following phase transfer from organic solutions to water. The proposed technique allows for obtaining stable water-colloidal solutions of magnetic nanoparticles with sizes from 21 to 307 nm synthesized by thermal decomposition or coprecipitation techniques. Those stabilized by DOPAC nanoparticles were shown to be efficient in the magnetomechanical actuation of DNA duplexes, drug delivery of doxorubicin to cancer cells, and targeted delivery by conjugation with antibodies. Moreover, the diversity of possible biomedical applications of the resulting nanoparticles was presented. This finding is important in terms of nanoparticle design for various biomedical applications and will reduce nanomedicines manufacturing time, along with difficulties related to comparative studies of magnetic nanoparticles with different magnetic core characteristics.

Impact of Magnetite Nanowires on In Vitro Hippocampal Neural Networks

Nanomaterials design, synthesis, and characterization are ever-expanding approaches toward developing biodevices or neural interfaces to treat neurological diseases. The ability of nanomaterials features to tune neuronal networks' morphology or functionality is still under study. In this work, we unveil how interfacing mammalian brain cultured neurons and iron oxide nanowires' (NWs) orientation affect neuronal and glial densities and network activity. Iron oxide NWs were synthesized by electrodeposition, fixing the diameter to 100 nm and the length to 1 µm. Scanning electron microscopy, Raman, and contact angle measurements were performed to characterize the NWs' morphology, chemical composition, and hydrophilicity. Hippocampal cultures were seeded on NWs devices, and after 14 days, the cell morphology was studied by immunocytochemistry and confocal microscopy. Live calcium imaging was performed to study neuronal activity. Using random nanowires (R-NWs), higher neuronal and glial cell densities were obtained compared with the control and vertical nanowires (V-NWs), while using V-NWs, more stellate glial cells were found. R-NWs produced a reduction in neuronal activity, while V-NWs increased the neuronal network activity, possibly due to a higher neuronal maturity and a lower number of GABAergic neurons, respectively. These results highlight the potential of NWs manipulations to design ad hoc regenerative interfaces.

Non-pyrogenic highly pure magnetosomes for efficient hyperthermia treatment of prostate cancer

We report the fabrication of highly pure magnetosomes that are synthesized by magnetotactic bacteria (MTB) using pharmaceutically compatible growth media, i.e., without compounds of animal origin (yeast extracts), carcinogenic, mutagenic, or toxic for reproduction (CMR) products, and other heavy metals than iron. To enable magnetosome medical applications, these growth media are reduced and amended compared with media commonly used to grow these bacteria. Furthermore, magnetosomes are made non-pyrogenic by being extracted from these micro-organisms and heated above 400 °C to remove and denature bacterial organic material and produce inorganic magnetosome minerals. To be stabilized, these minerals are further coated with citric acid to yield M-CA, leading to fully reconstructed chains of magnetosomes. The heating properties and anti-tumor activity of highly pure M-CA are then studied by bringing M-CA into contact with PC3-Luc tumor cells and by exposing such assembly to an alternating magnetic field (AMF) of 42 mT and 195 kHz during 30 min. While in the absence of AMF, M-CA are observed to be non-cytotoxic, they result in a 35% decrease in cell viability following AMF application. The treatment efficacy can be associated with a specific absorption rate (SAR) value of M-CA, which is relatively high in cellular environment, i.e., SAR_cell = 253 ± 11 W/g_Fe, while being lower than the M-CA SAR value measured in water, i.e., SAR_water = 1025 ± 194 W/g_Fe, highlighting that a reduction in the Brownian contribution to the SAR value in cellular environment does not prevent efficient tumor cell destruction with these nanoparticles. KEY POINTS : • Highly pure magnetosomes were produced in pharmaceutically compatible growth media • Non-pyrogenic and stable magnetosomes were prepared for human injection • Magnetosomes efficiently destroyed prostate tumor cells in magnetic hyperthermia.

Improvement of Hyperthermia Properties of Iron Oxide Nanoparticles by Surface Coating

Magnetic hyperthermia is an oncological therapy that exploits magnetic nanoparticles activated by radiofrequency magnetic fields to produce a controlled temperature increase in a diseased tissue. The specific loss power (SLP) of magnetic nanoparticles or the capability to release heat can be improved using surface treatments, which can reduce agglomeration effects, thus impacting on local magnetostatic interactions. In this work, Fe₃O₄ nanoparticles are synthesized via a coprecipitation reaction and fully characterized in terms of structural, morphological, dimensional, magnetic, and hyperthermia properties (under the Hergt-Dutz limit). Different types of surface coatings are tested, comparing their impact on the heating efficacy and colloidal stability, resulting that sodium citrate leads to a doubling of the SLP with a substantial improvement in dispersion and stability in solution over time; an SLP value of around 170 W/g is obtained in this case for a 100 kHz and 48 kA/m magnetic field.

Magnetic Iron Nanoparticles: Synthesis, Surface Enhancements, and Biological Challenges

This review focuses on the role of magnetic nanoparticles (MNPs), their physicochemical properties, their potential applications, and their association with the consequent toxicological effects in complex biologic systems. These MNPs have generated an accelerated development and research movement in the last two decades. They are solving a large portion of problems in several industries, including cosmetics, pharmaceuticals, diagnostics, water remediation, photoelectronics, and information storage, to name a few. As a result, more MNPs are put into contact with biological organisms, including humans, via interacting with their cellular structures. This situation will require a deeper understanding of these particles’ full impact in interacting with complex biological systems, and even though extensive studies have been carried out on different biological systems discussing toxicology aspects of MNP systems used in biomedical applications, they give mixed and inconclusive results. Chemical agencies, such as the Registration, Evaluation, Authorization, and Restriction of Chemical substances (REACH) legislation for registration, evaluation, and authorization of substances and materials from the European Chemical Agency (ECHA), have held meetings to discuss the issue. However, nanomaterials (NMs) are being categorized by composition alone, ignoring the physicochemical properties and possible risks that their size, stability, crystallinity, and morphology could bring to health. Although several initiatives are being discussed around the world for the correct management and disposal of these materials, thanks to the extensive work of researchers everywhere addressing the issue of related biological impacts and concerns, and a new nanoethics and nanosafety branch to help clarify and bring together information about the impact of nanoparticles, more questions than answers have arisen regarding the behavior of MNPs with a wide range of effects in the same tissue. The generation of a consolidative framework of these biological behaviors is necessary to allow future applications to be manageable.

Overcoming the blood–brain barrier for the therapy of malignant brain tumor: current status and prospects of drug delivery approaches

Besides the broad development of nanotechnological approaches for cancer diagnosis and therapy, currently, there is no significant progress in the treatment of different types of brain tumors. Therapeutic molecules crossing the blood–brain barrier (BBB) and reaching an appropriate targeting ability remain the key challenges. Many invasive and non-invasive methods, and various types of nanocarriers and their hybrids have been widely explored for brain tumor treatment. However, unfortunately, no crucial clinical translations were observed to date. In particular, chemotherapy and surgery remain the main methods for the therapy of brain tumors. Exploring the mechanisms of the BBB penetration in detail and investigating advanced drug delivery platforms are the key factors that could bring us closer to understanding the development of effective therapy against brain tumors. In this review, we discuss the most relevant aspects of the BBB penetration mechanisms, observing both invasive and non-invasive methods of drug delivery. We also review the recent progress in the development of functional drug delivery platforms, from viruses to cell-based vehicles, for brain tumor therapy. The destructive potential of chemotherapeutic drugs delivered to the brain tumor is also considered. This review then summarizes the existing challenges and future prospects in the use of drug delivery platforms for the treatment of brain tumors.

Mössbauer spectroscopic investigations on iron oxides and modified nanostructures: A review

Pure and doped iron oxide and hydroxide nanoparticles are highly potential materials for biological, environment, energy and other technological applications. On demand of the applications, single phase as well as multiple phase of different polymorphs or composites of iron oxides with compatible materials for example, zeolite, SiO₂, or Au are prepared. The properties of the as-synthesized nanoparticles are predominantly dictated by the local structure and the distribution of the cations. Mössbauer spectroscopy is a perfect and efficient characterization technique to investigate the local structure of the Mössbauer-active element such as Fe, Au, and Sn. In the present review, the local structure transformation on the optimization of the magnetite coexisted with iron hydroxides, spin dynamics of the bare, caped, core-shell and the composites of iron oxide nanoparticles (IONPs), dipole-dipole interactions and the diffusion of IONPs were discussed, based on the findings using Mössbauer spectroscopy.

Scalable Additive Construction of Arrayed Microstructures with Encoded Properties for Bioimaging

Microarrays are essential components of analytical instruments. The elements of microarrays may be imbued with additional functionalities and encodings using composite materials and structures, but traditional microfabrication methods present substantial barriers to fabrication, design, and scalability. In this work, a tool-free technique was reported to additively batch-construct micromolded, composite, and arrayed microstructures. The method required only a compatible carrier fluid to deposit a material onto a substrate with some topography. Permutations of this basic fabrication approach were leveraged to gain control over the volumes and positions of deposited materials within the microstructures. As a proof of concept, cell micro-carrier arrays were constructed to demonstrate a range of designs, compositions, functionalities, and applications for composite microstructures. This approach is envisioned to enable the fabrication of complex composite biological and synthetic microelements for biosensing, cellular analysis, and biochemical screening.

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.