Characterization of biophysical and metabolic properties of cells labeled with superparamagnetic iron oxide nanoparticles and transfection agent for cellular MR imaging

Microfluidic nanoprecipitation of PEGylated PLGA nanoparticles with rapamycin and performance evaluation

Rapamycin (RAP) is currently being developed as potential antibreast cancer drug. However, its poor solubility completely limits its use. The aim of this study was to develop polyethylene glycol-poly(lactide-co-glycolide) (PEG-PLGA)-based nanoparticles (NPs) to load RAP via microfluidics with an appropriate polyethylene glycol (PEG) content to enhance the bioavailability of RAP. Polydimethylsiloxane (PDMS) chips with a Y-shaped channel were designed to obtain RAP-loaded PEG-PLGA NPs (RAP-PEG-PLGA). The entrapment efficiency (EE) and drug loading (DL) as well as release profile of RAP-PEG-PLGA were evaluated, and their resistance to plasma albumin adsorption of NPs with different PEG contents was evaluated and compared. RAW264.7 and 4T1 cells were used to assess the antiphagocytic and anticancer cells effect of NPs, respectively. RAP-PEG-PLGA of around 124 nm in size were successfully prepared with the EE of 82.0% and DL of 12.3%, and sustained release for around 40 d. A PEG relative content of 10% within the PEG-PLGA molecule was shown superior in resisting protein adsorption. RAP-PEG-PLGA inhibited the growth of breast cancer cells when the concentration was over 10 μg/mL, and the inhibition efficiency was significantly higher than free RAP. Hence, the current RAP-PEG-PLGA could be a potential therapeutic system for breast cancer treatment.

Determination of the optical interference of iron oxide nanoparticles in fluorometric cytotoxicity assays

Nanomaterials are known to exhibit unique interactions with light. Iron oxide nanoparticles (IONPs), composed of magnetite (black iron oxide) specifically, are known to be highly absorptive throughout the visible portion of the spectrum. We sought to investigate and overcome optical interference of IONPs in colorimetric, fluorometric and luminescence assays by introducing additional controls and determining the concentration-dependent contribution to optical artifacts which could confound, skew, or invalidate results. We tested the in vitro cytotoxicity of ∼8 nm spherical magnetite nanoparticles capped with alginate on a human lung carcinoma (A549) cell line for different exposure periods and at various concentrations. We observed significant interference with both the MTT reagent and the absorption at 590 nm, a concentration-dependent reduction in the luminescence, fluorescence at ∼490 nm (viability marker), and fluorescence at 530 nm (cytotoxicity marker). After introducing an additional correction, we obtained more accurate results, including a clear decrease in viability at 12-h post-treatment, with apparent near complete recovery after 24-h in addition to a dose-independent, time-dependent alteration in the cell proliferation rate. A small increase in cytotoxicity was noted at the 24-h timepoint at the two highest concentrations. According to our results, the MTT reagents appear to interact substantially with IONPs at concentrations above 0.1 mg/mL, therefore, this assay is not recommended for IONP cytotoxicity assessment at higher concentrations.

Advances in superparamagnetic iron oxide nanoparticles modified with branched polyethyleneimine for multimodal imaging

Multimodal imaging are approaches which combines multiple imaging techniques to obtain multi-aspect information of a target through different imaging modalities, thereby greatly improve the accuracy and comprehensiveness of imaging. Superparamagnetic iron oxide nanoparticles (SPIONs) modified with branched polyethyleneimine have revealed good biocompatibility and stability, high drug loading capacity and nucleic acid transfection efficiency. SPIONs have been developed as functionalized platforms which can be further modified to enhance their functionalities. Those further modifications facilitate the application of SPIONs in multimodal imaging. In this review, we discuss the methods, advantages, applications, and prospects of BPEI-modified SPIONs in multimodal imaging.

Novel Strategies Using Sagacious Targeting for Site-Specific Drug Delivery in Breast Cancer Treatment: Clinical Potential and Applications

For more than a decade, researchers have been working to achieve new strategies and smart targeting drug delivery techniques and technologies to treat breast cancer (BC). Nanotechnology presents a hopeful strategy for targeted drug delivery into the building of new therapeutics using the properties of nanomaterials. Nanoparticles are of high regard in the field of diagnosis and the treatment of cancer. The use of these nanoparticles as an encouraging approach in the treatment of various cancers has drawn the interest of researchers in recent years. In order to achieve the maximum therapeutic effectiveness in the treatment of BC, combination therapy has also been adopted, leading to minimal side effects and thus an enhancement in the quality of life for patients. This review article compares, discusses and criticizes the approaches to treat BC using novel design strategies and smart targeting of site-specific drug delivery systems.

Redox-Activatable Magnetic Nanoarchitectonics for Self-Enhanced Tumor Imaging and Synergistic Photothermal-Chemodynamic Therapy

Oral squamous cell carcinoma (OSCC) is a prevalent malignancy of the head and neck region associated with high recurrence rates and poor prognosis under current diagnostic and treatment methods. The development of nanomaterials that can improve diagnostic accuracy and therapeutic efficacy is of great importance for OSCC. In this study, a redox-activatable nanoarchitectonics is designed via the construction of dual-valence cobalt oxide (DV-CO) nanospheres, which can serve as a contrast agent for magnetic resonance (MR) imaging, and exhibit enhanced transverse and longitudinal relaxivities through the release and redox of Co3+ /Co2+ in an acidic condition with glutathione (GSH), resulting in self-enhanced T1 /T2 -weighted MR contrast. Moreover, DV-CO demonstrates properties of intracellular GSH-depletion and hydroxyl radicals (•OH) generation through a Fenton-like reaction, enabling strengthened chemodynamic (CD) effect. Additionally, DV-CO displays efficient near-infrared laser-induced photothermal (PT) effect, thereby exhibiting synergistic PT-CD therapy for suppressing OSCC tumor cells. It further investigates the tumor-specific self-enhanced MR imaging of DV-CO both in subcutaneous and orthotopic OSCC mouse models, and demonstrate the therapeutic effects of DV-CO in orthotopic OSCC mouse models. Overall, the in vitro and in vivo findings highlight the excellent theranositc potentials of DV-CO for OSCC and offer new prospects for future advancement of nanomaterials.

Hydrophilic Copolymers with Hydroxamic Acid Groups as a Protective Biocompatible Coating of Maghemite Nanoparticles: Synthesis, Physico-Chemical Characterization and MRI Biodistribution Study

Superparamagnetic iron oxide nanoparticles (SPION) with a "non-fouling" surface represent a versatile group of biocompatible nanomaterials valuable for medical diagnostics, including oncology. In our study we present a synthesis of novel maghemite (γ-Fe₂O₃) nanoparticles with positive and negative overall surface charge and their coating by copolymer P(HPMA-co-HAO) prepared by RAFT (reversible addition-fragmentation chain-transfer) copolymerization of N-(2-hydroxypropyl)methacrylamide (HPMA) with N-[2-(hydroxyamino)-2-oxo-ethyl]-2-methyl-prop-2-enamide (HAO). Coating was realized via hydroxamic acid groups of the HAO comonomer units with a strong affinity to maghemite. Dynamic light scattering (DLS) demonstrated high colloidal stability of the coated particles in a wide pH range, high ionic strength, and the presence of phosphate buffer (PBS) and serum albumin (BSE). Transmission electron microscopy (TEM) images show a narrow size distribution and spheroid shape. Alternative coatings were prepared by copolymerization of HPMA with methyl 2-(2-methylprop-2-enoylamino)acetate (MMA) and further post-polymerization modification with hydroxamic acid groups, carboxylic acid and primary-amino functionalities. Nevertheless, their colloidal stability was worse in comparison with P(HPMA-co-HAO). Additionally, P(HPMA-co-HAO)-coated nanoparticles were subjected to a bio-distribution study in mice. They were cleared from the blood stream by the liver relatively slowly, and their half-life in the liver depended on their charge; nevertheless, both cationic and anionic particles revealed a much shorter metabolic clearance rate than that of commercially available ferucarbotran.

Concurrent Dual-Contrast Enhancement Using Fe3O4 Nanoparticles to Achieve a CEST Signal Controllability

Traditional T₂ magnetic resonance imaging (MRI) contrast agents have defects inherent to negative contrast agents, while chemical exchange saturation transfer (CEST) contrast agents can quantify substances at trace concentrations. After reaching a certain concentration, iron-based contrast agents can "shut down" CEST signals. The application range of T₂ contrast agents can be widened through a combination of CEST and T₂ contrast agents, which has promising application prospects. The purpose of this study is to develop a T₂ MRI negative contrast agent with a controllable size and to explore the feasibility of dual contrast enhancement by combining T₂ with CEST contrast agents. The study was carried out in vitro with HCT-116 human colon cancer cells. A GE SIGNA Pioneer 3.0 T medical MRI scanner was used to acquire CEST images with different saturation radio-frequency powers (1.25/2.5/3.75/5 μT) by 2D spin echo-echo planar imaging (SE-EPI). Magnetic resonance image compilation (MAGiC) was acquired by a multidynamic multiecho 2D fast spin-echo sequence. The feasibility of this dual-contrast enhancement method was assessed by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, dynamic light scattering, ζ potential analysis, inductively coupled plasma, X-ray photoelectron spectroscopy, X-ray powder diffraction, vibrating-sample magnetometry, MRI, and a Cell Counting Kit-8 assay. The association between the transverse relaxation rate r₂ and the pH of the iron-based contrast agents was analyzed by linear fitting, and the linear relationship between the CEST effect in different B₁ fields and pH was analyzed by the ratio method. Fe₃O₄ nanoparticles (NPs) with a mean particle size of 82.6 ± 22.4 nm were prepared by a classical process, and their surface was successfully modified with -OH active functional groups. They exhibited self-aggregation in an acidic environment. The CEST effect was enhanced as the B₁ field increased, and an in vitro pH map was successfully plotted using the ratio method. Fe₃O₄ NPs could stably serve as reference agents at different pH values. At a concentration of 30 μg/mL, Fe₃O₄ NPs "shut down" the CEST signals, but when the concentration of Fe₃O₄ NPs was less than 10 μg/mL, the two contrast agents coexisted. The prepared Fe₃O₄ NPs had almost no toxicity, and when their concentration rose to 200 μg/mL at pH 6.5 or 7.4, they did not reach the half-maximum inhibitory concentration (IC₅₀). Fe₃O₄ magnetic NPs with a controllable size and no toxicity were successfully synthesized. By combining Fe₃O₄ NPs with a CEST contrast agent, the two contrast agents could be imaged simultaneously; at higher concentrations, the iron-based contrast agent "shut down" the CEST signal. An in vitro pH map was successfully plotted by the ratio method. CEST signal inhibition can be used to realize the pH mapping of solid tumors and the identification of tumor active components, thus providing a new imaging method for tumor efficacy evaluation.

Development of Positively Charged Poly-L-Lysine Magnetic Nanoparticles as Potential MRI Contrast Agent

A colloidal solution of magnetic nanoparticles (MNPs) modified with biocompatible positively charged poly-L-lysine (PLL) with an oleate (OL) layer employed as an initial coating was produced as a potential MRI contrast agent. The effect of various PLL/MNPs' mass ratios on the samples' hydrodynamic diameter, zeta potential, and isoelectric point (IEP) was studied by the dynamic light-scattering method. The optimal mass ratio for MNPs' surface coating was 0.5 (sample PLL_0.5-OL-MNPs). The average hydrodynamic particle size in the sample of PLL_0.5-OL-MNPs was 124.4 ± 1.4 nm, and in the PLL-unmodified nanoparticles, it was 60.9 ± 0.2 nm, indicating that the OL-MNPs' surface became covered by PLL. Next, the typical characteristics of the superparamagnetic behavior were observed in all samples. In addition, the decrease in saturation magnetizations from 66.9 Am²/kg for MNPs to 35.9 and 31.6 Am²/kg for sample OL-MNPs and PLL_0.5-OL-MNPs also confirmed successful PLL adsorption. Moreover, we show that both OL-MNPs and PLL_0.5-OL-MNPs exhibit excellent MRI relaxivity properties and a very high r₂⁽*⁾/r₁ ratio, which is very desirable in biomedical applications with required MRI contrast enhancement. The PLL coating itself appears to be the crucial factor in enhancing the relaxivity of MNPs in MRI relaxometry.

Cellular 1H MR Relaxation Times in Healthy and Cancer Three-Dimensional (3D) Breast Cell Culture

Noninvasive measurements of ¹H Magnetic Resonance Imaging (MR) relaxation times in a three-dimensional (3D) cell culture construct are presented. Trastuzumab was used as a pharmacological component delivered to the cells in vitro. The purpose of this study was to evaluate the Trastuzumab delivery by relaxation times in 3D cell cultures. The bioreactor has been designed and used for 3D cell cultures. Four bioreactors were prepared, two with normal cells and two with breast cancer cells. The relaxation times of HTB-125 and CRL 2314 cell cultures were determined. An immunohistochemistry (IHC) test was performed before MRI measurements to confirm the amount of HER2 protein in the CRL-2314 cancer cells. The results showed that the relaxation time of CRL2314 cells is lower than normal HTB-125 cells in both cases, before and after treatment. An analysis of the results showed that 3D culture studies have potential in evaluating treatment efficacy using relaxation times measurements with a field of 1.5 Tesla. The use ¹H MRI relaxation times allows for the visualization of cell viability in response to treatment.

Nanomaterial-Based Antimicrobial Coating for Biomedical Implants: New Age Solution for Biofilm-Associated Infections

Recently, the upsurge in hospital-acquired diseases has put global health at risk. Biomedical implants being the primary source of contamination, the development of biomedical implants with antimicrobial coatings has attracted the attention of a large group of researchers from around the globe. Bacteria develops biofilms on the surface of implants, making it challenging to eradicate them with the standard approach of administering antibiotics. A further issue of current concern is the fast resurgence of resistance to conventional antibiotics. As nanotechnology continues to advance, various types of nanomaterials have been created, including 2D nanoparticles and metal and metal oxide nanoparticles with antimicrobial properties. Researchers from all over the world are using these materials as a coating agent for biomedical implants to create an antimicrobial environment. This comprehensive and contemporary review summarizes various metals, metal oxide nanoparticles, 2D nanomaterials, and their composites that have been used or may be used in the future as an antimicrobial coating agent for biomedical implants, as well as their succinct mode of action to combat biofilm-associated infection and diseases.

In Vivo Cellular Magnetic Imaging: Labeled vs. Unlabeled Cells

Superparamagnetic iron oxide (SPIO)-labeling of cells has been applied for magnetic resonance imaging (MRI) cell tracking for over 30 years, having resulted in a dozen or so clinical trials. SPIO nanoparticles are biodegradable and can be broken down into elemental iron, and hence the tolerance of cells to magnetic labeling has been overall high. Over the years, however, single reports have accumulated demonstrating that the proliferation, migration, adhesion and differentiation of magnetically labeled cells may differ from unlabeled cells, with inhibition of chondrocytic differentiation of labeled human mesenchymal stem cells (hMSCs) as a notable example. This historical perspective provides an overview of some of the drawbacks that can be encountered with magnetic labeling. Now that magnetic particle imaging (MPI) cell tracking is emerging as a new in vivo cellular imaging modality, there has been a renaissance in the formulation of SPIO nanoparticles this time optimized for MPI. Lessons learned from the occasional past pitfalls encountered with SPIO-labeling of cells for MRI may expedite possible future clinical translation of (combined) MRI/MPI cell tracking.

Sensitization of glioblastoma cancer cells to radiotherapy and magnetic hyperthermia by targeted temozolomide-loaded magnetite tri-block copolymer nanoparticles as a nanotheranostic agent

AIMS

Recently, the development of new strategies in the treatment and diagnosis of cancer cells such as thermo-radiation-sensitizer and theranostic agents have received a great deal of attention. In this work, folic acid-conjugated temozolomide-loaded SPION@PEG-PBA-PEG nanoparticles (TMZ-MNP-FA NPs) were proposed for use as magnetic resonance imaging (MRI) contrast agents and to enhance the cytotoxic effects of hyperthermia and radiotherapy.

MAIN METHODS

Nanoparticles were synthesized by the Nano-precipitation method and their characteristics were determined by dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). To evaluate the thermo-radio-sensitization effects of NPs, C6 cells were treated with nanoparticles for 24 h and then exposed to 6-MV X-ray radiation. After radiotherapy, the cells were subjected to an alternating magnetic field (AMF) hyperthermia. The therapeutic potential was assessed using clonogenic assay, ROS generation measurement, flow cytometry assay, and qRT-PCR analysis. Also, the diagnostic properties of the nanoparticles were assessed by MRI.

KEY FINDINGS

MRI scanning indicated that nanoparticles accumulated in C6 cells could be tracked by T2-weighted MR imaging. Colony formation assay proved that TMZ-MNP-FA NPs enhanced the anti-proliferation effects of AMF by 1.94-fold compared to AMF alone (P < 0.0001). Moreover, these NPs improved the radiation effects with a dose enhancement factor of 1.65. All results showed that the combination of carrier-based chemotherapy with hyperthermia and radiotherapy caused a higher anticancer efficacy than single- or two-modality treatments.

SIGNIFICANCE

The nanoparticles advanced in this study can be proposed as the promising theranostic and thermo-radio-sensitizer platform for the diagnosis and tri-modal synergistic cancer therapy.

Development of 3D Thermoplastic Polyurethane (TPU)/Maghemite (ϒ-Fe2O3) Using Ultra-Hard and Tough (UHT) Bio-Resin for Soft Tissue Engineering

The use of soft tissue engineering scaffolds is an advanced approach to repairing damaged soft tissue. To ensure the success of this technique, proper mechanical and biocompatibility properties must be taken into consideration. In this study, a three-dimensional (3D) scaffold was developed using digital light processing (DLP) and ultra-hard and tough (UHT) bio-resin. The 3D scaffold structure consisted of thermoplastic polyurethane (TPU) and maghemite (ϒ-Fe2O3) nanoparticles mixed with UHT bio-resin. The solution sample for fabricating the scaffolds was varied with the concentration of the TPU (10, 12.5, and 15% wt/v) and the amount of ϒ-Fe2O3 (1, 3, and 5% v/v) added to 15% wt/v of TPU. Before developing the real geometry of the sample, a pre-run of the DLP 3D printing process was done to determine the optimum curing time of the structure to be perfectly cured, which resulted in 30 s of curing time. Then, this study proceeded with a tensile test to determine the mechanical properties of the developed structure in terms of elasticity. It was found that the highest Young’s Modulus of the scaffold was obtained with 15% wt/v TPU/UHT with 1% ϒ-Fe2O3. Furthermore, for the biocompatibility study, the degradation rate of the scaffold containing TPU/UHT was found to be higher compared to the TPU/UHT containing ϒ-Fe2O3 particles. However, the MTT assay results revealed that the existence of ϒ-Fe2O3 in the scaffold improved the proliferation rate of the cells.

Purinoceptor Targeted Cytotoxicity of Adenosine Triphosphate-Conjugated Biogenic Selenium Nanoparticles in Human Colon Cancer Cells

The adenosine triphosphate (ATP)-conjugated biogenic selenium nanoparticles (SeNPs) for P2 (purinoceptors) receptor-targeted anti-colon cancer activity were developed in this study. First, the SeNPs were synthesized using Trichoderma extracts (TE) and then conjugated with ATP to enhance their anticancer activity. The developed SeNPs had an oval crystalline structure with an average diameter size of 26.45 ± 1.71 d. nm, while the ATP-SeNPs were 78.6 ± 2.91 d. nm. The SeNPs contain Se, and less persistence of P while the ATP-SeNPs have high level of P, and Se in the energy-dispersive spectroscopy (EDS). Further, both nanoparticles exhibited larger sizes in the dynamic light scattering (DLS) analysis than in the transmission electron microscopy (TEM) analysis. The DLS and Fourier transform infrared spectroscopy (FTIR) results provide evidence that the amine group (-NH2) of ATP might bind with the negatively charged SeNPs through covalent bonding. The IC50 concentration was 17.25 ± 1.16 µg/mL for ATP-SeNPs and 61.24 ± 2.08 µg/mL against the caco-2 cell line. The IC50 results evidenced the higher cytotoxicity of ATP-SeNPs in the caco-2 cell line than in HEK293 cells. ATP-SeNPs trigger the anticancer activity in the caco-2 cell line through the induction of mitochondrial membrane potential (MMP) loss and nucleus damage. The biocompatibility test of hemolysis and the egg CAM assay confirmed the non-toxicity of these nanoparticles. Overall, the results proved that the newly developed ATP-SeNPs exhibited higher cytotoxicity in the caco-2 cell line than SeNPs. However, further molecular and in vivo experiments are required to develop the ATP-SeNPs as a candidate drug for cancer-targeted therapeutics.

Theranostic applications of stimulus-responsive systems based on Fe2O3

According to the interaction of nanoparticles with biological systems, enthusiasm for nanotechnology in biomedical applications has been developed in the past decades. Fe2O3 nanoparticles, as the most stable iron oxide, have special merits that make them useful widely for detecting diseases, therapy, drug delivery, and monitoring the therapeutic process. This review presents the fabrication methods of Fe2O3-based materials and their photocatalytic and magnetic properties. Then, we highlight the application of Fe2O3-based nanoparticles in diagnosis and imaging, different therapy methods, and finally, stimulus-responsive systems, such as pH-responsive, magnetic-responsive, redox-responsive, and enzyme-responsive, with an emphasis on cancer treatment. In addition, the potential of Fe2O3 to combine diagnosis and therapy within a single particle called theranostic agent will be discussed.

Tracking Neural Stem Cells in vivo: Achievements and Limitations

Neural stem cell (NSC) therapies are developing rapidly and have been proposed as a treatment option for various neurological diseases, such as stroke, Parkinson's disease and multiple sclerosis. However, monitoring transplanted NSCs, exploring their location and migration, and evaluating their efficacy and safety have all become serious and important issues. Two main problems in tracking NSCs have been noted: labeling them for visibility and imaging them. Direct labeling and reporter gene labeling are the two main methods for labeling stem cells. Magnetic resonance imaging and nuclear imaging, including positron emission tomography, single-photon emission computed tomography, and optical imaging, are the most commonly used imaging techniques. Each has its strengths and weaknesses. Thus, multimodal imaging, which combines two or more imaging methods to complement the advantages and disadvantages of each, has garnered increased attention. Advances in image fusion and nanotechnology, as well as the exploration of new tracers and new imaging modalities have substantially facilitated the development of NSC tracking technology. However, the safety issues related to tracking and long-term tracking of cell viability are still challenges. In this review, we discuss the merits and defects of different labeling and imaging methods, as well as recent advances, challenges and prospects in NSC tracking.

Options for imaging cellular therapeutics in vivo: a multi-stakeholder perspective

Cell-based therapies have been making great advances toward clinical reality. Despite the increase in trial activity, few therapies have successfully navigated late-phase clinical trials and received market authorization. One possible explanation for this is that additional tools and technologies to enable their development have only recently become available. To support the safety evaluation of cell therapies, the Health and Environmental Sciences Institute Cell Therapy-Tracking, Circulation and Safety Committee, a multisector collaborative committee, polled the attendees of the 2017 International Society for Cell & Gene Therapy conference in London, UK, to understand the gaps and needs that cell therapy developers have encountered regarding safety evaluations in vivo. The goal of the survey was to collect information to inform stakeholders of areas of interest that can help ensure the safe use of cellular therapeutics in the clinic. This review is a response to the cellular imaging interests of those respondents. The authors offer a brief overview of available technologies and then highlight the areas of interest from the survey by describing how imaging technologies can meet those needs. The areas of interest include imaging of cells over time, sensitivity of imaging modalities, ability to quantify cells, imaging cellular survival and differentiation and safety concerns around adding imaging agents to cellular therapy protocols. The Health and Environmental Sciences Institute Cell Therapy-Tracking, Circulation and Safety Committee believes that the ability to understand therapeutic cell fate is vital for determining and understanding cell therapy efficacy and safety and offers this review to aid in those needs. An aim of this article is to share the available imaging technologies with the cell therapy community to demonstrate how these technologies can accomplish unmet needs throughout the translational process and strengthen the understanding of cellular therapeutics.

Labelling of human Wharton's jelly-derived mesenchymal stem cells with gold nanorods by biomimicry method

Mesenchymal stem cell (MSC)-based cell therapy can provide opportunities for the treatment of various diseases. However, when used in vivo, these cells should be labelled and monitored by a non-invasive method during delivery to the desired locations within the body. This study describes a biomimicry method that effectively labels human Wharton's jelly-derived MSCs (hWJ-MSCs) with a photoacoustics (PA) contrast agent, gold nanorods (GNRs), without the need for transfection agents (TAs). In this method for cell labelling, the hWJ-MSCs were co-incubated with non-adherent cells isolated from fresh umbilical cord for 2 days immediately before incubation with GNRs. Next, hWJ-MSCs were labelled with the GNRs at a concentration of approximately 10¹⁰ nanorads/mL (NR/mL) followed by transmission electron microscopy (TEM) and inductively coupled plasma mass spectroscopy (ICP-MS) to verify their labelling effectiveness. The GNRs-labelled MSCs prepared by this method had an intracellular gold (Au) concentration of 3.4 ± 0.4 pg/cell, which is an acceptable amount for cell labelling.

Nanohybrids of Magnetically Intercalated Optical Metamaterials for Magnetic Resonance/Raman Imaging and In Situ Chemodynamic/Photothermal Therapy

Target-specific reactive oxygen species (ROS)-based cancer treatments with high therapeutic efficacy and minimal side effects have been identified recently as a potentially effective cancer management strategy. Herein, we report the fabrication of a targeted nanotheranostic agent built on an iron oxide nanoparticle-decorated graphene-gold hybrid [plasmonic magnetic nanoprobe (PMNP)] for self-guided magnetic resonance (MR)/surface-enhanced Raman scattering imaging and photothermal therapy (PTT)/chemodynamic therapy (CDT). In the presence of glutathione, which is abundant in the tumor environment, the iron oxide nanoparticles undergo in situ reduction, which in turn generates hydroxyl radicals via a Fenton reaction to realize targeted destruction of tumor cells. Moreover, the localized production of heat benefited from the near-infrared absorption of the PMNP accelerates the intratumoral ROS generation process, with a synergistic effect of CDT/PTT. Furthermore, the probe offers an accurate visualization of the intracellular localization of the material through SERS/MR dual imaging channels. In view of the advantages offered by the tumor-specific stimuli-responsive nature of the probe, the PMNP presents as an effective tool for cancer management.

Intravascular Application of Labelled Cell Spheroids: An Approach for Ischemic Peripheral Artery Disease

Mesenchymal stem cells (MSC) are known for their vascular regeneration capacity by neoangiogenesis. Even though, several delivery approaches exist, particularly in the case of intravascular delivery, only limited number of cells reach the targeted tissue and are not able to remain on site. Applicated cells exhibit poor survival accompanied with a loss of functionality. Moreover, cell application techniques lead to cell death and impede the overall MSC function and survival. 3D cell spheroids mimic the physiological microenvironment, thus, overcoming these limitations. Therefore, in this study we aimed to evaluate and assess the feasibility of 3D MSCs spheroids for endovascular application, for treatment of ischemic peripheral vascular pathologies. Multicellular 3D MSC spheroids were generated at different cell seeding densities, labelled with ultra-small particles of iron oxide (USPIO) and investigated in vitro in terms of morphology, size distribution, mechanical stability as well as ex vivo with magnetic resonance imaging (MRI) to assess their trackability and distribution. Generated 3D spheroids were stable, viable, maintained stem cell phenotype and were easily trackable and visualized via MRI. MSC 3D spheroids are suitable candidates for endovascular delivery approaches in the context of ischemic peripheral vascular pathologies.

Chitosan Functionalized Magnetic Nanoparticles to Provide Neural Regeneration and Recovery after Experimental Model Induced Peripheral Nerve Injury

(1) Background: Peripheral nerve injuries have a great impact on a patient's quality of life and a generally poor outcome regarding functional recovery. Lately, studies have focused on different types of nanoparticles and various natural substances for the treatment of peripheral nerve injuries. This is the case of chitosan, a natural compound from the crustaceans' exoskeleton. The present study proposes to combine chitosan benefic properties to the nanoparticles' ability to transport different substances to specific locations and evaluate the effects of magnetic nanoparticles functionalized with chitosan (CMNPs) on peripheral nerve injuries' rehabilitation by using an in vivo experimental model. (2) Methods: CMNPs treatment was administrated daily, orally, for 21 days to rats subjected to right sciatic nerve lesion and compared to the control group (no treatment) by analyzing the sciatic functional index, pain level, body weight, serum nerve growth factor levels and histology, TEM and EDX analysis at different times during the study. (3) Results: Animals treated with CMNPs had a statistically significant functional outcome compared to the control group regarding: sciatic functional index, pain-like behavior, total body weight, which were confirmed by the histological and TEM images. (4) Conclusions: The results of the study suggest that CMNPs appear to be a promising treatment method for peripheral nerve injuries.

Magnetic Targeting of Human Olfactory Mucosa Stem Cells Following Intranasal Administration: a Novel Approach to Parkinson's Disease Treatment

Among the various therapeutic procedures used for improving PD, stem cell-based therapy has been shown to be a promising method. Olfactory ectomesenchymal stem cells (OE-MSCs) are a great source of stem cells for PD. Also, the intranasal administration (INA) of stem cells to the neural lesion has several advantages over the other approaches to cellular injections. However, improving the efficacy of INA to produce the highest number of cells at the lesion site has always been a controversial issue. For this purpose, this study was designed to apply the magnetically targeted cell delivery (MTCD) approach to OE-MSCs in the injured striatum area through the IN route in order to explore their outcomes in rat models of PD. Animals were randomly classified into four groups including control, PD model, treatment-NTC (treated with INA of non-target cells), and treatment-TC (treated with INA of target cells). The Alg-SPIONs-labeled OE-MSCs were stained successfully using the Prussian blue method with an intracellular iron concentration of 2.73 pg/cell. It was able to reduce signal intensity in the striatum region by increasing the number of these cells, as shown by the magnetic resonance imaging (MRI). Behavioral evaluation revealed that the administration of OE-MSCs with this novel advanced stem cell therapy alleviated Parkinson's motor dysfunction. Further, histological evaluations confirmed the functional enhancement of dopaminergic neuron cells by the expression of Nurr1, Dopamine transporter (DAT), and paired-like homeodomain transcription factor 3 (TH). Overall, this study showed that INA of OE-MSCs in the MTCD approach enhanced stem cells' therapeutic effects in PD models.

Magnetic PLGA microspheres loaded with SPIONs promoted the reconstruction of bone defects through regulating the bone mesenchymal stem cells under an external magnetic field

Superparamagnetic iron oxide nanoparticles (SPIONs) have been presented to regulate the migration and osteogenic differentiation of bone mesenchymal stem cells (BMSCs) under magnetic field (MF). However, the toxicity and short residence for the massively exposed SPIONs at bone defects compromises their practical application. Herein, SPIONs were encapsulated into PLGA microspheres to overcome these shortcomings. Three types of PLGA microspheres (PFe-I, PFe-II and PFe-III) were prepared by adjusting the feeding amount of SPIONs, in which the practical SPIONs loading amounts was 1.83%, 1.38% and 1.16%, respectively. The average diameter of the fabricated microspheres ranged from 160 μm to 200 μm, having the porous and rough surfaces displayed by SEM. Moreover, they displayed the magnetic property with a saturation magnetization of 0.16 emu/g. In vitro cell studies showed that most of BMSCs were adhered on the surface of PFe-II microspheres after 2 days of co-culture. Moreover, the osteoblasts differentiation of BMSCs was significantly promoted by PFe-II microspheres after 2 weeks of co-culture, as shown by detecting osteogenesis-related proteins expressions of ALP, COLI, OPN and OCN. Afterward, PFe-II microspheres were surgically implanted into the defect zone of rat femoral bone, followed by exposure to an external MF, to evaluate their bone repairing effect in vivo. At 6th week after treatment with PFe-II + MF, the bone mineral density (BMD, 263.97 ± 25.99 mg/cm³), trabecular thickness (TB.TH, 0.58 ± 0.08 mm), and bone tissue volume/total tissue volume (BV/TV, 78.28 ± 5.01%) at the defect zone were markedly higher than that of the PFe-II microspheres alone (BMD, 194.34 ± 26.71 mg/cm³; TB.TH, 0.41 ± 0.07 mm; BV/TV, 50.49 ± 6.41%). Moreover, the higher expressions of ALP, COLI, OPN and OCN in PFe-II + MF group were displayed in the repairing bone. Collectively, magnetic PLGA microspheres together with MF may be a promising strategy for repairing bone defects.

A Perspective on Cell Tracking with Magnetic Particle Imaging

Many labs have been developing cellular magnetic resonance imaging (MRI), using both superparamagnetic iron oxide nanoparticles (SPIONs) and fluorine-19 (19F)-based cell labels, to track immune and stem cells used for cellular therapies. Although SPION-based MRI cell tracking has very high sensitivity for cell detection, SPIONs are indirectly detected owing to relaxation effects on protons, producing negative magnetic resonance contrast with low signal specificity. Therefore, it is not possible to reliably quantify the local tissue concentration of SPION particles, and cell number cannot be determined. 19F-based cell tracking has high specificity for perfluorocarbon-labeled cells, and 19F signal is directly related to cell number. However, 19F MRI has low sensitivity. Magnetic particle imaging (MPI) is a new imaging modality that directly detects SPIONs. SPION-based cell tracking using MPI displays great potential for overcoming the challenges of MRI-based cell tracking, allowing for both high cellular sensitivity and specificity, and quantification of SPION-labeled cell number. Here we describe nanoparticle and MPI system factors that influence MPI sensitivity and resolution, quantification methods, and give our perspective on testing and applying MPI for cell tracking.

Magnetically responsive polycaprolactone nanocarriers for application in the biomedical field: magnetic hyperthermia, magnetic resonance imaging, and magnetic drug delivery

There are huge demands on multifunctional nanocarriers to be used in nanomedicine. Herein, we present a simple and efficient method for the preparation of multifunctional magnetically responsive polymeric-based nanocarriers optimized for biomedical applications. The hybrid delivery system is composed of drug-loaded polymer nanoparticles (poly(caprolactone), PCL) coated with a multilayer shell of polyglutamic acid (PGA) and superparamagnetic iron oxide nanoparticles (SPIONs), which are known as bio-acceptable components. The PCL nanocarriers with a model anticancer drug (Paclitaxel, PTX) were formed by the spontaneous emulsification solvent evaporation (SESE) method, while the magnetically responsive multilayer shell was formed via the layer-by-layer (LbL) method. As a result, we obtained magnetically responsive polycaprolactone nanocarriers (MN-PCL NCs) with an average size of about 120 nm. Using the 9.4 T preclinical magnetic resonance imaging (MRI) scanner we confirmed, that obtained MN-PCL NCs can be successfully used as a MRI-detectable drug delivery system. The magnetic hyperthermia effect of the MN-PCL NCs was demonstrated by applying a 25 mT radio-frequency (f = 429 kHz) alternating magnetic field. We found a Specific Absorption Rate (SAR) of 55 W g-1. The conducted research fulfills the first step of investigation for biomedical application, which is mandatory for the planning of any in vitro and in vivo studies.

Biomedical Applications of Multifunctional Polymeric Nanocarriers: A Review of Current Literature

Polymeric nanomaterials have become a prominent area of research in the field of drug delivery. Their application in nanomedicine can improve bioavailability, pharmacokinetics, and, therefore, the effectiveness of various therapeutics or contrast agents. There are many studies for developing new polymeric nanocarriers; however, their clinical application is somewhat limited. In this review, we present new complex and multifunctional polymeric nanocarriers as promising and innovative diagnostic or therapeutic systems. Their multifunctionality, resulting from the unique chemical and biological properties of the polymers used, ensures better delivery, and a controlled, sequential release of many different therapeutics to the diseased tissue. We present a brief introduction of the classical formulation techniques and describe examples of multifunctional nanocarriers, whose biological assessment has been carried out at least in vitro. Most of them, however, also underwent evaluation in vivo on animal models. Selected polymeric nanocarriers were grouped depending on their medical application: anti-cancer drug nanocarriers, nanomaterials delivering compounds for cancer immunotherapy or regenerative medicine, components of vaccines nanomaterials used for topical application, and lifestyle diseases, ie, diabetes.

Molecular imaging in tracking cancer stem cells: A review

Cancer stem cells (CSCs) have critical roles in tumor development, progression, and recurrence. They are responsible for current cancer treatment failure and remain questionable for the design and development of new therapeutic strategies. With this issue, medical imaging provides several clues for finding biological mechanisms and strategies to treat CSCs. This review aims to summarize current molecular imaging approaches for detecting CSCs. In addition, some promising issues for CSCs finding and explaining biological mechanisms have been addressed. Among the molecular imaging approaches, modalities including Magnetic resonance imaging (MRI) and positron emission tomography (PET) have the greatest roles and several new approaches such as optical imaging are in progress.

Potential Toxicity of Iron Oxide Magnetic Nanoparticles: A Review

The noteworthy intensification in the development of nanotechnology has led to the development of various types of nanoparticles. The diverse applications of these nanoparticles make them desirable candidate for areas such as drug delivery, coasmetics, medicine, electronics, and contrast agents for magnetic resonance imaging (MRI) and so on. Iron oxide magnetic nanoparticles are a branch of nanoparticles which is specifically being considered as a contrast agent for MRI as well as targeted drug delivery vehicles, angiogenic therapy and chemotherapy as small size gives them advantage to travel intravascular or intracavity actively for drug delivery. Besides the mentioned advantages, the toxicity of the iron oxide magnetic nanoparticles is still less explored. For in vivo applications magnetic nanoparticles should be nontoxic and compatible with the body fluids. These particles tend to degrade in the body hence there is a need to understand the toxicity of the particles as whole and degraded products interacting within the body. Some nanoparticles have demonstrated toxic effects such inflammation, ulceration, and decreases in growth rate, decline in viability and triggering of neurobehavioral alterations in plants and cell lines as well as in animal models. The cause of nanoparticles' toxicity is attributed to their specific characteristics of great surface to volume ratio, chemical composition, size, and dosage, retention in body, immunogenicity, organ specific toxicity, breakdown and elimination from the body. In the current review paper, we aim to sum up the current knowledge on the toxic effects of different magnetic nanoparticles on cell lines, marine organisms and rodents. We believe that the comprehensive data can provide significant study parameters and recent developments in the field. Thereafter, collecting profound knowledge on the background of the subject matter, will contribute to drive research in this field in a new sustainable direction.

Multifunctional nanoparticles in stem cell therapy for cellular treating of kidney and liver diseases

The review gives an overview of the mechanisms of internalization and distribution of nanoparticles in stem cells this is achieved via providing analysis of the methods used in exploring the migration routes of stem cells, and their reciprocity. In addition, exploring microenvironment target in the body, and tracking the fate of exogenously transplanted stem cells by using innovative and non-invasive techniques will also be discussed. Such techniques like magnetic resonance imaging (MRI), multimodality tracking, optical imaging, and nuclear medicine imaging, which were designed to follow up stem cell migration. This review will explain the various distinctive strategies to enhance homing of labeled stem cells with nanoparticles into damaged hepatic and renal tissues, this purpose was obtained by inducing a specific gene into stem cells, various chemokines, and applying an external magnetic field. Also, this work illustrates how to improve nanoparticles uptake by using transfection agents or covalently binding an exogenous protein (i.e., Human immunodeficiency virus-Tat protein) or conjugating a receptor-specific monoclonal antibody or make modifications to iron coat. It contains stem cell labeling methods such as extracellular labeling and internalization approaches. Ultimately, our review indicates trails of researchers in nanoparticles utilization in stem cell therapy in both kidney and liver diseases.

Prospect of Different Types of Magnetic Nanoparticles in Stem Cell Therapy

Magnetic targeting (MT) has been an emerging technology which is used to improve the delivery and retention of transplanted therapeutic cells in target site over the past 20 years. Meanwhile, stem cells have also been a research hotspot in cell therapy in recent years. Several researchers have combined the MT technology with Stem cell therapy in order to improve the efficacy. However, Different types of Magnetic Nano particles (MNPs) have presented different effects, and how to choose a proper MNPs became a question. This article aims to introduce the preparation method and application field of different types of magnetic Nanoparticles, discuss the pros and cons of different types of MNPs in stem cell therapy and make a prospect of MT technology in Stem cell therapy.

Nano-immunoimaging

Immunoimaging is a rapidly growing field stoked in large part by the intriguing triumphs of immunotherapy. On the heels of immunotherapy's successes, there exists a growing need to evaluate tumor response to therapy particularly immunotherapy, stratify patients into responders vs. non-responders, identify inflammation, and better understand the fundamental roles of immune system components to improve both immunoimaging and immunotherapy. Innovative nanomaterials have begun to provide novel opportunities for immunoimaging, in part due to their sensitivity, modularity, capacity for many potentially varied ligands (high avidity), and potential for multifunctionality/multimodality imaging. This review strives to comprehensively summarize the integration of nanotechnology and immunoimaging, and the field's potential for clinical applications.

Magnetic Nanoparticles as In Vivo Tracers for Alzheimer’s Disease

Drug formulations and suitable methods for their detection play a very crucial role in the development of therapeutics towards degenerative neurological diseases. For diseases such as Alzheimer’s disease, magnetic resonance imaging (MRI) is a non-invasive clinical technique suitable for early diagnosis. In this review, we will discuss the different experimental conditions which can push MRI as the technique of choice and the gold standard for early diagnosis of Alzheimer’s disease. Here, we describe and compare various techniques for administration of nanoparticles targeted to the brain and suitable formulations of nanoparticles for use as magnetically active therapeutic probes in drug delivery targeting the brain. We explore different physiological pathways involved in the transport of such nanoparticles for successful entry in the brain. In our lab, we have used different formulations of iron oxide nanoparticles (IONPs) and protein nanocages as contrast agents in anatomical MRI of an Alzheimer’s disease (AD) brain. We compare these coatings and their benefits to provide the best contrast in addition to biocompatibility properties to be used as sustainable drug-release systems. In the later sections, the contrast enhancement techniques in MRI studies are discussed. Examples of contrast-enhanced imaging using advanced pulse sequences are discussed with the main focus on important studies in the field of neurological diseases. In addition, T1 contrast agents such as gadolinium chelates are compared with the T2 contrast agents mainly made of superparamagnetic inorganic metal nanoparticles.

Magnetic targeted delivery of the SPIONs-labeled mesenchymal stem cells derived from human Wharton's jelly in Alzheimer's rat models

Alzheimer's disease (AD) as a progressive neurodegenerative disorder is one of the leading causes of death globally. Among all treatment approaches, mesenchymal stem cells (MSCs)-based therapy is a promising modality for neurological disorders including the AD. This study aimed to magnetically deliver human Wharton's jelly-derived MSCs (WJ-MSCs) toward the hippocampal area within the AD rat's brain and determine the effects of them in cognitive improvement. Rats were randomly divided into five groups as follow: vehicle-treated control, AD model (injection of 8 μg/kg of amyloid β 1-42), IV-NTC (treated with IV-injected Non-Targeted Cells), IV-TC (treated with IV-injected Targeted Cells), and ICV-NTC (treated with Intracerebroventricular-injected Non-Targeted Cells). WJ-MSCs were labeled with dextran-coated superparamagnetic iron oxide nanoparticles (dex-SPIONs, 50 μg/ml), by bio-mimicry method. SPIONs-labeled MSCs were highly prussian blue positive with an intracellular iron concentration of 2.9 ± 0.08 pg/cell, which were successfully targeted into the hippocampus of AD rats by a halbach magnet array as magnetic targeted cell delivery (MTCD) technique. Presence of SPIONs-labeled cells in hippocampal area was proved by magnetic resonance imaging (MRI) in which signal intensity was reduced by increasing the number of these cells. Behavioral examinations showed that WJ-MSCs caused memory and cognitive improvement. Also, histological assessments showed functional improvement of hippocampal cells by expression of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE). Overall, this study indicates MTCD approach as an alternative in MSC-based regenerative medicine because it approximately has the same results as invasive directly ICV-injection method has.

Sensitivity of quantitative relaxometry and susceptibility mapping to microscopic iron distribution

PURPOSE

Determine the impact of the microscopic spatial distribution of iron on relaxometry and susceptibility-based estimates of iron concentration.

METHODS

Monte Carlo simulations and in vitro experiments of erythrocytes were used to create different microscopic distributions of iron. Measuring iron with intact erythrocyte cells created a heterogeneous distribution of iron, whereas lysing erythrocytes was used to create a homogeneous distribution of iron. Multi-echo spin echo and spoiled gradient echo acquisitions were then used to estimate relaxation parameters ( R 2 and R 2 * ) and susceptibility.

RESULTS

Simulations demonstrate that R 2 and R 2 * measurements depend on the spatial distribution of iron even for the same iron concentration and volume susceptibility. Similarly, in vitro experiments demonstrate that R 2 and R 2 * measurements depend on the microscopic spatial distribution of iron whereas the quantitative susceptibility mapping (QSM) susceptibility estimates reflect iron concentration without sensitivity to spatial distribution.

CONCLUSIONS

R 2 and R 2 * for iron quantification depend on the spatial distribution or iron. QSM-based estimation of iron concentration is insensitive to the microscopic spatial distribution of iron, potentially providing a distribution independent measure of iron concentration.

Combined Magnetoliposome Formation and Drug Loading in One Step for Efficient Alternating Current-Magnetic Field Remote-Controlled Drug Release

We have developed a reproducible and facile one step strategy for the synthesis of doxorubicin loaded magnetoliposomes by using a thin-layer evaporation method. Liposomes of around 200 nm were made of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and iron oxide nanoparticles (NPs) with negative, positive, and hydrophobic surfaces that were incorporated outside, inside, or between the lipid bilayers, respectively. To characterize how NPs are incorporated in liposomes, advanced cryoTEM and atomic force microscope (AFM) techniques have been used. It was observed that only when the NPs are attached outside the liposomes, the membrane integrity is preserved (lipid melt transition shifts to 38.7 °C with high enthalpy 34.8 J/g) avoiding the leakage of the encapsulated drug while having good colloidal properties and the best heating efficiency under an alternating magnetic field (AMF). These magnetoliposomes were tested with two cancer cell lines, MDA-MB-231 and HeLa cells. First, 100% of cellular uptake was achieved with a high cell survival (above 80%), which is preserved (83%) for doxorubicin-loaded magnetoliposomes. Then, we demonstrate that doxorubicin release can be triggered by remote control, using a noninvasive external AMF for 1 h, leading to a cell survival reduction of 20%. Magnetic field conditions of 202 kHz and 30 mT seem to be enough to produce an effective heating to avoid drug degradation. In conclusion, these drug-loaded magnetoliposomes prepared in one step could be used for drug release on demand at a specific time and place, efficiently using an external AMF to reduce or even eliminate side effects.

Hemolysis tendency of anticancer nanoparticles changes with type of blood group antigen: An insight into blood nanoparticle interactions

Different blood groups of ABO system have specific antigen which bestows them with different biochemical properties and hence they can show different hemolytic activity. In this report, hemolytic activity of thiol-functionalized Fe₃O₄-Au nanoparticles were studied in presence and absence of doxorubicin and the effect of various thiol coatings were correlated towards their hemolysis tendency. The nanoparticles were functionalized with four different amino thiols, cysteamine (CEA), cystamine (CA), cysteine (Cys) and cystine (Cyt) to form Fe₃O₄-Au CEA, Fe₃O₄-Au CA, Fe₃O₄-Au Cys and Fe₃O₄-Au Cyt nanoparticles which were loaded with anticancer drug, doxorubicin. The functionalization was characterized using ATR-FTIR, HR-TEM, XPS and other spectroscopic methods. Maximum drug encapsulation efficiency of 83% was observed with Fe₃O₄-Au CA nanoparticles. In-vitro experiments were performed on HeLa cells to check the cellular uptake and cytotoxicity using MTT assay. Hemolytic activity was then analyzed with all the blood groups (positive and negative). The amino acid functionalized, Fe₃O₄-Au Cys and Fe₃O₄-Au Cyt nanoparticles, shows lesser hemolysis compared to amino thiol functionalized Fe₃O₄-Au CEA, and Fe₃O₄-Au CA nanoparticles. In positive blood groups, the Fe₃O₄-Au CA nanoparticles shows the highest rate of hemolysis followed by Fe₃O₄-Au CEA, while the lowest hemolysis rate was observed for Fe₃O₄-Au Cyt nanoparticles. For negative blood groups, the thiol coated nanoparticles show more abrupt hemolysis rate depending upon the type of antigen.

Achieving arsenic concentrations of <1 μg/L by Fe(0) electrolysis: The exceptional performance of magnetite

Consumption of drinking water containing arsenic at concentrations even below the World Health Organization provisional limit of 10 μg/L can still lead to unacceptable health risks. Consequently, the drinking water sector in the Netherlands has recently agreed to target 1 μg/L of arsenic in treated water. Unfortunately, in many poor, arsenic-affected countries, the costs and complexity of current methods that can achieve <1 μg/L are prohibitive, which highlights the need for innovative methods that can remove arsenic to <1 μg/L without costly support infrastructure and complicated supply chains. In this work, we used Fe(0) electrolysis, a low cost and scalable technology that is also known as Fe(0) electrocoagulation (EC), to achieve <1 μg/L residual dissolved arsenic. We compared the arsenic removal performance of green rust (GR), ferric (oxyhydr)oxides (Fe(III) oxides) and magnetite (Mag) generated by EC at different pH (7.5 and 9) in the presence of As(III) or As(V) (initial concentrations of 200-11,000 μg/L). Although GR and Fe(III) oxides removed up to 99% of initial arsenic, neither Fe phase could reliably meet the 1 μg/L target at both pH values. In contrast, EC-generated Mag consistently achieved <1 μg/L, regardless of the initial As(V) concentration and pH. Only solutions with initial As(III) concentrations ≥2200 μg/L resulted in residual arsenic >1 μg/L. As K-edge X-ray absorption spectroscopy showed that Mag also sorbed arsenic in a unique mode, consistent with partial arsenic incorporation near the particle surface. This sorption mode contrasts with the binuclear, corner sharing surface complex for GR and Fe(III) oxides, which could explain the difference in arsenic removal efficiency among the three Fe phases. Our results suggest that EC-generated Mag is an attractive method for achieving <1 μg/L particularly in decentralized water treatment.

Noninvasive Tracking of Implanted Cells: Superparamagnetic Iron Oxide Nanoparticles as a Long-Term, Multimodal Imaging Label

Superparamagnetic iron oxide (SPIO) nanoparticles can function as specific, long-term multimodal contrast agents for noninvasive imaging studies. Here we describe how to achieve high-resolution, long-term, serial images of single-label transplanted cells through two complementary imaging techniques: magnetic resonance imaging (MRI) and microcomputed tomography (μCT).

An optimal architecture of magneto-plasmonic core-shell nanoparticles for potential photothermal applications

In this work, the optical responses of Fe3O4@Au and Fe3O4@Ag are comprehensively investigated using the discrete dipole approximation. It is found that the resonance wavelength and absorption efficiency strongly depend on the composition of the core and shell, geometry of the nanoparticles, core to particle volume ratio, core radius and shell thickness. The strongest impact is due to the shell material, the shape of the nanoparticles and their combination. When the composition of the shell is changed from gold to silver, instead of one fundamental resonance peak the absorption spectrum shows two, corresponding to the bonding plasmon mode at the nanoparticle-environment interface and antibonding mode at the core-shell interface. The results also reveal a much higher tunability of the resonance wavelength as well as larger enhancement of the absorption efficiency as the spherical nanoparticle stretches to a prolate ellipsoidal shape. Furthermore, higher order plasmon modes appear in the absorption spectrum of prolate nanoparticles with a large aspect ratio. The existence of several plasmon modes together with wide tunability makes these nanoparticles good candidates for applications where two or more simultaneous absorption bands at different frequencies are required. These results might motivate experimentalists to optimize the synthesis of magnetic-plasmonic core-shell NPs in different applications as far as absorption is concerned.

Polyethyleneimine coated Fe3O4 magnetic nanoparticles induce autophagy, NF-κB and TGF-β signaling pathway activation in HeLa cervical carcinoma cells via reactive oxygen species generation

Fe₃O₄ magnetic nanoparticles (MNPs), as one of the most intensively researched NPs, have a range of applications in cancer treatments. In current research, we have focused on the influences of MNPs on cancer cells. We chose polyethyleneimine (PEI) coated MNPs (PEI-MNPs) as a model and they are colloidally stable in biological media. It can be proved that PEI-MNPs result in autophagy induction via mTOR-Akt-p70S6 K and ATG7 signaling pathways. For the first time, we have reported that PEI-MNPs activate both NF-κB and TGF-β signaling, two key pro-inflammatory pathways, in cancer cells. More significantly, we have found that autophagy induction and NF-κB and TGF-β activation can be efficiently suppressed through the inhibition of PEI-MNP dependent reactive oxygen species (ROS) over-production. ROS are deemed as a 'double edge sword' for cancer cells, owing to the cancer-suppressing and cancer-promoting actions. Our findings would be useful for designing MNPs induced ROS anti-cancer strategies or diminishing long-term toxic effects.

H2 O2 -Sensitive Upconversion Nanocluster Bomb for Tri-Mode Imaging-Guided Photodynamic Therapy in Deep Tumor Tissue

Low penetration depth of excited light, undesirable distribution of photosensitizers, severe hypoxia, and inefficient reactive oxygen species (ROS) generation in tumors, lead to the poor therapeutic effects in photodynamic therapy. Herein, a multifunctional nanocluster bomb (UCGM naonoparticles) composed of upconversion nanoparticles (NPs), CeO_x , graphite-C₃ N₄ (g-C₃ N₄ ) NPs, and metformin (Met) are developed to mitigate the hypoxia by oxidizing H₂ O₂ into O₂ due to the catalysis of CeO_x . The presence of Met can act on the mitochondrion to inhibit the respiration of tumor cells, further improving the O₂ level. Meanwhile, g-C₃ N₄ NPs are released from UCGM NPs and penetrate tumor tissue deeply because of their small size. Upon 808 nm laser illumination, UCGM NPs show remarkable photothermal ability and efficiently convert near infrared to ultraviolet light to activate the g-C₃ N₄ NPs to generate ROS in a whole tumor to facilitate a combined antitumor effect against deeply located tumors. Moreover, these UCGM NPs also display excellent performances in upconversion luminescence, magnetic resonance imaging, and computerized tomographic imaging, making them a potential imaging-guided drug delivery system in cancer therapy.

Magnetically Actuated Degradable Microrobots for Actively Controlled Drug Release and Hyperthermia Therapy

Microrobots facilitate targeted therapy due to their small size, minimal invasiveness, and precise wireless control. A degradable hyperthermia microrobot (DHM) with a 3D helical structure is developed, enabling actively controlled drug delivery, release, and hyperthermia therapy. The microrobot is made of poly(ethylene glycol) diacrylate (PEGDA) and pentaerythritol triacrylate (PETA) and contains magnetic Fe₃ O₄ nanoparticles (MNPs) and 5-fluorouracil (5-FU). Its locomotion is remotely and precisely controlled by a rotating magnetic field (RMF) generated by an electromagnetic actuation system. Drug-free DHMs reduce the viability of cancer cells by elevating the temperature under an alternating magnetic field (AMF), a hyperthermic effect. 5-FU is released from the proposed DHMs in normal-, high-burst-, and constant-release modes, controlled by the AMF. Finally, actively controlled drug release from the DHMs in normal- and high-burst-release mode results in a reduction in cell viability. The reduction in cell viability is of greater magnitude in high-burst- than in normal-release mode. In summary, biodegradable DHMs have potential for actively controlled drug release and hyperthermia therapy.

Co-precipitation Synthesis of Near-infrared Iron Oxide Nanocrystals on Magnetically Targeted Imaging and Photothermal Cancer Therapy via Photoablative Protein Denature

Near-infrared (NIR)-based nanomaterials that provide efficient tumor ablation for cancer therapy have been reported. However, the issues of biocompatibility of metals or ions in inorganic nanoparticles systems such as copper and gold nanoparticles are still a matter of concern. In this study, we developed a facile and ligand-assisted co-precipitation method to synthesize biocompatible iron oxide (IO) nanocrystals with NIR absorption that provided T2-weighted magnetic resonance (MR) images and photothermal ablation characteristics suitable for cancer theranostics. Our results showed that 150-nm particles can be synthesized and optimized by using different amounts of ligand. NIR-IO nanocrystals of this size showed high photothermal conversion efficiency (21.2%) and T2-weighted MR contrast (transverse relaxivity value approximately 141 S-1 mM-1). The NIR-IO nanocrystals showed no cytotoxicity in HT-29 colorectal cancer cells without irradiation, whereas the viability of cells that received NIR-IO nanocrystals decreased significantly after 808-nm laser irradiation. The mechanism of cell death may involve alterations in protein secondary structure and membrane permeability. For in vivo studies, 4-fold enhanced tumor accumulation was significantly observed of NIR-IO nanocrystals with a magnetic field (MF) application, resulting in a 3-fold higher T2-weighted MR signal than that produced by a commercial T2-weighted MR contrast agent (Resovist®) and excellent photothermal efficacy (approximately 53 °C) for cancer treatment. The innovative NIR-IO nanocrystals showed excellent biocompatibility and have great potential as a theranostic agent against cancer.

Externally Controlled Cellular Transport of Magnetic Iron Oxide Particles with Polysaccharide Surface Coatings

Recently, due to their promising applications in biomedicine, magnetic iron oxide nanoparticles (MPs) have become one of the research hotspots in the nanomedicine field. Since various synthetic modifications have been widely applied to these nanoparticles for better targeting behaviors, it is meaningful to apply the optimal magnetic field condition for each case. This will enable creating a safe and efficient drug targeting using different types of MPs. In the present study, we aimed to find out any changes of transepithelial transport of polysaccharide-coated MPs by applying the continuous or the pulsatile magnetic field condition. Our results with heparin-functionalized MPs indicate that the particle concentrations and the external magnetic field could influence the transepithelial permeability of the particles. In the presence of a continuously applied magnetic density, heparin-MPs at high concentrations, by forming magnetically-induced aggregation of particles over the cell surface layer, showed a lower cellular transport than those at low concentrations. Furthermore, the results from the quantitative chemical assays and imaging analyses showed that transepithelial transport of heparin-MPs (negatively charged) under the pulsatile magnetic field was higher than that under the continuous magnetic field (CP), whereas the starch-MPs (neutrally charged) showed a small difference in transepithelial transport or cell retention between pulsatile vs. continuous magnetic field conditions. Taken together, our results suggest that the external magnetic field should be differentially applied to control the cellular drug transport depending on the physicochemical properties of the surface chemistry of magnetic particles.

D-mannose-Coating of Maghemite Nanoparticles Improved Labeling of Neural Stem Cells and Allowed Their Visualization by ex vivo MRI after Transplantation in the Mouse Brain

Magnetic resonance imaging (MRI) of superparamagnetic iron oxide-labeled cells can be used as a non-invasive technique to track stem cells after transplantation. The aim of this study was to (1) evaluate labeling efficiency of D-mannose-coated maghemite nanoparticles (D-mannose(γ-Fe2O3)) in neural stem cells (NSCs) in comparison to the uncoated nanoparticles, (2) assess nanoparticle utilization as MRI contrast agent to visualize NSCs transplanted into the mouse brain, and (3) test nanoparticle biocompatibility. D-mannose(γ-Fe2O3) labeled the NSCs better than the uncoated nanoparticles. The labeled cells were visualized by ex vivo MRI and their localization subsequently confirmed on histological sections. Although the progenitor properties and differentiation of the NSCs were not affected by labeling, subtle effects on stem cells could be detected depending on dose increase, including changes in cell proliferation, viability, and neurosphere diameter. D-mannose coating of maghemite nanoparticles improved NSC labeling and allowed for NSC tracking by ex vivo MRI in the mouse brain, but further analysis of the eventual side effects might be necessary before translation to the clinic.

Investigating the prospects of bacterial biosurfactants for metal nanoparticle synthesis - a comprehensive review

Establishing biological synthesis of nanoparticles is increasing nowadays in the field of nanotechnology. The search for an optimal source with durability, stability, capacity to withstand higher environmental conditions with excellent characteristics is yet to meet. Consequently, there is need to create an eco-friendly strategy for metal nanoparticle synthesis. One approach investigated in this review is the use of biosurfactants to enhance the synthesis biologically. In comparison with the other technologies, biosurfactants are less toxic and exhibit higher properties. This method is different from the conventional practice like physical and chemical methods. Several research studies represented that the biosurfactant influences the production of nanoparticles about 2-50 nm. In this manner, the research towards the biosurfactant has raised. This review also addressed the feasibility of biosurfactant and their benefits in the synthesis of metallic nanoparticles. The findings from this review can recommend a conceivable use of biosurfactant as a source for metal nanoparticle synthesis.