Novel magnetic iron oxide nanoparticles coated with poly(ethylene imine)-g-poly(ethylene glycol) for potential biomedical application: synthesis, stability, cytotoxicity and MR imaging

Surface-modified magnetite nanoparticles using polyethylene terephthalate waste derivatives for oil spill remediation

This work aims at synthesizing new cross-linked poly ionic liquids, CPILs, VIMDE-Cl and CPIL, VIMDE-TFA, utilizing polyethylene terephthalate waste as a precursor and applying them to magnetite nanoparticles surface modification, producing surface-modified magnetite nanoparticles, SMNPs, VDCL/MNPs, and VDTA/MNPs, respectively. The structures of VIMDE-Cl and VIMDE-TFA, VDCL/MNPs, and VDTA/MNPs, were verified using different techniques. The particle sizes of SMNPs, VDCL/MNPs, and VDTA/MNPs, were evaluated with a transmission electron microscope and dynamic light scattering. The compatibility of VDCL/MNPs and VDTA/MNPs with crude oil components and their response to an external magnet were also measured using contact angle measurements and a vibrating sample magnetometer. The data confirmed the formation of SMNPs, nanosized structure, compatibility with oil components, and response to an external magnet. For that, VDCL/MNPs and VDTA/MNPs were applied for oil spill recovery using different SMNP : crude oil weight ratios. The impact of contact time on SMNPs' performance was also evaluated. The data indicated increased performance with an increase in SMNPs ratio, reaching maximum values of 99% and 96% for VDCL/MNPs and VDTA/MNPs, respectively, at SMNPs : crude oil ratio of 1 : 1. According to the results, the optimal contact time was 6 min, resulting in 89% and 97% performance for VDCL/MNPs and VDTA/MNPs at 1 : 4 SMNPs : crude oil ratio.

Application of Functionalized Fe3O4 Magnetic Nanoparticles Using CTAB and SDS for Oil Separation from Oil-in-Water Nanoemulsions

Using magnetic nanoparticles (MNPs) for emulsified oil separation from wastewater is becoming increasingly widespread. This study aims to synthesize MNPs using amphiphilic coatings to stabilize the MNPs and prevent their agglomeration for efficiently breaking oil-in-water nanoemulsions. We coat two different sizes of Fe₃O₄ nanoparticles (15-20 and 50-100 nm) using cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) with surfactant-to-MNP mass ratios of 0.4 and 0.8. We study the effect of various variables on the demulsification performance, including the MNP size and concentration, coating materials, and MNP loading. Based on the oil-water separation analysis, the smaller size MNPs (MNP-S) show a better demulsification performance than the larger ones (MNP-L ) for a 1000 ppm dodecane-in-water emulsion containing nanosized oil droplets (250-300 nm). For smaller MNPs (MNP-S) and at low dosage level of 0.5 g/L, functionalizing with surfactant-to-MNP mass ratio of 0.4, the functionalization increases the separation efficiency (SE) from 57.5% for bare MNP-S to 86.1% and 99.8 for the SDS and CTAB coatings, respectively. The highest SE for MNP-S@CTAB and the zeta potential measurements imply that electrostatic attraction between negatively charged oil droplets (-55.9 ± 2.44 mV) and positively charged MNP-S@CTAB (+35.8 ± 0.34 mV) is the major contributor to a high SE. Furthermore, the reusability tests for MNP-S@CTAB reveal that after 10 cycles, the amount of oil adsorption capacity decreases slightly, from 20 to 19 mg/g, indicating an excellent stability of synthesized nanoparticles. In conclusion, functionalized MNPs with tailored functional groups feature a high oil SE that could be effectively used for oil separation from emulsified oily wastewater streams.

Functionalized Magnetite Nanoparticles Using Two New Ionic Liquids for Efficient Oil Spill Cleanup

Recently, magnetite nanoparticles (MNPs) have gained great attention for oil spill cleanup due to their unique properties, e.g., high oil removal efficiency, high surface area, and response to an external magnetic field. The efficiency of MNPs for oil spill uptake can be enhanced by functionalizing their surface using different materials. Furthermore, the functionalization of MNP surface using these materials promotes their chemical stability. This study aims to functionalize the surface of magnetite nanoparticles (MNPs) using two newly synthesized hydrophobic ionic liquids (ILs) and apply them for oil spill cleanup. ILs were synthesized by the reaction of glycidyl-4-nonyl ether (GE) with fatty amines, either octadecylamine (OA) or dodecylamine (DA), to yield the corresponding amines, GEOA and GEDA, respectively. GEOA and GEDA were quaternized with acetic acid (AA) to produce the corresponding ILs, GEOA-IL and GEDA-IL. The produced ILs, GEOA-IL and GEDA-IL, were applied for the surface modification of magnetite nanoparticles (MNPs), producing surface-modified MNPs, GO-MNPs and GD-MNPs, respectively. GO-MNPs and GD-MNPs were characterized using Fourier transform infrared, X-ray diffraction, transmission electron microscopy, dynamic light scattering, contact angle, and vibrating sample magnetometer. Their oil removal efficiency (ORE) was investigated at different MNP : crude oil ratios ranging from 1 : 1–1 : 50. GO-MNPs and GD-MNPs showed high ORE even at low MNP ratios. Furthermore, GO-MNPs showed higher oil removal efficiency than GD-MNPs, which may be explained using GEOA-IL containing a longer alkyl chain for MNP surface modification in comparison to GEDA-IL. Furthermore, GO-MNPs and GD-MNPs displayed excellent reusability in five cycles, with a slight decrease in ORE with increasing cycles.

Fabrication of magnetite nanomaterials employing novel ionic liquids for efficient oil spill cleanup

The oil spill represents one of the most important pollution sources for marine environments, that occurs due to tanker collisions, ship accidents, and platforms. Several techniques are used for treating oil spill disasters including chemical, physical, and biochemical. The use of chemicals, magnetite nanomaterials (MNMs) in particular, is one of the most applied techniques used for oil spill remediation due to their low cost, fast remediation, and reusability. This work aims to synthesize and use new ionic liquids (ILs) for the modification of MNMs surfaces to enhance their performance for crude oil uptake. For that, octadecylamine (OA) was reacted with epichlorohydrin (EH), followed by reaction with either diethylenetriamine (DT), or tetraethylenepentamine (TP) to obtain corresponding amines, OADT, and OATP, respectively. The produced amines were quaternized using acetic acid (AA) forming corresponding ILs, OADT-IL, and OATP-IL. The obtained ILs, OADT-IL, and OATP-IL were applied for modification of magnetite nanomaterials (MNMs) surface to obtain the surface-modified MNMs, DT-MNMs, and TP-MNMs, respectively. The surface-modified MNMs were characterized using different techniques including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and contact angle. The efficacy of DT-MNMs, and TP-MNMs for heavy crude oil uptake (EMU) was evaluated. Further, the factors affecting on the crude oil uptake including MNMs: heavy crude oil ratio, and contact time were also evaluated. The data exhibited that, the EMU relatively declined as the ratio of DT-MNMs, and TP-MNMs decreased. Even at low MNMs:crude oil ratio (1:50), DT-MNMs, and TP-MNMs displayed EMU 87%, and 90%, respectively, which means 1 g of either DT-MNMs, or TP-MNMs can uptake 45 g, or 43.5 g, respectively. These values are high as compared with other studies that reported the use of MNMs for oil spill cleanup. Furthermore, the data indicated that the EMU increased as the contact time increased, and reached maximum EMU of 98% for both MNMs samples after 10 min.

Synthesis and characterization of CoxFe1-xFe2O4 nanoparticles by anionic, cationic, and non-ionic surfactant templates via co-precipitation

The cobalt ferrite nanoparticles (Co_xFe_1-xFe₂O₄) were synthesized by the surfactant templated co-precipitation method using various surfactants namely sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB), and Tween20. Under the substitution, the Co_xFe_1-xFe₂O₄ particles were synthesized at various Co²⁺ and Fe²⁺ mole ratios (x = 1, 0.6, 0.2, and 0) with the SDS. The cobalt ferrite nanoparticles were characterized for their morphology, structure, magnetic, and electrical properties. All Co_xFe_1-xFe₂O₄ nanoparticles showed the nanoparticle sizes varying from 16 to 43 nm. In the synthesis of CoFe₂O₄, the SDS template provided the smallest particle size, whereas the saturated magnetization (M_s) of CoFe₂O₄ was reduced by using CTAB, SDS, and Tween20. For the Co_xFe_1-xFe₂O₄ as synthesized by the SDS template at 1.2 CMC, the M_s increased with increasing Fe²⁺ mole ratio. The highest M_s of 100.4 emu/g was obtained from the Fe₃O₄ using the SDS template. The Fe₃O₄ nanoparticle is potential to be used in various actuator and biomedical devices.

Fabrication of Environmental-Friendly Magnetite Nanoparticle Surface Coatings for the Efficient Collection of Oil Spill

Over the past few decades, there has been an increased trend for the use of natural compounds and their derivatives as alternatives to traditional chemicals and is due to their renewability, green character, and wide availability. This work aims to convert sodium alginate (S.ALG), a natural polysaccharide, into amides through its conversion to alginic acid (H.ALG). The formed H.ALG was esterified using methanol, followed by a reaction with octadecylamine (OA) and dodecylamine (DA) to produce corresponding amides, OA-ALG, and DA-ALG, respectively. The synthesized OA-ALG and DA-ALG were used as capping agents to further form hydrophobic magnetite nanoparticles (MNPs), OA-MNPs and DA-MNPs, respectively. The chemical structures, morphology, hydrophobicity, and magnetic properties of OA-MNPs and DA-MNPs were investigated using different instrumental techniques. Furthermore, the efficacy of as-synthesized MNPs as oil spill collectors were also evaluated using different ratios of MNPs:crude oil. From the analysis of results, the OA-MNPs and DA-MNPs exhibited high efficiency in the collection of oil spill even at low ratios of MNPs:crude oil.

Combined Approach of Compression Molding and Magnetic Attraction to Micropatterning of Magnetic Polydimethylsiloxane Composite Surfaces with Excellent Anti-Icing/Deicing Performance

The accumulation of ice and contaminants on the surface of composite insulators will cause high energy consumption or even major hazards to power systems. In this work, the polydimethylsiloxane (PDMS) silicone rubber was modified by surface micropatterning and material compositing. Highly crosslinked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) was used to directly coat ferroferric oxide (Fe₃O₄) nanoparticles. The obtained core-shell Fe₃O₄@PZS microspheres were loaded with carbon nanotubes (CNTs) to get CNTs/Fe₃O₄@PZS as the photothermal magnetic filler. The PDMS/CNTs/Fe₃O₄@PZS surfaces with micronscale truncated cones were prepared via a combined method of compression molding and magnetic attraction. The 1H,1H,2H,2H-perfluorodecyltrichlorosilane-coated template and magnetic field can increase the height of the microstructure to ∼76 μm and maintain the contact angle of microstructured PDMS/CNTs/Fe₃O₄@PZS surfaces at a high level (∼152°). Compared with the flat PDMS surface, the micronscale truncated cones extend the freezing time from 4.5 to 11.5 min and also undermine the ice adhesion strength from ∼25 to ∼17 kPa for the microstructured PDMS/CNTs/Fe₃O₄@PZS surface. The temperature of the PDMS/CNTs/Fe₃O₄@PZS surface molded with magnetic attraction increases linearly with time and the internal magnetic fillers and achieves 280 °C in 10 s. The efficiency of temperature rise is increased by ∼46%, and hence the entire frozen water droplet can melt within 20 s. The strategy combining active deicing with passive anti-icing undoubtedly promotes the development of high efficiency anti-icing materials and can be applied on insulators to prevent icing flashover.

Cytostatic and Cytotoxic Effects of Hollow-Shell Mesoporous Silica Nanoparticles Containing Magnetic Iron Oxide

Among the different types of nanoparticles used in biomedical applications, Fe nanoparticles and mesoporous siliceous materials have been extensively investigated because of their possible theranostic applications. Here, we present hollow-shell mesoporous silica nanoparticles that encapsulate iron oxide and that are prepared using a drug-structure-directing agent concept (DSDA), composed of the model drug tryptophan modified by carbon aliphatic hydrocarbon chains. The modified tryptophan can behave as an organic template that allows directing the hollow-shell mesoporous silica framework, as a result of its micellisation and subsequent assembly of the silica around it. The one-pot synthesis procedure facilitates the incorporation of hydrophobically stabilised iron oxide nanoparticles into the hollow internal silica cavities, with the model drug tryptophan in the shell pores, thus enabling the incorporation of different functionalities into the all-in-one nanoparticles named mesoporous silica nanoparticles containing magnetic iron oxide (Fe₃O₄@MSNs). Additionally, the drug loading capability and the release of tryptophan from the silica nanoparticles were examined, as well as the cytostaticity and cytotoxicity of the Fe₃O₄@MSNs in different colon cancer cell lines. The results indicate that Fe₃O₄@MSNs have great potential for drug loading and drug delivery into specific target cells, thereby overcoming the limitations associated with conventional drug formulations, which are unable to selectively reach the sites of interest.

A Perspective on Modelling Metallic Magnetic Nanoparticles in Biomedicine: From Monometals to Nanoalloys and Ligand-Protected Particles

The focus of this review is on the physical and magnetic properties that are related to the efficiency of monometallic magnetic nanoparticles used in biomedical applications, such as magnetic resonance imaging (MRI) or magnetic nanoparticle hyperthermia, and how to model these by theoretical methods, where the discussion is based on the example of cobalt nanoparticles. Different simulation systems (cluster, extended slab, and nanoparticle models) are critically appraised for their efficacy in the determination of reactivity, magnetic behaviour, and ligand-induced modifications of relevant properties. Simulations of the effects of nanoscale alloying with other metallic phases are also briefly reviewed.

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.

A cation exchange strategy to construct a targeting nanoprobe for enhanced T1-weighted MR imaging of tumors

Excellent imaging performance and good biocompatibility of contrast agents are considered as prerequisites for accurate tumor diagnosis. In this study, a novel imaging nanoprobe with actively targeting performance based on ultrasmall paramagnetic iron oxide (USPIO) nanoparticles was constructed by a facile cation exchange strategy followed by conjugation with transferrin (Tf). The stable gadolinium (Gd3+) chelation endows the nanoparticles (NPs) with a low value of r2/r1 (1.28) and a relatively high r1 value of 3.2 mM-1 s-1, enabling their use for T1-weighted positive magnetic resonance (MR) imaging. This constructed transferrin modified gadolinium-iron chelate nanoprobe, named as TUG, shows high biocompatibility within a given dose range. More importantly, compared with clinically used Gd-based small molecule contrast agents, the obtained TUG can be more engulfed by breast cancer cells, showing much enhanced T1-weighted positive MR imaging in both subcutaneous and orthotopic tumor models of breast cancer. This novel nanoprobe holds great promise to be utilized as a targeting contrast agent with high efficacy for T1-weighted positive MR imaging.

Peptide-Decorated Ultrasmall Superparamagnetic Nanoparticles as Active Targeting MRI Contrast Agents for Ovarian Tumors

Magnetic resonance imaging (MRI) is widely applied in medical research and diagnosis, and a MRI contrast medium plays a crucial role in improving the sensitivity of detection. Ultrasmall superparamagnetic iron oxides (USPIOs) exhibit the potential as a T₂ enhancement contrast medium for MRI due to their excellent magnetic response performance; however, to endow them with specific tumor targetability, long-term circulation performance has always been a hot topic in this field. In this study, a well-designed procedure of chemical coprecipitation, surface modification, and peptide grafting was applied to prepare the active tumor-targeting USPIOs@F127-WSG, in which Pluronic F127 (F127) and the peptide WSGPGVWGASVK (peptide-WSG) were selected as the template agent and the ovarian tumor-targeting ligand, respectively. The results showed that single USPIOs@F127-WSG particles were Fe₃O₄ nanoparticles regulated by the confinement effect of F127 micelles with a uniform globular morphology and size (∼9 nm), and peptide-WSG was grafted for their tumor targetability. USPIOs@F127-WSG particles presented superparamagnetic behavior with high T₂ relaxivity (r₂ = 278.15 mM^-1 s^-1) and in vitro targetability for SKOV-3 cells due to the special binding between peptide-WSG and specific receptors of SKOV-3. The test results in vivo verified the targetability of USPIOs@F127-WSG by their specific aggregation in the tumor regions, leading to the T₂-weighted MRI contrast enhancement. These outstanding properties indicate that USPIOs@F127-WSG have great potential to be applied as the active tumor-targeting contrast agent for MRI.

Evaluation of the Ability of Nanostructured PEI-Coated Iron Oxide Nanoparticles to Incorporate Cisplatin during Synthesis

Nanoparticles (NPs) have a high potential for biological applications as they can be used as carriers for the controlled release of bioactive factors. Here we focused on poly(ethylenimine) (PEI)-coated iron oxide hybrid NPs obtained by hydrothermal synthesis in high pressure conditions and evaluated their behavior in culture medium in the presence or absence of cells, as well as their ability to incorporate antitumor drug cisplatin. Our results showed that the hydrothermal conditions used for Fe-PEI NPs synthesis allowed the incorporation of cisplatin, which even increased its anti-tumor effects. Furthermore, the commonly occurring phenomenon of NPs aggregation in culture medium was exploited for further entrapment of other active molecules, such as the fluorescent dye DiI and valinomycin. The molecules bound to NPs during synthesis or during aggregation process were delivered inside various cells after in vitro and in vivo direct contact between cells and NPs and their biological activity was preserved, thus supporting the therapeutic value of Fe-PEI NPs as drug delivery tools.

Biofunctionalized Hybrid Magnetic Gold Nanoparticles as Catalysts for Photothermal Ablation of Colorectal Liver Metastases

Purpose To demonstrate that anti-MG1 conjugated hybrid magnetic gold nanoparticles (HNPs) act as a catalyst during photothermal ablation (PTA) of colorectal liver metastases, and thus increase ablation zones. Materials and Methods All experiments were performed with approval of the institutional animal care and use committee. Therapeutic and diagnostic multifunctional HNPs conjugated with anti-MG1 monoclonal antibodies were synthesized, and the coupling efficiency was determined. Livers of 19 Wistar rats were implanted with 5 × 10⁶ rat colorectal liver metastasis cell line cells. The rats were divided into three groups according to injection: anti-MG1-coupled HNPs (n = 6), HNPs only (n = 6), and cells only (control group, n = 7). Voxel-wise R2 and R2* magnetic resonance (MR) imaging measurements were obtained before, immediately after, and 24 hours after injection. PTA was then performed with a fiber-coupled near-infrared (808 nm) diode laser with laser power of 0.56 W/cm² for 3 minutes, while temperature changes were measured. Tumors were assessed for necrosis with hematoxylin-eosin staining. Organs were analyzed with inductively coupled plasma mass spectrometry to assess biodistribution. Therapeutic efficacy and tumor necrosis area were compared by using a one-way analysis of variance with post hoc analysis for statistically significant differences. Results The coupling efficiency was 22 μg/mg (55%). Significant differences were found between preinfusion and 24-hour postinfusion measurements of both T2 (repeated measures analysis of variance, P = .025) and T2* (P < .001). Significant differences also existed for T2* measurements between the anti-MG1 HNP and HNP-only groups (P = .034). Mean temperature ± standard deviation with PTA in the anti-MG1-coated HNP, HNP, and control groups was 50.2°C ± 7.8, 51°C ± 4.4, and 39.5°C ± 2.0, respectively. Inductively coupled plasma mass spectrometry revealed significant tumor targeting and splenic sequestration. Mean percentages of tumor necrosis in the anti-MG1-coated HNP, HNP, and control groups were 38% ± 29, 14% ± 17, and 7% ± 8, respectively (P = .043). Conclusion Targeted monoclonal antibody-conjugated HNPs can serve as a catalyst for photothermal ablation of colorectal liver metastases by increasing ablation zones. ^© RSNA, 2017.

Direct Electron Transfer of Cellobiose Dehydrogenase on Positively Charged Polyethyleneimine Gold Nanoparticles

Efficient conjugation between biomolecules and electrode materials is one of the main challenges in the field of biosensors. Cellobiose dehydrogenase (CDH) is a monomeric enzyme, which consists of two separate domains: one catalytic dehydrogenase domain (DH_CDH ) carrying strongly bound flavin adenine dinucleotide (FAD) in the active site and a cytochrome domain (CYT_CDH ) carrying a b-type heme connected by a flexible linker region. Herein, we report on the development of a lactose biosensor, based on direct electron transfer (DET) from CDH from Phanerochaete sordida (PsCDH) electrostatically attached onto polyethyleneimine-stabilized gold nanoparticles (PEI@AuNPs) used to cover a conventional polycrystalline solid gold disk electrode. PEI@AuNPs were synthesized in aqueous solution using PEI as reducing agent for Au^III and as stabilizer for the nanoparticles. The heterogeneous electron-transfer (ET) rate (k_s ) for the redox reaction of immobilized PsCDH at the modified electrodes was calculated based on the Laviron theory and was found to be (39.6±2.5) s^-1 . The proposed lactose biosensor exhibits good long term stability as well as high and reproducible sensitivity to lactose with a response time less than 5 s and a linear range from 1 to 100 μm.

Micro and nanotechnologies in heart valve tissue engineering

Due to the increased morbidity and mortality resulting from heart valve diseases, there is a growing demand for off-the-shelf implantable tissue engineered heart valves (TEHVs). Despite the significant progress in recent years in improving the design and performance of TEHV constructs, viable and functional human implantable TEHV constructs have remained elusive. The recent advances in micro and nanoscale technologies including the microfabrication, nano-microfiber based scaffolds preparation, 3D cell encapsulated hydrogels preparation, microfluidic, micro-bioreactors, nano-microscale biosensors as well as the computational methods and models for simulation of biological tissues have increased the potential for realizing viable, functional and implantable TEHV constructs. In this review, we aim to present an overview of the importance and recent advances in micro and nano-scale technologies for the development of TEHV constructs.

Super-paramagnetic loaded nanoparticles based on biological macromolecules for in vivo targeted MR imaging

Target-specific MRI contrast agent based on super-paramagnetic iron oxide-chitosan-folic acid (SPIONP-CS-FA) nanoparticles was fabricated by using an ionotropic gelation method, which involved the loading of SPIONPs at various concentrations into CS-FA nanoparticles by electrostatic interaction. The SPIONP-CS-FA nanoparticles were characterized by ATR-FTIR, XRD, TEM, and VSM techniques. This study revealed that the advantages of this system would be green fabrication, low cytotoxicity at iron concentrations ranging from 0.52 mg/L to 4.16 mg/L, and high water stability (pH 6) at 4°C over long periods. Average particle size and positive zeta-potential of the SPIONP-CS-FA nanoparticles was found to be 130 nm with narrow size distribution and 42 mV, respectively. In comparison to SPIONP-0.5-CS nanoparticles, SPIONP-0.5-CS-FA nanoparticles showed higher and specific cellular uptake levels into human cervical adenocarcinoma cells due to the presence of folate receptors, while in vivo results (Wistar rat) indicated that only liver tissue showed significant decreases in MR image intensity on T2 weighted images and T2* weighted images after post-injection, in comparison with other organs. Our results demonstrated that SPIONP-CS-FA nanoparticles can be applied as an either tumor or organ specific MRI contrast agents.

Novel magnetic iron oxide nanoparticles coated with sulfonated asphaltene as crude oil spill collectors

This work aims to apply modified asphaltene for capping of magnetite to form dispersed hydrophobic magnetic nanomaterials for environmental applications.

Recent Advances in Synthesis, Properties and Applications of Magnetic Oxide Nanomaterials

Oxide nanomaterials are in great demand due to their unique physical, chemical and structural properties. The nanostructured materials with desired magnetic properties are the future of power electronics. Unique magnetic properties and excellent biocompatibility of these materials found applications in pharmaceutical field also. For these applications, the synthesis of magnetic oxide nanomaterials with required properties is highly desirable. Till now, various techniques have been evolved for the synthesis of oxide nanomaterials with full control over their shape, size, morphology and magnetic properties. In nanoscale, the magnetic properties are totally different from their bulk counterparts. In this range, each nanoparticle acts as a single magnetic domain and shows fast response to applied magnetic field. This review article discusses the synthesis techniques, properties and the applications of magnetic oxide nanomaterials. Various characterization techniques for magnetic materials have been discussed along with the literature of iron oxide, nickel oxide, and cobalt oxide nanomaterials. The challenges for further development of these materials have also been presented to broaden their rapidly emerging applications.

Tailored functionalization of iron oxide nanoparticles for MRI, drug delivery, magnetic separation and immobilization of biosubstances

In this critical review, we outline various covalent and non-covalent approaches for the functionalization of iron oxide nanoparticles (IONPs). Tuning the surface chemistry and design of magnetic nanoparticles are described in relation to their applicability in advanced medical technologies and biotechnologies including magnetic resonance imaging (MRI) contrast agents, targeted drug delivery, magnetic separations and immobilizations of proteins, enzymes, antibodies, targeting agents and other biosubstances. We review synthetic strategies for the controlled preparation of IONPs modified with frequently used functional groups including amine, carboxyl and hydroxyl groups as well as the preparation of IONPs functionalized with other species, e.g., epoxy, thiol, alkane, azide, and alkyne groups. Three main coupling strategies for linking IONPs with active agents are presented: (i) chemical modification of amine groups on the surface of IONPs, (ii) chemical modification of bioactive substances (e.g. with fluorescent dyes), and (iii) the activation of carboxyl groups mainly for enzyme immobilization. Applications for drug delivery using click chemistry linking or biodegradable bonds are compared to non-covalent methods based on polymer modified condensed magnetic nanoclusters. Among many challenges, we highlight the specific surface engineering allowing both therapeutic and diagnostic applications (theranostics) of IONPs and magnetic/metallic hybrid nanostructures possessing a huge potential in biocatalysis, green chemistry, magnetic bioseparations and bioimaging.

Angiopep-pluronic F127-conjugated superparamagnetic iron oxide nanoparticles as nanotheranostic agents for BBB targeting

Pluronic® F127-modified water-dispersible poly(acrylic acid)-bound iron oxide (PF127-PAAIO) nanoparticles have been prepared as diagnostic agents. A blood-brain-barrier penetrating peptide, angiopep-2 (ANG), was further conjugated onto the surface of the PF127-PAAIO (ANG-PF127-PAAIO) for brain targeting. The ANG-PF127-PAAIO shows negligible cell cytotoxicity, better cellular uptake, and higher T₂-weighted image enhancement than the PF127-PAAIO in U87 cells. Using an ex vivo blood-brain barrier (BBB) model, we showed that the ANG-PF127-PAAIO shows better permeability to bypass the BBB. This is because the ANG-PF127-PAAIO has a dual-targeting ability, recognition of the low-density lipoprotein receptor-related protein and clathrin-mediated receptor on the U87 surface. Thus, the ANG-PF127-PAAIO is a potential nanotheranostic agent for brain dysfunction.

Core/shell nanoparticles in biomedical applications

Nanoparticles have several exciting applications in different areas and biomedial field is not an exception of that because of their exciting performance in bioimaging, targeted drug and gene delivery, sensors, and so on. It has been found that among several classes of nanoparticles core/shell is most promising for different biomedical applications because of several advantages over simple nanoparticles. This review highlights the development of core/shell nanoparticles-based biomedical research during approximately past two decades. Applications of different types of core/shell nanoparticles are classified in terms of five major aspects such as bioimaging, biosensor, targeted drug delivery, DNA/RNA interaction, and targeted gene delivery.

Superparamagnetic iron oxide nanoparticles for delivery of therapeutic agents: opportunities and challenges

INTRODUCTION

Bearing in mind that many promising drug candidates have the problem of reaching their target site, the concept of advanced drug delivery can play a significant complementary role in shaping modern medicine. Among other nanoscale drug carriers, superparamagnetic iron oxide nanoparticles (SPIONs) have shown great potential in nanomedicine. The intrinsic properties of SPIONs, such as inherent magnetism, broad safety margin and the availability of methods for fabrication and surface engineering, pave the way for diverse biomedical applications. SPIONs can achieve the highest drug targeting efficiency among carriers, since an external magnetic field locally applied to the target organ enhances the accumulation of magnetic nanoparticles in the drug site of action. Moreover, theranostic multifunctional SPIONs make simultaneous delivery and imaging possible. In spite of these favorable qualities, there are some toxicological concerns, such as oxidative stress, unpredictable cellular responses and induction of signaling pathways, alteration in gene expression profiles and potential disturbance in iron homeostasis, that need to be carefully considered. Besides, the protein corona at the surface of the SPIONs may induce few shortcomings such as reduction of SPIONs targeting efficacy.

AREAS COVERED

In this review, we will present recent developments of SPIONs as theranostic agents. The article will further address some barriers on drug delivery using SPIONs.

EXPERT OPINION

One of the major success determinants in targeted in vivo drug delivery using SPIONs is the adequacy of magnetic gradient. This can be partially achieved by using superconducting magnets, local implantation of magnets and application of magnetic stents. Other issues that must be considered include the pharmacokinetics and in vivo fate of SPIONs, their biodegradability, biocompatibility, potential side effects and the crucial impact of protein corona on either drug release profile or mistargeting. Surface modification of SPIONs can open up the possibility of drug delivery to intracellular organelles, drug delivery across the blood-brain barrier, modifying metabolic diseases and a variety of other multimodal and/or theranostic applications.

Cytotoxic effect of magnetic iron oxide nanoparticles synthesized via seaweed aqueous extract

Magnetic iron oxide nanoparticles (Fe₃O₄ MNPs) are among the most useful metal nanoparticles for multiple applications across a broad spectrum in the biomedical field, including the diagnosis and treatment of cancer. In previous work, we synthesized and characterized Fe₃O₄ MNPs using a simple, rapid, safe, efficient, one-step green method involving reduction of ferric chloride solution using brown seaweed (Sargassum muticum) aqueous extract containing hydroxyl, carboxyl, and amino functional groups mainly relevant to polysaccharides, which acts as a potential stabilizer and metal reductant agent. The aim of this study was to evaluate the in vitro cytotoxic activity and cellular effects of these Fe₃O₄ MNPs. Their in vitro anticancer activity was demonstrated in human cell lines for leukemia (Jurkat cells), breast cancer (MCF-7 cells), cervical cancer (HeLa cells), and liver cancer (HepG2 cells). The cancer cells were treated with different concentrations of Fe₃O₄ MNPs, and an MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay was used to test for cytotoxicity, resulting in an inhibitory concentration 50 (IC₅₀) value of 23.83±1.1 μg/mL (HepG2), 18.75±2.1 μg/mL (MCF-7), 12.5±1.7 μg/mL (HeLa), and 6.4±2.3 μg/mL (Jurkat) 72 hours after treatment. Therefore, Jurkat cells were selected for further investigation. The representative dot plots from flow cytometric analysis of apoptosis showed that the percentages of cells in early apoptosis and late apoptosis were increased. Cell cycle analysis showed a significant increase in accumulation of Fe₃O₄ MNP-treated cells at sub-G1 phase, confirming induction of apoptosis by Fe₃O₄ MNPs. The Fe₃O₄ MNPs also activated caspase-3 and caspase-9 in a time-response fashion. The nature of the biosynthesis and therapeutic potential of Fe₃O₄ MNPs could pave the way for further research on the green synthesis of therapeutic agents, particularly in nanomedicine, to assist in the treatment of cancer.

"Fastening" porphyrin in highly cross-linked polyphosphazene hybrid nanoparticles: powerful red fluorescent probe for detecting mercury ion

It is a significant issue to overcome the concentration-quenching effect of the small fluorescent probes and maintain the high fluorescent efficiency at high concentration for sensitive and selective fluorescent mark or detection. We developed a new strategy to "isolate" and "fasten" porphyrin moieties in a highly cross-linked poly(tetraphenylporphyrin-co-cyclotriphosphazene) (TPP-PZS) by the polycondensation of hexachlorocyclotriphosphazene (HCCP) and 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (TPP-(OH)4) in a suitable solvent. The resulting TPP-PZS particles were characterized with transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), (31)P nuclear magnetic resonance (NMR), and ultraviolet and visible (UV-vis) absorption spectra. Remarkably, TPP-PZS particles obtained in acetone emitted a bright red fluorescence both in powder state and in solution because the aggregation of porphyrin moieties in "H-type" (face-to-face) and "J-type" (edge-to-edge) was effectively blocked. The fluorescent TPP-PZS particles also showed superior resistance to photobleaching, and had a high sensitivity and selectivity for the detection of Hg(2+) ions. The TPP-PZS particles were therefore used as an ideal material for preparing test strips to quickly detect/monitor the Hg(2+) ions in a facile way.

Chitosan-triphosphate nanoparticles for encapsulation of super-paramagnetic iron oxide as an MRI contrast agent

Super-paramagnetic iron oxide nanoparticles (SPIONPs) were encapsulated at various concentrations within chitosan-triphosphate (SPIONPs-CS) nanoparticles using an ionotropic gelation method. The encapsulation of SPIONPs within CS nanoparticles enhanced their dispersion ability in aqueous solution, with all particles being lower than 130 nm in size and having highly positive surface charge. The SPIONPs-CS nanoparticles exhibited crystalline structure and super-paramagnetic behavior, as seen in non-encapsulated SPIONPs. The morphology of SPIONPs-CS nanoparticles showed that they almost spherical in shape. The effect of phantom environments (culture medium and 3% agar solution) on either T1 or T2 weighted MRI was investigated using a clinical 1.5T MRI scanner. The results revealed that 3% agar solution showed relaxation values higher than the culture medium, leading to a significant decrease in the MR image intensity. Our results demonstrated that the SPIONPs-CS nanoparticles can be applied as tissue-specific MRI contrast agents.