High impact of in situ dextran coating on biocompatibility, stability and magnetic properties of iron oxide nanoparticles

Comparative Study of Antioxidant Activity of Dextran-Coated Iron Oxide, Gold, and Silver Nanoparticles Against Age-Induced Oxidative Stress in Erythrocytes

Erythrocytes undergo several changes during human aging and age-related diseases and, thus, have been studied as biomarkers of the aging process. The present study aimed to explore the antioxidant ability of metal and metal oxide nanoparticles (NPs) such as iron oxide (Fe3O4), gold (Au), and silver (Ag) to mitigate age-related oxidative stress in human erythrocytes. Metal and metal oxide NPs behave like antioxidative enzymes, directly influencing redox pathways and thus have better efficiency. Additionally, biopolymer coatings such as dextran enhance the biocompatibility of these NPs. Therefore, dextran-coated Fe3O4, Au, and Ag NPs were synthesized using wet chemical methods and were characterized. Their hemocompatibility and ability to protect erythrocytes from age-induced oxidative stress were investigated. The Fe3O4 and Au NPs were observed to protect erythrocytes from hydrogen peroxide and age-induced oxidative damage, including decreased antioxidant levels, reduced activity of antioxidative enzymes, and increased amounts of oxidative species. Pretreatment with NPs preserved the morphology and membrane integrity of the erythrocyte. However, Ag NPs induced oxidative stress in erythrocytes similar to hydrogen peroxide. Therefore, dextran-coated Fe3O4 and Au nanoparticles have the potential to be employed as antioxidant therapies against age-related oxidative stress.

Magnetic Nanoparticles: A Comprehensive Review from Synthesis to Biomedical Frontiers

Nanotechnology has opened new doors of exploration, particularly in materials science and healthcare. Magnetic nanoparticles (MNP), the tiny magnets, because of their various properties, have the potential to bring about radical changes in the field of medicine. The distinctive surface chemistry, nontoxicity, biocompatibility, and, in particular, the inducible magnetic moment of magnetic materials has attracted a great deal of interest in morphological structures from a variety of scientific domains. This review presents a concise overview of MNPs and their crucial properties and synthesis routes. It also aims to highlight the continuous synthesis methods available for MNP production. In recent years, the use of computational methods for understanding the behavior of nanoparticles has been on the rise. Thus, we also discuss the numerical models developed to understand how magnetic nanoparticles can be used in magnetic hyperthermia and targeting the Circle of Wilis. With the increasing use of MNPs in biomedical applications, it becomes necessary to understand the mechanisms of toxicity, which are elucidated in this review. The review focuses on the biomedical applications of MNPs in drug delivery, theranostics, and MRI contrasting agents. We anticipate that this article will broaden the perspective on magnetic nanoparticles and help to understand their functionality and applicability better.

Performance evaluation of dextran-coated CaFe12O19/MnFe2O4 exchange-spring composites for the self-heating properties at radio frequency field

The CaFe12O19/MnFe2O4 composites with the hard (CaFe12O19) and soft (MnFe2O4) magnetic phases, were prepared by chemical co-precipitation method. The prepared composites were calcined at three different temperatures to form different phases. The structural, morphological, and magnetic properties of composite were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), room temperature vibrational sample magnetometer (VSM), and transmission electron microscopy (TEM). The presence of the hard and soft phases has been confirmed without any secondary phase from XRD analysis, indicating the formation of composite. The crystallite size is found to be in the range of 24-44 nm calculated by Scherrer's formula. The TEM revealed hexagonal platelets of CaFe12O19 with spinel MnFe2O4 particles with an average particle size of 48 nm formed at the surface of the CaFe12O19/MnFe2O4 composite. The room temperature magnetic properties of composite were evaluated by employing VSM. The magnetic measurements have displayed enhancement in coercivity and magnetization for CaFe12O19/MnFe2O4, indicating that the composite possessed excellent exchange coupling. The composite's enhanced energy product ((BH)max) made it highly promising for biomedical applications such as hyperthermia. The exchange-spring coupled magnetic composite was coated with dextran to make it biocompatible, which is necessary for hyperthermia applications. The coating was confirmed using Fourier transform infrared spectroscopy (FTIR). Cytotoxicity tests on Vero cell lines showed that the coated composites had an excellent (>95%) cell survival rate. The hyperthermia heating of composite was measured for different concentrations of composite (0.25, 0.5, 1, 2, and 4 mg/mL) from which specific loss power (SLP) was calculated. From these SLP values, the optimized concentration was identified.

Dextran coated iron oxide nanoparticles loaded with protocatechuic acid as multifunctional therapeutic agents

Nowadays, there is a growing interest in multifunctional therapeutic agents as valuable tools to improve and expand the applicability field of traditional bioactive compounds. In this context, the synthesis and main characteristics of dextran-coated iron oxide nanoparticles (IONP-Dex) loaded with both an antioxidant, protocatechuic acid (PCA), and an antibiotic, ceftazidime (CAZ) or levofloxacin (LEV) are herein reported for the first time, with emphasis on the potentiation effect of PCA on drugs activity. All nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry, differential scanning calorimetry and dynamic light scattering. As evidenced by DPPH method, IONP-Dex loaded with PCA and LEV had similar antioxidant activity like those with PCA only, but higher than PCA and CAZ loaded ones. A synergy of action between PCA and each antibiotic co-loaded on IONP-Dex has been highlighted by an enhanced activity against reference bacterial strains, such as S. aureus and E. coli after 40 min of incubation. It was concluded that PCA, which is the main cause of the antioxidative properties of loaded nanoparticles, further improves the antimicrobial activity of IONP-Dex nanoparticles when was co-loaded with CAZ or LEV antibiotics. All constructs also showed a good biocompatibility with normal human dermal fibroblasts.

Protective potential of naringenin and its nanoformulations in redox mechanisms of injury and disease

Increasing evidence suggests that elevated intracellular levels of reactive oxygen species (ROS) play a significant role in the pathogenesis of many diseases. Increased intracellular levels of ROS can lead to the oxidation of lipids, DNA, and proteins, contributing to cellular damage. Hence, the maintenance of redox hemostasis is essential. Naringenin (NAR) is a flavonoid included in the flavanones subcategory. Various pharmacological actions have been ascribable to this phytochemical composition, including antioxidant, anti-inflammatory, antibacterial, antiviral, antitumor, antiadipogenic, neuro-, and cardio-protective activities. This review focused on the underlying mechanism responsible for the antioxidative stress properties of NAR and its' nanoformulations. Several lines of in vitro and in vivo investigations suggest the effects of NAR and its nanoformulation on their target cells via modulating signaling pathways. These nanoformulations include nanoemulsion, nanocarriers, solid lipid nanoparticles (SLN), and nanomicelle. This review also highlights several beneficial health effects of NAR nanoformulations on human diseases including brain disorders, cancer, rheumatoid arthritis, and small intestine injuries. Employing nanoformulation can improve the pharmacokinetic properties of NAR and consequently efficiency by reducing its limitations, such as low bioavailability. The protective effects of NAR and its' nanoformulations against oxidative stress may be linked to the modulation of Nrf2-heme oxygenase-1, NO/cGMP/potassium channel, COX-2, NF-κB, AMPK/SIRT3, PI3K/Akt/mTOR, BDNF, NOX, and LOX-1 pathways. Understanding the mechanism behind the protective effects of NAR can facilitate drug development for the treatment of oxidative stress-related disorders.

Folic acid-conjugated dextran-coated Zn0.6Mn0.4Fe2O4 nanoparticles as systemically delivered nano heaters with self-regulating temperature for magnetic hyperthermia therapy of liver tumors

Successful cancer treatment using magnetic hyperthermia therapy (MHT) strongly depends on biocompatible magnetic nanoparticles (NPs). They can effectively accumulate in tumor tissues after systemic injection and generate heat in the therapeutic temperature range (42-48 °C) by exposure to an AC magnetic field (AMF). For this purpose, folic acid-conjugated dextran-coated Zn0.6Mn0.4Fe2O4 (FA-Dex-ZMF) NPs were synthesized as smart nano heaters with self-regulating temperatures for MHT of liver tumors. Animal studies on BALB/c mice showed that the prepared NPs did not cause acute toxicity upon administration up to 100 mg kg-1. Likewise, no significant changes in hematological and biochemical factors were observed. FA-Dex-ZMF NPs were studied by exposing them to different safe AC magnetic fields (f = 150 kHz, H = 6, 8, and 10 kA m-1). Calorimetric experiments revealed that the NPs reached the desired temperature range (42-48 °C), which was suitable for MHT. Moreover, the efficacy of FA-Dex-ZMF NPs in MHT of liver tumors was investigated in vivo in liver-tumor-bearing mice. The obtained results revealed that the average volume of tumors in the control group increased 2.2 times during the study period. In contrast, the tumor volume remained almost constant during treatment in the MHT group. The results indicated that folic acid-conjugated dextran-coated Zn0.6Mn0.4Fe2O4 NPs with self-regulating temperature could be a promising tool for systemically delivered MHT.

Magnetic Iron Oxide Nanoparticles for Brain Imaging and Drug Delivery

Central nervous system (CNS) disorders affect as many as 1.5 billion people globally. The limited delivery of most imaging and therapeutic agents into the brain is a major challenge for treatment of CNS disorders. With the advent of nanotechnologies, controlled delivery of drugs with nanoparticles holds great promise in CNS disorders for overcoming the blood-brain barrier (BBB) and improving delivery efficacy. In recent years, magnetic iron oxide nanoparticles (MIONPs) have stood out as a promising theranostic nanoplatform for brain imaging and drug delivery as they possess unique physical properties and biodegradable characteristics. In this review, we summarize the recent advances in MIONP-based platforms as imaging and drug delivery agents for brain diseases. We firstly introduce the methods of synthesis and surface functionalization of MIONPs with emphasis on the inclusion of biocompatible polymers that allow for the addition of tailored physicochemical properties. We then discuss the recent advances in in vivo imaging and drug delivery applications using MIONPs. Finally, we present a perspective on the remaining challenges and possible future directions for MIONP-based brain delivery systems.

1H-NMR Relaxation of Ferrite Core-Shell Nanoparticles: Evaluation of the Coating Effect

We investigated the effect of different organic coatings on the ¹H-NMR relaxation properties of ultra-small iron-oxide-based magnetic nanoparticles. The first set of nanoparticles, with a magnetic core diameter ds1 = 4.4 ± 0.7 nm, was coated with polyacrylic acid (PAA) and dimercaptosuccinic acid (DMSA), while the second set, ds2 = 8.9 ± 0.9 nm, was coated with aminopropylphosphonic acid (APPA) and DMSA. At fixed core diameters but different coatings, magnetization measurements revealed a similar behavior as a function of temperature and field. On the other hand, the ¹H-NMR longitudinal r1 nuclear relaxivity in the frequency range ν = 10 kHz ÷ 300 MHz displayed, for the smallest particles (diameter ds1), an intensity and a frequency behavior dependent on the kind of coating, thus indicating different electronic spin dynamics. Conversely, no differences were found in the r1 relaxivity of the biggest particles (ds2) when the coating was changed. It is concluded that, when the surface to volume ratio, i.e., the surface to bulk spins ratio, increases (smallest nanoparticles), the spin dynamics change significantly, possibly due to the contribution of surface spin dynamics/topology.

Response of the Endogenous Antioxidant Defense System Induced in RAW 264.7 Macrophages upon Exposure to Dextran-Coated Iron Oxide Nanoparticles

Presently, iron oxide nanoparticles are the only ones approved for clinical use as contrast agents in magnetic resonance imaging (MRI). Even though there is a high demand for these types of nanoparticles both for clinical use as well as for research, there are difficulties in obtaining stable nanoparticles with reproducible properties. In this context, in this study, we report the obtaining by an adapted coprecipitation method of dextran-coated maghemite nanoparticles (ɤ-Fe2O3 NPs). The morphology and structure of the dextran-coated maghemite nanoparticles (ɤ-Fe2O3 NPs) were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The TEM and SEM micrographs highlighted the obtaining of particles of nanometric size and spherical shape morphology. Furthermore, the high-resolution transmission electron microscopy (HRTEM), as well as selected area diffraction (SAED), revealed that the obtained samples presented the structure of cubic maghemite. In this study, we also explored the effects of the co-precipitation synthesized dextran-coated maghemite nanoparticles (ɤ-Fe2O3 NPs) on the redox status of macrophages. For cytotoxicity evaluation of these NPs, murine macrophages (RAW 264.7 cell line) were exposed to different concentrations of dextran-coated maghemite nanoparticles (ɤ-Fe2O3 NPs) corresponding to 0-500 μg Fe3+/mL and incubated for 24, 48, and 72 h. Intracellular iron uptake, changes in the oxidative stress parameters (reactive oxygen species production and malondialdehyde level), and the activity of antioxidant enzymes, as well as GSH concentration in cells, were evaluated after incubation with a lower (50 μg Fe3+/mL) and higher (500 μg Fe3+/mL) dose of NPs. The results indicated a significant decrease in RAW 264.7 cell viability after 72 h in the presence of NPs at concentrations above 25 μg Fe3+/mL. An important accumulation of NPs, dependent on dose and exposure time, was detected in macrophages, but it induced only a limited raise in the oxidative status. We showed here that the antioxidant capacity of RAW 264.7 macrophages was efficient in counteracting dextran-coated maghemite nanoparticles (ɤ-Fe2O3 NPs) toxicity even at higher doses.

Surface modified iron-oxide based engineered nanomaterials for hyperthermia therapy of cancer cells

Magnetic hyperthermia is emerging as a promising alternative to the currently available cancer treatment modalities. Superparamagnetic iron-oxide nanoparticles (SPIONs) are extensively studied functional nanomaterials for biomedical applications, owing to their tunable physio-chemical properties and magnetic properties. Out of various ferrite classes, spinel and inverse-spinel ferrites are widely used but are affected by particle size distribution, particle shape, particle-particle interaction, geometry, and crystallinity. Notably, their heating ability makes them suitable candidates for heat-mediated cancer cell ablation or hyperthermia therapy. Exposing SPIONs to an externally applied magnetic field of appropriate frequency and intensity causes them to release heat to ablate cancer cells. Majorly, three heating mechanisms are exhibited by magnetic nanomaterials: Nèel relaxation, Brownian relaxation, and hysteresis losses. In SPIONs, Nèel and Brownian relaxations dominate, whereas hysteric losses are negligible. These nanomaterials possess high magnetization values capable of generating heat to ablate cancer cells. Furthermore, surface functionalization of these materials imparts the ability to selectively target cancer cells and deliver cargo to the affected area sparing the normal body cells. The surface of nanoparticles can be functionalized with various physical, chemical, and biological coatings. Moreover, hyperthermia can be applied in combination with other cancer treatment modalities in order to enhance the efficiency of treatment.

Targeted Imaging of Lung Cancer with Hyperpolarized 129Xe MRI Using Surface-Modified Iron Oxide Nanoparticles as Molecular Contrast Agents

Hyperpolarized 129Xe (HP 129Xe) MRI enables functional imaging of various lung diseases but has been scarcely applied to lung cancer imaging. The aim of this study is to investigate the feasibility of targeted imaging of lung cancer with HP 129Xe MRI using surface-modified iron oxide nanoparticles (IONPs) as molecular targeting contrast agents. A mouse model of lung cancer (LC) was induced in nine mice by intra-peritoneal injection of urethane. Three months after the urethane administration, the mice underwent lung imaging with HP 129Xe MRI at baseline (0 h). Subsequently, the LC group was divided into two sub-groups: mice administered with polyethylene glycol-coated IONPs (PEG-IONPs, n = 4) and folate-conjugated dextran-coated IONPs (FA@Dex-IONPs, n = 5). The mice were imaged at 3, 6, and 24 h after the intravenous injection of IONPs. FA@Dex-IONPs mice showed a 25% reduction in average signal intensity at cancer sites at 3 h post injection, and a 24% reduction at 24 h post injection. On the other hand, in PEG-IONPs mice, while a signal reduction of approximately 28% was observed at cancer sites at 3 to 6 h post injection, the signal intensity was unchanged from that of the baseline at 24 h. Proton MRI of LC mice (n = 3) was able to detect cancer five months after urethane administration, i.e., later than HP 129Xe MRI (3 months). Furthermore, a significant decrease in averaged 1H T2 values at cancer sites was observed at only 6 h post injection of FA@Dex-IONPs (p < 0.05). As such, the targeted delivery of IONPs to cancer tissue was successfully imaged with HP 129Xe MRI, and their surface modification with folate likely has a high affinity with LC, which causes overexpression of folate receptors.

Covalently-Bonded Coating of L-Arginine Modified Magnetic Nanoparticles with Dextran Using Co-Precipitation Method

In this study, L-arginine (Arg) modified magnetite (Fe₃O₄) nanoparticles (RMNPs) were firstly synthesized through a one-step co-precipitation method, and then these aminated nanoparticles (NPs) were, again, coated by pre-oxidized dextran (Dext), in which aldehyde groups (DextCHO) have been introduced on the polymer chain successfully via a strong chemical linkage. Arg, an amino acid, acts as a mediator to link the Dext to a magnetic core. The as-synthesized Arg-modified and Dext-coated arginine modified Fe₃O₄ NPs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Both synthesized samples, XRD pattern and FT-IR spectra proved that the core is magnetite. FT-IR confirmed that the chemical bonds of Arg and Dext both exist in the samples. SEM images showed that the NPs are spherical and have an acceptable distribution size, and the VSM analysis indicated the superparamagnetic behavior of samples. The saturation magnetization was decreased after Dext coating, which confirms successive coating RMNPs with Text. In addition, the TGA analysis demonstrated that the prepared magnetic nanocomposites underwent various weight loss levels, which admitted the modification of magnetic cores with Arg and further coating with Dext.

Recent advances in surface modification of micro- and nano-scale biomaterials with biological membranes and biomolecules

Surface modification of biomaterial can improve its biocompatibility and add new biofunctions, such as targeting specific tissues, communication with cells, and modulation of intracellular trafficking. Here, we summarize the use of various natural materials, namely, cell membrane, exosomes, proteins, peptides, lipids, fatty acids, and polysaccharides as coating materials on micron- and nano-sized particles and droplets with the functions imparted by coating with different materials. We discuss the applicability, operational parameters, and limitation of different coating techniques, from the more conventional approaches such as extrusion and sonication to the latest innovation seen on the microfluidics platform. Methods commonly used in the field to examine the coating, including its composition, physical dimension, stability, fluidity, permeability, and biological functions, are reviewed.

Smart and Multi-Functional Magnetic Nanoparticles for Cancer Treatment Applications: Clinical Challenges and Future Prospects

Iron oxide nanoparticle (IONPs) have become a subject of interest in various biomedical fields due to their magnetism and biocompatibility. They can be utilized as heat mediators in magnetic hyperthermia (MHT) or as contrast media in magnetic resonance imaging (MRI), and ultrasound (US). In addition, their high drug-loading capacity enabled them to be therapeutic agent transporters for malignancy treatment. Hence, smartening them allows for an intelligent controlled drug release (CDR) and targeted drug delivery (TDD). Smart magnetic nanoparticles (SMNPs) can overcome the impediments faced by classical chemo-treatment strategies, since they can be navigated and release drug via external or internal stimuli. Recently, they have been synchronized with other modalities, e.g., MRI, MHT, US, and for dual/multimodal theranostic applications in a single platform. Herein, we provide an overview of the attributes of MNPs for cancer theranostic application, fabrication procedures, surface coatings, targeting approaches, and recent advancement of SMNPs. Even though MNPs feature numerous privileges over chemotherapy agents, obstacles remain in clinical usage. This review in particular covers the clinical predicaments faced by SMNPs and future research scopes in the field of SMNPs for cancer theranostics.

Protein precoating modulates biomolecular coronas and nanocapsule-immune cell interactions in human blood

The biomolecular corona that forms on particles upon contact with blood plays a key role in the fate and utility of nanomedicines. Recent studies have shown that precoating nanoparticles with serum proteins can improve the biocompatibility and stealth properties of nanoparticles. However, it is not fully clear how precoating influences biomolecular corona formation and downstream biological responses. Herein, we systematically examine three precoating strategies by coating bovine serum albumin (single protein), fetal bovine serum (FBS, mixed proteins without immunoglobulins), or bovine serum (mixed proteins) on three nanoparticle systems, namely supramolecular template nanoparticles, metal-phenolic network (MPN)-coated template (core-shell) nanoparticles, and MPN nanocapsules (obtained after template removal). The effect of protein precoating on biomolecular corona compositions and particle-immune cell interactions in human blood was characterized. In the absence of a pre-coating, the MPN nanocapsules displayed lower leukocyte association, which correlated to the lower amount (by 2-3 fold) of adsorbed proteins and substantially fewer immunoglobulins (more than 100 times) in the biomolecular corona relative to the template and core-shell nanoparticles. Among the three coating strategies, FBS precoating demonstrated the most significant reduction in leukocyte association (up to 97% of all three nanoparticles). A correlation analysis highlights that immunoglobulins and apolipoproteins may regulate leukocyte recognition. This study demonstrates the impact of different precoating strategies on nanoparticle-immune cell association and the role of immunoglobulins in bio-nano interactions.

Preparation and characterization of glucose-conjugated super-paramagnetic iron oxide nanoparticles (G-SPIONs) for removal of Edwardsiella tarda and Aeromonas hydrophila from water

The present research was conducted to prepare efficient G-SPIONs by co-precipitation to remove Edwardsiella tarda and Aeromonas hydrophila from the aqueous solution. The synthesized G-SPIONs were characterized by UV-Vis spectrophotometer, DLS, FEG-TEM, FT-IR, XRD, and VSM analysis. The results showed that the synthesized G-SPIONs had super-paramagnetic properties (58.31 emu/g) and spherical shape (16 ± 3 nm). The antibacterial activity was assessed in sterilized distilled water at different G-SPIONs concentrations viz. 0, 1.5, 3, 6, 12, 24, 48, 120, and 240 mg/L against E. tarda and A. hydrophila with various bacterial loads viz. 1 × 10³ , 1 × 10⁴ , 1 × 10⁵ , 1 × 10⁶ , and 1 × 10⁷  CFU/ml at different time intervals 15, 30, 45, and 60 min. At a lower bacterial load of E. tarda and A. hydrophila 1 × 10³ -1 × 10⁴  CFU/ml, 100% bacterial load was removed by 15 min exposure with NPs concentration 6-48 mg/L and 1.5-6 mg/L, respectively. Cent percent bacterial removal was observed in both the bacterial species even at higher bacterial load (1 × 10⁵ -1 × 10⁷  CFU/ml) by increasing exposure time (15-60 min) and nanoparticle concentration as well (24-240 mg/L). At an initial bacterial load of E. tarda and A. hydrophila (1 × 10³ -1 × 10⁷  CFU/ml), the EC₅₀ ranged between 0.01-6.51 mg/L and 0.02-3.84 mg/L, respectively, after 15-60 min exposure. Thus, it is concluded that the antibacterial effect of G-SPIONs depends on concentration and exposure time. Hence, G-SPIONs can be used as an antibacterial/biocidal agent to treat Edwardsiellosis and Aeromonosis disease in aquaculture.

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.

Breast cancer suppression by curcumin-naringenin-magnetic-nano-particles: In vitro and in vivo studies

BACKGROUND

The limitations of surgery, radiotherapy, and chemotherapy in cancer treatment and the increase in the application of nanomaterials in the field of biomedicine have promoted the use of nanomaterials in combination with radiotherapy for cancer treatment.

OBJECTIVE

To improve the efficiency of cancer treatment, curcumin-naringenin loaded dextran-coated magnetic nanoparticles (CUR-NAR-D-MNPs) were used as chemotherapy and in combination with radiotherapy to verify their effectiveness in treating tumors.

METHODS

CUR-NAR-D-MNPs were prepared and studied by several characterization methods. Median inhibitory concentration (IC50) and cellular toxicity were evaluated by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay. The cell death and radiosensitization were studied by acridine orange/ethidium bromide dual staining of MCF-7 human breast cancer cells.

RESULTS

CUR-NAR-D-MNPs induce apoptosis and inhibited cell proliferation through reactive oxygen species (ROS) generation. CUR-NAR-D-MNPs used alone had a certain therapeutic effect on tumors. CUR-NAR-D-MNPs plus radiotherapy significantly reduced the tumor volume and led to cell cycle arrest and induction of apoptosis through modulation of P53high, P21high, TNF-αlow, CD44low, and ROShigh signalingCONCLUSIONS:CUR-NAR-D-MNPs are effective in the treatment of tumors when combined with radiotherapy, and show radiosensitization effects against cancer proliferation in vitro and in vivo.

Heat dissipation in Sm3+ and Zn2+ co-substituted magnetite (Zn0.1SmxFe2.9-xO4) nanoparticles coated with citric acid and pluronic F127 for hyperthermia application

In this work, Sm³⁺ and Zn²⁺ co-substituted magnetite Zn_0.1Sm_xFe_2.9-xO₄ (x = 0.0, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoparticles, have been prepared via co-precipitation method and were electrostatically and sterically stabilized by citric acid and pluronic F127 coatings. The coated nanoparticles were well dispersed in an aqueous solution (pH 5.5). Magnetic and structural properties of the nanoparticles and their ferrofluids were studied by different methods. XRD studies illustrated that all as-prepared nanoparticles have a single phase spinel structure, with lattice constants affected by samarium cations substitution. The temperature dependence of the magnetization showed that Curie temperatures of the uncoated samples monotonically increased from 430 to 480 °C as Sm³⁺ content increased, due to increase in A-B super-exchange interactions. Room temperature magnetic measurements exhibited a decrease in saturation magnetization of the uncoated samples from 98.8 to 71.9 emu/g as the Sm³⁺ content increased, which is attributed to substitution of Sm³⁺ (1.5 µB) ions for Fe³⁺ (5 µB) ones in B sublattices. FTIR spectra confirmed that Sm³⁺ substituted Zn_0.1Sm_xFe_2.9-xO₄ nanoparticles were coated with both citric acid and pluronic F127 properly. The mean particle size of the coated nanoparticles was 40 nm. Calorimetric measurements showed that the maximum SLP and ILP values obtained for Sm³⁺ substituted nanoparticles were 259 W/g and 3.49 nHm²/kg (1.08 mg/ml, measured at f = 290 kHz and H = 16kA/m), respectively, that are related to the sample with x = 0.01. Magnetic measurements revealed coercivity, which indicated that hysteresis loss may represent a substantial portion in heat generation. Our results show that these ferrofluids are potential candidates for magnetic hyperthermia applications.

Preparation and Characterization of Dextran Coated Iron Oxide Nanoparticles Thin Layers

In the present study, we report the synthesis of a dextran coated iron oxide nanoparticles (DIO-NPs) thin layer on glass substrate by an adapted method. The surface morphology of the obtained samples was analyzed by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), optical, and metallographic microscopies. In addition, the distribution of the chemical elements into the DIO-NPs thin layer was analyzed by Glow Discharge Optical Emission Spectrometry (GDOES). Furthermore, the chemical bonds formed between the dextran and iron oxide nanoparticles was investigated by Fourier Transform Infrared Spectroscopy (FTIR). Additionally, the HepG2 viability incubated with the DIO-NPs layers was evaluated at different time intervals using MTT (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The goal of this study was to obtain a DIO-NPs thin layer which could be used as a coating for medical devices such as microfluidic channel, microchips, and catheter. The results of the surface morphology investigations conducted on DIO-NPs thin layer suggests the presence of a continuous and homogeneous layer. In addition, the GDOES results indicate the presence of C, H, Fe, and O signal intensities characteristic to the DIO-NPs layers. The presence in the IR spectra of the Fe-CO metal carbonyl vibration bonds prove that the linkage between iron oxide nanoparticles and dextran take place through carbon–oxygen bonds. The cytotoxicity assays highlighted that HepG2 cells morphology did not show any noticeable modifications after being incubated with DIO-NPs layers. In addition, the MTT assay suggested that the DIO-NPs layers did not present any toxic effects towards HEpG2 cells.

Chelator-Free/Chelator-Mediated Radiolabeling of Colloidally Stabilized Iron Oxide Nanoparticles for Biomedical Imaging

The aim of this study was to develop a bioimaging probe based on magnetic iron oxide nanoparticles (MIONs) surface functionalized with the copolymer (p(MAA-g-EGMA)), which were radiolabeled with the positron emitter Gallium-68. The synthesis of the hybrid MIONs was realized by hydrolytic condensation of a single ferrous precursor in the presence of the copolymer. The synthesized MagP MIONs displayed an average D_h of 87 nm, suitable for passive targeting of cancerous tissues through the enhanced permeation and retention (EPR) effect after intravenous administration, while their particularly high magnetic content ascribes strong magnetic properties to the colloids. Two different approaches were explored to develop MIONs radiolabeled with ⁶⁸Ga: the chelator-mediated approach, where the chelating agent NODAGA-NHS was conjugated onto the MIONs (MagP-NODAGA) to form a chelate complex with ⁶⁸Ga, and the chelator-free approach, where ⁶⁸Ga was directly incorporated onto the MIONs (MagP). Both groups of NPs showed highly efficient radiolabeling with ⁶⁸Ga, forming constructs which were stable with time, and in the presence of PBS and human serum. Ex vivo biodistribution studies of [⁶⁸Ga]Ga- MIONs showed high accumulation in the mononuclear phagocyte system (MPS) organs and satisfactory blood retention with time. In vivo PET imaging with [⁶⁸Ga]Ga-MagP MIONs was in accordance with the ex vivo biodistribution results. Finally, the MIONs showed low toxicity against 4T1 breast cancer cells. These detailed studies established that [⁶⁸Ga]Ga- MIONs exhibit potential for application as tracers for early cancer detection.

Advanced Functional Nanostructures based on Magnetic Iron Oxide Nanomaterials for Water Remediation: A Review

The fast growth of industrialization combined with the increasing population has led to an unparalleled demand for providing water in a safe, reliable, and cost-effective way, which has become one of the biggest challenges of the twenty-first century faced by global society. The application of nanotechnology in water treatment and pollution cleanup is a promising alternative in order to overcome the current limitations. In particular, the application of magnetic iron oxide nanoparticles (MIONs) for environmental remediation has currently received remarkable attention due to its unique combination of physicochemical and magnetic properties. Given the broadening use of these functional engineered nanomaterials, there is a growing concern about the adverse effects upon exposure of products and by-products to the environment. This makes vitally relevant the development of green chemistry in the synthesis processes combined with a trustworthy risk assessment of the nanotoxicity of MIONs as the scientific knowledge of the potential hazard of nanomaterials remains limited. This work provides comprehensive coverage of the recent progress on designing and developing iron oxide-based nanomaterials through a green synthesis strategy, including the use of benign solvents and ligands. Despite the limitations of nanotoxicity and environmental risks of iron oxide-based nanoparticles for the ecosystem, this critical review presents a contribution to the emerging knowledge concerning the theoretical and experimental studies on the toxicity of MIONs. Potential improvement of applications of advanced iron oxide-based hybrid nanostructures in water treatment and pollution control is also addressed in this review.

A Full Set of In Vitro Assays in Chitosan/Tween 80 Microspheres Loaded with Magnetite Nanoparticles

Microspheres have been proposed for different medical applications, such as the delivery of therapeutic proteins. The first step, before evaluating the functionality of a protein delivery system, is to evaluate their biological safety. In this work, we developed chitosan/Tween 80 microspheres loaded with magnetite nanoparticles and evaluated cell damage. The formation and physical-chemical properties of the microspheres were determined by FT-IR, Raman, thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), and SEM. Cell damage was evaluated by a full set of in vitro assays using a non-cancerous cell line, human erythrocytes, and human lymphocytes. At the same time, to know if these microspheres can load proteins over their surface, bovine serum albumin (BSA) immobilization was measured. Results showed 7 nm magnetite nanoparticles loaded into chitosan/Tween 80 microspheres with average sizes of 1.431 µm. At concentrations from 1 to 100 µg/mL, there was no evidence of changes in mitochondrial metabolism, cell morphology, membrane rupture, cell cycle, nor sister chromatid exchange formation. For each microgram of microspheres 1.8 µg of BSA was immobilized. The result provides the fundamental understanding of the in vitro biological behavior, and safety, of developed microspheres. Additionally, this set of assays can be helpful for researchers to evaluate different nano and microparticles.

Influence of Dextran Molecular Weight on the Physical Properties of Magnetic Nanoparticles for Hyperthermia and MRI Applications

Dextran-coated magnetic nanoparticles are promising biocompatible agents in various biomedical applications, including hyperthermia and magnetic resonance imaging (MRI). However, the influence of dextran molecular weight on the physical properties of dextran-coated magnetic nanoparticles has not been described sufficiently. We synthesise magnetite nanoparticles with a dextran coating using a co-precipitation method and study their physical properties as a function of dextran molecular weight. Several different methods are used to determine the size distribution of the particles, including microscopy, dynamic light scattering, differential centrifugal sedimentation and magnetic measurements. The size of the dextran-coated particles increases with increasing dextran molecular weight. We find that the molecular weight of dextran has a significant effect on the particle size, efficiency, magnetic properties and specific absorption rate. Magnetic hyperthermia measurements show that heating is faster for dextran-coated particles with higher molecular weight. The different molecular weights of the coating also significantly affected its MRI relaxation properties, especially the transversal relaxivity r₂. Linear regression analysis reveals a statistically significant dependence of r₂ on the differential centrifugal sedimentation diameter. This allows the targeted preparation of dextran-coated magnetic nanoparticles with the desired MRI properties. These results will aid the development of functionalised magnetic nanoparticles for hyperthermia and MRI applications.

Immobilization of alcohol dehydrogenase from Saccharomyces cerevisiae onto carboxymethyl dextran-coated magnetic nanoparticles: a novel route for biocatalyst improvement via epoxy activation

A novel method is described for the immobilization of alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae onto carboxymethyl dextran (CMD) coated magnetic nanoparticles (CMD-MNPs) activated with epoxy groups, using epichlorohydrin (EClH). EClH was used as an activating agent to bind ADH molecules on the surface of CMD-MNPs. Optimal immobilization conditions (activating agent concentration, temperature, rotation speed, medium pH, immobilization time and enzyme concentration) were set to obtain the highest expressed activity of the immobilized enzyme. ADH that was immobilized onto epoxy-activated CMD-MNPs (ADH-CMD-MNPs) maintained 90% of the expressed activity. Thermal stability of ADH-CMD-MNPS after 24 h at 20 °C and 40 °C yielded 79% and 80% of initial activity, respectively, while soluble enzyme activity was only 19% at 20 °C and the enzyme was non-active at 40 °C. Expressed activity of ADH-CMD-MNPs after 21 days of storage at 4 °C was 75%. Kinetic parameters (K_M, v_max) of soluble and immobilized ADH were determined, resulting in 125 mM and 1.2 µmol/min for soluble ADH, and in 73 mM and 4.7 µmol/min for immobilized ADH.

Role of inorganic nanoparticle degradation in cancer therapy

Nanomaterials are currently widely exploited for their potential in the development of novel cancer therapies, and so far, mainly nanoparticles (NPs) consisting of liposomes and polymers have made their way into the clinic. However, major bottlenecks for the clinical translation of other types of NPs (i.e. inorganic) are the lack of knowledge concerning their long-term distribution in vivo and their potential toxicity. To counter this, various research groups have worked on soluble NPs, such as zinc oxide (ZnO), copper oxide (CuO), and silver (Ag), which tend to dissolve spontaneously into their ionic form, releasing toxic metal ions and leading to reactive oxygen species (ROS) generation when exposed to cellular environments. By fine-tuning the dissolution kinetics of these NPs, it is possible to control the level of ROS production and thus cytotoxicity to selectively destroy tumor tissue. Specifically, cancer cells tend to exhibit a higher basal level of oxidative stress compared to normal cells due to their higher metabolic rates, and therefore, by engineering NPs that generate sufficient ROS that barely exceed toxic thresholds in cancer cells, normal cells will only experience reversible transient damage. This review focuses on the use of these soluble inorganic NPs for selective cancer therapy and on the various in vitro and in vivo studies that have aimed to control the dissolution kinetics of these NPs, either through particle doping or surface modifications.

One-pot preparation of hyaluronic acid-coated iron oxide nanoparticles for magnetic hyperthermia therapy and targeting CD44-overexpressing cancer cells

In the present study, a facile one-pot hydrothermal method is introduced for preparation of hyaluronic acid-coated Fe₃O₄ nanoparticles (Fe₃O₄@HA NPs) for theranostic applications. In the proposed method, hyaluronic acid acts simultaneously as a biocompatible coating layer and as a targeting ligand for CD44 receptor overexpressed on the surface of breast cancer cells. The obtained product with narrow hydrodynamic size distribution exhibited a high colloidal stability at physiological pH for more than three months. Cytotoxicity measurements indicated a negligible toxicity of the prepared sample against L929 normal cells. Preferential targeting of Fe₃O₄@HA NPs to CD44-overexpressing cancer cells was studied by comparing the uptake of the prepared nanoparticles by MDA-MB-231 cancer cells (positive CD44 expression) and L929 normal cells (negative CD44 expression). Uptake of the Fe₃O₄@HA NPs by MDA-MB-231 cells was found to be 4-fold higher than the normal cells. Also, the in vitro analysis showed that, the uptake of Fe₃O₄@HA NPs by MDA-MB-231 breast cancer cells is significantly enhanced as compared to non-targeted dextran-coated Fe₃O₄ NPs. Moreover, the heat generation capability of the Fe₃O₄@HA NPs for magnetic hyperthermia application was studied by exposing the prepared nanoparticles to different safe alternating magnetic fields (f = 120 kHz, H = 8, 10, and 12 kA/m). The intrinsic loss power obtained for Fe₃O₄@HA NPs was about 3.5 nHm²/kg, which is about 25-fold larger than that of obtained for commercial available Fe₃O₄ nanoparticles for biomedical applications. Good colloidal stability, biocompatibility, high heating efficacy, and targeting specificity to CD44 receptor-overexpressing cancer cells could make the Fe₃O₄@HA NPs as a promising multifunctional platform for diagnosis and therapeutic applications.

Polyethylenimine-dextran-coated magnetic nanoparticles loaded with miR-302b suppress osteosarcoma in vitro and in vivo

Aim: We attempted to synthesize a magnetic gene carrier with poly(ethylenimine), dextran and iron oxide nanoparticles (PDIs) for miR-302b transfection in vitro and in vivo. Materials & methods: The nanoparticles were characterized for hydrodynamic properties, ζ potential and DNA-binding ability, evaluated by transmission electron microscopy. Cellular internalization, magnetofection efficiency and anti-osteosarcoma effects were investigated in osteosarcoma (OS) cells and OS-bearing nude mice. Results: PDIs were successfully prepared and showed mild cytotoxicity. A magnetic field efficiently enabled transport of PDI/pmiR302b to OS cells in OS-bearing nude mice, exerting the anti-osteosarcoma effect of miR-302b at the tumor site. The inhibitory effect of miR-302b on osteosarcoma-bearing nude mice may be attributed to regulation of the Hippo pathway through YOD1. Conclusion: Low-cytotoxic PDIs have potential applications as a magnetic transport carrier for future osteosarcoma treatment.

Effects of multiple injections on the efficacy and cytotoxicity of folate-targeted magnetite nanoparticles as theranostic agents for MRI detection and magnetic hyperthermia therapy of tumor cells

Folate-targeted iron oxide nanoparticles (FA@Fe3O4 NPs) were prepared by a one-pot hydrothermal method and then used as cancer theranostic agents by combining magnetic resonance imaging (MRI) and magnetic hyperthermia therapy (MHT). Crystal structure, morphology, magnetic properties, surface functional group, and heating efficacy of the synthesized nanoparticles were characterized by XRD, TEM, VSM, FTIR, and hyperthermia analyses. The results indicated that the crystal structure, magnetic properties, and heating efficacy of the magnetite nanoparticles were improved by hydrothermal treatment. Toxicity of the prepared NPs was assessed in vitro and in vivo on the mammary cells and BALB/c mice, respectively. The results of the in vitro toxicity analysis showed that the FA@Fe3O4 NPs are relatively safe even at high concentrations of the NPs up to 1000 µg mL-1. Also, the targetability of the FA@Fe3O4 NPs for the detection of folate over-expressed cancer cells was evaluated in an animal model of breast tumor using MRI analysis. It was observed that T2-weighted magnetic resonance signal intensity was decreased with the three-time injection of the FA@Fe3O4 NPs with 24 h interval at a safe dose (50 mg kg-1), indicating the accumulation and retention of the NPs within the tumor tissues. Moreover, the therapeutic efficacy of the MHT using the FA@Fe3O4 NPs was evaluated in vivo in breast tumor-bearing mice. Hyperthermia treatment was carried out under a safe alternating magnetic field permissible for magnetic hyperthermia treatment (f = 150 kHz, H = 12.5 mT). The therapeutic effects of the MHT were evaluated by monitoring the tumor volume during the treatment period. The results showed that the mice in the control group experienced an almost 3.5-fold increase in the tumor volume during 15 days, while, the mice in the MHT group had a mild increase in the tumor volume (1.8-fold) within the same period (P < 0.05). These outcomes give promise that FA@Fe3O4 NPs can be used as theranostic agents for the MRI and MHT applications.

In Vitro and In Vivo Antioxidant Activity of the New Magnetic-Cerium Oxide Nanoconjugates

BACKGROUND

Cerium oxide nanoparticles present the mimetic activity of superoxide dismutase, being able to inactivate the excess of reactive oxygen species (ROS) correlated with a large number of pathologies, such as stents restenosis and the occurrence of genetic mutations that can cause cancer. This study presents the synthesis and biological characterisation of nanoconjugates based on nanoparticles of iron oxide interconnected with cerium oxide conjugates.

METHODS

The synthesis of magnetite-nanoceria nanoconjugates has been done in several stages, where the key to the process is the coating of nanoparticles with polyethyleneimine and its chemical activation-reticulation with glutaraldehyde. The nanoconjugates are characterised by several techniques, and the antioxidant activity was evaluated in vitro and in vivo.

RESULTS

Iron oxide nanoparticles interconnected with cerium oxide nanoparticles were obtained, having an average diameter of 8 nm. Nanoconjugates prove to possess superparamagnetic properties and the saturation magnetisation varies with the addition of diamagnetic components in the system, remaining within the limits of biomedical applications. In vitro free-radical scavenging properties of nanoceria are improved after the coating of nanoparticles with polyethylenimine and conjugation with magnetite nanoparticles. In vivo studies reveal increased antioxidant activity in all organs and fluids collected from mice, which demonstrates the ability of the nanoconjugates to reduce oxidative stress.

CONCLUSION

Nanoconjugates possess magnetic properties, being able to scavenge free radicals, reducing the oxidative stress. The combination of the two properties mentioned above makes them excellent candidates for theranostic applications.

Recent Advances in Continuous-Flow Particle Manipulations Using Magnetic Fluids

Magnetic field-induced particle manipulation is simple and economic as compared to other techniques (e.g., electric, acoustic, and optical) for lab-on-a-chip applications. However, traditional magnetic controls require the particles to be manipulated being magnetizable, which renders it necessary to magnetically label particles that are almost exclusively diamagnetic in nature. In the past decade, magnetic fluids including paramagnetic solutions and ferrofluids have been increasingly used in microfluidic devices to implement label-free manipulations of various types of particles (both synthetic and biological). We review herein the recent advances in this field with focus upon the continuous-flow particle manipulations. Specifically, we review the reported studies on the negative magnetophoresis-induced deflection, focusing, enrichment, separation, and medium exchange of diamagnetic particles in the continuous flow of magnetic fluids through microchannels.

Pharmaceutical Applications of Iron-Oxide Magnetic Nanoparticles

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

Succinylated heparin monolayer coating vastly increases superparamagnetic iron oxide nanoparticle T2 proton relaxivity

Superparamagnetic iron oxide nanoparticles (SPIONs) have a history of clinical use as contrast agents in T₂ weighted MRI, though relatively low T₂ relaxivity has caused them to fall out of favor as new faster MRI techniques have gained prominence. We demonstrate that SPIONs coated with a monolayer of succinylated heparin (Su-HP-SPIONs) exhibit over four-fold increased T₂ relaxivity (460 mM^-1 s^-1) as compared to the clinically approved SPION-based contrast agent Feridex (98.3 mM^-1 s^-1) due to greatly increased water interaction from increased hydrophilicity and thinner coating as supported by our proposed parametric model. In vivo, the performance increase of the Su-HP-SPIONs in T₂ MRI imaging of xenograft tumors is ten-fold that of our in-house synthesized Feridex analogue, due to better tumor localization from the smaller size imparted by the thinner coating. In addition to these significantly improved magnetic properties, the succinylated heparin coating also exhibits favorable synthetic reproducibility, solution stability, and biocompatibility. These findings demonstrate the untapped potential of SPIONs as possible high performance clinical T₂ contrast agents.

A review on the biosynthesis of metal and metal salt nanoparticles by microbes

Metal nanoparticles have received great attention from researchers across the world because of a plethora of applications in agriculture and the biomedical field as antioxidants and antimicrobial compounds. Over the past few years, green nanotechnology has emerged as a significant approach for the synthesis and fabrication of metal nanoparticles. This green route employs various reducing and stabilizing agents from biological resources for the synthesis of nanoparticles. The present article aims to review the progress made in recent years on nanoparticle biosynthesis by microbes. These microbial resources include bacteria, fungi, yeast, algae and viruses. This review mainly focuses on the biosynthesis of the most commonly studied metal and metal salt nanoparticles such as silver, gold, platinum, palladium, copper, cadmium, titanium oxide, zinc oxide and cadmium sulphide. These nanoparticles can be used in pharmaceutical products as antimicrobial and anti-biofilm agents, targeted delivery of anticancer drugs, water electrolysis, waste water treatment, biosensors, biocatalysis, crop protection against pathogens, degradation of dyes etc. This review will discuss in detail various microbial modes of nanoparticles synthesis and the mechanism of their synthesis by various bioreducing agents such as enzymes, peptides, proteins, electron shuttle quinones and exopolysaccharides. A thorough understanding of the molecular mechanism of biosynthesis is the need of the hour to develop a technology for large scale production of bio-mediated nanoparticles. The present review also discusses the advantages of various microbial approaches in nanoparticles synthesis and lacuna involved in such processes. This review also highlights the recent milestones achieved on large scale production and future perspectives of nanoparticles.

Polycarboxylated Dextran as a Multivalent Linker: Synthesis and Target Recognition of the Antibody-Nanoparticle Bioconjugates in PBS and Serum

Nanoparticles (NPs) functionalized with antibodies on their surface are used in a wide range of research applications. However, the bioconjugation chemistry between the antibodies and the surface of nanoparticles can be very challenging, often accompanied by several undesired effects such as nanoparticle aggregation, antibody denaturation, or poor target recognition of the surface-bound antibodies. Here, we report on a synthesis of fluorescent silica nanoparticle-antibody (NP-Ab) conjugates, in which polycarboxylated dextran is used as the multivalent linker. First, we present a synthetic methodology to prepare polycarboxylated dextrans with molecular weights of 6, 40, and 70 kDa. Second, we used water-soluble, polycarboxylated dextrans as a multivalent spacers/linkers to immobilize antibodies onto fluorescent silica nanoparticles. The prepared NP-Ab conjugates were tested in a direct binding assay format in both phosphate-buffered saline buffer and whole serum to investigate the role of the spacer/linker in the capacity of the NP-Ab to specifically recognize their target in "clean" and also in complex media. We have compared the dextran conjugates with two standards: (a) NP-Ab with antibodies attached on the surface of nanoparticles through the classical physical adsorption method and (b) NP-Ab where an established poly(amidoamine) (PAMAM) dendrimer was used as the linker. Our results showed that the polycarboxylated 6 kDa dextran facilitates antibody immobilization efficiency of nearly 92%. This was directly translated into the improved molecular recognition of the NP-Ab, which was measured by a direct binding assay. The signal-to-noise ratio in buffered solution for the 6 kDa dextran NP-Ab conjugates was 81, nearly 3 times higher than that of PAMAM G4.5 conjugates and 9 times higher than the physically adsorbed NP-Ab sample. In whole serum, the effect of 6 kDa dextran was more hindered due to the formation of protein corona but the signal-to-noise ratio was at least double that of the physically adsorbed NP-Ab conjugates.

Biomedical Imaging: Principles, Technologies, Clinical Aspects, Contrast Agents, Limitations and Future Trends in Nanomedicines

This review article presents the state-of-the-art in the major imaging modalities supplying relevant information on patient health by real-time monitoring to establish an accurate diagnosis and potential treatment plan. We draw a comprehensive comparison between all imagers and ultimately end with our focus on two main types of scanners: X-ray CT and MRI scanners. Numerous types of imaging probes for both imaging techniques are described, as well as reviewing their strengths and limitations, thereby showing the current need for the development of new diagnostic contrast agents (CAs). The role of nanoparticles in the design of CAs is then extensively detailed, reviewed and discussed. We show how nanoparticulate agents should be promising alternatives to molecular ones and how they are already paving new routes in the field of nanomedicine.

Surface Modification of Magnetic Iron Oxide Nanoparticles

Functionalized iron oxide nanoparticles (IONPs) are of great interest due to wide range applications, especially in nanomedicine. However, they face challenges preventing their further applications such as rapid agglomeration, oxidation, etc. Appropriate surface modification of IONPs can conquer these barriers with improved physicochemical properties. This review summarizes recent advances in the surface modification of IONPs with small organic molecules, polymers and inorganic materials. The preparation methods, mechanisms and applications of surface-modified IONPs with different materials are discussed. Finally, the technical barriers of IONPs and their limitations in practical applications are pointed out, and the development trends and prospects are discussed.

Multifunctional magnetic cargo-complexes with radical scavenging properties

Core-shell magnetic nanoparticle synthesis offers the opportunity to engineering their physical properties for specific applications when the intrinsic magnetic properties can be associated with other interesting ones. The purpose of this study was to design, synthesize, and characterize core-shell magnetic nanoparticles that mimic superoxide dismutase activity offering the possibility of guidance and therapeutic action. We proposed, for the first time, the synthesis and characterization of the nanocarriers comprised of magnetite nanoparticles functionalized with branched polyethyleneimine of low molecular weight (1.8 kDa) permitting the loading of the protocatechuic acid or its inclusion complex with anionic sulfobutylether-β-cyclodextrin for active drug delivery, in order to combine the useful properties of the magnetite and the protocatechuic acid antioxidant effect. NMR and DSC analyses confirmed the formation of the inclusion complex between sulfobutylether-β-cyclodextrin and protocatechuic acid, while structural and compositional analyses (FT-IR, TEM, XRD) revealed the synthesis of the multifunctional magnetic systems. Due to the possibility of being formulated as blood system injectable suspensions, antioxidant activity (using DPPH test) and cytotoxicity (using MTS assay on normal human dermal fibroblasts cells) were also measured, showing adequate properties to be used in biomedical applications. Moreover, we proposed a nanocarrier that would be able to load unstable active principles and with very low solubility in biological fluids to increase their biological ability.