Interaction Of Iron Oxide Nanoparticles Research Articles

Size, polyglycerol grafting, and net surface charge of iron oxide nanoparticles determine their interaction and toxicity in Caenorhabditis elegans

The widespread application of engineered nanoparticles (NPs) in environmental remediation has raised public concerns about their toxicity to aquatic organisms. Although appropriate surface modification can mitigate the ecotoxicity of NPs, the lack of polymer coating to inhibit toxicity completely and the insufficient knowledge about charge effect hinder the development of safe nanomaterials. Herein, we explored the potential of polyglycerol (PG) functionalization in alleviating the environmental risks of NPs. Iron oxide NPs (ION) of 20, 100, and 200 nm sizes (IONS, IONM and IONL, respectively) were grafted with PG to afford ION-PG. We examined the interaction of ION and ION-PG with Caenorhabditis elegans (C. elegans) and found that PG suppressed non-specific interaction of ION with C. elegans to reduce their accumulation and to inhibit their translocation. Particularly, IONS-PG was completely excluded from worms of all developmental stages. By covalently introducing sulfate, carboxyl and amino groups onto IONS-PG, we further demonstrated that positively charged IONS-PG-NH3+ induced high intestinal accumulation, cuticle adhesion and distal translocation, whereas the negatively charged IONS-PG-OSO3– and IONS-PG-COO– were excreted out. Consequently, no apparent deleterious effects on brood size and life span were observed in worms treated by IONS-PG and IONS-PG bearing negatively charged groups. This study presents new surface functionalization approaches for developing ecofriendly nanomaterials.

Interaction of Iron Oxide Nanoparticles with Macrophages Is Influenced Distinctly by "Self" and "Non-Self" Biological Identities.

Upon contact with biological fluids like serum, a protein corona (PC) complex forms on iron oxide nanoparticles (IONPs) in physiological environments and the proteins it contains influence how IONPs act in biological systems. Although the biological identity of PC-IONP complexes has often been studied in vitro and in vivo, there have been inconsistent results due to the differences in the animal of origin, the type of biological fluid, and the physicochemical properties of the IONPs. Here, we identified differences in the PC composition when it was derived from the sera of three species (bovine, murine, or human) and deposited on IONPs with similar core diameters but with different coatings [dimercaptosuccinic acid (DMSA), dextran (DEX), or 3-aminopropyl triethoxysilane (APS)], and we assessed how these differences influenced their effects on macrophages. We performed a comparative proteomic analysis to identify common proteins from the three sera that adsorb to each IONP coating and the 10 most strongly represented proteins in PCs. We demonstrated that the PC composition is dependent on the origin of the serum rather than the nature of the coating. The PC composition critically affects the interaction of IONPs with macrophages in self- or non-self identity models, influencing the activation and polarization of macrophages. However, such effects were more consistent for DMSA-IONPs. As such, a self biological identity of IONPs promotes the activation and M2 polarization of murine macrophages, while a non-self biological identity favors M1 polarization, producing larger quantities of ROS. In a human context, we observed the opposite effect, whereby a self biological identity of DMSA-IONPs promotes a mixed M1/M2 polarization with an increase in ROS production. Conversely, a non-self biological identity of IONPs provides nanoparticles with a stealthy character as no clear effects on human macrophages were evident. Thus, the biological identity of IONPs profoundly affects their interaction with macrophages, ultimately defining their biological impact on the immune system.

COMPARATIVE CHARACTERIZATION OF AQUEOUS SUSPENSIONS OF MAGNETIC IRON OXIDE NANOPARTICLES WITH DIFFERENT PHASE COMPOSITIONS

The interaction of iron oxide nanoparticles with an aqueous medium has been studied. The composition of the nanoparticles corresponds to magnetite–maghemite solid solutions with different Fe2+/Fe3+ ratios. Nanoparticles that most closely correspond to the composition of maghemite (γ-Fe2O3) have largest hydrodynamic diameters and cause a drastic decrease in the pH of the dispersion medium during the dispersion of the powders in water. Nanoparticles that have a phase composition of a solid solution corresponding to the middle of the magnetite–maghemite series are characterized by a gradual and less pronounced decrease in pH. It has been shown that dilution of aqueous suspensions obtained from preliminarily dried powders within a concentration range of 100–0.001 mg/L followed by sonication leads to a significant increase in the hydrodynamic diameter of iron oxide particles. A possible mechanism of the studied interaction of nanoparticles with the aqueous medium has been considered. This mechanism comprises the hydration of Lewis acid sites formed by iron ions and changes in the character of the dissociation of hydroxyl groups depending on the pH of a suspension. The effect of surface passivation of the studied nanopowders with oleic acid on the processes under consideration has been investigated. The results obtained make it possible to predict the aggregative stability and a number of other characteristics of the studied suspensions being diluted with water.

Iron oxide nanoparticles reversibly affect sperm quality in Wistar rats.

Iron oxide nanoparticles (IONP) are being utilised for various biomedical applications due to their unique properties like superparamagnetism and greater colloidal stability. Interaction of IONP with male reproductive system is underrepresented in the literature. Current study strives to demonstrate the effects of IONP on sperm quality, reproductive hormones and fertility of adult Wistar rats. Spherical IONP with 15-20 nm size were injected for a maximum of 60 days in three different exposure schemes. Three increasing doses (20, 40 and 80 mg/kg) along with a control group were tested. Sperm count, sperm viability, motility and morphology were scored after the experimental periods. A group of rats was used to examine male fertility. Concentrations of male reproductive hormones in serum were also measured in all groups. Total sperm count and motility was significantly decreased in treated groups in comparison to control after 60 days of exposure. Changes in sperm viability and sperm morphology mostly proved to be statistically insignificant. Serum concentrations reproductive hormones like testosterone, luteinizing hormone and follicular stimulating hormone varied insignificantly between control and treatment groups. Male fertility was also not affected due to the exposure. Further, it is also reported that a 45-day recovery period restores the sperm quality up to a considerable extent. Overall, the study demonstrates that long term exposure of IONP has adverse effects on male sperm production and function that can be reversed if exposure is withdrawn.

Co-exposure of iron oxide nanoparticles and glyphosate-based herbicide promote liver toxicity in guppy (Poecilia reticulata): A histochemical and ultrastructural approach.

Citrate functionalized iron oxide nanoparticles (IONPs) are employed for various purposes-including environmental remediation but the interaction of IONPs with aquatic contaminants is poorly understood. Among those, glyphosate-based herbicides are toxic and affect target organs such as the liver. Evaluations of livers of female Poecilia reticulata by exposures to IONPs at a concentration of 0.3mg/L were performed with association to: (1) 0.65 mg of glyphosate per litter and (2) 1.3mg of glyphosate per litter of Roundup Original, and (3) glyphosate P.A at 0.65 mg/L. These associations were carried out progressively, after 7, 14, and 21 days. We detected circulatory disturbances, inflammatory responses, activation of the immune system, regressive changes, and progressive responses with changes in the connective tissue and decreased glycogen reserve from days 14 to 21. Ultrastructural changes in the Disse space and microvilli of hepatocytes indicated decreased contact surface area. In general, the damage was time and concentration dependent, increasing from 7 to 14 days and tending to stabilize from 14 to 21 days. Therefore, herbicide-associated IONPs functioned as xenobiotics inducing intense cellular detoxification processes and activation of hepatic immune responses.

Mechanistic insight into differential interactions of iron oxide nanoparticles with native, glycated albumin and their effect on erythrocytes parameters

Nanoparticles and protein bioconjugates have been studied for multiple biomedical applications. We sought to investigate the interaction and structural modifications of bovine serum albumin (BSA) with iron oxide nanoparticles (IONPs). The IONPs were green synthesized using E. crassipes aqueous leaf extract following characterization using transmission electron microscopy, energy dispersive X-ray analysis and X-ray diffraction. Two different concentrations of native/glycated albumin (0.5 and 1.5 mg/ml) with IONPs were allowed to interact for 1 h at 37 °C. Glycation markers, protein modification markers, cellular antioxidant, and hemolysis studies showed structural modifications and conformational changes in albumin due to the presence of IONPs. UV–visible absorbance resulted in hyperchromic and bathochromic effects of IONPs-BSA conjugates. Fluorescence measurements of tyrosine, tryptophan, advanced glycated end products, and ANS binding assay were promising and quenching effects proved IONPs-BSA conjugate formation. In FTIR of BSA-IONPs, transmittance was increased in amide A and B bands while decreased in amide I and II bands. In summary, native PAGE, HPLC, and FTIR analysis displayed a differential behaviour of IONPs with native and glycated BSA. These results provided an understanding of the interaction and structural modifications of glycated and native BSA which may provide fundamental repercussions in future studies.

Co-exposure of iron oxide nanoparticles and glyphosate-based herbicide induces DNA damage and mutagenic effects in the guppy (Poecilia reticulata)

Iron oxide nanoparticles (IONPs) have been tested to remediate aquatic environments polluted by chemicals, such as pesticides. However, their interactive effects on aquatic organisms remain unknown. This study aimed to investigate the genotoxicity and mutagenicity of co-exposure of IONPs (γ-Fe2O3 NPs) and glyphosate-based herbicide (GBH) in the fish Poecilia reticulata. Thus, fish were exposed to citrate-functionalized γ-Fe2O3 NPs (0.3 mg L−1; 5.44 nm) alone or co-exposed to γ-Fe2O3 NPs (0.3 mg L−1) and GBH (65 and 130 μg of glyphosate L−1) during 14 and 21 days. The genotoxicity (DNA damage) was analyzed by comet assay, while the mutagenicity evaluated by micronucleus test (MN test) and erythrocyte nuclear abnormalities (ENA) frequency. The co-exposure induced clastogenic (DNA damage) and aneugenic (nuclear alterations) effects on guppies in a time-dependent pattern. Fish co-exposed to NPs and GBH (130 μg glyphosate L−1) showed high DNA damage when compared to NPs alone and control group, indicating synergic effects after 21 days of exposure. However, mutagenic effects (ENA) were observed in the exposure groups after 14 and 21 days. Results showed the potential genotoxic and mutagenic effects of maghemite NPs and GBH co-exposure to freshwater fish. The transformation and interaction of iron oxide nanoparticles with other pollutants, as herbicides, in the aquatic systems are critical factors in the environmental risk assessment of metal-based NPs.

Harnessing iron-oxide nanoparticles towards the improved bactericidal activity of macrophage against Staphylococcus aureus

Iron oxide nanoparticles (IONPs) have been increasingly used in various biomedical applications in preclinical and clinical settings. Although the interactions of IONPs with macrophages have been well-reported in the context of nanoparticle toxicity, harnessing the capacity of IONPs in reprograming macrophages towards bactericidal activity has not been explored. Here, using an in vitro culture model of macrophages and an in vivo mouse model of skin wound infection by Staphylococcus aureus (S. aureus), we demonstrated that IONPs in combination with a strategy to trigger the Fenton reaction could significantly enhance bactericidal effects of macrophages against intracellular S. aureus by inducing a M1 macrophage polarization that stimulates the production of reactive oxygen species. Our study supports that harnessing the characteristic of IONPs to tune macrophage polarization to exhibit a bactericidal activity may provide a new strategy for treating infectious diseases.

Rational Design of Iron Oxide Binding Peptide Tags.

Owing to their extraordinary magnetic properties and low-cost production, iron oxide nanoparticles (IONs) are in the focus of research. In order to better understand interactions of IONs with biomolecules, a tool for the prediction of the propensity of different peptides to interact with IONs is of great value. We present an effective implicit surface model (EISM), which includes several interaction models. Electrostatic interactions, van der Waals interactions, and entropic effects are considered for the theoretical calculations. However, the most important parameter, a surface accessible area force field contribution term, derives directly from experimental results on the interactions of IONs and peptides. Data from binding experiments of ION agglomerates to different peptides immobilized on cellulose membranes have been used to parameterize the model. The work was carried out under defined environmental conditions; hence, effects because of changes, for example structure or solubility by changing the surroundings, are not included. EISM enables researchers to predict the binding of peptides to IONs, which we then verify with further peptide array experiments in an iterative optimization process also presented here. Negatively charged peptides were identified as best binders for IONs in Tris buffer. Furthermore, we investigated the constitution of peptides and how the amount and position of several amino acid side chains affect peptide-binding. The incorporation of glycine leads to higher binding scores compared to the incorporation of cysteine in negatively charged peptides.

Seed Priming with Iron Oxide Nanoparticles Triggers Iron Acquisition and Biofortification in Wheat (Triticum aestivum L.) Grains

Iron deficiency anaemia is a major challenge among consumers in developing countries. Given the deficiency of iron in the diet, there is an urgent need to devise a strategy for providing the required iron in the daily diet to counter the iron deficiency anaemia. We propose that iron biofortification of wheat (Triticum aestivum L.) through seed priming would be an innovative strategy to address this issue. This investigation attempts to find the interaction of iron oxide nanoparticles on germination, growth parameters and accumulation of grain iron in two contrasting wheat genotypes WL711 (low-iron genotype) and IITR26 (high-iron genotype). Wheat seeds were primed with different concentrations of iron oxide nanoparticles in the range of 25–600 ppm, resulting in differential accumulation of grain iron contents. We observed a pronounced increase in germination percentage and shoot length at 400 and 200 ppm treatment concentrations in IITR26 and WL711 genotypes, respectively. Intriguingly, the treatment concentration of 25 ppm demonstrated higher accumulation with a significant increase in grain iron contents to 45.7% in IITR26 and 26.8% in WL711 genotypes, respectively. Seed priming represents an innovative and user-friendly approach for wheat biofortification which triggers iron acquisition and accumulation in grains.

Separation of superparamagnetic magnetite nanoparticles by capillary zone electrophoresis using non-complexing and complexing electrolyte anions and tetramethylammonium as dispersing additive.

Separations of bare superparamagnetic magnetite nanoparticles (BSPMNPs, approx. 11 nm diameter) was performed using non-complexing (nitrate) and complexing (chloride, citrate and phosphate) electrolyte ions with additions of tetramethylammonium hydroxide (TMAOH), which is commonly applied to control the synthesis of stable iron oxides. The use of TMAOH as a background electrolyte (BGE) additive for capillary electrophoresis (CE) separations provided for the first time electropherograms of BSPMNPs exhibiting symmetrical and highly reproducible peaks, free of spurious spikes characteristic of nanoparticle clusters. Consequently, accurate determination of the electrophoretic effective mobility of BSPMNPs was possible, yielding a value of -3.345E-08 m2 V-1 s-1 (relative standard deviation (RSD) of 0.500%). The obtained mobilities of BSPMNPs in the presence of various electrolyte ions show that the degree of complexation with the surface of BSPMNPs follows the order chloride < citrate < phosphate, correlating with the stabilities of Fe(III) complexes with the respective anions. Finally, bare and carboxylated iron oxide nanoparticles were successfully separated in only 10 min using 10 mM Tris-nitrate containing 20mM of TMAOH as electrolyte. Our findings show that simple and rapid CE experiments are an excellent tool to characterise and monitor properties and interactions of iron oxide nanoparticles with other molecules for surface modification purposes.

Toxicity evaluation of magnetic iron oxide nanoparticles reveals neuronal loss in chicken embryo

Magnetic iron oxide nanoparticles (IONs) display the ability to cross blood − brain barrier and are envisioned as diagnostic and therapeutic applications, but there are few studies on their potential embryonic toxicity in higher vertebrates. This study investigates interaction of IONs with egg albumen and its subsequent toxicity on chicken embryo. Physicochemical interactions of IONs with egg albumen revealed alterations in friccohesity and secondary structural changes due to weak Vander Waals forces. Toxicity assessment of IONs (10, 25, 50, 100, and 200 µg/ml doses) on chicken embryo accounted for 100% mortality at 200 µg/ml dose due to Fe2+ ions overload. However, lower doses (50 and 100 µg/ml) recorded decrement in whole weights and crown-rump lengths of chicken embryo possibly due to ION–albumen interactions. Histology of brain tissue revealed degeneration of neurons (50–60%) at 10–100 µg/ml dose range of IONs. Toxicity studies of IONs with diverse animal models are needed to set a toxicity benchmark for preventing embryonic toxicity prior to its use in biomedical applications. This is the first study on toxicity assessment of IONs in chicken embryo.

Effect of surface functionalisation on the interaction of iron oxide nanoparticles with polymerase chain reaction

The combination of nanoparticles with the polymerase chain reaction (PCR) can have benefits such as easier sample handling or higher sensitivity, but also drawbacks such as loss of colloidal stability or inhibition of the PCR. The present work systematically investigates the interaction of magnetic iron oxide nanoparticles (MIONs) with the PCR in terms of colloidal stability and potential PCR inhibition due to interaction between the PCR components and the nanoparticle surface. Several types of MIONs with and without surface functionalisation by sodium citrate, dextran and 3-aminopropyl-triethoxysilane (APTES) were prepared and characterised by Transmission Electron Microscopy (TEM), dynamic light scattering (DLS) and Fourier Transform Infrared (FT-IR) spectroscopy. Colloidal stability in the presence of the PCR components was investigated both at room temperature and under PCR thermo-cycling. Dextran-stabilized MIONs show the best colloidal stability in the PCR mix at both room and elevated temperatures. Citrate- and APTES-stabilised as well as uncoated MIONs show a comparable PCR inhibition near the concentration 0.1mgml−1 while the inhibition of dextran stabilized MIONs became apparent near 0.5mgml−1. It was demonstrated that the PCR could be effectively carried out even in the presence of elevated concentration of MIONs up to 2mgml−1 by choosing the right coating approach and supplementing the reaction mix by critical components, Taq DNA polymerase and Mg2+ ions.

Interaction of iron oxide nanoparticles synthesized by laser target evaporation with polyacrylamide in composites and ferrogels

Iron oxide magnetic nanoparticles (MNPs) with average diameter 11.7 nm synthesized by laser target evaporation were used for the synthesis of composites and ferrogels based on polyacrylamide network. The chemical composition of MNPs corresponded to maghemite. It was shown that intact MNPs strongly interacted with polyacrylamide polymeric network, while the adsorption of electrostatic stabilizer on the surface of MNPs efficiently prevents such interaction. Synthesis of ferrogels was performed by the radical polymerization of acrylamide in electrostatically stabilized suspensions of MNPs in water. It was shown that the molecular structure, water uptake, and compression modulus can be controlled by the concentration of monomer taken in the synthesis.

MPQ-cytometry: a magnetism-based method for quantification of nanoparticle–cell interactions

Precise quantification of interactions between nanoparticles and living cells is among the imperative tasks for research in nanobiotechnology, nanotoxicology and biomedicine. To meet the challenge, a rapid method called MPQ-cytometry is developed, which measures the integral non-linear response produced by magnetically labeled nanoparticles in a cell sample with an original magnetic particle quantification (MPQ) technique. MPQ-cytometry provides a sensitivity limit 0.33 ng of nanoparticles and is devoid of a background signal present in many label-based assays. Each measurement takes only a few seconds, and no complicated sample preparation or data processing is required. The capabilities of the method have been demonstrated by quantification of interactions of iron oxide nanoparticles with eukaryotic cells. The total amount of targeted nanoparticles that specifically recognized the HER2/neu oncomarker on the human cancer cell surface was successfully measured, the specificity of interaction permitting the detection of HER2/neu positive cells in a cell mixture. Moreover, it has been shown that MPQ-cytometry analysis of a HER2/neu-specific iron oxide nanoparticle interaction with six cell lines of different tissue origins quantitatively reflects the HER2/neu status of the cells. High correlation of MPQ-cytometry data with those obtained by three other commonly used in molecular and cell biology methods supports consideration of this method as a prospective alternative for both quantifying cell-bound nanoparticles and estimating the expression level of cell surface antigens. The proposed method does not require expensive sophisticated equipment or highly skilled personnel and it can be easily applied for rapid diagnostics, especially under field conditions.

Lipid peroxidation and its control in Anguilla anguilla hepatocytes under silica-coated iron oxide nanoparticles (with or without mercury) exposure

Having multidisciplinary applications, iron oxide nanoparticles can inevitably enter aquatic system and impact inhabitants such as fish. However, the studies in this context have ignored the significance of obvious interaction of iron oxide nanoparticles with other persistent co-contaminants such as mercury (Hg) in the modulation of the toxicity and underlying mechanisms of iron oxide nanoparticles and Hg alone, and concomitant exposures. This study aimed to evaluate lipid peroxidation (LPO) and its control with glutathione (GSH) and associated enzymes (such as glutathione reductase, GR; glutathione peroxidase, GPX; glutathione sulfo-transferase, GST) in European eel (Anguilla anguilla L.) hepatocytes exposed to stressors with following schemes: (i) no silica-coated iron oxide nanoparticles functionalized with dithiocarbamate (Fe3O4@SiO2/Si DTC, hereafter called 'FeNPs'; size range 82 ± 21 to 100 ± 30nm) or Hg, (ii) FeNPs (2.5μgL(-1)) alone, (iii) Hg (50μgL(-1)) alone and (iv) FeNPs + Hg concomitant condition during 0 to 72h. The exhibition of a differential coordination between GSH regeneration (determined as GR activity) and GSH metabolism (determined as the activity of GPX and GST) was perceptible in A. anguilla hepatocytes in order to control FeNPs, Hg and FeNPs + Hg exposure condition-mediated LPO. This study revealed the significance of a fine tuning among GR, GPX and GST in keeping LPO level under control during FeNPs or Hg alone exposure, and a direct role of total GSH (TGSH) in the control of LPO level and impaired GSH metabolism under the concomitant (FeNPs + Hg) exposure. An interpretation of the fish risk to FeNPs in a multi-pollution state should equally consider the potential outcome of the interaction of FeNPs with other contaminants.

Role of iron oxide impurities in electrocatalysis by multiwall carbon nanotubes: An investigation using a novel magnetically modified ITO electrodes

The role of iron oxide impurities in the electrocatalytic properties of multiwall carbon nanotubes (MWCNTs) prepared by catalytic chemical vapour decomposition method (CCVD) is studied in detail. A novel magnetically modified electrodes have been developed by which MWCNTs were immobilized on indium-tin oxide (ITO) electrodes, without any chemical binders. The electro-catalytic oxidation of dopamine, and reduction of hydrogen peroxide have been studied by cyclic voltammetry on magnetically modified electrodes with (i) MWCNTs with occluded iron oxide impurities (Fe-MWCNTs), (ii) MWCNTs grown on iron oxide nanoparticle particulate films (Io-MWCNTs) and (iii) pristine iron oxide nanoparticle particulate film (Io-NPs). A shift towards less positive potentials for the oxidation of dopamine was observed which is in the order of Fe-MWCNTs < Io-MWCNTs < Io-NPs. Similarly, trend towards less negative potentials for the reduction of hydrogen peroxide was observed. Thus, the electrocatalytic activities displayed by MWCNTs have been attributed to the iron oxide impurities associated with it. The systematic variation was related to the nature of interaction of iron oxide nanoparticles with MWCNT surface.

Biological magnetic cellular spheroids as building blocks for tissue engineering

Magnetic nanoparticles (MNPs), primarily iron oxide nanoparticles, have been incorporated into cellular spheroids to allow for magnetic manipulation into desired shapes, patterns and 3-D tissue constructs using magnetic forces. However, the direct and long-term interaction of iron oxide nanoparticles with cells and biological systems can induce adverse effects on cell viability, phenotype and function, and remain a critical concern. Here we report the preparation of biological magnetic cellular spheroids containing magnetoferritin, a biological MNP, capable of serving as a biological alternative to iron oxide magnetic cellular spheroids as tissue engineered building blocks. Magnetoferritin NPs were incorporated into 3-D cellular spheroids with no adverse effects on cell viability up to 1week. Additionally, cellular spheroids containing magnetoferritin NPs were magnetically patterned and fused into a tissue ring to demonstrate its potential for tissue engineering applications. These results present a biological approach that can serve as an alternative to the commonly used iron oxide magnetic cellular spheroids, which often require complex surface modifications of iron oxide NPs to reduce the adverse effects on cells.

Interactions of Iron Oxide Nanoparticles with the Immune System: Challenges and Opportunities for their Use in Nano-oncology

Iron oxide (IO) nanoparticles hold great promise as diagnostic and therapeutic agents in oncology. Their intrinsic physical properties make IO nanoparticles particularly interesting for simultaneous drug delivery, molecular imaging, and applications such as localized hyperthermia. Multiple non-targeted IO nanoparticle preparations have entered clinical trials, but more exciting, new tumortargeted IO nanoparticle preparations are currently being tested in preclinical settings. This paper will analyze the challenges faced by this new theranostic modality, with a specific focus on the interactions of IO nanoparticles with the innate and adaptive immune systems, and their effect on nanoparticle biodistribution and tumor targeting. Next, we will review the critical need for innovative surface chemistry solutions and strategies to overcome the immune interactions that prevent existing tumor-targeted IO preparations from entering clinical trials. Finally, we will provide an outlook for the future role of IO nanoparticles in oncology, which have the promise of becoming significant contributors to improved diagnosis and treatment of cancer patients.

The interaction, stability and response to an external stimulus of iron oxide nanoparticle–casein nanocomplexes

The interaction of iron oxide nanoparticles with casein micelles was studied using Dynamic Light Scattering (DLS) size measurement, Ultraviolet–visible (UV–vis) spectroscopy, Fourier Transform InfraRed (FTIR) spectroscopy, ThermoGravimetric Analysis (TGA), rheology and phase contrast microscopy. The whole milk and skimmed milk treated nanocomplex show an absorption peak at 196nm, due to the peptide bond of casein. The DLS studies show that the milk treated nanocomplex of average primary particle size ∼38nm form hydroclusters of size ∼615nm that disintegrate into smaller clusters upon sonication. The FTIR spectrum of skimmed milk treated nanocomplex shows the characteristic peaks of casein and the nanoparticles. The peaks at 3365cm−1, 1722cm−1, 1652cm−1 and 1585cm−1 (of casein) and a broad peak at 585cm−1 (of FeO bond vibration of Fe3O4) were observed for the nanocomplex. The TGA results of skimmed milk treated nanocomplex show a weight loss of ∼13.3%. The rheological studies show that skimmed milk treated nanocomplex exhibit good mechanical stability, whereas the uncoated nanoparticles exhibit poor mechanical stability. The response of uncoated nanoparticles and milk treated nanocomplex to an applied magnetic field shows that iron oxide–casein nanocomplexes reversibly self assemble to form one dimensional chains along the direction of applied magnetic field when the dipolar interaction energy exceeds the thermal energy. Since casein is non-toxic and inexpensive, iron oxide nanoparticle–casein nanocomplexes may find applications in controlled release drug delivery systems.