Surface modification of monodisperse magnetite nanoparticles for improved intracellular uptake to breast cancer cells

Nanoparticles have been widely used for a variety of biomedical applications and there is a growing need for highly specific and efficient uptake of the nanoparticles into target cells. Poly(ethylene glycol) (PEG), folic acid (FA), and their conjugate PEG-FA were attached to magnetite nanoparticles to compare their effects on the improvement of intracellular uptake of the nanoparticles to human breast cancer cells, BT-20. AFM and TEM results indicated that the nanoparticles after surface modification were monodisperse, with coatings on individual nanoparticles. The cell culture experiments showed that the PEG-FA coated nanoparticles were internalized into BT-20 cancer cells and exhibited higher efficiency of intracellular uptake than only PEG- or FA-coated nanoparticles. The surface modification protocols can also be used to modify the surfaces of other nanoparticles for targeting intracellular delivery.     

Magnetic hybrid modified electrodes,based on magnetite nanoparticle containing polyaniline and poly(3,4-ethylenedioxythiophene)

In this paper, we report on the direct electrodeposition of magnetic hybrids based on magnetite nanoparticle containing poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI) in the presence of magnetite and the special conducting electrolyte, potassium tetraoxalate. The optimal electropolymerization processes (monitored by scanning electron microscopy) were performed potentiostatically, and the incorporation of the iron oxide into the polymeric film was demonstrated by Diffuse Reflectance UV-Visible Spectroscopy (DR-UV–vis) and transmission electron microscopic measurements. Electrochemical quartz crystal nanobalance proved that both the neat PEDOT and the PEDOT/magnetite hybrid show anion exchange behaviour. Cyclic voltammetric features of the polymers and their hybrids exhibited an enhanced redox capacity of the composites. The difference in the effect of the scanning rate on this capacity increase in the two cases could be interpreted by the assumption that the presence of magnetite manifests dominantly in the enhanced intrinsic electroactivity of PANI, while in the case of the PEDOT composite, the extra charge is more connected to the charge surplus originating from the redox activity of the nanoparticles.

     

Loading magnetic nanoparticles into sperm cells does not affect their functionality

The spontaneous loading of magnetite nanoparticles into sperm cell was carried out by mixing an aqueous colloidal solution of Fe3O4-PVA with sperm cells (10(8) cells/ml) for 2 h at 37 degrees C suspended in glucose-free modified Tyrode solution. The penetration of the magnetite nanoparticles into the sperm cells was monitored by conventional analytical chemistry. We have demonstrated that the motility and the ability to undergo the acrosome reaction (i.e., the ability to fertilize the egg) were not affected by the presence of the magnetite nanoparticles.     

Magnetic hybrid modified electrodes, based on magnetite nanoparticle containing polyaniline and poly(3,4-ethylenedioxythiophene)

In this paper, we report on the direct electrodeposition of magnetic hybrids based on magnetite nanoparticle containing poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI) in the presence of magnetite and the special conducting electrolyte, potassium tetraoxalate. The optimal electropolymerization processes (monitored by scanning electron microscopy) were performed potentiostatically, and the incorporation of the iron oxide into the polymeric film was demonstrated by Diffuse Reflectance UV-Visible Spectroscopy (DR-UV?Cvis) and transmission electron microscopic measurements. Electrochemical quartz crystal nanobalance proved that both the neat PEDOT and the PEDOT/magnetite hybrid show anion exchange behaviour. Cyclic voltammetric features of the polymers and their hybrids exhibited an enhanced redox capacity of the composites. The difference in the effect of the scanning rate on this capacity increase in the two cases could be interpreted by the assumption that the presence of magnetite manifests dominantly in the enhanced intrinsic electroactivity of PANI, while in the case of the PEDOT composite, the extra charge is more connected to the charge surplus originating from the redox activity of the nanoparticles.     

纳米四氧化三铁表面酸碱性质研究

制备了纳米Fe3O4, 并对其进行了表征和表面酸碱行为研究. 实验结果表明, Fe3O4表面在水溶液中有非常明显的酸碱性质. 随着纳米Fe3O4加入量的增多, 溶液pH缓冲能力增强, 二者之间成正比, 据此可定量地测定H+在纳米氧化铁表面的吸附量. 运用MEDUSA和WINSGW计算软件计算了表面组分在溶液中的分布， 并讨论了表面电荷对表面组分分布的影响.     

Dendrimer modified magnetite nanoparticles for protein immobilization

A cascading polyamidoamine (PAMAM) dendrimer was synthesized on the surface of magnetite nanoparticles to allow enhanced immobilization of bovine serum albumin (BSA). Characterization of the synthesis revealed exponential doubling of the surface amine from generations one through four starting with an amino silane initiator. Furthermore, transmission electron microscopy (TEM) revealed clear dispersion of the dendrimer-modified magnetite nanoparticles in methanol solution. The dendrimer-modified magnetite nanoparticles were used to carry out magnetic immobilization of BSA. BSA immobilizing efficiency increased with increasing generation from one to five and BSA binding amount of magnetite nanoparticles modified with G5 dendrimer was 7.7 times as much as that of magnetite nanoparticles modified with only aminosilane. There are two major factors that improve the BSA binding capacity of dendrimer-modified magnetite nanoparticles: one is that the increased surface amine can be conjugated to BSA by a chemical bond through glutaraldehyde; the other is that the available area has increased due to the repulsion of surface positive charge.     

Study of uptake and loss of silica nanoparticles in living human lung epithelial cells at single cell level

The toxicology of nanomaterials is a blooming field of study, yet it is difficult to keep pace with the innovations in new materials and material applications. Those applications are quickly being introduced in research, industrial, and consumer settings. Even though the cytotoxicity of many types of nanoparticles has been demonstrated, the behavior of those particles in a biological environment is not yet fully known. This work characterized the following over time: protein adsorption on silica particle surfaces, the internalization of particles in human lung carcinoma (A549) cells when coated with different specific proteins or no proteins at all, and the cellular loss of particles following the removal of extracellular particles. Proteins were shown to quickly saturate the particle surface, followed by a competitive process of particle agglomeration and protein adsorption. Uptake of particles peaked at 8–10 h, and it was determined that, in this system, the charge of the protein-coated particles changed the rate of uptake if the charge difference was great enough. Cells internalized particles lacking any adsorbed proteins with approximately 3 times the rate of protein-coated particles with the same charge. Although particles exited cells over time, the process was slower than uptake and did not near completion within 24 h. Finally, analysis at the single cell level afforded observations of particle agglomerates loosely associated with cell membranes when serum was present in the culture medium, but in the absence of serum, particles adhered to the dish floor and formed smaller agglomerates on cell surfaces. Although data trends were easily distinguished, all samples showed considerable variation from cell to cell. Figure Silica-capped fluorescent semiconductor nanoparticles as internalized by human lung epithelial cells and adsorbed to a glass substrate in protein-free culture medium.     

Antioxidant Activity of Bioactive Peptide Fractions from Germinated Soybeans Conjugated to Fe3O4 Nanoparticles by the Ugi Multicomponent Reaction

The conjugation of biomolecules to magnetic nanoparticles has emerged as promising approach in biomedicine as the treatment of several diseases, such as cancer. In this study, conjugation of bioactive peptide fractions from germinated soybeans to magnetite nanoparticles was achieved. Different fractions of germinated soybean peptides (>10 kDa and 5–10 kDa) were for the first time conjugated to previously coated magnetite nanoparticles (with 3-aminopropyltriethoxysilane (APTES) and sodium citrate) by the Ugi four-component reaction. The crystallinity of the nanoparticles was corroborated by X-ray diffraction, while the particle size was determined by scanning transmission electron microscopy. The analyses were carried out using infrared and ultraviolet–visible spectroscopy, dynamic light scattering, and thermogravimetry, which confirmed the coating and functionalization of the magnetite nanoparticles and conjugation of different peptide fractions on their surfaces. The antioxidant activity of the conjugates was determined by the reducing power and hydroxyl radical scavenging activity. The nanoparticles synthesized represent promising materials, as they have found applications in bionanotechnology for enhanced treatment of diseases, such as cancer, due to a higher antioxidant capacity than that of fractions without conjugation. The highest antioxidant capacity was observed for a >10 kDa peptide fraction conjugated to the magnetite nanoparticles coated with APTES.     

A study of magnetic liquids with the help of a paramagnetic sensor

The paramagnetic sensor method was used to study local magnetic fields in a magnetite aqueous suspension. The sensor was 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl, a stable nitroxide radical. The lines in the EPR spectrum of the sensor were demonstrated to be broadened due to the dipole-dipole interaction with magnetite nanoparticles. It was established that no spin exchange occurred between sensor molecules and magnetite nanoparticles. The g-factor was found to decrease with the concentration of magnetite nanoparticles in the suspension. The mean strengths of the local magnetic fields calculated from changes in the EPR spectrum of the sensor proved to be substantially lower than the values determined from magnetic measurements. This difference was accounted for by the formation of linear aggregates of magnetite nanoparticles under the action of a magnetic field.     

Synthesis and characterization of polypyrrole–magnetite–vitamin B12 hybrid composite electrodes

In this study vitamin B12 covered magnetite nanoparticles have been incorporated into a conducting polypyrrole. This polymer was electrochemically synthesized in the presence of the B12-coated magnetite. The adsorption of B12 was demonstrated by the decrease in absorbance of the vitamin in the supernatant liquid after B12 has been in contact with magnetite sol overnight. The composition of the layers was studied by the electrochemical quartz crystal microbalance technique during the polymerization. The slope of the mass change–charge curves indicate the incorporation of 27 m/m% magnetite and 15 m/m% B12. The redox transformation of the film in monomer- and nanoparticle-free solutions was also investigated by this method and the difference in the virtual molar masses of the moving species was evidenced. The morphology and the composition of the layers were characterized by scanning electron microscopy combined with energy dispersive X-ray microanalysis measurements, which latter proved the successful incorporation of the magnetic and bio-active components. The electrochemical behavior of the films unambiguously showed the complex redox activity of the composites and the current surplus were quantified by the redox capacity of the layers. These data show the doubling of the redox capacity in case of the hybrid material compared to the neat polymer. The successful enrichment of B12 can be exploited in the recently evidenced redox mediation process performed by a PPy/B12 film.     

A Comparative Study of Receptor-Targeted Magnetosome and HSA-Coated Iron Oxide Nanoparticles as MRI Contrast-Enhancing Agent in Animal Cancer Model

Magnetosomes are specialized organelles arranged in intracellular chains in magnetotactic bacteria. The superparamagnetic property of these magnetite crystals provides potential applications as contrast-enhancing agents for magnetic resonance imaging. In this study, we compared two different nanoparticles that are bacterial magnetosome and HSA-coated iron oxide nanoparticles for targeting breast cancer. Both magnetosomes and HSA-coated iron oxide nanoparticles were chemically conjugated to fluorescent-labeled anti-EGFR antibodies. Antibody-conjugated nanoparticles were able to bind the MDA-MB-231 cell line, as assessed by flow cytometry. To compare the cytotoxic effect of nanoparticles, MTT assay was used, and according to the results, HSA-coated iron oxide nanoparticles were less cytotoxic to breast cancer cells than magnetosomes. Magnetosomes were bound with higher rate to breast cancer cells than HSA-coated iron oxide nanoparticles. While 250 μg/ml of magnetosomes was bound 92 ± 0.2%, 250 μg/ml of HSA-coated iron oxide nanoparticles was bound with a rate of 65 ± 5%. In vivo efficiencies of these nanoparticles on breast cancer generated in nude mice were assessed by MRI imaging. Anti-EGFR-modified nanoparticles provide higher resolution images than unmodified nanoparticles. Also, magnetosome with anti-EGFR produced darker image of the tumor tissue in T2-weighted MRI than HSA-coated iron oxide nanoparticles with anti-EGFR. In vivo MR imaging in a mouse breast cancer model shows effective intratumoral distribution of both nanoparticles in the tumor tissue. However, magnetosome demonstrated higher distribution than HSA-coated iron oxide nanoparticles according to fluorescence microscopy evaluation. According to the results of in vitro and in vivo study results, magnetosomes are promising for targeting and therapy applications of the breast cancer cells.     

Tryptanthrin-loaded nanoparticles for delivery into cultured human breast cancer cells, MCF7: the effects of solid lipid/liquid lipid ratios in the inner core

Tryptanthrin is an ancient medicine which recently was also found to have a function of downregulating multidrug resistance (MDR). However, tryptanthrin is insoluble in water, which limits its availability for delivery into cancer cells. There is a need to improve delivery systems to increase the inhibition of MDR. The aim of this study was to employ nanoparticles encapsulating tryptanthrin to improve the delivery and promote the sustained release of this drug. The approach was to encapsulate tryptanthrin in various nanoparticles, including solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), and lipid emulsions (LEs). We compared the particle size and zeta potential of these nanoparticles, and evaluated the partitioning behavior of tryptanthrin in them. We also determined the release kinetics of tryptanthrin from these nanoparticles. Moreover, cellular cytotoxicity toward and uptake of tryptanthrin-loaded nanoparticles by human breast cancer cells were determined. We found that the mean particle size of NLCs was lower, and the partition coefficient was higher than those of SLNs, and an increased tryptanthrin release rate was found with the NLC delivery system. NLCs achieved the sustained release of tryptanthrin without an initial burst. In particular, the NLC-C formulation, composed of a mixture of Compritol and squalene as the core materials, showed the highest release rate and cytotoxic effect. Confocal laser scanning microscopic images confirmed drug internalization into cells which enhanced the endocytosis of the particles. These results suggested that NLCs can potentially be exploited as a drug carrier for topical or intravenous use in the future.     

Monodisperse Magnetite Nanoparticles Coupled with Nuclear Localization Signal Peptide for Cell‐Nucleus Targeting

Functionalization of monodisperse superparamagnetic magnetite (Fe₃O₄) nanoparticles for cell specific targeting is crucial for cancer diagnostics and therapeutics. Targeted magnetic nanoparticles can be used to enhance the tissue contrast in magnetic resonance imaging (MRI), to improve the efficiency in anticancer drug delivery, and to eliminate tumor cells by magnetic fluid hyperthermia. Herein we report the nucleus‐targeting Fe₃O₄ nanoparticles functionalized with protein and nuclear localization signal (NLS) peptide. These NLS‐coated nanoparticles were introduced into the HeLa cell cytoplasm and nucleus, where the particles were monodispersed and non‐aggregated. The success of labeling was examined and identified by fluorescence microscopy and MRI. The work demonstrates that monodisperse magnetic nanoparticles can be readily functionalized and stabilized for potential diagnostic and therapeutic applications.     

Engineering polyzwitterion with acylsulfonamide-based betaine structure for protonated switch of surface chemistry at tumoral pH and reductive responsive drug release of polymeric micelles

The surface chemistry of stimulus-responsive nanoparticles plays an important role in mediating nano-bio interactions in cancer nanomedicine by targeting the unique features of the tumor microenvironment, such as low extracellular pH. To develop therapeutic nanoparticles with high sensitivity and instant response to slight pH differences in the systemic circulation, we produced a novel polyzwitterion with acylsulfonamide-based betaine structure by one-step modification of polycarboxybetaine (PCB) with benzene sulfonamide. The zwitterionic micellar shells show high antifouling in the blood circulation and acutely convert into positive charge via acylsulfonamide protonation, thereby improving cell affinity at tumor sites. Moreover, a disulfide bond between the shell and poly-ε-caprolactone (PCL) core allows for reductive-responsive release of doxorubicin (DOX) after internalization of the polymeric micelles. Finally, in vitro and in vivo competition assays demonstrated that dual responsive drug-loaded micelles have better anticancer efficiency than free DOX or micelles without zwitterionic pH-responsive properties. Thus, we have developed a simple and valuable strategy to enhance pH sensitivity of micellar carriers for cancer treatment.     

Effect of the Incorporation of Proteins on the Performance of Carbon Paste Electrodes Modified with Electrogenerated Magnetite Nanoparticles towards the Reduction of Hydrogen Peroxide

This work reports the effect of the incorporation of different proteins within carbon paste electrodes (CPE) modified with electrochemically synthesized magnetite nanoparticles (20 nm) on the electrochemical response towards hydrogen peroxide. Scanning electron microscopy images reveal that the proteins produce a more efficient dispersion of the nanoparticles within the composite. When CPE is modified with 5.0 % w/w magnetite and 5.0 % w/w albumin the sensitivity for hydrogen peroxide at ?0.100 V is enhanced 40 times and the charge transfer resistance significantly decreases. The increase in sensitivity and the decrease in R_ct was dependent on the nature of the protein.     

Efficiency of layered double hydroxide nanoparticle-mediated delivery of siRNA is determined by nucleotide sequence

In this paper, we report the novel finding that the cellular delivery efficiency of siRNAs or their mimic double-stranded (ds)DNA using layered double hydroxide (LDH) nanoparticles is dependent upon the nucleotide sequence. Efficacy of LDH-mediated delivery of four different siRNAs into cortical neurons and NIH 3T3 cells was found to vary widely (from 6 to 80%, and 2-11%, respectively). Our investigation into the formation of dsDNA-LDH complexes through monitoring the dsDNA:LDH mass ratio at the point of zero charge (PZC) indicated that the degree of intercalation of the individual dsDNA sequences into the LDH nanoparticles varied significantly. The dsDNA:LDH mass ratio at the PZC was found to be dependent on the nucleotide sequence. We further observed that PZC for each sequence was positively related to the extent of LDH-mediated internalization of the equivalent siRNA into neurons and fibroblasts. This novel finding therefore suggests that the mass ratio at the PZC is a useful predictive tool with which to assess the intercalation efficiency of selected siRNA sequences into the LDH interlayer and subsequent internalization into the cell cytoplasm. This finding will allow a more controlled approach to the design of suitable siRNA sequences for LDH-mediated siRNA delivery.     

不同形貌Fe3O4纳米粒子的氧化沉淀法制备与表征

用一种方法成功合成出了球体、四方体、八面体、不规则多面体、三角形和不规则颗粒等六种具有不同形貌的Fe₃O₄纳米粒子，通过扫描电子显微镜(SEM)表征了粒子形貌。试样经过X-射线衍射(XRD)表征具有尖晶石结构，且结晶良好。经震动样品磁强计(VSM)测定，各种形貌的Fe₃O₄纳米粒子都具有良好的磁性，其中八面体形貌的Fe₃O₄纳米粒子的饱和磁化强度达到86.56 emu·g^-1，剩磁为10.64 emu·g^-1，矫顽力为138 Oe。讨论了不同形貌的Fe₃O₄纳米粒子的形成机制，得出了晶核的生长环境对纳米粒子的形貌有重要影响的结论。     

Positive surface charge enhances selective cellular uptake and anticancer efficacy of selenium nanoparticles

Surface charge plays a key role in cellular uptake and biological actions of nanomaterials. Selenium nanoparticles (SeNPs) are novel Se species with potent anticancer activity and low toxicity. This study constructed positively charged SeNPs by chitosan surface decoration to achieve selective cellular uptake and enhanced anticancer efficacy. The results of structure characterization revealed that hydroxyl groups in chitosan reacted with SeO(3)(2-) ion to form special chain-shaped intermediates, which could be decomposed to form crystals upon reduction by ascorbic acid. The initial colloids nucleated and then assembled into spherical SeNPs. The positive charge of the NH(3)(+) group on the outer surface of the nanoparticles contributed to the high stability in aqueous solutions. Moreover, a panel of four human cancer cell lines were found to be susceptible to SeNPs, with IC(50) values ranging from 22.7 to 49.3 μM. Chitosan surface decoration of SeNPs significantly enhanced the selective uptake by endocytosis in cancer cells and thus amplified the anticancer efficacy. Treatment of the A375 melanoma cells with chitosan-SeNPs led to dose-dependent apoptosis, as evidenced by DNA fragmentation and phosphatidylserine translocation. Our results suggest that the use of positively charged chitosan as a surface decorator could be a simple and attractive approach to achieve selective uptake and anticancer action of nanomaterials in cancer cells.     

UCST-like hybrid PAAm-AA/Fe3O4 microgels. Effect of Fe3O4 nanoparticles on morphology, thermosensitivity and elasticity

The incorporation of metal oxide nanoparticles into microgels forming hybrid systems gives additional functionalities to the system and widens the field of potential application in biomedicine, biotechnology, and other fields. In particular, there have been very few investigations regarding UCST-like hybrid microgels. In connection with this, we report the preparation of UCST-like hybrid microgels of magnetite nanoparticles (Fe(3)O(4)) encapsulated in poly(acrylamide-acrylic acid) microgel matrix via an inverse emulsion polymerization method. The key factor in the preparation of hybrid microgels is the need to divide in two the aqueous phase of the emulsion and feed them separately in order to avoid the aggregation of magnetic nanoparticles prior to polymerization reaction. The morphology, size, and spherical shape of hybrid microgels are determined by scanning electron microscopy. The encapsulation of magnetite nanoparticles within the polymer matrix is confirmed by transmission electron microscopy. Dynamic light scattering is employed to study both the swelling UCST-like behavior and the surface charge of the hybrid microgels. Swelling measurements confirm that the incorporation of magnetite does not affect the thermosensitivity of the system. In order to highlight the rheological behavior that can affect the final potential applications of these hybrid systems, a deep study of the viscoelastic properties is carried out by means of an oscillatory rheometer. The dependence of G' and G' of the microgel dispersions with the frequency suggests a gel-like behavior and hence the occurrence of structural organization. In order to understand this structure formation and the influence of the magnetite in the interaction between hybrid microgels, scaling theory was applied. In terms of rheology, the addition of magnetite leads to a change in the interaction between hybrid microgels giving rise to an increase in the elasticity of the system.     

Design of sugar–oligonucleotide conjugates installed gold nanoparticle for effective delivery to hepatic parenchymal cells

A novel oligonucleotide delivery system that is based on oligonucleotide–nanoparticle conjugates has been described. Installed oligonucleotides were modified with the carbohydrate at the 3′ terminus, accordingly, constructed nanoparticles display clustered carbohydrates on their outer layer for the targeted delivery of oligonucleotides. The method for the construction of ligand-functionalized nanoparticle was simple and reproducible. The stability of the nanoparticles displaying clustered carbohydrates greatly increased in serum compared to nanoparticles without carbohydrates. In order to investigate the targetability of oligonucleotide–nanoparticle conjugates into primary hepatic parenchymal cells, freshly isolated rat hepatocytes were incubated with nanoparticles and the amount of internalized gold nanoparticles was evaluated by an inductively coupled plasma mass spectroscopy analysis. Nanoparticles displaying clustered carbohydrates internalized more efficiently than nanoparticles without carbohydrate modifications. In particular, the cellular uptakes of oligonucleotide-conjugated gold nanoparticle increased 1.7 ～2.0-fold by galactose modification. Competition assay revealed that clustered galactose enhanced the internalization of the nanoparticle into primary hepatic parenchymal cells by a receptor-mediated process.