Nanoparticles may serve as carriers in targeted therapeutics; interaction of the nanoparticles with a biological system may determine their targeting effects and therapeutic efficacy. Epigallocatechin-3-gallate (EGCG), a major component of tea catechins, has been conjugated with nanoparticles and tested as an anticancer agent. We investigated whether EGCG may enhance nanoparticle uptake by tumor cells. Cellular uptake of a dextran-coated magnetic nanoparticle (MNP) was determined by confocal microscopy, flow cytometry or a potassium thiocyanate colorimetric method. We demonstrated that EGCG greatly enhanced interaction and/or internalization of MNPs (with or without polyethylene glycol) by glioma cells, but not vascular endothelial cells. The enhancing effects are both time- and concentration-dependent. Such effects may be induced by a simple mix of MNPs with EGCG at a concentration as low as 1-3 μM, which increased MNP uptake 2- to 7-fold. In addition, application of magnetic force further potentiated MNP uptake, suggesting a synergetic effect of EGCG and magnetic force. Because the effects of EGCG were preserved at 4 °C, but not when EGCG was removed from the culture medium prior to addition of MNPs, a direct interaction of EGCG and MNPs was implicated. Use of an MNP-EGCG composite produced by adsorption of EGCG and magnetic separation also led to an enhanced uptake. The results reveal a novel interaction of a food component and nanocarrier system, which may be potentially amenable to magnetofection, cell labeling/tracing, and targeted therapeutics.

BackgroundPoly-l-lysine (PLL) enhances nanoparticle (NP) uptake, but the molecular mechanism remains unresolved. We asked whether PLL may interact with negatively charged glycoconjugates on the cell surface and facilitate uptake of magnetic NPs (MNPs) by tumor cells.MethodsPLL-coated MNPs (PLL-MNPs) with positive and negative ζ-potential were prepared and characterized. Confocal and transmission electron microscopy was used to analyze cellular internalization of MNPs. A colorimetric iron assay was used to quantitate cell-associated MNPs (MNPcell).ResultsCoadministration of PLL and dextran-coated MNPs in culture enhanced cellular internalization of MNPs, with increased vesicle size and numbers/cell. MNPcell was increased by eight- to 12-fold in response to PLL in a concentration-dependent manner in human glioma and HeLa cells. However, the application of a magnetic field attenuated PLL-induced increase in MNPcell. PLL-coating increased MNPcell regardless of ζ-potential of PLL-MNPs, whereas magnetic force did not enhance MNPcell. In contrast, epigallocatechin gallate and magnetic force synergistically enhanced PLL-MNP uptake. In addition, heparin, but not sialic acid, greatly reduced the enhancement effects of PLL; however, removal of heparan sulfate from heparan sulfate proteoglycans of the cell surface by heparinase III significantly reduced MNPcell.ConclusionOur results suggest that PLL-heparan sulfate proteoglycan interaction may be the first step mediating PLL-MNP internalization by tumor cells. Given these results, PLL may facilitate NP interaction with tumor cells via a molecular mechanism shared by infection machinery of certain viruses.

Low-toxicity magnetic nanocarriers (MNCs) composed of a shell of poly [aniline-co-N-(1-one-butyric acid) aniline] over a Fe 3 O 4 magnetic nanoparticle core were developed to carry recombinant tissue plasminogen activator (rtPA) in MNC-rtPA for targeted thrombolysis.With an average diameter of 14.8 nm, the MNCs exerted superparamagnetic properties. Up to 276 µg of active rtPA was immobilized per mg of MNCs, and the stability of the immobilized rtPA was greatly improved during storage at 4°C and 25°C. In vitro thrombolysis testing with a tubing system demonstrated that magnet-guided MNC-rtPA showed significantly improved thrombolysis compared with free rtPA and reduced the clot lysis time from 39.2 ± 3.2 minutes to 10.8 ± 4.2 minutes. In addition, magnet-guided MNC-rtPA at 20% of the regular rtPA dose restored blood flow within 15-25 minutes of treatment in a rat embolism model without triggering hematological toxicity. In conclusion, this improved system is based on magnetic targeting accelerated thrombolysis and is potentially amenable to therapeutic applications in thromboembolic diseases.

A series of rare earth molybdates, Y2−xEux(MoO4)3 for x=0.4, 0.8, 1.2, 1.6 and 2.0 were prepared by solid‐state method and their crystal structures, photo luminescent characteristics were investigated. The powders are mainly studied for their red light emission efficiency under near UV excitation. The crystal structures of the powders were found to depend on annealing temperature and the yttrium concentration. Mixtures of monoclinic (C2/c) and orthorhombic (Pba2, Pbna) structures were formed in varying proportions depending on the value of x and annealing temperatures (700°–800°C). The luminescence behavior depended on the resultant composition of the crystal phase and the Eu3+ concentration. The excitation spectra showed the characteristic and broad O→Mo charge transfer (CT) band of the MoO4 tetrahedra and the sharp intra‐configurational 4f–4f transitions of Eu3+ in the host lattice. The integrated emission ratio (5D0→7F2/5D0→7F1) of Eu3+ depends on the annealing temperature and reveals that the local site symmetry of Eu3+ ions decreases with increasing concentration of Eu3+. The emission spectra obtained by exciting at 396 nm, gave highest red emission intensity for Y0.4Eu1.6(MoO4)3 annealed at 700°C/6 h among this series of samples.

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