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The distribution characteristics of nanoparticles associated with cells are crucial to many applications, including magnetic hyperthermia, drug carriers, etc. To clarify the locations when nanoparticles enter the in vivo environments is a necessity. In this work, superparamagnetic iron oxide nanoparticles modified with polyethylene glycol (PEG-SPIONs) were prepared by high temperature thermal decomposition method, and then stereotaxic injections of PEG-SPIONs into the substantia nigra of Sprague-Dawley rats were performed. The distribution of nanoparticles in rat brain was observed by inductively coupled plasma emission spectrometer (ICP-OES) and transmission electron microscopy (TEM). It was found that the iron contents were higher in the olfactory bulb, temporal lobe, prefrontal cortex and thalamus after the injection of PEG-SPIONs for 24 h and 7 days, PEG-SPIONs were mostly distributed around the axonal membrane and dendritic membrane, and a small amount were distributed near the myelin membrane and mitochondrial membrane, which can be ascribed to the nature of PEG, the hydration size and Zeta potential of PEG-SPIONs. Along with their magnetocaloric effect the PEG-SPIONs have potential to act on the ion channels on the cell membrane under an alternating current magnetic field. • The surface of SPIONs was modified with polyethylene glycol (PEG-SPIONs). • PEG-SPIONs had good biocompatibility and hydrophilicity. • The PEG-SPIONs showed good magnetocaloric effect. • PEG-SPIONs tended to be adsorbed on the cell membranes in rat brains. • PEG-SPIONs have potential to act on the cell membrane ion channels in rats. [ABSTRACT FROM AUTHOR]

Superparamagnetic iron oxide nanoparticles (SPIONs) conjugated with hyaluronic acid (HA) functional groups have potential applications as cell targeting materials. However, SPIONs incubated with high-molecular weight HA can result in severe agglomeration. In this work, we found that when modified with degraded HA (hyaluronan oligosaccharides (oHAs)), the nanoparticles were uniformly dispersed with small hydrodynamic sizes, and the oHA-modified SPIONs exerted minimal cytotoxicity. With the same functional groups as HA, the oHA-modified SPIONs may have various biomedical applications. [ABSTRACT FROM AUTHOR]

In this paper, we present a multi-proxy weak blind signature scheme based on quantum entanglement swapping of Bell states. In the scheme, proxy signers can finish the signature instead of original singer with his/her authority. It can be applied to the electronic voting system, electronic paying system, etc. The scheme uses the physical characteristics of quantum mechanics to implement delegation, signature and verification. It could guarantee not only the unconditionally security but also the anonymity of the message owner. The security analysis shows the scheme satisfies the security features of multi-proxy weak signature, singers cannot disavowal his/her signature while the signature cannot be forged by others, and the message owner can be traced. [ABSTRACT FROM AUTHOR]

T-shape double quantum dot molecule A–B interference with the action of time-dependent external field is designed. Using the Keldysh non-equilibrium Green's function method, spin-dependent average current as a function of quantum dot energy is obtained. The magnitude and position of average current resonance peaks can be controlled by adjusting interdot coupling strength, frequency and amplitude of time-dependent electric field. The conversion between zero and non-zero value for average current can be realized under the condition with or without the action of time-dependent external field, respectively, which is the basis for the design of controlled quantum switch. Under the combined action of the external magnetic flux and Rashba spin–orbit coupling strength, the spin-polarized average current can be observed. Dc current–voltage characteristics are researched. [ABSTRACT FROM AUTHOR]