Nanoscale & Nanoscale Advances Blog

In this HOT Nanoscale article the authors report on the biodistribution of gold nanoparticles (Au@DTDTPA) after intravenous injection into healthy rats.

Gold nanoparticles have shown great potential as radiosensitisers for radiotherapy so the biodistribution of the nanoparticles in healthy tissues constitutes a crucial issue that must be addressed to guarantee the optimal use of these particles. Owing to the propensity of gold for absorbing X-ray photons, these nanoparticles behave as contrast agents for X-ray imaging. Moreover, Au@DTDTPA-Gd nanoparticles can be followed up by magnetic resonance imaging (MRI), since the organic shell, DTDTPA, is composed of polyaminocarboxylate ligands which are well known for entrapping gadolinium ions. Both complementary imaging modalities are well suited for monitoring the accumulation in a specific tissue or in a tumor. However scintigraphy appears better suited for a complete biodistribution study because of its greater sensitivity and the possibility to image the whole body for a duration that is compatible with the pharmacokinetics. The authors demonstrated that the replacement of the gadolinium ions by ^99mTc and ¹¹¹In ions renders the Au@DTDTPA nanoparticles suitable for the study of the biodistribution by scintigraphy. The radiolabeled gold nanoparticles (Au@DTDTPA-X, with X = ^99mTc and ¹¹¹In) exhibit high radiochemical purities and radiolabeling stabilities.

The tracking of the radiolabeled Au@DTDTPA nanoparticles by planar scintigraphy and single photon emission computed tomography (SPECT) after intravenous injection associated to the post-mortem analysis showed that these particles exhibit safe behavior: the nanoparticles are removed from the body essentially by renal clearance while no accumulation is observed in the organs (except those involved in the renal clearance (kidneys, bladder)). Moreover the physicochemical properties of Au@DTDTPA-X nanoparticles impede any reticuloendothelial system uptake as reflected by the low uptake by phagocyte-rich organs (liver and spleen).

The follow-up by at least three different imaging modalities (X-ray imaging, MRI, scintigraphy), the absence of undesirable accumulation and the removal by urine suggest Au@DTDTPA nanoparticles are very promising for in vivo applications, especially for image-guided radiotherapy.

Read this HOT article in full today:

The biodistribution of gold nanoparticles designed for renal clearance
Christophe Alric, Imen Miladi, David Kryza, Jacqueline Taleb, Francois Lux, Rana Bazzi, Claire Billotey, Marc Janier, Pascal Perriat, Stéphane Roux and Olivier Tillement
DOI: 10.1039/C3NR00012E

Scientists based in The Netherlands report a series of novel reversible photoswitches based on diarylethene embedded in a matrix of dodecanethiol on Au(111). The authors used scanning tunneling microscopy to study the effect as the “on” state appears higher than the “off” state by several Ångstroms.

Such switches are being used in the important field of molecular electronics.

Read the full details of this exciting work today:

Reversible light induced conductance switching of asymmetric diarylethenes on gold: surface and electronic studies
Arramel, Thomas C. Pijper, Tibor Kudernac, Nathalie Katsonis, Minko van der Maas, Ben L. Feringa and Bart J. van Wees
DOI: 10.1039/C3NR00832K

Scientists working at Yonsei University in Korea have prepared 1 dimensional logic gates and static random access memory (SRAM)
circuits from single zinc oxide nanowires, in combination with Al₂O₃, gold and indium tin oxide.

The excellent performance of the nanowires suggests that using long single nanowires could lead to further exciting developments in the nano-electronics field.

Full details can be found in this HOT Nanoscale Communication:

Long single ZnO nanowire for logic and memory circuits: NOT, NAND, NOR gate, and SRAM
Young Tack Lee, Syed Raza Ali Raza, Pyo Jin Jeon, Ryong Ha, Heon-Jin Choib and Seongil Im
DOI: 10.1039/C3NR01015E

Scientists from Singapore report the development of a nanoparticle-based drug delivery vehicle that is capable of releasing drugs upon external stimuli.
They have made amphiphilic polymer coated gold nanoparticles which self-assemble into vesicles. The hydrophobic polymer on the gold nanoparticle surface can be converted to a hydrophilic polymer by UV light illumination, creating a mechanism to monitor drug release. By examining the gold nanostructure surface plasmon band shifts (and for drugs that happen to be fluorescent), the release profile can be controlled and monitored in real time.
The team investigate the loading and photo-regulated release of the fluorescent model drug, doxorubicin (DOX), by the plasmonic vesicles. DOX as a potent anticancer drug suffers from side effects such as cardiac toxicity, and therefore drug delivery systems that allow the targeted delivery of DOX are highly desirable.

Read the full details of this HOT Nanoscale article:

Photolabile plasmonic vesicles assembled from amphiphilic gold nanoparticles for remote-controlled traceable drug delivery
Jibin Song, Zheng Fang, Chenxu Wang, Jiajing Zhou, Bo Duan, Lu Pu and Hongwei Duan
DOI: 10.1039/C3NR01350B

Scientists in France report a new type of hybrid plasmonic device where there is a quantitative, reversible change in the localised surface plasmon resonance wavelength on changing the refractive index – so the plasmon resonance can be controlled. The devices could be used as temperature sensors or as switching elements for signal modulation in plasmonic nano-circuits.

Check out this exciting research today:

Synergistic switching of plasmonic resonances and molecular spin states
Khaldoun Abdul-Kader, Manuel Lopes, Carlos Bartual, Olena Kraieva, Edna Hernandez, Lionel Salmon, William Nicolazzi, Franck Carcenac, Christophe Thibault, Gábor Molnár and Azzedine Bousseksou
DOI: 10.1039/C3NR01337E

A novel zinc oxide microwire optical resonator with parallelogram-shaped cross section has been made by chemists based in China and Taiwan. The material can effectively control light in two dimensions, and could play the part of a building block in the development of optoelectronic devices.

Read this HOT Nanoscale communication today:

Optical modulation of ZnO microwire optical resonators with a parallelogram cross-section
Yang Liu, Hongxing Dong, Shulin Sun, Wenhui Liu, Jinxin Zhan, Zhanghai Chen, Jun Wang and Long Zhang
DOI: 10.1039/C3NR00700F

A method of manufacturing porous nanolayers using temperature sensitive substrates has been developed by scientists working in Germany.

Traditionally such materials are made using flame spray pyrolysis (FSP), but this process is limited by the thermal sensitivity of the substrate onto which the nanoparticles are coated. Furthermore the mechanical stability of the layers is often weak in liquid environments.

The new process involves separating the pyrolysis step from the introduction of the final substrate material. In stage one the nanoparticles (eg titanium dioxide) are coated onto an initial substrate, using FSP, to create an intermediate porous nanolayer material. In stage two a new substrate is applied to the intermediate material to create a ‘nanoparticle sandwich’, which is passed through rollers under pressure and at low temperature. The nanoparticle layer transfers to the new substrate to yield the final material.

The technique produces materials that have superior mechanical stability, and opens up the possibility of using different substrates, such as polypropylene foil.

Read this HOT Nanoscale article today:

Transfer of highly porous nanoparticle layers to various substrates through mechanical compression
Sven Oliver Schopf, Samir Salameh and Lutz Mädler
DOI: 10.1039/C3NR34235B