Nanoscale & Nanoscale Advances Blog

A Nanoscale Communication on optical imaging of ligand-protein binding has been featured in C&EN this week.

The work by Nancy Xu uses the PHOTON method to map single ligand molecules in single protein–ligand complexes.

Read the ‘HOT’ Nanoscale Communication today:

Multicolored nanometre-resolution mapping of single protein–ligand binding complexes using far-field photostable optical nanoscopy (PHOTON)
Tao Huang and Xiao-Hong Nancy Xu
Nanoscale, 2011, DOI: 10.1039/C1NR10182J

Issue 4, 2011 of Nanoscale is now online, here are just some of the highlights…

Review
Electrostatics at the nanoscale
David A. Walker, Bartlomiej Kowalczyk, Monica Olvera de la Cruz and Bartosz A. Grzybowski, Nanoscale, 2011, 3, 1316

Feature article
Supramolecular assembly/reassembly processes: molecular motors and dynamers operating at surfaces
Artur Ciesielski and Paolo Samorì, Nanoscale, 2011, 3, 1397

‘HOT’ Communication
A simple and scalable graphene patterning method and its application in CdSe nanobelt/graphene Schottky junction solar cells
Yu Ye, Lin Gan, Lun Dai, Yu Dai, Xuefeng Guo, Hu Meng, Bin Yu, Zujin Shi, Kuanping Shang and Guogang Qin, Nanoscale, 2011, 3, 1477

Issue 4’s front cover features the review by Luis M. Liz-Marzán on controlled assembly of plasmonic colloidal nanoparticle clusters (DOI: 10.1039/C0NR00804D).

Browse the whole issue today online.

Scientists in China have developed a simple method for time-lapse imaging of single molecule reactions in situ by using DNA origami as a reaction surface.

The team recorded the whole dynamic process of the streptavidin–biotin binding reaction. They found that at a streptavidin concentration of 7.6 nM, the binding ratio increased steadily up to nearly 100% within 30 minutes.

This novel single-molecule reaction detection method, at the nanometre scale, may prove useful to study other macromolecule behavior and reaction kinetics, say the researchers.

Reference:
N Wu, X Zhou, D M Czajkowsky, M Ye, D Zeng, Y Fu, C Fan, J Hu and B Li, Nanoscale, 2011, DOI: 10.1039/ c1nr10181a

A team from Canada and the US has demonstrated that InP/ZnS quantum dots show low levels of cytotoxicity in cell lines related to reactive oxygen species production.

Indium phosphide quantum dots have emerged as a less hazardous alternative to cadmium-based particles, but their cytotoxicity has not been well examined, says the team, until now. Although their constituent elements are of very low toxicity to cells in culture, they nonetheless exhibit phototoxicity related to generation of reactive oxygen species by excited electrons and/or holes interacting with water and molecular oxygen, they add.

Using spin-trap electron paramagnetic resonance spectroscopy and reporter assays, the researchers found a considerable amount of superoxide and a small amount of hydroxyl radical formed under visible illumination of biocompatible InP quantum dots with a single ZnS shell, comparable to what is seen with CdTe. A double thickness shell reduces the reactive oxygen species concentration approximately two-fold. Survival assays in five cell lines correspondingly indicate a distinct reduction in toxicity with the double shell InP quantum dots. Toxicity varies significantly across cell lines according to the efficiency of uptake, being overall significantly less than what is seen with CdTe or CdSe/ZnS.

This indicates that InP quantum dots are a useful alternative to cadmium-containing quantum dots, while remaining capable of electron-transfer processes that may be undesirable or which may be exploited for photosensitisation applications, concludes the team.

Read the Nanoscale article today:
H Chibli, L Carlini, S Park, N M Dimitrijevic and J L Nadeau, Nanoscale, 2011
DOI: 10.1039/c1nr10131e

Electrochemistry of folded graphene edges

Adriano Ambrosi, Alessandra Bonanni and Martin Pumera
Nanoscale, 2011, C1NR10136F

Graphene  has many exciting potential applications, from solar cells to antibacterial sheets. There has been intensive research into the various properties of graphene, and it has been shown to have excellent electronic, electrochemical, optical, mechanical and thermal properties. As graphene has a planar form, it is important to consider the affects of conformational changes of the sheets such as folding and wrinkling, which can alter electrical and electrochemical properties. An important consideration here is the properties of graphene edges, as opposed to on the sheet’s surface.

Pumera and coworkers from Nanyang Technological University, Singapore, have conducted a study of the electrochemistry of folded graphene edges, and compared it to that of open edges. Folded edges have a very different structure compared to closed edges, and therefore it is natural to assume that they should possess different physical, chemical and electronic properties. Pumera et al. conclude in their paper that the electrochemical properties are superior at the open edges, discovering that the electron transfer rate is about 35 times faster at open-edged graphene structures than at folded-edged graphenes. This could be an extremely important consideration when synthesising graphene-based materials for many applications, particularly sensing and bio-sensing, as pointed out by the authors.

To read the full article, click here.