Nanoscale & Nanoscale Advances Blog

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.

Articles from both Nanoscale and Energy & Environmental Science are listed as Thomson Reuters ISI fast-breaking papers this month.

Each month, ScienceWatch tracks which papers are ‘Fast Breaking’, i.e. have the highest percentage increase in citations, and for April both Nanoscale and Energy & Environmental Science papers are top in the Chemistry and Environmental fields, respectively.

Surprisingly, both papers are also by the same author, Frederik Krebs – so our congralutions go out to Professor Krebs!

April’s ISI fast-breaking papers

Field: Chemistry

Upscaling of polymer solar cell fabrication using full roll-to-roll processing
Frederik C. Krebs, Thomas Tromholt and Mikkel Jørgensen
Nanoscale, 2010, 2, 873-886

Field: Environment/Ecology

Manufacture, integration and demonstration of polymer solar cells in a lamp for the “Lighting Africa” initiative
Frederik C. Krebs, Torben D. Nielsen, Jan Fyenbo, Mads Wadstrøm and Marie S. Pedersen
Energy Environ. Sci., 2010, 3, 512-525

Nanoscale ‘HOT’ Communication – read it today!

Silver nanoplates on commercial copper foil were prepared by a reproducible and cost-effective wet chemical method and those can be used as a reliable surface-enhanced Raman spectroscopy substrate.

Silver nanoplates prepared by modified galvanic displacement for surface-enhanced Raman spectroscopy
Yongchao Lai, Wenxiao Pan, Dongju Zhang and Jinhua Zhan
Nanoscale, 2011, DOI: 10.1039/C0NR01030H