Nanoscale & Nanoscale Advances Blog

Graphene has been the focus of intense research over the past couple of decades. Its unique optical, electrical, thermal and mechanical properties mean that graphene is the ideal 2D material for probing interfacial interactions.  The ability to tune the electronic properties of graphene has enabled the highly sensitive detection of various gases, biomolecules and organic molecules. However, the ability to perform selective measurements using such substrates remains a significant barrier needing to be overcome.

Graphene FET with adsorbed molecules on the surface.

Cervenka and co-workers have devised graphene field electric transistors (FETs) to study the interfacial interactions of two nitrogen hetrocycles, using the knowledge that the electronic structure of graphene can be tuned between n and p-type doping due to the adsorption of electron donating/accepting molecules. Using a combination of electronic transport and XPS measurements this study has shown that molecular recognition can be achieved through the use of FETs due to the presence of non-polar and polar moieties within the analyte molecules.

Significantly, the simplicity of this study opens up the possibility of studying a variety of chemical species selectivity on graphene based sensor devices.

Graphene field effect transistor as a probe of electronic structure and charge transfer at organic molecule–graphene interfaces
Jiri Cervenka, Akin Budi, Nikolai Dontschuk, Alastair Stacey, Anton Tadich, Kevin J. Rietwyk, Alex Schenk, Mark T. Edmonds, Yuefeng Yin, Nikhil Medhekar, Martin Kalbac and Chris I. Pakes
Nanoscale, 2015, 7, 1471-1478. DOI: 10.1039/C4NR05390G

Dr Derek Craig is a guest web writer for the Nanoscale blog. He is a Post Doctoral Research Fellow at the University of St. Andrews based in the fields of Biophotonics and Materials Science. With a background in chemistry, his work mainly focuses on the synthesis of nano to meso materials and the use of imaging techniques to study biological samples.

Schematic structure of the fluorescent nanodiamond crystal coated with a biocompatible methacrylamide copolymer grown from an ultrathin silica shell.

Diamonds have always attracted mankind – whether it be in the form of jewellery or knives to cut hard samples! However, a new form of diamond that has attracted scientific fascination in recent times are nanodiamonds, which are tiny nanocrystals of carbon that can be made fluorescent with doping and surface functionalized with various ligands for specific biological targeting. This has immense potential for the bioimaging community, where biologists always seek bright and stable tools for imaging biological processes for longer times without losing signals.

In the present work, Cigler et al. addressed a challenging system, marking integrins (hallmark molecular markers for cancer) present on cancer cells with nanodiamonds. Most nanoparticles aggregate in biological media and on cell surfaces. The authors intelligently coated the diamonds with specific polymers to prevent their aggregation and then functionalized them with multiple cyclic-RGD motifs (a small tripeptide Arg-Gly-Asp that binds strongly to integrins on the cancer cells). The binding was successful and most importantly, specific uptake of these nanodiamonds through integrins was addressed. The best advantage that the nanodiamonds offer is their extremely bright fluorescent properties, which can be explored to image even single nanodiamonds.

Although much fine tuning and multiplexing with different types of diamonds and receptors is still needed, the successful and specific binding and uptake of these nanodiamonds in cancer cells opens new doors, not only for targeted bioimaging, but it could also be applied further to live animals for diagnosis and sensing.

Dr Dhiraj Bhatia

Designing the nanobiointerface of fluorescent nanodiamonds: highly selective targeting of glioma cancer cells
Jitka Slegerova, Miroslav Hajek, Ivan Rehor, Frantisek Sedlak, Jan Stursa, Martin Hruby and Petr Cigler

Nanoscale, 2015, 7, 415-420. DOI: 10.1039/C4NR02776K

Dr Dhiraj Bhatia is a guest web writer for the Nanoscale blog. He is a chemist by training and received his PhD in Chemical Biology of Nucleic Acids from the National Center for Biological Sciences, TIFR India with an outstanding thesis award in 2013. He joined the Chemical Biology department at the Curie Institute, Paris, as an HFSP long term Postdoctoral Fellow and is currently investigating the mechanisms of endocytois using various chemical biology tools.

Pathway illustrating the formation of AC@Ag hybrids.

A novel environmentally friendly method has been presented for the synthesis of dual metallic silver (Ag) and gold (Au) nanoparticles on aminoclay nanosheets (ACN). Typically, synthesis of metal nanoparticles requires the aid of toxic reducing agents or complex chemical synthesis and purification.  Baker and co-workers have proposed a one-pot method that utilizes ACN to stabilize precipitating nanoparticles, thus discovering that photochemical reduction using natural unfocused light to be the most time- and energy-efficient method for producing stable nanodispersions in water.

The dual AgAu materials were investigated as catalysts and anti-microbial agents and interestingly showed better activity than analogues synthesised from gold or silver alone. This article highlights the advantages of green synthesis and the potential of hybrid metallic nanoparticles in two different applications. The authors speculate that this generic method could also be expanded to drug delivery, water purification and biological applications.

Sunlight-assisted route to antimicrobial plasmonic aminoclay catalysts
Sudhir Ravula, Jeremy B. Essner, Wendy A. La, Luis Polo-Parada, Roli Kargupta, Garret J. Hull, Shramik Sengupta and Gary A. Baker

Nanoscale, 2015, 7, 86-91. DOI: 10.1039/C4NR04544K

Dr Mike Barrow is a guest web writer for the Nanoscale blog. He currently works as a Postdoctoral Researcher at the University of Liverpool.