UNCD Horizon from ADT

ADT have once again added to their repertoire of diamond products, with the latest addition to the family being the world's smoothest commercially available vapour-deposited diamond. Using chemical-mechanical planarisation (CMP - a standard industry polishing technique) ADT have reduced the roughness of their UNCD wafers from 10nm to 1nm.

ADT hope the outstanding smoothness of their new material will pave the way for more efficient RF devices, and the material is already being used to fabricate nanophotonics for applications ranging from bio-chemical sensing to optical information processing.

The artwork for this post is the UNCD Horizon wafer patterned with the ADT logo, courtesy of Dr. Warren McKenzie, University of New South Wales. To find out more about UNCD Horizon (and other ADT products, including all-diamond AFM tips) follow the Advanced Diamond Technologies Ltd. link on the group list to the right hand side.

Nanodiamonds for gene delivery

I said in my last post I was looking forward to Dean Ho's next nanodiamond (ND) application, but I didn't expect it to come so soon.

This time, Ho's group are using NDs for gene delivery into cells, where NDs are increasing the gene insertion efficiency 70 times. This has been achieved by using the superlative biocompatibility of NDs, along with their ability to be easily chemically functionalised with any desired chemical. Exploiting these two properties of NDs have resulted in dramatic improvements on existing gene insertion techniques.

"A low molecular weight polymer called polyethyleneimine-800 (PEI800) currently is a commercial approach for DNA delivery," said Xue-Qing Zhang, a postdoctoral researcher in Ho's group and the paper's first author. "It has good biocompatibility but unfortunately is not very efficient at delivery. Forms of high molecular weight PEI have desirable high DNA delivery efficiencies, but they are very toxic to cells."

Zhang et al. functionalised NDs with PEI800 using amine groups as covalent linkers. The 70x improvement of gene insertion efficiency is in comparison to the convention approach of using PEI800, and the NDs have allowed PEI800 to retain its function and biocompatibility whilst increasing gene insertion efficiency. Zhang et al. believe this use of NDs to be a rapid, scalable, and broadly applicable gene therapy strategy, and with further work hope the technology will treat diseases ranging from inherited disorders to acquired conditions and cancer.

"There's a long road ahead before the technology is ready for clinical use," Ho said, "but we are very pleased with the exciting properties and potential of the nanodiamond platform."


As a diamond engineer, diamond's biological applications are those which excite me most, yet most diamond engineers I have met come from physical backgrounds. Where do these bio-inspired ideas come from? The answer is simple; Ho is from a Physiological Science background, so has a plethora of problems to address - rather than a pile of nanodiamonds that need using. I need to find me a doctor...

The full paper can be found here in ACS Nano.

Savlon? No thanks, I've got nanodiamonds

I've finished my paper (sigh of relief) so I'm going to report on what's been flooding the diamondnet: nanodiamonds for insulin delivery.

You may remember back in October last year I wrote a piece on Dean Ho and his remarkable use of nanodiamonds (embed in polymer films) to deliver chemotherapeutic drugs to post-operated tumour sites. This time, wounds in general are the target.

Insulin has recently been identified as an agent for fighting bacterial infection, hence if you have a wound a bit of insulin would not go unwanted - that is if it's infected. Shimkunas et al. have adsorbed insulin onto nanodiamonds that is only released when the local pH increases above usual physiological levels. This happens during infections, allowing targeted delivery of insulin to wounds. Ho hopes to incorporate the ND-insulin complexes into gels for direct application on wounds.

So what will be next for Ho's lab? Nanodiamond is one of the best adsorbers of proteins at the nanoscale: Its oxygen terminated surface (unless otherwise treated) gives proteins high binding affinities to nanodiamonds above other nanoparticles, and their curvature and size is (controversially) thought to allow proteins and enzymes to adsorb and remain in their native and functional states. As a biologically minded but physically trained scientist, I wait with baited breath to see which protein will be given the next ND treatment.

I'm nearly back, I promise

It's been ages hasn't it! Well it's going to be a bit longer I'm afraid. I'm currently writing up a paper (watch this space) and blogging has taken a back seat for the last few months.

Meanwhile, I thought I'd share some tools I've recently found that make science a lot easier. The first one I feel a bit embarrassed to mention, as I think I'm a late adopter on this one:

Scopus. It's better than Google Scholar, Science Direct and WoS put together in my opinion.

Secondly, this one's Mac-only I'm afraid, but its caught on like wild-fire in the lab. Papers. Get it now.

And finally, I've been hunting high and low for something to replace my illegible paper logbook that looks like a 5-year old's scrapbook. If you're like me, you think the concept of printing out a graph and sticking it in an actual book (what are they again?) is a bit out of date. If you're showing similar symptoms I'd recommend Journler to you. It's like an organised diary that you can attach any file, folder, website, email, video or you-name-it to. Get it while it's free.

Thank you to my readers who have been checking back on the blog while I've been AWOL.

Metal matrices and diamond injections

Today is just a quick roundup of some of the latest diamond news. I have some deadlines looming...

A project called ExtreMat has just come into my attention, where Professor H. Peter Degischer and Co. are in the process of fabricating new materials for extreme environements. Degischer is using 100µm diamond particles coated in silver and connected with tiny silicon bridges to create a new composite material for extreme application.

"We examined some metal matrix composites and their interfacial bonding which are promising for use in nuclear reactor heat sinks, rocket engines or in power electronics. The characterisation of these heterogeneous materials falls within our area of competency", says Degischer, Head of the Institute of Materials Science and Material Technology at the TU Vienna. The team hope the material to be resistant to very high heat fluxes and temperatures, physico-chemically aggressive media, complex mechanical loads and highly energetic radiation field.

The second news item reminds me of a previous post I wrote on Nanodiamond printing. A team of researchers at Northwestern University have developed a tool called the Nanofountain Probe that functions in two different ways. Firstly, the probe acts like a fountain pen. The drug-coated nanodiamonds serve as the ink, allowing researchers to create devices by "writing" with it. The second mode functions as a micro syringe for single cell application, permitting direct injection of biomolecules or chemicals into individual cells.

The research was led by Horacio Espinosa, a Professor of mechanical engineering, and Dean Ho, an assistant Professor of mechanical and biomedical engineering, both at the McCormick School of Engineering and Applied Science at Northwestern University. Their results were recently published online in the scientific journal Small.

Thinner than theory: Diamond nanorods

How thin can diamond nanorods be? Theory would lead you to believe that 2.7nm is the smallest possible diamond-diameter, however Shang et al. from the University of Ulster have recently shown diamond nanorods (DNRs) can be grown to the ultrathin size of 2.1nm.

Below 2.7nm thickness DNRs are thought to be energetically unstable. Shang et al. have ascribed the existence of their thinner-than-theory DNRs to a tapered graphene sheath around the DNR, which they claim could be responsible for the system's low free energy, and thus stability.

As well as housing the DNR, Shang et al. also speculate that the graphene sheath could act as a 'high pressure reactive nanocell' that self-assembles and catalyses DNR growth during PECVD. The group suggest that the curvature of a piece of graphene (seeded onto a surface) could possibly give rise to a surface tension or additional pressure that creates a thermodynamic nano-climate in favour of DNR growth over carbon nanotubes (CNTs) or amorphous carbon.

Upon measuring the threshold field emission of the DNRs, Shang et al. found them to compare favourably to most nanostructured emitters (CNT, ZnO, CNx, GaAs, GaN, AlN, BCN, etc.); however they did fair worse than oriented high density multiwall CNTs. The group measured 1mA/cm2 at 1.9V/µm, and performed admirably against the metric of field emission for flat panel displays.

The full paper, which employs a host of imaging techniques to characterise the DNRs, can be found here.

When Semi Turns To Super

I haven't posted much on Boron-doped diamond (BDD) superconductivity yet as I'm fairly unacquainted with it, so it was a pleasant surprise recently to see the cover of Nature Materials devoted to an initiating review of 'Superconducting group-IV semiconductors', by Blase et al.

It's a review so I'll leave the scientific details for you to discover, but I would like to point you in the direction of a good figure on the 'evolution of the electronic density of states and band structure with increasing p-type doping'.

Also in the news, here is a recent interview with the De Beers Group Managing Director Gareth Penny from the IDEX website.

$6.1 million and 50 nanometers

This week I'm killing two birds with one post by highlighting some recent stories from the diamond community. Last week the University of California, Santa Barbara, (UCSB) received a $6.1 million grant from DAPRA and AFOSR to develop diamond as the material of choice for quantum computing processing. The project will cover all corners of quantum computing, bringing together physicists, electrical engineers, material scientists and computer scientists to deliver the complete diamond-computing package.

"We are extremely excited by the rapid pace of discoveries in this emerging area of science and technology. This vital support offers extraordinary collaborative research opportunities for students to engage at the frontiers of the field in areas spanning fundamental physics to materials science," said David Awschalom, principal investigator for both projects and Professor of Physics and Electrical and Computer Engineering at UCSB.

On the other side of the pond, Dr. David Moran from the University of Glasgow has recently unveiled his group's most recent creation - the smallest diamond transistor in the world. The diamond gate measures only 50nm, which halves the previous record held by NTT (Japan).

Dr. Moran explains, “by developing a diamond transistor technology, we aim to tap into the truly amazing properties of this exciting material which could prove fundamental to the development of several next generation technologies. These require a very fast and ideally high-power transistor technology that needs to be able to operate in adverse weather/temperature conditions. This is where a diamond transistor technology would excel.”