New Brain Probe Design Mimics Wood Wasp

Imagine this little probe digging into your brain, tooth by tooth. Like a wood wasp boring into a pine to lay its eggs, a human surgeon will penetrate your brain in search of interesting neuro-treasure. What are you hiding in there?

The researchers have developed a prototype silicon needle consisting of two shafts with 50-micrometre-long fin-shaped teeth. Motors oscillate the two shafts to propel the device forwards in the same way as the wood wasp's ovipositor (see diagram).

...Unlike existing rigid surgical probes, the device will be flexible enough to move along the safest possible route, bypassing high-risk areas of the brain during surgery, for example. It could also reduce the number of incisions needed to deliver cancer therapies to different parts of a tumour, as it can burrow its way to hard-to-reach areas.

Emma Johnson, who works on bio-inspired engineering at the University of Reading, UK, says that the device is likely to be better suited to harder, fibrous tissues like bone and muscle than to soft brain tissue. _NS

Oh, OK, thanks Emma. I was getting a little worried there. ;-)

Better brain probes are certainly on the way. It is important for neuro-clinicians to be able to access deep brain structures without damaging more superficial structures and pathways along the way. A silicon needle might work for rigid structures like bone if it is strong enough and not too brittle. A "silicone" or similarly flexible probe may be more suitable for tissue with the consistency of brain if it can track along a desired path reasonably well. Being able to slip a probe between nerve bundles and around brain nuclei may make for a happier post-surgical aftermath.

Eventually, nano-technological probes will be given most of the intra-cranial exploratory tasks.

Bio-Nano: The Big Future of Small Dimensions

The promise of a nanotech/biotech convergence is coming closer to realisation. In the Netherlands, at the Technical University of Delft, the Kavli Institute of Nanoscience is forming a Department of Bionanoscience.

Bionanoscience is the discipline where biology and nanoscience meet. The molecular building blocks of living cells are the focus of bionanoscience. The nanotechnology toolkit enables the precise depiction, study and control of biological molecules. This creates new insights into the fundamental workings of living cells. Furthermore, it is increasingly possible to use the elements of the cell, to the extent that – in a new disruptive field like synthetic biology – gene regulation systems, artificial biomolecules and nanoparticles can be developed and applied within the cells.

The incorporation of new biological building blocks in cells is highly promising for applications in, for instance, medical science and industrial biotechnology. This link to synthetic biology makes bionanoscience highly relevant in the quest to design dedicated bioconversion organisms for the efficient production of bioproducts and biofuels (more here).

Science at the interface of nanotechnology and biotechnology is also seen as having a wide range of potential applications in agriculture and bioconversion: from nanoprocessing biomass for cellulosic ethanol, to the development of nano-catalysts and nano-channels for plant oil based fuels; from cellulose nano-crystals and fibre-enhanced bioplastics, to the design of micro-dosing technologies for nutrients, fertilisers and pesticides, to intelligent nano-bio-sensors and environmental sensors that improve agriculture and make it more sustainable_____Source

Delft's new department of bionanoscience aims to explore the full range of potential for the interface of the two disciplines. That will be impossible, of course, but it is a very good goal.
There are several areas where bionanoscience could impact on the path to the next level. Certainly bionano tools (almost makes you want to say "banana" tools) will affect the way genetic changes are made to the human genome. Bionano will impact brain-machine interfacing. Bionano sensors will allow remote control by thought, of robotic manipulators in space and undersea environments.

The list of ways that bionano will change our world, and help shape new levels of existence, is too long. It would be premature to try to make such a list.

Nanotechnology Developing Implantable Nano-Kidneys to Replace Dialysis

Dialysis is a poor substitute for working kidneys. But there is a perpetual shortage of donor kidneys for transplant. Technology Review looks at nanotechnology research that hopes to provide a better alternative to dialysis--an implantable nanotech kidney.

The common regimen of three half-day blood-cleansing sessions per week removes, on average, just 17 percent of the toxins that a healthy kidney would clear, so that only one-third of all dialysis patients survive more than five years of treatment.

Nanotechnology could offer an alternative, according to nephrologist William Fissell at the University of Michigan. He and colleagues are working on nano-pore membranes that could enable dialysis to be miniaturized into implantable devices that provide round-the-clock clearance of toxins, untethering dialysis patients from bulky pumps and clinics. "This is a fundamentally liberating technology," says Fissell.

....As currently practiced, dialysis is a crude procedure. Patients are hooked up intravenously to a powerful pump that circulates their blood through a cartridge of porous plastic fibers. Fluids, dissolved toxins, and salts pass through the fibers and are discarded, while the proteins and blood cells caught in the sieve are supplemented with electrolyte before returning to the patient. The filter's poor fluid dynamics are a function of their imprecision: filter manufacturing produces a wide range of pores, so to avoid having too many large pores, which would suck out valuable proteins, the fibers must be manufactured with a preponderance of very small pores. The machine's pump makes up the difference, forcing blood through these inefficient sieves.

In contrast, Fissell and Roy etch pores into ultrathin wafers of silicon with lithographic precision. The result is a homogenous array of pores, each capable of flow rates several orders of magnitude higher than the average pore in a conventional filter. The pores mimic the exquisitely precise yet efficient diaphragms that filter blood in a human kidney, resembling a panel of Venetian blinds, says Fissell.

Current prototypes contain roughly 10,000 pores per square millimeter, according to Fissell. Next-generation membranes, now being engineered, will have more than 100,000 pores or slits per square millimeter and provide more than 10 times the flow.

....Fissell's team is testing whether the kidney sorts not only by size but also by generating electrical charges that repel protein chains, which are also charged. They're modeling various chemical modifications to introduce charges on the surface of the silicon pores.

To make the system practical will require rendering the membranes biocompatible. Unmodified silicon strongly attracts proteins, and thus a silicon nano-pore membrane would rapidly clog if implanted in the body. Fissell's colleague at the University of Michigan, David Humes, has initiated animal studies with the nano membranes to identify surface treatments or alternative membrane materials that will prevent clogging in implants.

Humes hopes to use the membranes to fashion a more sophisticated version of the implant that would contain living kidney cells--analogous to his "bioartificial" Renal Assist Device that's currently in phase two clinical trials (see "Saving Lives with Living Machines," July/August 2003). In an implantable version of the bio-artificial kidney, nano-pore membranes would protect the live kidney cells from immune cells and antibodies, which have thwarted most bio-artificial organ implants to date. The live kidney cells, in turn, would improve the function of the implant by reabsorbing and returning to the bloodstream some of the fluids and salts that pass through the nano-pore membrane. Eventually, bio-artificial implants that recover fluids and salts and divert the remaining ultrafiltrate to the bladder might even eliminate the need for external electrolyte and ultrafiltrate bags.

Source.

Replacement organs that work well, and allow mobility, would improve the lives of hundreds of thousands of people. Whether from nanotechnology, stem cell research, or other advanced technology, most people in need of replacement organs would probably not quibble.

Biological Nanomachines--First in their Class

Life as we know it would not exist if not for incredible numbers of tiny bio-machines, molecular sized powerhouses that work at fantastic speeds, and with amazing efficiencies. I recently discovered a fine nano-blog by Will Ware, a software engineer who writes software for nano-engineering and development. This past New Year's Eve morning, Will wrote a fine posting on "Nanomachines in Nature," that I recently discovered. Will lets us know that there are indeed people in the nanotech culture who admire nano-biomachines, and who are willing to learn from them.

Kinesin and dynein are proteins that move along a microtubule and can drag along a mechanical load (another molecule). They are among several molecular motors found in nature. Another example is the flagella that push bacteria around in pond water, driven by a motor that looks like it came from a mechanical parts catalog.

....Some people are using these molecular machines to plan nanotechnology roadmaps, and there has been some laboratory progress. We won't have real nanotechnology any time soon, but these are excellent steps in that direction. Biomechanics hints at a lot of interesting things we can do with available cellular mechanisms.

To people thinking about the long term, as I like to do, these efforts are stepping stones. We'll use them to build tools, and use those tools to build other tools, with the eventual goal of a manufacturing infrastructure that permits us to build large rationally-designed products to atomic precision.

I am encouraged to see such enthusiasm for bio-nano from Will, and others like him. Read Will's entire posting, with great links and a fine graphic, here.

There has been a bit of discussion at The Speculist, and at Responsible Nanotechnology, about two previous postings "Nanotechnology Learns from Biology" and "Holy Grail of Enzymatics." Will's posting adds quite a bit to that discussion.

Update: Here is a link to an excellent set of publications from Bionano.neu.edu. It comes from one of the links obtained from Wills post above. There is far more activity on this front than I previously realised. Thanks again to Will Ware.
For anyone interested in the NSTI Bio Nano conference in Boston this May, here is the website for that event.

Update 13 March 2006: Here is a bizjournal article discussing the explosion of patent applications for bio-nano.

Nanotechnology Learns from Biology

Nanotechnologists too often approach the assembly of their nano-machines on a de novo basis, ignoring the legions of nano-machines that evolved over a billion years ago. Nano-engineers had better begin learning from the biologically evolved nanodynamic structures, or they will be made irrelevant by bio-nano engineers.

An Oxford University physicist sees the future of nanotechnology in the workings of one of Nature's tiniest motors, that which allows some bacteria to swim by rotating slender filaments known as flagella.

'The bacterial flagellar motor is an example of finished bio-nanotechnology, and understanding how it works and assembles is one of the first steps towards making man-made machines on the same tiny scale,' said Dr Richard Berry, a Tutorial Fellow in Physics at Oxford University. 'The smallest man-made rotary motors so far are thousands of times bigger.'

This motor has the same power-to-weight ratio as an internal combustion engine, spins at up to 100,000 rpm and achieves near-perfect efficiency. Yet at only 50 nanometres across, one hundred million would fit onto a full-stop. The only other natural rotary electric motor is in the enzyme ATP-synthase.

Dr Berry is a member of the Rotary Molecular Motors Group in the Oxford Department of Physics. He presented his research at the Biophysical Society's Annual Meeting in Salt Lake City, Utah, on Sunday 19 February.

The physicist and his Japanese colleagues changed the proteins normally found in the motor of E Coli to make it run on sodium instead of hydrogen ions. This allowed them to reduce its speed of rotation by lowering the level of sodium ions present. They also made the actions of the motor more easily detectable by attaching tiny beads to stubs of flagella. Ultimately 26 distinct steps could be observed in each of its revolutions.

'The motor runs on electric current, the flow of hydrogen or sodium ions across the cell membrane, and each step may be caused by one or two sodium ions passing through the motor,' explained Dr Berry.

The tools involved included optical tweezers, which employ light beams to hold and to measure transparent particles, and a high-speed fluorescence microscope which can capture 2500 images per second.

Here is the source for this report.

Dr. Berry presented his findings to a meeting of Biophysicists in Salt Lake City on February 19.