Conventional silicon-based computing, which has advanced by leaps and bounds in recent decades, is pushing against its practical limits. DNA computing could help take the digital era to the next level. Scientists are now reporting progress toward that goal with the development of a novel DNA-based GPS. They describe their advance in ACS’ ("Programmable DNA-Mediated Multitasking Processor"). 
Scientists have programmed DNA to calculate multiple GPS routes at the same time. (Image: American Chemical Society) Jian-Jun Shu and colleagues note that Moore’s law, which marked its 50th anniversary in April, posited that the number of transistors on a computer chip would double every year. This doubling has enabled smartphone and tablet technology that has revolutionized computing, but continuing the pattern will come with high costs. In search of a more affordable way forward, scientists are exploring the use of DNA for its programmability, fast processing speeds and tiny size. So far, they have been able to store and process information with the genetic material and perform basic computing tasks. Shu’s team set out to take the next step. The researchers built a programmable DNA-based processor that performs two computing tasks at the same time. On a map of six locations and multiple possible paths, it calculated the shortest routes between two different starting points and two destinations. The researchers say that in addition to cost- and time-savings over other DNA-based computers, their system could help scientists understand how the brain’s “internal GPS” works.
read more "The next step in DNA computing: GPS mapping?"
Scientists have programmed DNA to calculate multiple GPS routes at the same time. (Image: American Chemical Society) Jian-Jun Shu and colleagues note that Moore’s law, which marked its 50th anniversary in April, posited that the number of transistors on a computer chip would double every year. This doubling has enabled smartphone and tablet technology that has revolutionized computing, but continuing the pattern will come with high costs. In search of a more affordable way forward, scientists are exploring the use of DNA for its programmability, fast processing speeds and tiny size. So far, they have been able to store and process information with the genetic material and perform basic computing tasks. Shu’s team set out to take the next step. The researchers built a programmable DNA-based processor that performs two computing tasks at the same time. On a map of six locations and multiple possible paths, it calculated the shortest routes between two different starting points and two destinations. The researchers say that in addition to cost- and time-savings over other DNA-based computers, their system could help scientists understand how the brain’s “internal GPS” works.
Comparison of nanomaterials sizes. (click on image to enlarge) But Professor Sonia Trigueros, co-director of the Oxford Martin Programme on Nanotechnology, is inching closer to developing a nano-scale drug delivery system with the aim of specifically targeting cancer cells. Working with a team of chemists, engineers and physicists, Trigueros has embarked on an ambitious mission to tackle cancer at the ‘nano’ level – less than 100 nanometers wide. There’s still a long way to go, but Trigueros is making decent headway, and has recently tackled a major problem of working at a nano level. And at this year’s Wired Health conference – which looked at the future of health care, wellbeing and genomics – she told us about her recent progress, and her visions for the future. At the nano level Some of us will remember the periodic table displayed in our science classrooms which told us about the properties of each element. But working on a nano level everything changes, and elements behave completely differently. Elements have different properties at the nano level than they do at the micro level, explained Prof Trigueros to the Wired Health 2015 audience. This poses big problems for researchers trying to make nano-scale devices, which can be made out of a number of different materials, including gold, silver and carbon. All these materials are highly unstable at the nano level. “After you make the nanostructures you only have minutes to a couple of days to work,” she said. They are really unstable, especially when you put them in water.” This isn’t ideal, considering our bodies are made up mostly of water. Trigueros’ recent work has focused on trying to stabilise tiny tubes made of carbon, called carbon nanotubes, which hold drugs inside the tube so they can be delivered into cancer cells. She has now found a way of keeping them stable for more than two years and in temperatures up to 42ºC. To do this, she wraps DNA around the structures, like a tortilla wraps around the fillings of a burrito. While this accomplishes the goal of keeping the nanostructures stable inside the body this doesn’t do much good if the DNA can’t unwrap to deliver the drugs. But, according to Trigueros, she has shown that, once inside a cell, the DNA easily unwinds and releases its payload. Truly targeted drug delivery So how does it all work? How do the drugs get into the cancer cells? Trigueros’s nanotubes exploit the differences between cancer cells and healthy cells – in this case, differences in the membranes that hold them together. “Cancer cells are more permeable than normal cells so the nanotubes can get through the cell membrane. And once they are in, they unwrap and deliver drug,” explained Trigueros. Exploiting differences in their permeability is one way to target the cancer cells, but Trigueros explains that there is more than one way to create a truly targeted drug delivery system. “We can attach whatever we want on DNA,” she said. “So you can attach a protein that recognises cancer cells”. 
Attaching proteins to DNA could create a truly targeted drug delivery system. From theory to reality While this all sounds great in theory, will it actually work in reality? Trigueros has now started preliminary tests on laboratory grown lung cancer cells, she told us during an interview. And this has shown tentative promise, she says, citing unpublished data on their effectiveness at killing these cells in the lab. Others are cautiously optimistic. “This is a really exciting prospect,” says Professor Duncan Graham, nanotechnology expert and advisor to Cancer Research UK. “A common concern with carbon nanotubes is toxicity, but when coated with DNA this concern could be removed,” he explains, “and it also addresses a fundamental issue, which is that they collect into clusters that become a solid mass and so are unable to leave the body.” In theory, once Trigueros’s nanotubes have finished their job they are tiny enough (50 nanometres) to be excreted through urine. This isn’t the first time carbon nanotubes have been used in cancer research: a US research team has used them, for example, to target and collect images of tumours in mice. But the combination of drug delivery and cancer-specific targeting is what interests Professor Graham. “Unlike previous work using carbon nanotubes, this approach is set to target the tumour specifically, potentially meaning fewer side effects and a lower dosage. I look forward to seeing this in animal models which is where the real proof of activity lies,” he said. But he’s cautious, stressing that Trigueros’s work has not yet been peer-reviewed and published. Next steps Next Trigueros is aiming towards starting animal trials and, eventually, she wants to begin clinical trials in patients – that is if everything goes well. She hopes to focus on how nanostructures could be used to cross the blood-brain barrier – the brain’s highly selective ‘bouncer’ that only lets certain molecules across. This has been notoriously difficult to get past, making targeting cancers in the brain more difficult. But there is a still a long way to go and a lot of problems to tackle. In the shorter term, we’ll be keeping an eager eye on her drug delivery research, as her ideas continue to develop.
Polymer Nanocone Array: The surface is a polymeric nanocone array that is generated by colloidal lithography, i.e. a masking of a polymeric substrate by nanoscale beads followed by a reactive ion etching. The inset shows more detailed structure to the individual nanocones which have 20nm ridges along their length. The image was acquired using a Zeiss Auriga SEM with the InLens detector and a 2keV electron beam. (Image: Kyle Nowlin; Advisor: Dr. Dennis LaJeunesse; University of North Carolina Greensboro, Joint School of Nanoscience and Nanoengineering, Department of Nanoscience) Thirty-two images were submitted by 10 students from universities across the country. Images were posted online for public voting. The top five images advanced to the semifinalist round. The final winner was chosen by representatives of the National Nanotechnology Initiative member agencies. The winning image will be displayed on Nano.gov for a month. For more information on the EnvisioNano contest rules and judges, visit the EnvisioNano page on Nano.gov. Kyle's description of his research: "Many insects display nanostructured surfaces (NSS) on their cuticles and many of these native NSS are inherently antimicrobial and kill microbes by mechanical/structure means. Our research explores the mechanisms that underlie the rupture of microbes on NSS. The native insect cuticles are complex materials that are difficult to replicate and to control specific surface properties. We have applied a colloidal lithographic process to generate novel synthetic NSS materials that resemble their biological insect cuticle counterparts in scale and shape but by using different polymeric materials to make these NSS can control surface properties of our biomimetic NSS. In this manner we will systematically identify the mechanical and physiochemical properties of rupturing NSS that lead to microbial demise. The goal of this research is to develop novel means of controlling the spread of pathogenic bacteria and fungi through nanostructured materials." This work was supported by the North Carolina Biotechnology Center (NCBC) Biotechnology Research Grant and through the generous support of Dr. James Ryan, the Joint School of Nanoscience and Nanoengineering, and the State of North Carolina.