Artificial Blood Vessels, a new Strongest Material and Nanosensor Manufacture

August 10

This week we look at a new method of constructing artificial blood vessels. This will help those that need bypass surgery and that don’t have suitable donor vessels. We investigate a new material (made from some very surprising ingredients) that is four times stronger than steel. We examine a new method for use in the manufacture of nano sensors. Finally we update progress on LK-99 and Self Driving Taxis.

Artificial Blood Vessels

Currently when we undergo bypass surgery the surgeon will use a blood vessel from elsewhere in the body to replace the clogged or damaged vessel. In some cases non-living grafts of synthetic polymers can be used. However small diameter coronary arteries that feed blood to the heart cannot be replaced with synthetic vessels as blood will clot on their surface and obstruct the graft. Some patients lack suitable vessels to replace the coronary artery due to previous surgeries or co-morbidities such as diabetes.

A team at the University of Melbourne have developed tissue engineered blood vessels that may turn out to be a viable option. Blood vessels are complex multilayered tissues. Their structure is directly related to their performance making creating artificial blood vessels extremely challenging.

The inner most layer of a blood vessel is the endothelium layer. It is a single layer of specialized cells that support blood flow and prevent coagulation. Around this is a 3D layer of smooth muscle cells that wrap like rings around the blood vessel. This gives mechanical strength and the ability to contract and relax to manage blood pressure.

The team has combined multiple materials and fabrication techniques from previous attempts to develop artificial blood vessels. The result is a fast, inexpensive and scalable method for tissue engineering blood vessels.

Initially a framework on which the blood vessel layers is created. A layer of polymer fibers were electro spun onto a mandrel. This gave the tubular shape required for the blood vessel graft. Electro spinning uses an electrical voltage to draw polymer stream into thin fibers that mimic the protein structure of our native tissues. A freezing technique is then used to align the fibers in a similar way to the smooth muscle cells in our vessels. An endothermic layer of cells was then grown on the inside of the tube. These cells will spontaneously align with the fibers. This layer also provides appropriate mechanical properties which enables the graft to be sutured to native blood cells.

A layer of soft hydrogel is then cast around the electro spun fibers. This prevents leakage and acts as a scaffold for the smooth muscle cells. Soft hydrogels allowed the smooth muscle cells to rapidly and spontaneously align in a 3D structure, mimicking our native vessels.

There is still work to be done to make the artificial vessels ready for clinical use however it is hoped that it will not be too long before artificial blood vessels can provide an option for those without suitable donor vessels.

The Strongest Material

A team at the University of Connecticut has developed an extraordinarily strong lightweight material using DNA and Glass. For the given density it is the strongest material that we know.

It is difficult to create a large piece of glass without flaws. The team therefore concentrated on developing very small flawless pieces of glass. They discovered that as long as glass is less than a micrometer thick it is always flawless as well as strong and lightweight. Flawless glass can withstand 10 tons of pressure.

The team then developed a structure of self assembling DNA and coated it with the very thin layer of glass like material only a few hundred atoms thick. The DNA skeleton reinforced the flawless coating of glass making the material very strong and lightweight. The resulting glass nano lattice is four times stronger than steel but five times lower in density.

Strong lightweight materials are needed in body armor, medical devices and safer and faster cars and airplanes. The material shows great promise as an energy saving material for vehicles and other devices that prioritize strength. The lead researcher is a huge fan of IronMan. He may have just invented the material that provides the strength in his body armor. Hopefully this is a good example of where life imitates art.

Revolutionizing Nano Sensor Manufacture

A team at Macquarie University in Sydney have developed a new technique to manufacture nano sensors which is far less carbon intensive, much cheaper, more efficient and more versatile.

Nano sensors are made up to billions of nanoparticles deposited onto a small sensor surface. Unfortunately most of these sensors do not work when first manufactured. The nanoparticles will self assemble into a network held together by weak natural bonds. This leaves many gaps and causes the failure to transmit electrical signals. The nano sensors are usually heated in an energy intensive 12 hour process to fuse the layers of nanoparticles thus creating channels that allow electrons to pass through the layers. This allows the sensor to function. This requires nano sensors to be made from a limited range of materials that can withstand the heat process.

The team found that by adding one droplet of ethanol onto the sensing layer it will help the atoms on the surface of the nanoparticles move around. This removes the gaps as the particles join to each other. This removes the need to heat the nano sensors and improved the efficiently and responsiveness of the sensors.

The technique was discovered by accident. After spilling some ethanol onto a sensor whist washing a crucible they found that the sensor was not destroyed as expected but it outperformed all the other samples. Further testing found that the key to the success of the method is the amount of ethanol required. Three microliters was too little, ten was too much however five microliters worked perfectly. It takes about one minute for the sensors to be activated.

The technique works on a range of nano sensors including sensors that detect carbon dioxide, methane, hydrogen and other gases.

A Couple of Updates

Self Driving Taxis

The was a lot of hype about self driving cars several years ago. Most of the claims being made about self driving capabilities were overstated (hello Elon). Reality is finally starting to catch up with the marketing hype.

Self driving car company, Cruize is now expanding to Los Angeles. This adds to their current operations in San Francisco, Austin, Dallas, Houston, Phoenix and Miami. The next cities to start are Nashville and Atlanta. Services are usually initially offered in off peak periods, with a safety driver and only in restricted suburban areas. As they prove effective and safe, driverless operations (without a safety driver and other restrictions) are allowed to expand their operational area in each city. Every new area takes less time to reach this approval level. Currently self driving taxis are not allowed on Freeways however they are being tested in San Francisco. Waymo has similar operational areas.

The self driving taxi companies currently have high costs and lose money on each ride. Expansion is slow at the moment. The operating cost however is rapidly dropping towards US$1 per mile. Once the cost falls below the market price of the ride, expansion will become rapid. It is possible that similar services may be launched in Australia in 2026 (the current predictions but as we know, regulatory approval can be slow).

LK-99

The room temperature superconductor that we spoke about last week is still firmly in the “maybe” category. There are a lot of researchers trying to replicate the findings with mixed results. This is partly due to the lack of information on how the original superconductor was created.

Firstly some history. LK-99 was named after the two lead scientists that first discovered the material in 1999, Sukbae Lee and Ji-Hoon Kim. As they lacked funding not much progress was made until the pandemic in 2020, when they were able to raise new funding. They set up a company to commercialize their findings and hired a COO. All progressed smoothly until March this year when the COO was fired. He then allegedly decided that he would publish the paper that was being worked on by Lee and Kim however he added his own name to the paper (remember only 3 people can be awarded a Nobel Prize for a single award each year). The paper was not complete, it was full of errors and it had not been peer reviewed. Despite these shortcomings it exploded with interest. The whole world is now racing to replicate the findings and to try and develop the technology.

There have been at least 5 theoretical papers published saying that the material “could work”. Few have been able to replicate the material and there have been mixed results amongst those that succeeded. This is mainly due to the lack of detail in the paper re the manufacturing process. The two ingredients need to be combined in an oven at an unpublished temperature. Some researchers are using home ovens so experimental control is not perfect.

The process requires some of the lead (Pb) atoms in the PbSO5 ingredient to be replaced by a copper atom. The angle at which this atom is replaced appears to be critical. This seems to be very difficult to replicate consistently. A group of Chinese researchers have claimed they get better results with gold rather than copper.

At the very least it is likely that the LK-99 discovery has shown us the way towards developing a room temperature superconductor. That in itself, is a very big step forward. At best, if something has been discovered, it is likely to take the remainder of this decade to get to commercial application.

Paying it Forward

If you have a start-up or know of a start-up that has a product ready for market please let me know. I would be happy to have a look and feature the startup in this newsletter. Also if any startups need introductions please get in touch and I will help where I can.

If you have any questions or comments please comment below.

I would also appreciate it if you could forward this newsletter to anyone that you think might be interested.

Till next week.