Nature at the nanoscale
Albert Einstein once said, “Look in to the nature, and then you will understand everything better”. In fact many scientists do just this each and every day. Many look in to nature for answers, some to understand what goes on and some, just for fun. Despite the reason, many would lean back to the chair, with “wow” in their mind. Well, I have, not once, twice but number of times. We never cease to be amazed by nature and yes, equally puzzled too. Amazingly, nature usually encloses its greatest of creations in smallest of things. Many of these still puzzles the scientist and even experts on the field. On the outset, some even look like wonders. We all started our life as a single cell and evolved to the billions of cells which makes who we are now. Each unique yet perfectly adopted to the function it intend to serve. Isn’t that an everyday wonder?
Over the years we have attained the power to look in to nature in the nanoscale. This ability has opened us the door to see instances where sophisticated nanotechnologies in action. They appear so perfect, as everything is in seamlessly planned and carried out by a higher force. In fact, they are highly optimized through millions of years of evolutionary progression. All the exotics of the nature disappears at the nanoscale, and strange world of atoms and molecules emerge. This world is not governed by the forces that we are familiar with. Forces like gravity and inertia play a very little role here, as the minute masses of the associated bodies generate negligible forces (gravitational force = mass x gravitational acceleration, inertia force = change of momentum/time). Yet, forces such as electrostatic, intermolecular and surface tension becomes more prominent. Workings of nature in the nanoscale that are governed by these forces may seem strange to us as we are more pursuant of forces of macroworld to explain things happening around us.
Examples of nanotechnology in nature
Nature is teaming with nanotechnology examples. Here are few of them.
DNA as nano data banks
DNA or deoxyribonucleic acid is a long chain molecule that is called nucleic acids. The structure of the DNA is made up of two backbones which spiral around each other in a well-known structure popularly known as a double helix formation. These two backbones of the DNA is decorated with nucleotides, which consists of a sugar (deoxyribose), one of four bases C:cytosine, T: thymine, A:adenine, G: guanine and a phosphate. Genetic information is stored as a sequence of nucleotides, more specifically in the order of four bases in the DNA double helix.
DNA is responsible for coordinating the production of amino acids at are building blocks of the life. Amino acids build proteins, proteins make tissues, tissues make organs, and functioning organs makes the life as we know it. As we know, each life is unique, and the uniqueness come from amino acids of which the production is controlled by the DNA. This is achieved by passing the right information about what acids to produce in each successive generation. This vast amount of information is stored in the DNA at the nanometer scale, just 2 nm thick and around 2.3 m long. It’s known that single gram of DNA, can store at least 5.5 Petabites (5500000 Gigabytes when an average computer has around 200 Gigabytes) of data. Unbelievable amount of genetic information ranging from skin color to certain behavioral traits is stored and delivered to each cell.
Molecular motors and motor proteins
Motors are devices that can convert some form of energy in to the kinetic energy or mechanical motion. The motors that we are quite used to are electrical motors, which converts the electrical energy in to the kinetic energy. In our body also, there are countless numbers of molecular machines so called molecular motors that are quite essential for movement in living organisms. These machines consumes the energy that is in the form of chemical energy and outputs a mechanical action. Most of the molecular motors that reside in our bodies, generate the energy from hydrolysis of ATP (Adenosine triphosphate); energy packets that is responsible for intercellular energy transfer.
Two of the most spectacular motor proteins in our body are called, dynein and kinesin. These responsible for delivery of cellular cargo by literally walking on the cytoskeletal microtubules (highways inside the cell) towards and outwards from the nucleus respectively. They have feet and legs to walk and hands to catch the cargo. As most of the other motor proteins they are also powered by hydrolysis of ATP.
Another wonderful example of molecular motor can be seen in the certain bacteria and animal sperm cells. These motors power so called propellers named flagellum and the power is generated by the flow of hydrogen ions across the cell membrane of the bacterium. These motors can reach to incredible speeds that average around 10,000 rpm higher than the rpms possible with most of the vehicles. Unlike most of the vehicle engines and electrical motors, these molecular motors are extremely energy efficient. These motors are complex protein assemblies that are highly engineered in the nanoscale level.
Viruses as nano-machines
From a nanotechnology outlook, viruses can be considered as nanomachines that are exclusively designed and fabricated to carry out attacks and infect cells of living organisms. A virus size might range from 20 to 250 nm. These viruses are equipped with devices that can fabricate specific proteins at different stages of the invasion process. Living organisms also have spectacular array of defenses that can defend against threats from viruses which are designed and optimized through millions of years of evolution. Yet, viruses often find their way to living cells, invade them and multiply. This is a marvelous feat, given that viruses have no brain, sensory adaptations, reproductive system or mechanism for movement. World in which viruses live is quite stickey, as intermolecular forces and liquid friction predominate over gravitational forces. On top of this Brownian motion makes all the particles wiggle around. Even under this troubling conditions, viruses are able to function and target specific receptors in the cells and binds with them to mount an attack on the cell. Inside the cell, they often use chemical camouflage to deceive cell defenses and hijack cell’s own transportation system to get them to the cell nucleus. Then they inject virus RNA to the nucleus, and literally, take control of the cell to make millions of replicates of them.
Many scientists look at viruses for inspiration. Given the limitations, the awesome effectiveness of viruses come from their architectural and biomedical design. Viruses have more advanced functionality than simple molecules or complex proteins. But there are much simpler than even most basic living organism.
Although for most of us nanotechnology seem futuristic and distant, it infect has a very strong hold of our lives. If nature did not deign and optimize many of the biological devices and machines, life itself would not exist as we know it. Studying and understanding the workings of nature at the nanoscale is quite vital to sharpen our own tools for nano fabrication. It also is a source of inspiration for many scientists as it shows the power of nanotechnology and provides the constant encouragement that “If nature can do it, we can figure out a way to do it too”.