Nanotechnology was regarded to be the technology of the future. Well, the future has come. Its no more the technology of the future. Scientists and engineers have become increasingly good at designing and engineering materials down at the level of atoms and molecules. Nanotechnology is the manipulation of matter at nanoscale which is about 1-100 nanometres. Its well known that everything in this universe is made out of atoms and it’s the atoms and the arrangement of these atoms that dictate the characteristics. Two wheels and a handle, although are said to make a bicycle, it’s called a bicycle only if they are assembled the right way. Otherwise, they are just parts and the functionality of bicycle can never be achieved. Atoms are just like the wheels, except they are smaller, however the idea remains the same. The arrangement of atoms decides how strong or how weak a substance is, or if the substance is transparent etc.
Here, I would be talking about the bottom-up approach. In this approach we try and control the atoms and their assembly in order to achieve the desired characteristics. Imagine a scattered pile cups in front of you and you are wearing the boxing gloves. You can move the cups around but you cannot control an individual cup. If you are asked to pick a cup at a time and arrange, it would be extremely hard or even impossible. Nanotechnology allows us to take the boxing gloves off, thus making it easier to pick one cup at a time and arrange in the desired manner. Nanotechnology has opened gates for research in every possible field. One such field is Biology.
The human body is made up of millions and millions of cells and each cell is made of several cell organelles. Each of which performs specific task. The energy required to perform these tasks is supplied by mitochondria, the powerhouse of the cell. Apart from the energy, there is cargo that needs to be transported to different parts of the cell. These activities are made possible by the nanomotors or the biological motors in the cell.
Bio-molecular motors like kinesins, myosins and ATP synthase have been created by nature and these are essential for the functioning of the cell and also regulate specific functions like inter-cellular cargo transportation and macroscopic muscle contraction. These are self-propelled and composed of proteins and are of the size within the nanoscale. Hence, these are called biological nanomotors. These motors are highly efficient and its evident by their relentless performance throughout the lifecycle of a cell.
ATP synthase or ATPase is a rotary motor and is responsible for catalytic synthesis of ATP molecules, accompanying rotary motion. Kinesins are motors that are responsible for transport of inter-cellular cargo and also the mitosis. Kinesins carry the cargo on their heads and walk on microtubules. The walking action is similar to that of the walking action of human beings. Kinesins have two leg like structures, and alternatively place each one at the front. The impressive performance of these motors stimulates the transition towards the artificial system.
The combination of bottom-up, self-controllable assembly and the design inspired by the natural biological motors has made it possible for the development of self-propelled synthetic nanomotors. The improvements in nanotechnology permits realization of autonomously synthetic motors with engineering features. These assembled nanomotors are expected to be extremely useful in the future and hold potential promise for targeted drug delivery, biodetoxification, cleaning wounds, blood clots and parasites.
The properties of the nanomotors can be conveniently variedby assembling different components such as polymer, nanoparticles, proteins, inorganic or organic functional molecules, vesicles etc. Therefore, controlled self-assembly of the motors enables achievement of functionalities like self-propulsion, regulated motion and controlled transportation by assembling corresponding components.
The development of these synthetic, self-propelling nanomotors is one of the most exciting yet challenging fields in nanotechnology. Controlling the motion of the motors is one of the challenges. The solution to this is also inspired by the biological model of chemotaxis and phototaxis. Now, immense control on the motion of these motors is achieved. The capability and the sophistication of the motors is continuously growing but so are the challenges associated with them and their applications in the areas of biomedicines. One of the major problems being biodegradability and biocompatibility as these motors are mainly manufactured from metals. Not just that, these motors must be efficient enough to function in different biological media.
In spite of these major challenges, with continuous innovation and development of controlled assembled self-propelling nanomotors will have a profound impact on future biomedical applications.