DNA Walker: Exploring Molecular Machines and Their Role in Nanotechnology

Chapter 1: DNA walker

A nucleic acid walker is able to move along a nucleic acid track in a DNA walker, which is a class of nucleic acid nanomachines described in the previous sentence. Within the year 2003, John H. Reif was the first person to define and give a name to the concept of a DNA walker.

In order to proceed, a nonautonomous DNA walker needs to undergo external changes at each step, but an autonomous DNA walker can move forward without subjecting itself to any external modifications. The mobility of the DNA walker was controlled by Shin, for example, who used 'control strands' that needed to be manually placed in a certain order according to the sequence of the template in order to achieve the intended course of motion. Shin was one of the several nonautonomous DNA walkers that were constructed.

Experimental demonstration of the first autonomous DNA walker, which did not require any external alterations for each stride, was carried out by the Reif group in the year 2004.

A range of motion that extends from linear to two and three dimensions, the ability to pick up and drop off molecular cargo, the ability to undertake DNA-templated synthesis, and higher velocity of motion are some of the functional qualities that DNA walkers possess. DNA walkers have the potential to be utilized in a wide variety of fields, including nanomedicine and nanorobotics. DNA hybridization, hydrolysis of DNA or ATP, and light are only some of the many possible fuel alternatives that have been investigated up until this point. comparable to the functions of the proteins dynein and kinesin, the DNA walker is responsible for a comparable function.

The development of DNA nanotechnology is regarded to be dependent on the discovery of a suitable nanoscale motor that is capable of autonomous, unidirectional, linear motion. It has been demonstrated that the walkers are able to move independently along linear, two-dimensional, and three-dimensional DNA 'tracks' by utilizing a wide variety of different systems.  The use of restriction enzymes to selectively break the 'track' in order to cause the forward mobility of the DNA walkers was demonstrated by Bath et al. in July of 2005. This presented an additional method for controlling the motion of DNA walkers. 2010 was the year that two distinct groups of researchers demonstrated the more advanced capabilities of walkers. These capabilities included the ability to selectively pick up and drop off molecular cargo as well as the ability to undertake DNA-templated synthesis as the walker goes along the track. Yehl et al. demonstrated in late 2015 that it was feasible to achieve rates of motion that were three orders of magnitude higher than those that had been observed in the past. This was accomplished by employing DNA-coated spherical particles that would roll on a surface that was changed with RNA that was complementary to the nanoparticle's DNA. The RNA was hydrolyzed with RNase H, which resulted in the release of the DNA that was attached to it and made it possible for the DNA to hybridize with RNA farther downstream. In 2018, Valero et al. described a DNA walker that was constructed using two circular double-stranded DNAs (dsDNAs) that were interlocked and catenated with one another, as well as an engineered T7 RNA polymerase (T7RNAP) that was firmly linked to one of the DNA circles. A catenated DNA wheel motor was created as a result of this stator-ring's ability to rotate the interlocked rotor-ring in a unidirectional manner using rolling circle transcription (RCT), which was powered by nucleotide triphosphate (NTP) hydrolysis. In order to direct its directional walking along specified ssDNA tracks that are placed on a DNA nanotube, the wheel motor generates long, repetitive RNA transcripts. These transcripts remain attached to the DNA-catenane and are utilized to guide the wheel motor's