The human genome is estimated to contain 20,000 – 25,000 genes which code for the production of proteins our bodies use for various functions. Our genomic material is made up of nucleotides also known as deoxyribonucleic acid (DNA). Imagine trying to detect a single gene amongst the three million nucleotide base pairs that make up the human genome. How is that possible?
DNA sequencing is the process of determining the precise order of nucleotides within a DNA molecule. According to the National Human Genome Research Institute, the first method for sequencing DNA was developed in the mid-1970s. At that time, scientists were only able to sequence a few base pairs per year, not nearly enough to determine the sequence of an entire gene. Since then, science has come a long way. The increased speed and decreased costs of sequencing has allowed individual genes to be sequenced on a routine basis with some labs sequencing over 100 bases per year. However; scientists are always looking for faster and cheaper methods.
Researchers from the Laboratory of Nanoscale Biology in Switzerland have identified a new method for DNA sequencing which uses translocation of DNA molecules across nanopore membranes. Typical nanopore DNA sequencing can be visualized in the video below. In the current study, researchers developed a film made of molybdenum disulfide (MoS2) and created a 3nm nanopore within the membrane itself. They then used a viscosity gradient system based on room temperature ionic liquids that was used to slow down the DNA translocation through the nanopores. The use of this gradient enabled them to increase the accuracy of nucleotide detection. The approach uses a statistical method to identify the four different nucleotides that make up DNA, which are identified by specific molecular signatures in the membrane nanopore.
The authors of the study explain that the viscosity gradient used in their experiment can also potentially be combined with other schemes of nanopore technologies such as traverse current signal technology used in high end electronics. Their method allows for optimal time resolution DNA strand-sequencing. Because this sequencing method allows potential for multiplexing, it could be performed at a reduced cost.
I am a postdoctoral researcher with interests in pre-harvest microbial food safety, nonthermal food processing technologies, zoonotic pathogens, and plant-microbe interactions. My current research projects involve the optimization of novel food processing technologies to reduce the number of foodborne pathogens on fresh produce. I am a food geek!