The smallest portable sequencer in the world is smaller than the palm of your hand and weighs about 100g. It looks like a cuboid with a sealed box. This is Minion, a DNA sequencing device introduced by Oxford Nanohole Technology Company. Besides its small size, MinION is quite simple to use. Simply plug the wiring into the USB hole of the computer, open the operating software to set the parameters, and then drop the sample into the preset hole of the instrument to start the analysis. MinION has two advantages: the length of readable DNA is extremely long (we successfully sequenced 200,000 pairs of base sequences in the experiment), and the reading results can be seen at the same time during the sequencing process without waiting for the program to be completely completed. This can not only deal with almost all the DNA decoding work aimed at non-genome sequencing, but also have the ability to track and use the sequencing results in real time, and there will be no problem that the results cannot be obtained because of the operation error or sample processing failure after sequencing.
The key technology-Nanohole Minion's detection chip is based on a non-conductive polymer film with holes, and each hole is embedded with protein nanochannels, which can only allow a single DNA to pass through. When DNA is split into two single strands by the enzyme that opens the double helix, one of them will be pushed through the protein channel bit by bit. At this time, the detection unit at the edge of the hole judges which of the gene codes A, T, C and G the passed molecule represents, and sends the judgment result to an external computer to record the sequence codes. After reading one of them, the complementary half will be sent in to read it again, and finally compared with each other to increase accuracy. In addition, because there are hundreds of holes on the chip, which can be read by many people at the same time, Oxford Nanohole Technology Company claims that it can sequence the password length of1.500 million bases at one time. Relatively speaking, the human genome * * * has about 3 billion bases, so in theory, it can be sequenced with 20 handheld MinION devices, which is far from the time-consuming 1 1 year of the original human genome sequencing project.
Limitation and improvement Although there are many advantages mentioned above, MinION's high error rate has always been its biggest pain point. Even though internal testers claim that the error rate is only 5%, many researchers find that the error rate can be as high as 30% after using it. Repetition of the same base sequence is the biggest problem in sequencing. And even if the accuracy rate can reach 95%, it is not as acceptable as the threshold of clinical and forensic medicine; Imagine that the genetic sequence between people is only 1%, so can the legal authorities use a machine with an accuracy of only 95% to determine that the DNA residue comes from a specific person, and make a conviction or even sentence to death? Compared with MinION, the sequencing machine of Illumina, an old brand of DNA sequencing, has an accuracy of >: 99.98%, and the cost of disposable consumables is much lower. But the fuselage is obviously bulky and expensive. In order to make up for this shortcoming and catch up with competitors, MinION developers are actively making improvements, such as improving the sensitivity of reading equipment or upgrading analysis software to spell out more accurate DNA sequences.
MinION will eventually subvert the existing biological research framework. Some people may question that the original DNA sequencer is very mature and the cost is relatively low. What is the competitiveness of a new product with an error rate as high as 30%? But just like the corporate goal of Oxford Nano-pore Technology Company: anyone can analyze any creature anywhere, and this portable DNA sequencing equipment can complete important work in time even in places where resources are scarce. For example, a few days ago, an Ebola virus epidemic broke out in West Africa. Some scientists took MinION into the epidemic area, obtained samples on the spot, and identified the virus strain that caused the epidemic in a short time. In addition, NASA is still testing whether this device can be used in a zero-gravity environment. It is expected that it will be put into the Mars exploration program in the future to analyze any organic matter on the red planet for the first time. In addition, MinION with improved accuracy can be used as a part of basic education in primary and secondary schools. Therefore, the new concept brought by MinION is that biological and genetic research will no longer be a high-threshold job with high knowledge and high capital, but will have the opportunity to be as popular as information technology. By then, everyone has a chance to be the next Darwin in the field of genetics!
refer to
1. Oxford nanohole official introduction page to MinION: nanopetech/products-services/Minion-mki2. The famous natural journal Minion reports: nature/news/Pint-size-DNA-sequencer-impressions-first-users-1.10.
Image source: Max Mollon/Explorations/zmscience/medicine/geic/Oxford-nanopore-Minion-u * * *-DNA-Sequencing-3219443/ro.wikipedia/wiki/secven% c8% 9bierea _ nanopore.
This article is reproduced from: GENEONLINE, the most professional media team in the field of genetics.
Subject: DNA, Nano, protein.