Gene sequencing laser

Gene sequencing is a new gene detection technology, which simply means to display the sequence of base ATGC in DNA/RNA molecules.Gene sequencing technology can be used to analyze and determine the full sequence of genes from blood or saliva, so as to target individual genes for prevention and treatment in advance.

In 1977, Walter Gilbert and Frederick Sanger established DNA sequencing technology and won the Nobel Prize in chemistry in 1980.From there, the technology that will dominate the future of the life sciences is widely used in research.

Over the past 40 years or so, gene sequencing has undergone many technological

The first generation of gene sequencing technology (Sanger sequencing) is based on the sequencing principle of Sanger dideoxy termination method, combined with fluorescence labeling and capillary array electrophoresis technology to realize the automation of sequencing. The basic method is chain termination or degradation method.The method was then converted to fluorescent nucleotide labeling, capillary electrophoresis differentiation and Laser detection, thus realizing the first generation of automated sequencing method.

The second-generation sequencing (NGS) achieves high-throughput sequencing at the expense of reading length, and the sequence of hundreds of thousands to millions of nucleic acid molecules can be obtained simultaneously in one operation.

The first generation of sequencing is synthetic termination sequencing, while the second generation of sequencing is pioneering in the introduction of reversible termination terminals, so as to achieve simultaneous synthesis and sequencing.The DNA is sequenced by a laser that excites a fluorescent signal during DNA replication, scanning it for special markers (commonly known as fluorescent molecular markers) carried by newly added bases.

The second generation sequencing with high flux, low cost, short time sequencing and other advantages, quickly occupied the dominant position in sequencing in the global market, its application areas including noninvasive prenatal testing (NIPT), pre-implantation genetic diagnosis (PGD/PGS)/screening, genetic disease diagnosis, tumor diagnosis and individualized treatment, gene detection, pathogenic microorganism, etc.

The third generation of DNA sequencing technology mainly includes three kinds: Helico Bioscience Single molecule sequencing technology, Pacific Bioscience Single molecule Realtime (SMRT) sequencing technology and Oxford Nanopore Single molecule sequencing technology (real-time sequencing of "electrical signal" changes brought by Nanopore).

Compared with the previous two generations of sequencing technology, its biggest feature is single molecule sequencing, which does not require PCR amplification and can theoretically determine the nucleic acid sequence of infinite length.Therefore, the third generation sequencing technology is also known as single molecule DNA sequencing, that is, the modern optical, polymer, nano technology and other means to distinguish the difference between the base signal principle, in order to achieve the purpose of direct reading sequence information.Without the use of biological or chemical reagents, costs can be further reduced.

The biggest problem with third-generation sequencing is the high error rate (15-40%).However, errors are random and do not have the bias of sequencing errors like the second-generation sequencing technology. Therefore, multiple sequencing can be used to effectively correct errors.

The ability to efficiently activate the fluorescence of the four chemical markers of DNA nucleotide (ACGT) by laser, and the ability to accurately distinguish the four fluorescent dyes, are crucial to gene sequencing.Therefore, the choice of laser will directly affect the accuracy and efficiency of sequencing.

At present, common wavelengths in the gene sequencing market are: 488 nm Blue Laser, 514 nm Green Laser, 532 nm green laser, 577nm Yellow Laser, 639nm Red Laser, 660nm red laser, 690nm red laser...

In the research and development and experiment of companies or universities, in addition to the requirements of optical parameters of lasers, more needs are "customized" solutions.Simple ones such as Optical Fiber transmission, spot shaping, more complex ones such as multi-wavelength synthesis, high consistency between multiple wavelengths and so on.