The development history of DNA sequencing technology is a magnificent journey from the embryonic stage of initial exploration to a glorious chapter of high-throughput and high precision. It has gone through multiple stages from preliminary exploration to high-throughput and high accuracy. Scientists continue to break through technical bottlenecks during these stages, pushing the boundaries of DNA sequencing to unprecedented heights, opening up a broad path for the research and application of life sciences.

1. Early exploration stage

1. Basic theoretical research: Since the double helix structure of DNA molecules was published in 1953, biological research has entered a more refined molecular era. More and more scientists are beginning to invest in molecular biology research, especially the study of DNA sequences, and DNA sequencing technology emerged as the times require.

2. Early sequencing methods: Before the invention of DNA sequencing technology, scientists had already completed the sequencing of biological macromolecules such as insulin protein and tRNA. These works laid the foundation for the development of DNA sequencing technology.

2. First-generation sequencing technology (traditional sequencing)

1. Dideoxy chain termination method (Sanger method): In the late 1970s, Frederick Sanger proposed a technology for rapid DNA sequence determination—the dideoxy chain termination method, also known as Sanger sequencing technology. This method adopts the principle of DNA replication, utilizes the chain termination effect of ddNTP (dideoxynucleotide triphosphate), and combines detection with radioactive isotopes or fluorescent labeling groups to achieve the determination of DNA sequences.

2. Development and application: Sanger sequencing technology has promoted the development of genomics, including the sequencing of many important genomes such as phage lambda DNA and the human genome. However, this method is complex and costly, which limits its application in large-scale sequencing.

3. Second-generation sequencing technology (high-throughput sequencing)

1. Technological innovation: In 2005, Roche launched the first second-generation sequencer, the Roche 454, marking the entry of life sciences into the era of high-throughput sequencing. Subsequently, the launch of Illumina series sequencing platforms further reduced sequencing costs and promoted the popularity of high-throughput sequencing in various research fields of life sciences.

2. Technical features: Second-generation sequencing technology adopts the principle of sequencing while synthesizing, by breaking DNA fragments into small segments and then randomly connecting them to a solid-phase matrix to perform PCR amplification and sequencing reactions. This technology has the advantages of high throughput, low cost, and high accuracy, and can process millions or even billions of DNA molecules simultaneously.

3. Wide application: Next-generation sequencing technology is widely used in research in multiple fields such as genomics, transcriptomics, and epigenetics, providing important support for disease diagnosis, drug research and development, crop breeding, etc.

4. Third-generation sequencing technology (single molecule sequencing)

1. Technical principle: Third-generation sequencing technology refers to single-molecule sequencing technology, including single-molecule fluorescence sequencing and nanopore sequencing. These technologies do not require PCR amplification and enable individual sequencing of each DNA molecule. Nanopore sequencing technology determines DNA sequences by detecting changes in current caused by DNA molecules passing through nanopores; single-molecule fluorescence sequencing technology determines DNA sequences by recording changes in fluorescence intensity when fluorescently labeled deoxynucleotides are incorporated into DNA chains.

2. Advantages and challenges: Third-generation sequencing technology has the advantages of long read length and low error rate, and can more accurately measure genetic variations such as complex structural variations. However, this technology is still in the development stage and faces challenges such as high cost and technical complexity.

DNA sequencing technology has experienced the bud of early exploration, leaped to the foundation of first-generation sequencing, then leapt to the prosperity of second-generation sequencing, and now reaches the innovation frontier of third-generation sequencing, showing a brilliant trajectory of continuous technological advancement and increasing cost optimization. With the continuous advancement of technology and reduction of costs, DNA sequencing will play an important role in more fields.