Molecular diagnostics of gene nucleic acids are developed based on the needs of modern life sciences, utilizing various advanced manufacturing and instrumentation technologies to create detection instruments. These instruments combine various testing techniques, analytical methods, and scientific principles from other foundational disciplines to qualitatively and quantitatively observe, compare, analyze, and judge biological individuals, organs, tissues, cells, and genes.
The above paragraph provides the most comprehensive description and definition of the molecular diagnostics industry. Molecular diagnostics in our country began in the 1960s and 1970s, but at that time, due to technological and equipment limitations, it was not widely recognized. Later, with the emergence and widespread application of PCR technology, molecular diagnostic techniques began to gradually penetrate the clinical application market from the field of infectious diseases, such as hepatitis, sexually transmitted diseases, and SARS.Currently, molecular diagnostic technologies and products are widely used in clinical settings. Today, I will introduce the main instruments and innovative products related to the molecular diagnostics industry.
Nucleic Acid Extraction Instruments
Nucleic acids are the genetic material of organisms and the cornerstone of molecular diagnostics. Traditional nucleic acid extraction methods generally use inorganic or organic substances to lyse cells, releasing nucleic acids, and then employ various methods for separation to achieve nucleic acid extraction, such as thermal lysis, alkaline lysis, ultrasonic lysis, etc.With the use of materials like nano-magnetic beads and silica membranes, nucleic acid extraction has entered the era of automation. The column centrifugation method based on silica membranes is now rarely used due to its cumbersome operation, while magnetic bead-based nucleic acid extraction methods have become mainstream.From a product design perspective, nucleic acid extraction instruments can be divided into upward suction and downward suction. The former refers to extraction completed by transferring magnetic beads, while the latter refers to extraction completed by transferring liquid.From a functional perspective, they can be divided into semi-automatic nucleic acid extraction instruments and fully automatic nucleic acid extraction stations. The former uses preloaded plates for extraction, requiring manual sample addition and nucleic acid transfer, with throughput typically in multiples of 12, such as 12, 24, 36, 48, and 96 samples. Popular products include the GeneRotex fully automatic rotating nucleic acid extractor, NP968-S nucleic acid extractor, EX3600, etc. After the COVID-19 pandemic, almost every PCR laboratory is equipped with nucleic acid extraction instruments, and many new products have emerged with improved design and functionality.Fully Automatic Nucleic Acid Extraction Stationsand semi-automatic nucleic acid extraction instruments differ mainly in that fully automatic stations can complete all operations from sample to PCR machine setup (sample addition, extraction, system configuration). Previously, manual lid opening was required, but with the introduction of various cup systems, lid opening is now machine-operated, making it more intelligent. Popular brands include Tianlong Technology’s 9600E, Shengxiang’s Natch CS, and Zhijiang’s Autrax, while imported products include Roche’s 4800, PE, and Holotest brands.
PCR Instruments (Systems)
After nucleic acid extraction, we enter the nucleic acid testing phase, where the main instrument involved is the PCR instrument. PCR instruments can be classified into three types based on their functions:Qualitative PCR Instruments, Fluorescent Quantitative PCR Instruments, and Digital PCR Instruments.Qualitative PCR Instrumentsare the earliest products, primarily functioning to complete nucleic acid amplification based on a set temperature gradient. Their emergence replaced the awkward situation of early PCR experiments requiring gradient water baths. In simple terms, this is a “temperature control system,” so the market price is relatively low. Examples include Genesy-96T, iCycling 96 gradient PCR instrument, Life Touch gene amplification instrument, etc.Fluorescent Quantitative PCR Instrumentshave a significant advantage over qualitative PCR instruments due to the addition of an optical system, and their amplification system and PCR principles differ. They incorporate fluorescent dyes or probes to monitor the entire PCR process in real-time through signal changes. This integration of amplification and detection functions into a closed-tube reaction greatly reduces the risk of contamination. Notable domestic brands include Shanghai Hongshi, Hangzhou Borui, Da’an Gene, Tianlong Technology, Yaru, and Anjisi, while mainstream foreign brands include ABI, Bio-Rad, Roche, and Thermo Fisher.Here, I will also teach you a method to distinguish between qualitative and quantitative PCR instruments in the laboratory: check if it connects to a computer. Generally, qualitative instruments have their own screens, while quantitative ones require a computer connection, for reference only.Digital PCR Instrumentsare a new technology product in the PCR instrument field, characterized by absolute quantification and ultra-high sensitivity. They utilize microfluidics and micro-nano manufacturing technology to disperse solutions into individual micro-reaction units, achieving true absolute quantification through software algorithms.In the foreign market, Bio-Rad and Thermo Fisher’s digital PCR are mainstream, while the domestic digital PCR industry is developing rapidly, with companies like Hangzhou Linghang, Xinyi Biology, Zhenzhun Biology, Shunde Yongnuo, and Xiaohai Turtle launching products one after another.Many people have previously asked me, do you think digital PCR instruments will replace fluorescent PCR instruments? Personally, I think it is unlikely. Cost is one aspect, and on the other hand, true clinical applications do not necessarily require such precise detection technology. With the precise advantages of digital PCR technology, its application areas will likely focus on monitoring transplant rejection free DNA, liquid biopsy, NIPT, etc. It’s like using a vegetable knife to kill a chicken and an electric knife to kill a cow; there’s no need to use an electric knife to kill a chicken.
Gene Sequencing Instruments
Gene sequencing is one of the currently popular fields in molecular diagnostic technology, aiming to obtain as many nucleic acid sequences as possible from the tested material to analyze their potential value. Currently, gene sequencing technology has developed to the fourth generation. The first-generation sequencing technology is the classic Sanger sequencing (dideoxy nucleotide chain termination sequencing), and commercial products still available on the market include Haier’s 13 respiratory panel, which is a product of Sanger sequencing combined with capillary electrophoresis;The second-generation sequencing technologyis currently the most widely used, characterized by high throughput. The main players in the market are Illumina and BGI, and there are many service companies based on further research and development;The third-generation sequencing technology, also known as single-molecule sequencing technology, addresses the library preparation and PCR amplification steps before sequencing in the first and second generations. If we look at the entire molecular diagnostic process, sequencing before the third generation was completed after processing by PCR instruments, but the third-generation sequencing technology places sequencing parallel to fluorescent quantitative PCR instruments, significantly lowering the threshold for sequencing technology and making it more universal.The fourth-generation sequencing technologyis technically an upgraded version of the third generation, which can be called the 3.5 generation technology, but the leap it brings is also significant, mainly reflected in cost control of detection equipment. It employs nanopore detection technology, making signal capture no longer reliant on high-speed cameras or high-resolution CCD cameras.
Gene Chip Instruments
Gene chip technology, also known as nucleic acid chips or microarray chips, is currently one of the most widely used types of biochip technology. It involves fixing designed nucleic acid fragments orderly on a solid-phase support, followed by hybridization with products amplified by PCR, and interpreting results through signal detection.Compared to fluorescent PCR technology, gene chip technology addresses the issue of target detection throughput, as a single chip can integrate a large number of detection targets, giving this technology a significant advantage in gene mutation and bacterial resistance. The main players now include BGI, Cap, Yanan, and Bohui Innovation.Previously, the clinical application of gene chips was mainly conducted in PCR areas, requiring PCR amplification before hybridization. However, automated products from companies like BGI and Bohui Innovation have expanded the application scenarios for gene chips, and automation is also the main direction for the future of gene chips.
Molecular POCT Instruments
Molecular POCT instruments are currently one of the more popular subfields, with industry expectations for them to move out of laboratories and into grassroots and clinical department markets. However, this journey is not easy.Those interested can refer to historical articles from IVD practitioners’ websites for more related information.Current popular technical directions for molecular POCT include microfluidics, microdroplets, chips, and rapid nucleic acid testing, with major brands already on the market including Youstada, BGI Crystal, Aoran, Baikangxin, and Wantai Beite. Successful domestic products include Cepheid’s GeneXpert system and Merieux’s Flimarray system.
Nucleic Acid Mass Spectrometry Instruments
After the rise of molecular diagnostics, many sub-technologies and fields have also gained popularity, and nucleic acid mass spectrometry is one of them. The principle of mass spectrometry is to ionize sample molecules and then apply force in an electric field to separate them, resulting in a mass spectrum.The ionization techniques used in nucleic acid mass spectrometry mainly include ESI and MALDI, both of which are soft ionization methods. Currently, the main nucleic acid mass spectrometry instruments on the market include Antu’s Autof ms1000, Clin-TOF II clinical time-of-flight mass spectrometry system, and Zhongyuan Huiji mass spectrometer EXS3000.
Molecular FISH Products
This is aoften overlookedsubfield of molecular diagnostics, as the products are mainly used in pathology departments, which are separated from the main battlefield of the testing department, resulting in lower attention and fewer market players. Compared to PCR and NGS, FISH technology has unique advantages in detecting chromosome number, structural abnormalities, gene deletions, rearrangements, and gene fusions.FISH detection is also the gold standard for detecting breast cancer HER2 gene and lung cancer ALK gene breaks, with the applicable instruments mainly being fluorescence microscopes.Source: IVD Practitioners’ Network Author: Suo Yan