In order to obtain information from the outside world, people must resort to the sensory organs. However, people's own sensory organs may not be enough in their production activities when they are studying the phenomena and laws of listening. To adapt to this situation, we need sensors. Therefore, it can be said that the sensor is an extension of the human five senses, and the chess is against the senses of the human being. A sensor is a device that converts a non-electrical signal into an electrical signal that satisfies the requirements for signal transmission, resolution, storage, display, recording, and control.
Sensors have long penetrated into a wide range of areas such as industrial production, space development, ocean exploration, environmental protection, resource surveys, medical diagnostics, bioengineering, and even heritage conservation. It can be exaggerated to say that from the space to the vast ocean, so that all kinds of complex engineering systems, almost every modern name, can not be separated from a variety of sensors.
There are many kinds of sensors. The sensor made by DNA molecules is called a gene sensor, which is a kind of biosensor. A DNA biosensor is a sensing device that converts the presence of a target DNA into a detectable electrical signal. It consists of two parts, one is the identification component, the DNA probe, and the other is the transducer. The protagonist of the recognition component is used to sense whether the sample contains the target DNA to be tested; the transducer converts the signal perceived by the recognition component to observe the recorded signal. Usually, a single-stranded DNA is solidified on a transducer, and hybridization of DNA molecules is performed to identify another DNA containing a complementary sequence to form a stable double-stranded DNA, and the target DNA is subjected to conversion by sound, light, and electric signals. Detection.
The principle of DNA biosensor is that a double-stranded DNA formed by hybridization of a single-stranded DNA molecule of a known nucleotide sequence immobilized on a sensor or a surface of a transducer probe to another complementary ss-DNA molecule will exhibit a certain The physical signal is finally reflected by the transducer.
However, DNA molecules are very small and fragile. How do we fix and use it? The immobilization technology of bio-sensitive materials is an important part of genetic sensor research and the key to the preparation of biosensors. This technology determines the performance, performance and quality of the sensor. The poor detail is also about the flexibility, linearity, stability and service life of the sensor. Nowadays, the techniques for immobilizing DNA probes include covalent bond method, self-assembled film method, electric assembly method and surface enrichment method.
The covalent bond bonding method is a method in which a bioactive molecule is bound to an electrode surface by a covalent bond to rapidly fix it. Before the electrode is fixed, the electrode is first pre-solved by activation, and then the active bonding group is introduced, and then the surface is covalently bonded, and the probe molecule containing the predetermined property group is fixed to the electrode surface.
The self-assembly method is also used to fix DNA. This technique generally utilizes a DNA fragment with a thiol group to form a self-assembled monolayer on the surface of the gold electrode to immobilize the nucleic acid probe.
In addition to these two methods, there are several commonly used fixed methods, and there is no mention of them.
DNA sensors are a special kind of sensor that has grown on the basis of mutual penetration of various disciplines such as biology, chemistry, physics, medicine, and electronics. It has strong specificity, and has a very high specific recognition ability between double strands of DNA molecules; the speed of analysis is fast, and the result can be obtained in 1 minute; the accuracy is high and the error is extremely small; the operating system is relatively simple, and the automatic analysis is simple; the cost Low, when used continuously, the price is low. In particular, it is highly automated, miniaturized and integrated.
With the development of molecular biology, people are gradually aware that except for injuries, including infectious diseases, hereditary diseases and malignant tumors, which are related to genes, it is very important to apply DNA sensors for genetic testing. .
For example, hepatitis B is a kind of infectious disease caused by hepatitis B virus (HBV), which has rapid spread, long ambush period and wide damage. The chronic asymptomatic HBV probationer or chronic asymptomatic HBV carrier in China has more than 120 million, which is HBV. There are the largest number of probationers. If the self-assembled monomolecular membrane technique described above is used, a single-stranded DNA probe of a probe of a ruthenium-based retouched probe is immobilized on the surface of a gold electrode to prepare a DNA electrochemical sensor, and an electroactive substance is used as a batching agent. A DNA sensor with good specificity, high sensitivity, and short response time can be obtained. It is more ideal for response to hepatitis B virus DNA in serum samples. In other words, DNA sensors can help us detect whether a person has been proficient in chronic asymptomatic HBV or has carried the virus correctly, quickly, and with high quality.
Biosensors have enjoyed encouraging developments in recent decades. After special molecular biology combined with new disciplines and new technologies such as microelectronics, optoelectronics, microfabrication technology and nanotechnology, this development is accelerating and is being carried out in various sectors of the national economy, such as food, pharmaceutical, chemical, and clinical. Inspection, biomedical, environmental monitoring and other fields have revealed broad application prospects.
For example, glucose levels are an important indicator of fruit maturity and shelf life. Biosensors have been developed to analyze glucose in white wine, apple juice, jam and honey. In the food industry, the freshness of foods and meats is particularly important for the evaluation of food quality. It has been developed to measure the concentration of substances such as inosine monophosphate produced during the degradation of fish, and to evaluate the freshness of the fish.
In recent years, the problem of environmental pollution has become increasingly serious. People are eager to have an instrument that can continuously, quickly and onlinely monitor pollutants. Biosensors meet people's requirements. In front of us, a considerable number of biosensors have been used in water environment monitoring and atmospheric environment monitoring.
In military medicine, timely and rapid detection of biotoxins is an effective measure against biological weapons. Biosensors have been used to monitor a variety of bacteria, viruses and their toxins, such as Bacillus anthracis, Yersinia pestis, Ebola hemorrhagic fever virus, botulinum toxoid and so on.
In addition, in forensic science, biosensors can be used for DNA identification, paternity testing, etc.
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