Key words: Gel imaging analysis system
  Chemiluminescence imaging
analysis system, multicolor fluorescence imaging analysis system, multifunctional living imaging analysis system  I. Introduction: As a basic science, molecular biology has penetrated into the branches of modern biology. With the continuous advancement of biological theory and experimental methods, its application fields are also expanding. Now, the influence of biology has expanded to include food, chemical, environmental protection, energy, metallurgy and many other fields. The branches of biology each have certain research content and are interdependent and interdependent. In addition, life as a form of material movement has its own biological laws, and at the same time contains and follows the laws of physics and chemistry. Therefore, biology has a close relationship with physics and chemistry. Bio-distribution on the surface of the earth is an important factor in the formation of the Earth's landscape. Therefore, biology and geoscience are also interpenetrating and intersecting each other.  Second, how to buy a gel imaging analysis system The development of digital imaging technology has become the vane of digital products and molecular imaging products. The sensitivity is getting higher and higher, the degree of automation is higher, the design is more humanized, and it becomes more and more easy to use like a fool camera. In addition, the appearance is also more compact and stylish. The practical application of molecular imaging analysis systems is gradually becoming more and more popular. There are many kinds of molecular imaging imaging analysis systems on the market. How to choose? Changsha Yali Biotechnology Co., Ltd. will give you directions! (1), according to the scope of application of the product to distinguish: 1. Ordinary gel imaging analysis system: suitable for visible light samples such as protein gel electrophoresis (Coomassie staining, silver staining), and ultraviolet light such as DNA/RNA (EB, TLC plates, SYBR Green); Conduct qualitative and quantitative analysis; 2. Chemiluminescence imaging analysis system: suitable for chemiluminescence/ultraviolet/visible gel imaging analysis systems, such as ECL, ECL PLUS, Southern, CDP Star, CSPD, Northern and Western hybrid chemiluminescence, etc. Sample detection; 3. Multi-color fluorescence imaging analysis system: suitable for fluorescence/chemiluminescence/visible gel imaging analysis systems, such as: EB, TLC plates, GFP plates, SYBR Green, SYBR Gold, SYBR Safe, Sypro Red, Sypro Orange, Texas Red , Rhodamine Red, Fluorescein, Deep Purple, Cy2, Cy3, Cy3.5, Cy5, fluorescent plates, etc.  4, multi-function in vivo imaging analysis system: suitable for bioluminescence (bioluminescence) and fluorescence (fluorescence) two technologies. Bioluminescence is the labeling of cells or DNA with a luciferase gene, while fluorescent techniques are labeled with fluorescent reporter groups (GFP, RFP), or fluorescent dyes such as Cyt and dyes;  Third, the composition of the gel imaging analysis system The basic bone of the gel imaging system
consists of a CCD camera, darkroom and analysis software. However, its function not only images agar enamel gel, but now the imager tends to be multifunctional, and it is also suitable for applications such as protein gel, fluorescing gel, blotting membrane and colony plate. In terms of Western Blot, the high-performance CCD molecular imaging system is comparable to film. The CCD is an abbreviation of the English name of a Charge Coupled Device and is a photoelectric conversion device. It is the core component of the gel image system. Most people have a certain understanding of digital cameras, and many people are experts in this field. Some people look at the pixels of the digital camera very heavy, but after comparison, it is found that some 4 million, 5 million pixel camera shots are not as good as the 300-pixel machine. Why? In fact, there are many factors affecting imaging. The indicators for measuring CCD quality are resolution, CCD size, dynamic range, sensitivity, quantum efficiency, signal-to-noise ratio, etc. Among them, the number of pixels and CCD size are important indicators. In fact, it refers to the size of the photosensitive device. Here, the larger the area of ​​the CCD sensor, the larger the CCD area, the more photons are captured, the better the photographic performance, and the lower the signal-to-noise ratio. In order to better understand the size of the CCD, the CCD specifications currently applied on the market are as follows: 1 inch - the target size is 12.7mm wide by 9.6mm high and 16mm diagonal. 2/3 inch - the target size is 8.8mm wide by 6.6mm high and 11mm diagonal. 1/2 inch - the target size is 6.4mm wide by 4.8mm high and 8mm diagonal. 1/3 inch - the target size is 4.8mm wide by 3.6mm high and 6mm diagonal. 1/4 inch - the target size is 3.2mm wide by 2.4mm high and 4mm diagonal. The resolution of CCD is from low to high: from about 450,000, about 1 million, about 1.4 million, about 2 million, about 3 million, about 4 million, about 5 million, and even higher, according to the temperature of CCD. Can be divided into normal temperature CCD camera and refrigeration CCD camera, refrigeration CCD: in the same full well electronic CCD, reduce CCD noise, can improve the CCD monitoring ability, hot or dark current is CCD for noise, noise in the Cool CCD basic Can be eliminated by the deep-cooled Peltier. After exposure for more than 5-10 seconds, the CCD chip will heat up. Without the chip of the cooling device, the "hot" or white pixels will cover the image, and the image will be visible everywhere. CCD structure design, digital methods, etc. will affect the noise. Of course, by improving the structure and optimizing the method, noise can also be reduced.  The applicability of the refrigeration CCD: Fluorescence and chemiluminescence itself are weak, so the CCD noise reduction is very high. A high-resolution digitally cooled CCD camera combined with a high-pass lens head system should be used to capture the extremely weak fluorescence of the signal. And chemiluminescence sample images, and can * reduce noise to a large extent, reduce background, and provide excellent image clarity. An optional excitation source and multiple filter wheels expand the range of applications for fluorescence/chemiluminescence imaging. Therefore, it is generally necessary to select a cooling CCD during fluorescence and chemiluminescence observation. Therefore, the excellent refrigeration CCD camera is the future development trend and must be required for the excellent molecular imaging imaging analysis system.  (1), resolution The size of the resolution and the pixel value are inseparable. The pixel refers to the photosensitive element that the CCD can be different. The tens of thousands of pixels we usually say are the number of these photosensitive elements. So in general, the more pixels, the more clear and delicate the imaging, of course, this is subject to many factors, as will be mentioned slowly. However, high pixels are not necessarily good CCDs. The reason is that the pixel size (Pixel Size) is also a very important factor. The same number of pixels, the denser the arrangement, the more likely the current interference between pixels is, and the "noise" is prone to occur. "The phenomenon of interference with imaging quality appears. Due to the limitations of the manufacturing process, the size will increase and the cost will increase in geometric progression. Nowadays, most manufacturers' CCDs use pixel merging technology in order to improve the sensitivity of images. What is the significance of pixel merging? Pixel merging is a very useful feature that can be used to increase the size and sensitivity of a pixel. The resolution is 795512 and the pixel size is 9u. When merged by 22, it becomes 398256 and the pixel size is 18u. After the .33 merge, it becomes 265170, the pixel size is 27u, and the sensitivity is increased by 9 times, so each pixel size is 27u.  (2), dynamic range value The dynamic range represents the ratio of *light to *dark in an image. The gray scale indicates a method for characterizing the brightness. The 12-bit representation is divided into 212=4096 levels from *dark to *light, and 16bit is divided into 216 levels. The higher the bit value is, the larger the subtle difference can be. As shown in the picture below, the human eye can only distinguish 40 gray scales, and for a 12-bit instrument can distinguish 4,096 gray scales. It is worth mentioning that, at present, the mainstream gel imaging CCD in the market is mainly 12bit, and the 16bit instrument generally has a resolution of about 2 million pixels. For the real 16bit, the pixel value is close. The 4 million CCD is very rare.    The difference between 12bit and 16bit in image resolution  To quantify the dynamic range requires an arithmetic formula, that is, dynamic range value = 20 log (well depth/read noise), where Well depth represents full-well electrons, which is the total value of the electronic signal that can be accepted when the CCD is saturated. Read noise is read. Noise (expressed by the number of electrons), each CCD will produce noise during the reading process, the smaller the noise, the higher the monitoring sensitivity. The full-well electron and the CCD bit value are related. Generally, the higher the bit value, the larger the value of the full-well electron. Examples are as follows: Well depth = 85,000 electrons, read noise = 12 electrons Dynamic range = 20 log (85,000/12), or 77dB. The higher the value of the dynamic range, the better the CCD performance.  (3), quantum efficiency The quantum efficiency of a CCD, also known as pixel sensitivity, refers to the ratio of the number of charges accumulated in a pixel well to the number of photons incident on a pixel surface at a certain exposure. The quantum efficiency of CCDs with different structures varies greatly. For example, if the number of charges accumulated in a pixel well in 100 photons is 50, the quantum efficiency is 50% (100 photons = 50 electrons means 50% efficiency). It is worth noting that the quantum efficiency of the CCD is related to the wavelength of the incident light.  (4), signal to noise ratio   When it comes to signal-to-noise ratio, you have to mention dark current. Dark current is a very important factor in CCD noise. Dark current refers to the charge generated by a pixel in a CCD sensor for a certain period of time without exposure. When we do chemiluminescence detection, the exposure required is longer, which causes the CCD to generate more dark current, which has a great impact on the quality of the image. Normally, by reducing the temperature of the CCD, * the effect of dark current on imaging is greatly reduced. The figure below shows the relationship between dark current and temperature. From the figure we can see that the dark current generated by the CCD decreases with the temperature drop, but at -23 °C the curve begins to gradual, which shows that the temperature is not Need to endlessly reduce. Therefore, when choosing a cold CCD, the temperature can generally reach your requirements at -25 ° C (excellent temperature, not below room temperature). Some CCDs are used to deduct dark currents from the background after the image is finally generated. This is effective for signals that are much stronger than the background, but there are more and more errors in the process of weak signal processing. The above is some introduction to the principle and influencing factors of CCD.  (5), optical lens Optical lens is an indispensable component of machine vision system, which directly affects the quality of imaging quality and affects the implementation and effect of the algorithm. Optical lens specifications are numerous and sometimes dizzy. The optical lens can be divided into short-focus lens, medium-focus lens and telephoto lens from the focal length; wide-angle, standard, telephoto lens from the field of view size; fixed aperture fixed-focus lens, manual aperture fixed-focus lens, Auto iris fixed focus lens, manual zoom lens, auto zoom lens, auto iris power zoom lens, electric three variable (aperture, focal length, focus variable) lens.  (6) Filter lens Fluorescence: EB, TLC plates, GFP plates, SYBR Green, SYBR Gold, SYBR Safe, SYPRO Red, SYPRO Orange, Texas Red, Rhodamine Red, Fluorescein, Deep Purple, Cy2, Cy3, Cy3.5, Cy5, fluorescent plates, etc. (It depends on the specific excitation source and filter) light source Excitation wavelength Absorption wavelength dye Blue 475nm 537nm SYBR Green, SYBR Gold, SYBR Safe, SYPRO Orange, Cy2, etc. Green 534nm 606nm SYPRO Red, Cy3, etc. Red 632nm 609nm Texas Red, Rhodamine Red, Cy5, etc. (7), data transmission The IEEE1394 bus is a high-speed serial bus that is currently fast*. The transmission rate supported by FireWire (IEEE1394) is 100Mbps, 200Mbps, 400Mbps, and the high transmission speed is 400Mbps/s. It provides special optimization for various devices that require a large amount of bandwidth. The interface can connect 63 different devices at the same time. IEEE1394 supports the hot plugging device like USB. IEEE1394 also supports plug-and-play. Now WIN98 SE, WIN2000, WIN ME, and WIN XP all support IEEE1394. In these operating systems, users can use IEEE1394 devices without installing drivers.  (8), software function Regardless of the type of computer, they are made up of hardware and software, and the two are inseparable. People refer to computers that do not have any software installed as bare metal. The gel imaging analysis system is no exception, and the hardware equipment is no better. If it is not equipped with good software, it can't play its proper function. As the function and use of the gel imaging system software are basically similar, here we introduce some features of * concern:  A. The basic functions of the software: qualitative, quantitative analysis, annotation, output image and other operations can be performed on different samples, such as strips, spots, clones, chips, cells or living animals. B. Image acquisition method: For chemiluminescence or multi-color fluorescent products, the software should have a film mode, which can perform image multi-integration function to enhance linear dynamic range and data accuracy. C. Easy to operate, the software should have operation aids to make the software operation easier and easier to use. * Good use of three-step lane and strip analysis can quickly calculate the molecular weight and content of proteins and nucleic acids. D. Database functions are also essential to retrieve, classify, or compare all generated images. The difference in strips can be graphically displayed using different display algorithm programs. E, exposure mode: should use a single exposure, multiple exposure, cumulative exposure, delay (timed) exposure multiple modes are optional. F, memory function: the software can memorize and automatically call the imaging data, so you can get reproducible results without setting each time. G, the software should be equipped with more than two sets, using the stand-alone version, multi-user version or online version, the users can operate independently of each other, do not interfere with each other, and do not confuse each other.Extract Powder
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