| Description | Low-Density Lipoprotein (LDL) in plasma is the main carrier of endogenous cholesterol. It is degraded and metabolized by binding to the LDL receptor (LDL-R) on cell membranes and serves as the primary vehicle for transporting cholesterol to peripheral tissues. However, when LDL, especially oxidized Low-Density Lipoprotein (LDL) in plasma is the main carrier of endogenous cholesterol. It is degraded and metabolized by binding to the LDL receptor (LDL-R) on cell membranes and serves as the primary vehicle for transporting cholesterol to peripheral tissues. However, when LDL, especially oxidized LDL (OX-LDL), is present in excess, the cholesterol it carries accumulates in the arterial walls, increasing the risk of atherosclerosis. Atherosclerosis is the pathological basis and risk factor for the majority of cardiovascular and cerebrovascular diseases.Detection Principle: In a cholesterol assay system containing cholesterol esterase (CHER) and cholesterol oxidase (CHOD), specific surfactants are added to selectively solubilize LDL-C for the determination of LDL-cholesterol. Other lipoproteins (HDL, VLDL, chylomicrons) do not react due to inhibition by the surfactants and sugar compounds, remaining in the form of lipoproteins in the reaction mixture. Based on this principle, LDL-cholesterol can be measured directly. Subsequently, esterase catalyzes the hydrolysis of cholesterol esters to generate Free Cholesterol (FC). FC is oxidized by cholesterol oxidase to produce 4-cholestenone and hydrogen peroxide. Hydrogen peroxide then reacts with 4-aminoantipyrine and other components to produce a red quinoneimine compound, which has a characteristic absorption peak at 546 nm. The LDL-C content is determined by measuring the absorbance at 546 nm.Component96TStorageReagent 118 mL2-8℃. Store in the dark.Reagent 26 mL2-8℃. Store in the dark.Standard1EA2-8℃. Store in the dark.Standard (Powder, 1 vial) Preparation:1. Before use, centrifuge at 8000 g, 4°C for 2 minutes to collect the powder at the bottom of the tube.2. Add 0.1 mL of distilled water to dissolve. Use within one week. The prepared concentration is as indicated on the label.User-Prepared Instruments and Reagents:Mortar (Homogenizer), balance, ice box (ice maker), benchtop centrifuge, adjustable micropipettes, water bath (oven, incubator, metal bath), 96-well plate, centrifuge tubes, microplate reader, distilled water (deionized water or ultrapure water are acceptable), ethanol.Experimental ProcedureIt is recommended to first perform a preliminary test using 1-3 samples with expected significant differences (e.g., different types or groups) to familiarize yourself with the procedure and to determine or adjust sample concentrations based on the preliminary results, preventing unnecessary waste of samples or reagents.1. Sample Extraction1.1 Tissue SamplesWeigh approximately 0.1 g of tissue sample and place it in a mortar. Add 1 mL of ethanol and homogenize in an ice bath. Centrifuge at 12,000 rpm, 4°C or room temperature for 10 minutes. Collect the supernatant for assay.Note: If increasing the sample amount, maintain a tissue mass (g) to ethanol volume (mL) ratio between 1:5 and 1:10.1.2 Liquid SamplesAssay clear liquid samples directly. If turbid, centrifuge and use the supernatant for assay.1.3 Bacterial/Cell SamplesCollect bacteria or cells into a centrifuge tube, centrifuge, and discard the supernatant. Add 1 mL of ethanol per approximately 5 million bacteria/cells. Disrupt the bacteria or cells by sonication in an ice bath (power 200W, pulse 3s on, 10s off, repeat 30 times). Centrifuge at 12,000 rpm, 4°C for 10 minutes. Collect the supernatant and keep it on ice for assay.*Note: If increasing the sample amount, maintain a bacteria/cell count (10⁴) to ethanol volume (mL) ratio between 500:1 and 1000:1.*2. Assay Steps2.1 Preheat the microplate reader for 30 minutes (or wait for the instrument to complete its self-check). Set the wavelength to 546 nm.2.2 Thaw all reagents to room temperature (25°C). Add reagents sequentially to a 96-well plate as follows:Reagent (µL)Test TubeStandard Tube (once)Blank Tube (once)Sample2.5Standard2.5Distilled Water2.5Reagent 1180180180Mix well and incubate at 37°C for 5 minutes. Read the absorbance at 546 nm for each tube (A1 ).Reagent 2606060Mix well and incubate at 37°C for 10 minutes. Read the absorbance at 546 nm for each tube (A2 ). Calculate ΔA = A2 - A1 for each tube.Note:(1) If the A2 value for the Test Tube is greater than 1, dilute the sample with ethanol. The dilution factor (D) must be substituted into the calculation formula.(2) If ΔA for the Test Tube is lower than ΔA for the Blank Tube, consider increasing the sample volume V1 (e.g., increase the sample volume in the Test Tube and the water volume in the Blank Tube to 5 µL or more, keeping Reagents 1 and 2 volumes unchanged; for the Standard Tube, keep at 2.5 µL and add 2.5 µL distilled water to make up volume) or increasing the sample weight W (e.g., to 0.2 g or more). The changed V1 or W must then be substituted into the calculation formula.3. Calculation of Results3.1 Based on Sample MassDerived Formula:LDL-C (µmol/g weight) = (CStandard × V2 ) × (ΔATest - ΔABlank ) ÷ (ΔAStandard - ΔABlank ) ÷ (W × V1 ÷ V) × DSimplified Formula:LDL-C (µmol/g weight) = CStandard × (ΔATest - ΔABlank ) ÷ (ΔAStandard - ΔABlank ) ÷ W × D3.2 Based on Protein ContentDerived Formula:LDL-C (µmol/mg prot) = (CStandard × V2 ) × (ΔATest - ΔABlank ) ÷ (ΔAStandard - ΔABlank ) ÷ (Cpr × V1 ÷ V) × DSimplified Formula:LDL-C (µmol/mg prot) = CStandard × (ΔATest - ΔABlank ) ÷ (ΔAStandard - ΔABlank ) ÷ Cpr × D3.3 LDL-C Content in LiquidsDerived Formula:LDL-C (mmol/L) = (CStandard × V2 ) × (ΔATest - ΔABlank ) ÷ (ΔAStandard - ΔABlank ) ÷ V1 × DSimplified Formula:LDL-C (mmol/L) = CStandard × (ΔATest - ΔABlank ) ÷ (ΔAStandard - ΔABlank ) × D3.4 Based on Cell CountDerived Formula:LDL-C (nmol/10⁴ cells) = (CStandard × V2 ) × 10³ × (ΔATest - ΔABlank ) ÷ (ΔAStandard - ΔABlank ) ÷ (500 × V1 ÷ V) × DSimplified Formula:LDL-C (nmol/10⁴ cells) = 2 × CStandard × (ΔATest - ΔABlank ) ÷ (ΔAStandard - ΔABlank ) × DParameter Definitions:CStandard : Concentration as indicated on the label (mmol/L or µmol/mL)V1 : Volume of sample added (0.0025 mL)V: Volume of extraction buffer (ethanol) added (1 mL)V2 : Volume of standard added (0.0025 mL)D: Dilution factor (1 if not diluted)500: Number of cells (in units of 10⁴)W: Sample weight (g)Cpr: Protein concentration of the supernatant (mg/mL); Aladdin's BCA Protein Quantification Kit (B665595) or Ready-to-Use BCA Protein Quantification Kit (R1491648) is recommended.Precautions1. It is recommended to first perform a preliminary test using 1-3 samples with expected significant differences (e.g., different types or groups) to familiarize yourself with the procedure. Based on the preliminary results, determine or adjust sample concentrations to prevent unnecessary waste of samples or reagents.2. This product is for research use only. Not for use in clinical diagnosis. For your safety and health, please wear a lab coat and disposable gloves during operation... Read More | The bacterial viability / toxicity detection kit contains two fluorescent dyes. Nucgreen is a green nucleic acid dye that can stain live and dead bacteria; Ethd III is a red nucleic acid dye that only stains dead bacteria with damaged cell membranes. When nucgreen and ethd III are properly mixed, The bacterial viability / toxicity detection kit contains two fluorescent dyes. Nucgreen is a green nucleic acid dye that can stain live and dead bacteria; Ethd III is a red nucleic acid dye that only stains dead bacteria with damaged cell membranes. When nucgreen and ethd III are properly mixed, the bacteria with intact cell membrane appear green, while the bacteria with damaged cell membrane can appear green and red under different channels, respectively. A common criterion for bacterial viability is the ability to propagate in a suitable nutrient medium, known as a growth assay. This kit is generally in good agreement with the growth assay results in liquid or solid medium. However, under certain conditions, membrane damaged bacteria may recover and propagate in nutrient medium, and such bacteria will be identified as dead bacteria in this assay. On the contrary, some bacteria with intact membranes may not be able to propagate in nutrient medium, but will be recognized as viable bacteria in this assay. Therefore, if there is a large difference between the test results of this kit and the bacterial growth assay, the above possibilities should be considered. Component： Product parameters： NucGreen: Ex/Em = 503/530 nm (结合 DNA)；EthD-III: Ex/Em = 530/620 nm (结合 DNA)。Usage:1 Preparation of control samples for live and dead bacteria (optional)1. Cultivate 4 mL of bacteria in liquid medium until late logarithmic phase.2. Prepare two 1 mL bacterial solutions in an EP tube and centrifuge for 10-15 minutes under 5000-10000 g conditions.3. Remove the supernatant and add 0.3 mL of 0.85% NaCl resuspended bacteria to one of the EP tubes, and 1 mL of 0.85% NaCl resuspended bacteria to the other tube.4. Add 0.7 mL of isopropanol to a tube containing 0.3 mL of 0.85% NaCl, and mix thoroughly (with a final concentration of 70% isopropanol) to prepare a dead bacterial sample.5. Incubate the two samples at room temperature for 1 hour and mix every 15 minutes.6. Centrifuge the two samples at 5000-10000 g for 10-15 minutes.7. Remove the supernatant, add 1 mL of 0.85% NaCl to resuspend the bacteria in both samples, and centrifuge again as in step 6.8. Use a spectrophotometer to measure the absorbance values (OD670) of two bacterial suspensions at 670 nm.9. Adjust the density of the two bacterial suspensions (live and dead) to 108 bacteria/mL (OD670 ≈ 0.3), and then dilute with 0.85% NaCl at 1:100 to achieve a final density of 106 bacteria/mL.10. Mix two bacterial suspensions as shown in the table below to obtain the required live cell ratio: dead cell ratio.Table 1 Mix live and dead bacterial suspensions by a certain volume to achieve the required ratio of live and dead cellsLive cells: Dead cellsVolume of viable bacterial suspension（mL）Volume of dead bacterial suspension（mL）0:10001.010:900.10.920:800.20.830:700.30.750:500.50.5100:01.00II Staining methods for fluorescence microscopy observation1. Mix 1 volume of component A, NucGreen, and 2 volumes of component B, EthD-III, in a microcentrifuge tube. After thorough mixing, add 8 volumes of 0.85% NaCl solution to obtain a 100 x dye solution.2. Every 100 µ L bacterial suspension, add 1 µ 100 x dye solution of L.3. Mix thoroughly and incubate at room temperature in the dark for 15 minutes.4. Take 5 µ The bacterial suspension after L staining was dropped onto a glass slide with an 18 mm square cover glass.5. Observe under a fluorescence microscope. The fluorescence of live and dead bacteria can be observed simultaneously under any standard FITC long-acting filter. Alternatively, live (green fluorescent) and dead (red fluorescent) bacteria can be observed using FITC and Cy3 (or Texas Red) channels, respectively.Attention: (1) Before staining bacteria, attention must be paid to removing residues of growth media. Nucleic acid and other media components can bind to NucGreen and EthD-III dyes in some way, resulting in unacceptable staining changes. A simple washing step is usually sufficient to remove interfering media components from bacterial suspension. It is not recommended to use phosphate buffer solutions as they can reduce staining efficiency. (2) Before starting the formal experiment, the dye concentration should be adjusted to distinguish between NucGreen labeling live bacteria and EthD-III labeling dead bacteria. The optimal concentration may vary depending on the bacterial strain. It is generally best to use the lowest dye concentration that can provide sufficient signal. The above conditions have been optimized for staining live/dead cells of Escherichia coli.III Before starting the staining method experiment of flow cytometry, please read the precautions under the fluorescence microscope staining steps.According to Table 1, add 11 different proportions of live and dead bacteria to the EP tube. Each of the 11 samples has a volume of 1 mL.2. Add 12 µ The A component of L, NucGreen, and 24 µ The B component EthD-III of L was mixed in a microcentrifuge tube. Add 3 to each of the 11 samples µ Mix the mixed dyes of L thoroughly by blowing them up and down several times. (Note: Additional control bacterial samples need to be prepared for separate NucGreen and EthD-III staining)3. Incubate at room temperature in the dark for 15 minutes.4. Analyze each sample using a flow cytometer, detect NucGreen positive cells using FITC channels, and detect EthD-III positive cells using PI or PE channels.Matters needing attention：1. please centrifuge the product to the bottom of the tube immediately before use, and then conduct subsequent experiments. 2. if the orifice plate is used for detection, a small amount of bacterial liquid can be left for imaging after standing for 10 min, which can effectively reduce the background. 3. in order to be closer to the real results, it is recommended to keep the brightness of red fluorescence consistent with that of green fluorescence in merge pictures. 4. fluorescent dyes have quenching problems. Please try to avoid light during experimental operation to slow down fluorescence quenching. 5. for your safety and health, please wear experimental clothes and disposable gloves.Scope of application：Staining of dead and live bacteria... Read More | The content of this cell is too long for an XLSX file (more than 32767 characters). Please use the CSV format for this export | Hydrogen peroxide, a reactive oxygen species produced through the metabolism of molecular oxygen, serves as both an intracellular signaling messenger and a source of oxidative stress. Hydrogen peroxide is generated in cells via multiple mechanisms such as the NOX-mediated ROS production by Hydrogen peroxide, a reactive oxygen species produced through the metabolism of molecular oxygen, serves as both an intracellular signaling messenger and a source of oxidative stress. Hydrogen peroxide is generated in cells via multiple mechanisms such as the NOX-mediated ROS production by neutrophils and macrophages (respiratory burst) or by the dismutase of superoxide anions produced as a result of electron leak during mitochondrial respiration. Abnormal hydrogen peroxide production contributes to oxidative cell damage and the progression of diseases such as asthma, atherosclerosis, osteoporosis, and neurodegeneration.Intracellular hydrogen peroxide assay kit has been used to measure intracellular hydrogen peroxide levels... Read More | The fluorescent dye PKH67 is suitable for conventional cell membrane labeling. It is a green fluorescent dye that can track cells in vitro and in vivo. It labels cells by binding to the lipid components of the membrane structure. PKH67 has low cytotoxicity, low fluorescence background, high fat The fluorescent dye PKH67 is suitable for conventional cell membrane labeling. It is a green fluorescent dye that can track cells in vitro and in vivo. It labels cells by binding to the lipid components of the membrane structure. PKH67 has low cytotoxicity, low fluorescence background, high fat solubility, can easily penetrate cell membranes, and has strong and stable green fluorescence. PKH67-labeled cells can be used for in vitro and in vivo proliferation studies, and have the function of not staining neighboring cells. In the process of cell division and proliferation, the fluorescence intensity of PKH67 will gradually decrease as the cells divide. The labeled fluorescence can be evenly distributed to the two sub-generation cells, so its fluorescence intensity is half that of the parent cell. According to this feature, It can be used to detect cell proliferation, cell cycle estimation and cell division, etc. The fluorescence of PKH67-labeled cells is very uniform, and the fluorescence distribution of sub-generation cells after division is also more uniform. In the process of cell division and proliferation, PKH67-labeled fluorescence can be evenly distributed between the two sub-generation cells, and the fluorescence intensity becomes half of that of the parent cell. According to the difference in fluorescence intensity, the undivided cells can be detected by flow cytometry. One time (1/2 the fluorescence intensity), the second time (1/4 the fluorescence intensity), three times (1/8 the fluorescence intensity), and more divisions of cells. PKH67 can detect splits up to six times or even more. In addition to the detection of cell proliferation, PKH67 can also be used for in vitro tracking of cells. After labeling, the fluorescence expression is stable in the cell, and the positive labeling rate is over 98%. The labeled cells have good morphology, which can effectively observe the cells in vitro. Induce differentiation; or inject labeled cells into the body, it can effectively show the migration and differentiation of transplanted cells in living tissues. PKH67-labeled cells can be used for in vivo observation for as long as several weeks. It is often used for in vivo cell detection experiments and experiments to observe long-term cell activity using fluorescence electron microscope. PKH67 is less toxic and does not affect cell proliferation. This method is simple to operate, does not use radioactive isotopes, and poses no safety hazards. You can get the desired experimental data faster, more accurately and more safely.Due to the longer length of the charcoal tail, internal studies have shown that PKH67 is less transferred between cells than PKH2. In in vivo studies using PKH1 and PKH2, the fluorescence intensity will slowly lose. Since this is a behavioral characteristic of green cell linker dye rather than red cell linker dye, PKH67 will have similar properties. The correlation between the in vitro cell membrane retention of non-dividing cells and the in vivo fluorescence half-life reveals that the in vivo fluorescence half-life of PKH67 is 10-12 days. Other green cell linker dyes with similar half-lives have been used to monitor the transport of lymphocytes and macrophages in the body within one to two months. The results indicate that PKH67 can also be used for medium-term in vivo tracking studies.The dye can stably bind to the lipid region of the cell membrane and emit fluorescence, and is mainly used for cell labeling in vitro, cell proliferation research in vitro, and cell tracing research in vivo and in vitro. The fluorescence half-life of PKH67 in vivo is 10-12 days. Compared with PKH-67, PKH-26 has a longer half-life, and the half-life of PKH26 labeled on rabbit red blood cells is more than 100 days. Especially suitable for in vitro proliferation research and long-term in vivo cell tracking research. After PKH67 labels the cells, flow cytometry is usually used for cell proliferation detection.Kit components0.1ml kits: P266290A-0.1ml P266290B-10ml1ml kits: P266290A-1ml P266290B-60mlDyes with A suffix and diluents with B suffix are used togetherPKH67 labeled cells show green fluorescence, the fluorescence wavelength: λex=490 nm, λem=502 nm.Storage conditions: -20℃ protected from light, valid for 1 yearPrecautions●Staining concentration varies according to the type of cell and the number of cells in each well.● The prepared PKH67 mother liquor is very easy to dissolve. It is recommended to store in aliquots and freeze-dry at ≦-20℃.● PKH67 working solution should be prepared for immediate use, and cannot be prepared in advance, because PKH67 will decompose due to the absorption of water and affect the dyeing effect.● PKH67 is easily decomposed and will deteriorate quickly in the water solution. Please avoid contact with water during use of mother liquor. The working fluid is in contact with the water during the process of labeling the cells within the permitted time range.● PKH67 fluorescent dye is a DMSO solution. It will solidify and stick to the bottom, wall or cap of the tube at a lower temperature such as 4℃ and ice bath. After being taken out of the refrigerator, it will return to room temperature and become After the liquid is in the state, remove the cap from the bottom of the tube. It can be used after it has completely melted in a 37°C water bath.● The number of generations or time that can be traced after different cell types are marked is quite different. Please make a test based on the actual situation or reference documents.Instructions1. Staining solution preparation:(1) Take out the PKH67 reagent from the refrigerator, let it stand for a few minutes to room temperature, or after a 37°C water bath, leave the tube containing PKH67, and be sure to leave the tube for a few minutes before opening the lid to allow the reagent to fully fall into the tube The lid can only be opened after the bottom.(2) According to the number of cell samples to be tested, dilute the probe 10 times with the diluent, and then use a suitable solution (such as non-clear medium, HBSS or PBS) to dilute the PKH67 mother liquor 25 times to prepare a stain Work fluid. The best working solution concentration should be adjusted according to different cells and your own experimental system. Generally, the cells can be diluted 250 times according to the final concentration of the mother liquor in the kit. Some cells may need to increase the concentration appropriately.2. Cell staining(1) Resuspend the prepared cells to be tested in 100µl of staining solution to a cell concentration of about 107/ml. You can also perform in-situ staining, as long as the staining solution is enough to cover the cells.(2) Culture the cells at 2～8℃ for 15～30 minutes. The best culture time is different for different cells.It is recommended to incubate the labeled cells in the staining solution at 37°C for 5 minutes, and then at 4°C for 15 minutes.Low-temperature incubation can reduce the endocytosis of the dye by the cells, help the dye to label the plasma membrane, and reduce the possibility of the dye localizing to cytoplasmic vesicles.(3) After separation, remove the supernatant, collect the cells, wash the cells 1-2 times with PBS or non-clear medium, and finally add PBS or non-clear medium to resuspend the cells.(4) Take 500µl of cell suspension and test with flow cytometer. Ex/Em=490/502nm.(5) Subsequently, the cells can be cultured according to the normal culture method.(6) The labeling effect can be directly observed under a fluorescence microscope, or the cell proliferation can be detected by a flow cytometer after an appropriate period of culture, or used for cell fluorescence traces for other specific experimental purposes... Read More |