| Description | Lactate dehydrogenase (LDH or LD) is a stable protein present in the cytoplasm of normal cells and normally cannot pass through the cell membrane. When cells are damaged, membrane permeability increases, and LDH is released extracellularly. A decrease in intracellular LDH and an increase in LDH in Lactate dehydrogenase (LDH or LD) is a stable protein present in the cytoplasm of normal cells and normally cannot pass through the cell membrane. When cells are damaged, membrane permeability increases, and LDH is released extracellularly. A decrease in intracellular LDH and an increase in LDH in the culture medium occur. Measuring the LDH activity in the culture medium or the LDH leakage rate can reflect drug-induced cytotoxicity. LDH belongs to the oxidoreductase family and can reversibly catalyze the redox reaction between lactate (L) and pyruvate (P). The reaction formula is: Lactate + NAD⁺ → Pyruvate + NADH + H⁺, where L → P is the forward reaction and P → L is the reverse reaction. Detection Principle: Using NAD⁺ as a hydrogen acceptor, LDH catalyzes the dehydrogenation of lactate to generate pyruvate. Pyruvate then reacts with dinitrophenylhydrazine to form pyruvate dinitrophenylhydrazone, which appears brownish-red in an alkaline solution. The color intensity is proportional to the pyruvate concentration. The absorbance at 440 nm can be measured using a microplate reader. The released LDH activity during cytotoxicity or the LDH activity in other samples can be calculated using formulas. This kit can be used for routine LDH activity detection and is more commonly used for cytotoxicity assays using LDH release as an indicator.This kit is for scientific research use only and is not intended for clinical diagnosis or other purposes.L1501786Component100T500TStorageL1501786ALDH Assay Buffer3 mL15 mL2-8℃. Store in the dark.L1501786BNAD1EA2EA-20℃L1501786CPhenylhydrazine Color Solution3 mL15 mL2-8℃. Store in the dark.L1501786DAlkaline Color Solution10 mL50 mLRT.L1501786ELDH Releasing Agent (10X)2 mL10 mLRT.User-Prepared Instruments and Reagents1. 96-well plate cultured test and control group cell samples, sterile PBS, culture medium, distilled water.2. Microplate centrifuge, 96-well plate or centrifuge, centrifuge tubes, incubator or water bath, microplate reader.Experimental Procedure1. Sample Preparation1.1 LDH Release AssaySeed an appropriate number of cells into a 96-well culture plate based on cell size and growth rate, so that the cell density does not exceed 90% confluency at the time of detection.Aspirate the culture medium, wash once with PBS, add fresh culture medium.Set up corresponding control groups according to experimental needs:Background Blank Control Well A: Culture medium without cells.Sample Control Well B: Control cells without drug treatment.Maximum Enzyme Activity Control Well C: Lysed samples from untreated cells.Drug-treated Sample Well D: Cells treated with the drug.Continue cultivation.Before detection, take out the cell culture plate. Add LDH Releasing Agent (10X) to the "Maximum Enzyme Activity Control Well C" at a volume equal to 10% of the original culture medium volume. Mix thoroughly by pipetting up and down several times. Continue cultivation for about 1 hour.Centrifuge the cell culture plate at 400 g for 5 minutes using a microplate centrifuge.Aspirate 5 µL of supernatant from each well and transfer it to the corresponding wells of a new 96-well plate for subsequent LDH detection.1.2 Cytotoxicity and Cell Proliferation Assay for Intracellular Total LDHSeed an appropriate number of cells into a 96-well culture plate based on cell size and growth rate, so that the cell density does not exceed 90% confluency at the time of detection.Treat with different drugs and set up appropriate controls.Centrifuge the cell culture plate at 400 g for 5 minutes using a microplate centrifuge.Aspirate the culture medium.Add 150 µL of LDH Releasing Agent diluted 10-fold with PBS. Shake the plate to mix thoroughly. Continue cultivation for about 1 hour.Centrifuge the cell culture plate at 400 g for 5 minutes using a microplate centrifuge.Aspirate 5 µL of supernatant from each well and transfer it to the corresponding wells of a new 96-well plate for subsequent cytotoxicity detection.1.3 Protein Concentration DeterminationAfter sample preparation, the protein concentration can be determined using a BCA Protein Assay Kit (Aladdin B665595 BCA Protein Quantification Kit or R1491648 Ready-to-Use BCA Protein Quantification Kit are recommended) to facilitate subsequent calculation of LDH content per unit protein weight in tissues or cells.2. Preparation of NAD SolutionTake one vial of NAD (powder) and dissolve it in 1.5 mL of deionized water.3. LDH Enzymatic ReactionAdd solutions sequentially according to the table below, taking care to avoid bubbles. If the enzyme activity in the sample is too high, reduce the sample volume or dilute appropriately before assay.Reagent (µL)Volume (µL)Test Sample (supernatant)5LDH Assay Buffer25NAD Solution5 Mix well, incubate at 37°C for 15 min. Phenylhydrazine Color Solution25 Mix well, incubate at 37°C for 15 min. Alkaline Color Solution100Distilled Water150 4. LDH Measurement Mix well and let stand at room temperature for 5 minutes. Measure the absorbance of each well at 440 nm using a microplate reader. 5. Result Calculation Cytotoxicity or Mortality Rate (%) = (A D - A B ) / (A C - A B ) × 100% If the absorbance value A γ of a known concentration *c* of an LDH enzyme standard and the absorbance value A γ0 of the standard blank control are measured simultaneously, the enzyme activity in the sample can be roughly calculated:LDH Activity in Test Sample (mU/mL) = (A B - A A ) / (A γ - A γ0 ) × *c* For accurate calculation of the absolute LDH enzyme activity in the sample, use a self-prepared LDH standard to plot a standard curve with the measured absorbance values. The enzyme activity of the sample can be calculated using the formula derived from the standard curve. Where: A A = Absorbance of Background Blank Control Well A A B = Absorbance of Sample Control Well B A C = Absorbance of Maximum Enzyme Activity Control Well C A D = Absorbance of Drug-treated Sample Well D 6. Results and Analysis The cytotoxicity of drugs or toxicants can be determined by directly comparing the LDH activity in each well. Higher LDH activity indicates higher cell membrane permeability and more severe cell damage.Precautions1. Use serum-free or low-serum concentration culture medium when culturing cells to exclude serum interference; otherwise, deviations may occur.2. EDTA inhibits LDH. Avoid using or thoroughly remove reagents containing EDTA during operation.3. Measure LDH as soon as possible after collection. If the collected cell culture medium is stored for too long, LDH activity may decrease.4. Use solutions prepared at the same time for the same batch of experiments. The volume of solutions used and the reaction time should be consistent.5. In the enzymatic reaction, the recommended supernatant sample volume is 2.5-10 µL. If the enzyme activity in the sample is too high, reduce the sample volume or dilute appropriately before assay.6. Measurement should be completed within 15 minutes after color development.7. The Alkaline Color Solution is somewhat corrosive; handle with care.8. Use reagents promptly after opening to avoid affecting subsequent experimental results.9. For your safety and health, please wear a lab coat and disposable gloves during operation... Read More | Inquire | Inquire | DescriptionIt contains a set of six different heterogeneous palladium catalysts, useful for rapid screening of catalysis conditions. It is in sampler format with individual components packaged for multiple experiments and mini scale-up. The cost of the kit is less than the total cost of individual DescriptionIt contains a set of six different heterogeneous palladium catalysts, useful for rapid screening of catalysis conditions. It is in sampler format with individual components packaged for multiple experiments and mini scale-up. The cost of the kit is less than the total cost of individual components.Catalysis Screening Kits... Read More | This kit is suitable for extracting total RNA from fresh whole blood (blood samples treated with anticoagulants such as citrate, EDTA, or heparin). It can process up to 1.5 ml of whole blood and elute to obtain high-purity RNA with a molecular weight greater than 200 bp. Multiple samples can be This kit is suitable for extracting total RNA from fresh whole blood (blood samples treated with anticoagulants such as citrate, EDTA, or heparin). It can process up to 1.5 ml of whole blood and elute to obtain high-purity RNA with a molecular weight greater than 200 bp. Multiple samples can be completed simultaneously within 1 hour. This product does not require the ultra centrifugation step of CsCl purification and LiCl or ethanol precipitation. It does not contain toxic solvents such as phenol or chloroform. The purified RNA effectively removes enzyme inhibitors and pollutants such as heme and heparin. It can be directly used in various molecular biology routine experiments, such as RT-PCR, Northern Blot, Dot Blot, in vitro translation, and so on.Self prepared reagents: β- Mercaptoethanol, 70% ethanol (prepared with water without RNase), anhydrous ethanol. R666034 Component 50 T Storage R666034A Buffer RBL (10×) 60 mL RT R666034B Buffer RL 35 mL RT R666034C Buffer RW1 40 mL RT R666034D Buffer RW2 (concentrate) 11 mL RT R666034E RNase-Free Water 10 mL RT R666034F Spin Columns FL with Collection Tubes 50 sets RT R666034G Spin Columns RM with Collection Tubes 50 sets RT R666034H RNase-Free Centrifuge Tubes (1.5 mL) 50 EA RT Preparation and important precautions before the experimentTo prevent RNase pollution, attention should be paid to the following aspects:1) Use RNase free plastic products and gun heads to avoid cross contamination.2) Glassware should be dry baked at a high temperature of 180 ℃ for 4 hours before use, while plastic containers can be soaked in 0.5M NaOH for 10 minutes, thoroughly rinsed with water, and then sterilized under high pressure.3) Prepare the solution using water without RNase.4) Operators should wear disposable masks and gloves, and change gloves frequently during the experiment.2. The sample should avoid repeated freezing and thawing, otherwise it will affect the yield and quality of RNA extraction. The sample can be stored in Buffer RL at -70 ℃ for one month.3. Before use, please check if there is any crystallization or precipitation in the Buffer RL. It can be dissolved again in a 56 ℃ water bath. Please add Buffer RL before use β- Mercaptoethanol, with a final concentration of 1%. Add 10 to 1 ml Buffer RL µ L β- Mercaptoethanol. join β- The buffer RL room temperature of mercaptoethanol can be stored for one month.4. Before the first use, anhydrous ethanol should be added to Buffer RW2 according to the instructions on the reagent bottle label.5. This reagent kit cannot be used for RNA extraction from frozen blood samples with anticoagulants added.6.10 × Buffer RBL needs to be diluted 10 times with water without RNase before use, and then stored at 2-8 ℃ after dilution.7. If downstream experiments are highly sensitive to DNA, it is recommended to treat RNA with DNase I that does not contain RNase.8. All centrifugation steps should be carried out at room temperature unless otherwise specified, and all operation steps should be carried out quickly.Operation steps1. Add 5 times the volume of 1 x Buffer RBL to fresh anticoagulant whole blood samples of 0.5-1.5 ml (please dilute 10 x Buffer RBL with RNase free water before use), gently vortex or invert and mix well. Incubate on ice for 10-15 minutes, mix twice during the incubation process.Attention: During the incubation process, the cloudy suspension will become transparent, indicating that red blood cells have been lysed. If necessary, the incubation time can be extended to 20 minutes. 2. Centrifuge at 4 ℃, 2100 rpm (~400 × g) for 10 minutes, and carefully discard the supernatant.3. Add 2 times the volume of the blood sample to the above precipitate with 1 x Buffer RBL (please dilute 10 x Buffer RBL with RNase free water before use), gently vortex, and resuspend the precipitate thoroughly. 4. Centrifuge at 4 ℃ and 2100 rpm for 10 minutes, carefully and thoroughly remove the supernatant.Note: This step must completely remove the supernatant, otherwise it will affect the lysis and lead to a decrease in RNA production.5. Add Buffer RL to the precipitate (check if it has been added before use β- Mercaptoethanol, 0.5-1.5 ml of blood sample added to 600 µ L Buffer RL, or less than 0.5 ml of blood sample added to 350 µ L Buffer RL, mix well.6. Transfer the obtained liquid to the spin columns FL that have been loaded into the collection tube, centrifuge at 12000 rpm (~13400 × g) for 2 minutes, collect the filtrate, and discard the filter column.7. Add 1 volume (600) to the obtained filtrate µ L or 350 µ l) Mix 70% ethanol (prepared without RNase water) well.Attention: Adding ethanol may cause precipitation and will not affect subsequent experiments.8. Add all the solution obtained in the previous step to the spin columns RM that have been loaded into the collection tube. If the solution cannot be added at once, it can be transferred in multiple batches. Centrifuge at 12000 rpm for 15 seconds, discard the waste liquid in the collection tube, and place the adsorption column back into the collection tube.9. Add 700 to the adsorption column µ Centrifuge at 12000 rpm for 15 seconds, discard the waste liquid from the collection tube, and place the adsorption column back into the collection tube.Optional steps: If conducting RNA experiments that are highly sensitive to trace amounts of DNA, replace step 9 with the following steps.1) Add 350 to the adsorption column µ Centrifuge at 12000 rpm for 15 seconds, discard the waste liquid from the collection tube, and place the adsorption column back into the collection tube.2) Preparation of DNase I mixture: Take 70 µ Reaction Buffer and 10 µ L DNase I storage solution, gently mix and prepare to a final volume of 80 µ The reaction solution of L.Attention: The above system is configured according to our company's DNase I (D665537) reaction system. Please refer to the corresponding manual for other company products.1) Add 350 to the adsorption column µ Centrifuge at 12000 rpm for 15 seconds, discard the waste liquid from the collection tube, and place the adsorption column back into the collection tube.2) Preparation of DNase I mixture: Take 70 µ Reaction Buffer and 10 µ L DNase I storage solution, gently mix and prepare to a final volume of 80 µ The reaction solution of L.Attention: The above system is configured according to our company's DNase I (D665537) reaction system. Please refer to the corresponding manual for other company products.3) Add 80 µ l of the prepared DNase I reaction solution directly to the adsorption column and incubate at 20-30 ℃ for 15 minutes.4) Add 350 to the adsorption column µ Centrifuge at 12000 rpm for 15 seconds, discard the waste liquid from the collection tube, and place the adsorption column back into the collection tube.10. Add 500 to the adsorption column µ Buffer RW2 (check if anhydrous ethanol has been added before use), centrifuge at 12000 rpm for 15 seconds, discard the waste liquid in the collection tube, and place the adsorption column back into the collection tube.11. Repeat step 10. 12. Centrifuge at 12000 rpm for 2 minutes and discard the waste liquid from the collection tube. Place the adsorption column at room temperature for a few minutes to thoroughly air dry.Note: The purpose of this step is to remove residual ethanol from the adsorption column, which can affect subsequent enzymatic reactions (such as enzyme digestion, PCR, etc.).13. Place the adsorption column in a new RNase free centrifuge tube and add 30-50 to the middle of the adsorption column µ Place RNase Free Water at room temperature for 1 minute, centrifuge at 12000 rpm for 1 minute, collect RNA solution, and store RNA at -70 ℃ to prevent degradation.Attention:1) The volume of RNase Free Water should not be less than 30 µ l. Small volume affects the recovery rate.2) If you want to increase RNA production, you can use 30-50 µ Repeat step 13 for the new RNase Free Water.3) If you want to increase the RNA concentration, you can add the obtained solution back to the adsorption column and repeat step 13... Read More |