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Description
Human CR2 ELISA KitProduct Specification Usage Experimental equipment required for the experiment: 1. Microplate reader (450nm) 2. High precision pipette and gun tips: 0. 5 10uL, 5 50uL, 20 200uL, 200 1000uL 3. 37 constant temperature box 4. Distilled water or deionized water Sample processing and requirements: Serum: Place the whole blood sample collected in the serum separation tube at room temperature for 2 hours or at 4 overnight, then centrifuge at 1000g for 20
Product Specification
| Usage |
Experimental equipment required for the experiment: 1. Microplate reader (450nm) 2. High-precision pipette and gun tips: 0.5-10uL, 5-50uL, 20-200uL, 200-1000uL 3. 37℃ constant temperature box 4. Distilled water or deionized water Sample processing and requirements: Serum: Place the whole blood sample collected in the serum separation tube at room temperature for 2 hours or at 4℃ overnight, then centrifuge at 1000×g for 20 minutes, and take the supernatant, or store the supernatant at -20℃ or -80℃, but avoid repeated freezing and thawing. Plasma: Collect the specimen using EDTA or heparin as an anticoagulant. Centrifuge the specimen at 1000 × g for 15 minutes at 2-8°C within 30 minutes of collection. The supernatant can be assayed or stored at -20°C or -80°C, but avoid repeated freezing and thawing. Tissue homogenization: Rinse the tissue with pre-chilled PBS (0.01M, pH 7.4) to remove residual blood (lysed red blood cells in the homogenate will affect the measurement results). Weigh the tissue and mince it. Add the minced tissue to the appropriate volume of PBS (generally a 1:9 weight-to-volume ratio, e.g., 1 g of tissue sample to 9 mL of PBS. The specific volume can be adjusted according to experimental needs and recorded. It is recommended to add protease inhibitors to the PBS) in a glass homogenizer and grind thoroughly on ice. To further lyse tissue cells, the homogenate can be sonicated or repeatedly frozen and thawed. Finally, centrifuge the homogenate at 5000 × g for 5-10 minutes, and the supernatant can be assayed. Other biological fluids: Centrifuge at 1000xg for 20 minutes, remove the supernatant, and test. Pre-test preparation: 1. Remove the test kit from the refrigerator 10 minutes in advance and equilibrate to room temperature. 2. Prepare the standard gradient working solution: Add 1 mL of universal diluent to the lyophilized standard, let it stand for 15 minutes to completely dissolve, then gently mix (concentration is 20 ng/mL). Then dilute to the following concentrations: 20 ng/mL, 10 ng/mL, 5 ng/mL, 2.5 ng/mL, 1.25 ng/mL, 0.625 ng/mL, 0.3125 ng/mL, and 0 ng/mL. Serial dilution method: Take 7 EP tubes and add 500 μL of universal diluent to each tube. Pipette 500 μL of the 20 ng/mL standard working solution into the first EP tube and mix thoroughly to make a 10 ng/mL standard working solution. Repeat this procedure for subsequent tubes. The last tube serves directly as a blank well; there is no need to aspirate the liquid from the penultimate tube. See the figure below for details. 3. Preparation of Biotinylated Antibody Working Solution: 15 minutes before use, centrifuge the concentrated biotinylated antibody at 1000×g for 1 minute. Dilute the 100× concentrated biotinylated antibody to a 1× working concentration using universal diluent (e.g., 10µL concentrate + 990µL universal diluent). Prepare immediately before use. 4. Prepare the enzyme conjugate working solution: 15 minutes before use, centrifuge the 100× concentrated enzyme conjugate at 1000×g for 1 minute. Dilute the 100× concentrated HRP enzyme conjugate to a 1× working concentration with universal diluent (e.g., 10 μL of concentrate + 990 μL of universal diluent). Prepare immediately. 5. Prepare the 1× wash solution: Dispense 10 mL of 20× wash solution into 190 mL of distilled water (concentrated wash solution removed from the refrigerator may crystallize; this is normal. Allow to stand at room temperature until the crystals have completely dissolved before preparing). Procedure: 1. Remove the desired strips from the aluminum foil bag after equilibration at room temperature for 10 minutes. Seal the remaining strips in a ziplock bag and return to 4°C. 2. Sample addition: Add 100 μL of sample or standard of varying concentrations to the corresponding wells. Add 100 μL of universal diluent to the blank wells. Cover with a film and incubate at 37°C for 60 minutes. (Recommendation: Dilute the sample to be tested at least 1-fold with universal diluent before adding it to the ELISA plate. This will reduce the impact of matrix effects on the test results. The sample concentration should be multiplied by the corresponding dilution factor when calculating the final sample concentration. It is recommended to run replicates for all test samples and standards.) 3. Add Biotinylated Antibody: Remove the ELISA plate and discard the liquid without washing. Add 100 μL of Biotinylated Antibody Working Solution directly to each well. Cover with a film and incubate at 37°C for 60 minutes. 4. Wash: Discard the liquid and add 300 μL of 1x Wash Solution to each well. Let stand for 1 minute, shake off the wash solution, and pat dry on absorbent paper. Repeat this process three times (a plate washer can also be used). 5. Add Enzyme Conjugate Working Solution: Add 100 μL of Enzyme Conjugate Working Solution to each well. Cover with a film and incubate at 37°C for 30 minutes. 6. Washing: Discard the liquid and wash the plate five times as in step 4. 7. Adding substrate: Add 90 μL of substrate (TMB) to each well, cover with a sealing film, and incubate at 37°C in the dark for 15 minutes. 8. Adding stop solution: Remove the ELISA plate and add 50 μL of stop solution directly to each well. Immediately measure the OD value of each well at a wavelength of 450 nm. Calculating experimental results: 1. Calculate the average OD value of the standard and sample replicates and subtract the OD value of the blank well as a correction factor. Plot the standard curve of the four-parameter logistic function on double-logarithmic graph paper, with concentration as the horizontal axis and OD value as the vertical axis. 2. If the sample OD value is higher than the upper limit of the standard curve, dilute the sample appropriately and retest. Multiply the sample concentration by the corresponding dilution factor. |
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| Theory | This kit uses a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). Sample, standard, biotin-labeled detection antibody, and HRP conjugate are sequentially added to microwells pre-coated with a capture antibody against Complement Receptor 2 (CR2). After incubation and washing, the sample is developed using the substrate TMB. TMB is converted to blue by HRP peroxidase and to yellow by acid. The intensity of the color is positively correlated with the amount of Complement Receptor 2 (CR2) in the sample. The absorbance (OD) is measured at 450 nm using a microplate reader to calculate the sample concentration. | |||||||||||||||||||||||||||||||||
| Source | Human | |||||||||||||||||||||||||||||||||
| Synonym | Human Complement Receptor 2 ELISA Kit | |||||||||||||||||||||||||||||||||
| Detection Type | Double antibody sandwich method | |||||||||||||||||||||||||||||||||
| Composition |
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| Background | Complement receptor type 2 (CR2), also known as complement C3d receptor, Epstein-Barr virus receptor, and CD21 (cluster of differentiation 21), is a protein encoded by the CR2 gene. CR2 participates in the complement system. It binds to iC3b (an inactive derivative of C3b), C3dg, or C3d. B cells express the CR2 receptor on their surface, enabling the complement system to function in B cell activation and maturation. CR2 interacts with CD19 and, on mature B cells, forms a complex with CD81 (TAPA-1). The CR2-CD19-CD81 complex is often referred to as the B cell co-receptor complex because when the B cell receptor binds to an antigen, CR2 binds to the absorbed antigen through the attached C3d (or iC3b or C3dg). This results in a greatly enhanced B cell response to the antigen. | |||||||||||||||||||||||||||||||||
| General Notes | 1. Strictly adhere to the specified incubation time and temperature to ensure accurate results. All reagents must be at room temperature (20-25°C) before use. Refrigerate reagents immediately after use. 2. Improper plate washing may result in inaccurate results. Ensure that all liquid in the wells is aspirated thoroughly before adding substrate. Do not allow the wells to dry out during incubation. 3. Remove any residual liquid and fingerprints from the bottom of the plate, as this will affect the OD value. 4. The substrate developer solution should be colorless or very light in color. Do not use substrate solution that has turned blue. 5. Avoid cross-contamination of reagents and specimens to prevent erroneous results. 6. Avoid direct exposure to strong light during storage and incubation. 7. Do not expose any reagents to bleaching solvents or the strong fumes emitted by bleaching solvents. Any bleaching agent will destroy the biological activity of the reagents in the kit. 8. Do not use expired products, and do not mix components with different product numbers and batches. 9. Recombinant proteins from sources other than the kit may not be compatible with the antibodies in this kit and will not be recognized. 10. If there is a possibility of disease transmission, all samples should be managed properly and samples and testing devices should be handled according to prescribed procedures. |
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| Storage Temp. | If the unopened kit is stored at 4°C, the shelf life is 6 months. | |||||||||||||||||||||||||||||||||
| Test Range | 0.31-20 ng/mL | |||||||||||||||||||||||||||||||||
| Applications | Serum, plasma, tissue homogenates and other biological fluids |
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4.6 ★★★★★
Based on 30 reviews
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Product Reviews
★★★★★ 5
All The Things!!
Format: Kindle
This is definitely worth reading! The spice is nice, but the story itself is truly an epic literary treat! Tessa and her Alphas are a powerhouse force of nature who will capture your heart. This story is also a great reminder of how fickle life can be and how quickly everything can change for anyone. Every single person, billionaire to janitor, is nothing but one tragic event away from being in the same situation as Tessa was in. ❤️
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on September 10, 2025
★★★★★ 4
Kind of difficult to get through for the first half but worth the read!
Format: Kindle
3.75/5 ⭐️
What this book lacked in being fully polished, it made up for in world and character building for sure!
While the first half was hard to get through, as this is a book that starts you in the present and then goes back and forth between different times in the past to get you up to speed with what’s happening in the future (and it’s not all chronological in the past which made it even harder), once all of the book is set in the present, Tessa and her pack, Ryder, Dixon, Mac, and Tray, (and of course Josie the cat,) all begin their journeys of finding themselves both individually and within their pack which is so rewarding to see after all of the tragedy and sadness detailed in their last few years leading up to meeting. I think this book could’ve done with another beta reader or two to polish up grammatical errors as well, some of those took me out of the story for a minute to try to figure out what was trying to be communicated.
Overall, this story filled with so many dichotomies of love and loss, grief and happiness, hurt and comfort, all culminating in a lovely story of a pack that strengthens each other after many tribulations, and it warms your heart so so much to see them go through every version of themselves, landing on secure and happy individuals who make a wonderful pack together.
Would absolutely recommend if you like slow burn, rockstar, big city, and initially heavy and a bit dark but fades into comfort and fluffy omegaverse stories!
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Reviewed in the United States on April 18, 2026
★★★★★ 3
i should have waited for there to be reviews posted
Format: Kindle
I'm being more generous than I should because this is a debut novel
i downloaded this book because i like why choose and band romances
i figured that it wouldn't take too long to get back to where the prologue was because the prologue seemed to be less than a day before they met
the FMC and the MMCs don't meet til 60 % of the way in which for a Romance novel kinda hard for the relationship to develop or for there to be plot beyond them just meeting in a way where the FMC really lacks agency
a lot of early plot and character things are forgotten about after they met
it's almost as if the last third of the book was written first and then they went back to write backstory separately but forgot there needs to be a plot
i get wanting to have background on the characters, but there has to be a way to do it without constant time jumps and no plot progression. Tessa's story jumps around a week lead up so much
also the band aspect is very much an afterthought in the novel
Spoilers--
one of the MMCs is openly pan and one of them has been dealing with a bi awakening but being somewhat defensive about it and once Tessa arrives that gets forgotten about til the epilogue and even then doesn't actually confront his sexuality
the wrap up of the church hiding her name is tied up with a quick sentence, but no real consequences for anyone
i honestly thought she forgot about family pack IRS deal until the final chapter and that gets resolved in an unsatisfying way
the pack is upset that Tessa gets viewed as an object and tricked into the contract but has no interest in making the company's wrongdoings public or trying to prevent this from happening to other omegas
tessa goes over a lot of struggles of homelessness but she only thinks about food waste once after joining the pack -- you'd think she'd use her newfound wealth and power to help other homeless individuals, especially youths and omegas. even a little side note to say that a portion of tour proceeds or her family fortune would go towards public food pantries and shelters would've done something to connect her beginning character to the end character
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Reviewed in the United States on August 3, 2025
★★★★★ 3
BORING and too long
Format: Kindle
I could not believe how wordy and boring this book was. No spice at all. Slow burn is really a NO burn. Almost DNF and now I’m sorry I stuck with it. 500 pages could ave been 150 and it would have been more than enough. I highly doubt not recommend this work of yuck.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 25, 2026
★★★★★ 4
Good read
Format: Kindle
Good book but good God was there a lot of preamble when I just wanted them to meet already haha
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on August 11, 2025
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