Assay Principle

The Human COL1α1 ELISA Kit (EJ1513531) employs a sandwich enzyme-linked immunosorbent assay (ELISA) format. In this method, a capture antibody specific to human COL1α1 is pre-coated onto the surface of a 96-well microplate. Standards, controls, and unknown samples are added to the wells, and any COL1α1 present binds to the immobilized capture antibody. After washing away unbound material, a biotinylated detection antibody targeting a distinct epitope of COL1α1 is added, forming a sandwich complex. Streptavidin-HRP conjugate is then applied, which binds to the biotin moiety. Following a final wash, a chromogenic substrate (typically TMB) is added and converted by HRP to a colored product. The reaction is stopped with an acid stop solution, and absorbance is measured at 450 nm. COL1α1 concentration in unknown samples is determined by interpolation from a standard curve.

Sample Preparation

Proper sample preparation is critical for accurate and reproducible results. Follow the guidelines below before proceeding to the assay procedure:

• Serum: Allow whole blood to clot at room temperature for 30 minutes. Centrifuge at 1,000–2,000 × g for 15 minutes at 2–8 °C. Collect the supernatant and avoid disturbing the clot. Use immediately or aliquot and store at −20 °C or −80 °C.
• Plasma: Collect blood into anticoagulant-containing tubes (e.g., EDTA or heparin). Centrifuge at 1,000–2,000 × g for 15 minutes at 2–8 °C. Collect the plasma layer carefully. Use immediately or store at −20 °C or −80 °C.
• Cell Culture Supernatants: Centrifuge samples to remove cells and debris. Test promptly or store at −80 °C in aliquots.
• Tissue Lysates: Homogenize tissue in an appropriate lysis buffer. Centrifuge to remove insoluble material. Determine total protein concentration and normalize samples before use.
• Dilution: If COL1α1 concentrations in samples are expected to exceed the upper limit of the standard curve, prepare serial dilutions in the provided sample diluent and apply the appropriate dilution factor when calculating results.
• Avoid: Repeated freeze-thaw cycles, hemolyzed or highly lipemic samples, and samples containing sodium azide, which may inhibit HRP activity.

Step-by-Step Assay Procedure

Before starting, bring all reagents and samples to room temperature (18–25 °C). Prepare standard dilutions according to the kit's standard curve preparation instructions. Perform all steps promptly and keep incubation times consistent across wells.

1. Standard Curve Preparation: Reconstitute the lyophilized standard with the volume of standard diluent specified in the kit insert. Prepare a series of dilutions to generate a standard curve spanning the kit's detection range. Include a blank (zero standard) in duplicate.
2. Sample and Standard Addition: Add 100 µL of standards, controls, and samples to the appropriate wells in duplicate. Seal the plate and incubate for the time and temperature specified in the kit insert (typically 90 minutes at 37 °C).
3. Washing: Discard the contents of the plate and wash each well with the provided wash buffer (typically 3–5 times). Blot the plate firmly on absorbent paper after the final wash to remove residual liquid.
4. Detection Antibody Addition: Add 100 µL of biotinylated anti-COL1α1 detection antibody to each well. Seal the plate and incubate as directed (typically 60 minutes at 37 °C).
5. Washing: Repeat the wash step as described above.
6. Streptavidin-HRP Addition: Add 100 µL of streptavidin-HRP conjugate to each well. Seal and incubate as directed (typically 30–45 minutes at 37 °C). Wash again.
7. Substrate Addition: Add 90–100 µL of TMB substrate solution to each well. Incubate in the dark for the specified time (typically 15–30 minutes at 37 °C). The solution should turn blue in wells containing COL1α1.
8. Stop Solution: Add 50 µL of stop solution to each well. The color will change from blue to yellow. Read absorbance at 450 nm within 10 minutes of adding the stop solution.

Note: Always refer to the specific kit insert provided with lot EJ1513531 for exact volumes, incubation times, and temperatures, as these may differ from the general guidance above.

Data Analysis & Standard Curve

After reading absorbance at 450 nm, subtract the mean absorbance of the blank (zero standard) wells from all other readings. Plot the corrected absorbance values (y-axis) against the corresponding COL1α1 standard concentrations (x-axis) to generate a standard curve. A four-parameter logistic (4PL) curve fit is recommended for best accuracy, and many ELISA data analysis software packages (e.g., MyAssays, SoftMax Pro) support this automatically.

To determine COL1α1 concentration in unknown samples, locate the sample's corrected absorbance on the y-axis, read across to the standard curve, and then down to the x-axis to obtain the concentration. If a sample was diluted prior to the assay, multiply the interpolated concentration by the dilution factor to obtain the actual concentration in the original sample.

Quality Control Criteria:

• The coefficient of variation (CV) between duplicate wells should be ≤15% for reliable results.
• Standard curve R² value should be ≥0.99 when using a 4PL fit.
• If control values fall outside acceptable ranges, repeat the assay.

Note: Specific detection range and sensitivity values are lot-dependent; consult the Certificate of Analysis (CoA) for lot EJ1513531 for exact figures.

Troubleshooting Common Issues

If unexpected results are obtained, consult the table of common issues below:

If issues persist after troubleshooting, contact Aladdin Scientific technical support with your lot number (EJ1513531) and a description of the problem.