R&D Systems ELISA for human CXCL12/SDF-1α

Judith Sunzenauer (last update 11.6.2013)

Procedures

Preparation:

• Bring all reagents and samples to room temperature before use.
• Run duplicates.
• Samples: an additional centrifugation step at 10.000xg for 10min at 4°C is necessary. Dilute EDTA plasma samples 1:4 with Calibrator Diluent RD6Q.
• Prepare Wash Buffer: Add 20ml of Wash Buffer Concentrate to 480ml a.dest (1:25 Dilution)
• Reconstitute CXCL12 Standard: add 1ml a.dest to vial of CXCL12 Standard (concentration of stock: 100.000pg/ml). Allow the standard to sit for a minimum of 30min prior to making dilutions.

• Produce the dilution series for CXCL12 Standardcurve:

Prepare 8 prelabeled polypropylene tubes and fill each tube with 500µl of Calibrator Diluent RD6Q excluding #1 which is filled with 900µl. Transfer 100µl Standard from the original vial to tube #1, mix thoroughly and transfer 500µl from tube #1 to #2,….. continue until tube #7. Fill tube #8 with Calibrator Diluent RD6Q.

Assay Procedure:

• Add 100µl of Assay Diluent RD1-55 to each well.
• Add 100µl of Standard Dilution #1-8 or sample per well.
• Seal the Plate and incubate 2h at room temperature on a horizontal orbital microplate shaker set at 500rpm.

• Aspirate each well.
• Wash 4 times with 400µl Wash Buffer.
• After the last wash, remove any remaining liquid and invert the plate and blot it against clean paper towels.
• Add 200µl of CXCL12/SDF1a Conjugate to each well.
• Seal and incubate for 2h at RT on the shaker.

Prepare Substrate Solution: mix color Reagents A and B in equal volumes within 15min of use. Protect from light!

• Wash 4 times with 400µl Wash Buffer.
• Add 200µl of Substrate Solution to each well.
• Incubate for 30min at RT and protect from light.

• Add 50µl Stop Solution to each well. Gently tap the plate to ensure mixing.
• Determine the OD at 450nm within 30min. Set wavelength correction to 540nm or 570nm.

Calculation of Results:

• If samples have been diluted, the concentration read from the standard curve must be multiplied by the dilution factor.
• Concentrations of the Standard Dilutions:

Sensitivity:

Handling Photometer + Software:

Make sure the laser is warmed up prior to scanning for 15min

Materials