Assay Solution AN0101

AN0101: Mouse TGF-β1 ELISA with Optimiser™ Microplates

Assay Solution for R&D Systems Mouse TGF-β1 DuoSet (Catalog Number DY1679)

Junhai Kai; Research & Development Group, MiCo BioMed, Cincinnati, OH USA

Introduction:

MiCo BioMed’ Optimiser™-based ELISAs offer a rapid, sensitive, and specific chemifluorescent-based ELISA procedure for the measurement of analytes using very small sample volumes. The Optimiser™ plate is SBS/ANSI-compliant and is compatible with traditional 96-well microplate instrumentation.

A mouse Transforming Growth Factor beta 1 (TGF-β1) ELISA (R&D Systems Catalog Number DY1679) has been successfully transferred from a conventional 96-well ELISA plate format to the Optimiser™ microplate platform to achieve the following key performance benefits.

• Sample Volume: 5 μl • Assay time: Total assay time ~ 2 hours (~ 4.5 hour savings) • Assay reagents: 80% saving on antibody use 75 assays for the cost of 15 • Sensitivity/Range: Equivalent sensitivity/range (31.2 – 2000 pg/ml) • Potential to increase sensitivity to ~ 1.6 pg/ml • Potential to achieve 3-log dynamic range: 31.2 – 22,800 pg/ml

Optimiser™ Method Development Process:

Please refer to the Assay Transfer Guide (Technical Support section of MiCo BioMed’s website) for details on the method development process. Each process step listed below requires 1 microplate (conventional for Step 1) and represents 1 experiment. In Step 2, the optimal coating buffer is selected from a panel of 12 coating buffers developed by MiCo BioMed.

Step 1:	Run a conventional ELISA to verify that the assay reagents perform as stated by the vendor(s). The mouse TGF-β1 reagents were tested in a high-binding NUNC plate according to the protocol provided by the vendor. The operating range was confirmed to be 31.2 – 2000 pg/ml as stated by vendor.
Step 2:	Select the optimal coating buffer for use with the Optimiser™-based ELISA. The coating buffer screening test showed that OptiBind™-G allows for most efficient binding of capture antibody to microfluidic channel surface.
Step 3:	Run antibody titrations to select the optimal capture and detection antibody concentrations. The titration study shows that 16 µg/ml of capture and 0.3 µg/ml of detection antibody exhibit best performance. As described further, this Optimiser™-based ELISA is more sensitive than a conventional plate ELISA and the user should determine the optimal antibody concentrations to maximize savings and achieve desired operating range.

Note that while capture and detection antibody concentrations for Optimiser™-based ELISAs may be 2 -4 times greater than those used in conventional ELISAs; the total quantity of antibody used in Optimiser™-based methods is significantly lower than that used in conventional ELISAs due to the much smaller reagent volumes used in the Optimiser™-based methods. Furthermore, sensitivity can be readily “tuned” for Optimiser™-based ELISAs using the repeat loading approach and antibody use can be further minimized if desired.

Comparison of Antibody Requirements for Conventional and Optimiser™-based ELISAs.

Antibody Method Ab Concentration (μg/mL) Ab Vol./well (μL) Ab/Plate (μg) Savings Capture antibody Conventional* 4 100 40 80% (With 4 μg coating Ab, either ~1 conventional plate or ~5 Optimiser™ plates can be run )** Optimiser™ 16 5 8 Detection antibody Conventional* 0.075 100 0.74 80% (With 0.74 μg coating Ab, either ~1 conventional plate or ~5 Optimiser™ plates can be run )** Optimiser™ 0.3 5 0.15

*Vendor recommendation **Using material provided in listed catalog #’s

 

Optimiser™-Based ELISA and Results for Mouse TGF-β1:

The detailed procedure for this Optimiser™-based ELISA is contained in a companion document (User Manual or Detailed Experimental Protocol). The materials used in the procedure are specified in the Materials Table.

Brief assay protocol Add 5 µl of anti-mouse (Ms) TGF-β1 capture antibody (16 µg/ml in OptiBind™-G); incubate for 10 min at RT. Add 5 μl of OptiWash™; wait 10 min. Add 5 μl of OptiBlock™; incubate for 10 min at RT. Add 5 µl recombinant (r) standard, control, and samples; incubate 20 min at RT. (Prepare rMs TGF-β1 in OptiBlock™ and samples in matrix-specific diluent) Add 5 μl of OptiWash™; wait 10 min. Add 5 µl of biotinylated anti-Ms TGF-β1 detection antibody (0.3 µg/ml in OptiBlock™); incubate for 10 min at RT Add 5 μl of OptiWash™; wait 10 min. Add 5 µl of MiCo BioMed’s SAv-HRP (OMR-HRP) (1:150 diluted in OptiBlock™); incubate for 10 min at RT Add 30 μl of OptiWash™; wait 10 min. Repeat step. Add 10 μl of OptiGlow™; wait 15 min; read.

The plate is read using an FLx800™ Fluorescence Microplate Reader (BioTek Instruments, Inc.) equipped with a 528/20 nm excitation filter and a 590/35 nm emission filter with a sensitivity setting of 44. The data is analyzed using Gen5™ software (BioTek Instruments, Inc.) and a standard curve is created by plotting Mouse TGF-β1 concentration vs background-adjusted RFU using a 4-parameter curve fit.

The standard curve range for the Optimiser™-based ELISA developed for Mouse TGF-β1 developed with R&D Systems’ Mouse TGF-β1 DuoSet (Catalog Number DY1679) is 31.2 – 2000 pg/mL. The range illustrated in R&D Systems’ Technical Data Sheet in which the same reagents were used in a conventional ELISA is 31.2 to 2000 pg/mL. The Optimiser™-based ELISA realized actual savings in time and labor (≈ 50%), capture antibody (80%) and detection antibody (80%) (Reagent Savings Table) when compared with a conventional ELISA using the same materials at the vendor’s recommended concentrations. A further ≈ 95% savings in sample volume would be expected. Using the methods outlined in Application Notes (Technical Support section of MiCo BioMed’s website), the sensitivity of this assay can be projected at ~ 1.6 pg/ml using the 20x sample repeat loading method and/or the operating range can be extended to ~3 Logs using the modified substrate ratio.

 

Materials Used:

 

Material	Vendor	Vendor’s Catalog #	Vendor Contact
Mouse TGF-β1 DuoSet	R&D Systems	DY16791	www.rndsystems.com
NUNC Maxisorp microplate	Thermo Scientific	456537	1-800-625-4327
Optimiser™ microplate (with Holder) 2	MiCo BioMed	OPH-10	www.micobiomed-usa.com Product categories: • Optimiser™ microplates • OptiMax™ buffers
Polypropylene v-bottom plate		OPT/FL-231
Coat buffer test panel 3		OMR-TEST
Buffer reagent pack (with substrate) 2		OMR-10-G
Streptavidin-HRP for Optimiser™		OMR-HRP

1 Capture and detection antibodies, rMs TGF-β1 from the Duoset have been used.

2 Optimiser™ plates and corresponding OptiMax™ buffer reagents are also available in 2-plate and 50-plate configuration.

3 OMR-TEST is required only for assay transfer. FOR RESEARCH USE ONLY. Not for use in diagnostic procedures.