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Quansys FAQs

How does this array work?

The Q-Plex technology consists of a printed array of capture antibodies to a variety of biological markers. The user adds an antigen standard and samples to individual wells of a 96-well plate. After incubation and washing, a mixture of biotinylated antibodies is added to the plate. This is followed by incubating with streptavidin-HRP or -dye and is completed by capturing the light produced from adding chemiluminescent substrate with an imaging system. Pixel intensity values from the images are used to construct a standard curve and calculate the concentrations of the unknown sample for each system. Please visit this webpage for a detailed description of our technology.

Are the results quantitative?

Yes, the array uses a standard curve to accurately quantify samples and the curve has been designed to encompass the biological ranges for individual proteins.

Does the standard curve encompass the lower limit of detection (LLD) for each cytokine?

The LLD is the lowest concentration of an analyte where its signal is distinguishable from the background (2 times the standard deviation of the mean of the background). This is different than the lower limit of quantification (LLOQ) which is the lowest concentration of an analyte that can be accurately measured. In many cases the typical standard curve does not reach the LLD nor the LLOQ for a given protein. The user has an option of using additional dilutions of the antigen mix to achieve the lower limit of quantification (LLOQ) for a given protein. A quick determination of LLOQ is to examine the backfit of your regression analysis and determine where the model no longer predicts within 80-120% of the actual standard value. I.E. the LLOQ is the lowest point where the backfit is within 80-120% of its corresponding value on the standard curve.

How should I dilute my sample if I expect a high response for one bio marker and a low response for another?

We recommend testing each sample in step dilutions. For example, when testing cell culture supernatant for unknown cytokine concentrations; a 1:2, a 1:10, and a 1:50 dilution are typically used.

Will different CCD and CMOS cameras give different pixel intensities and how will this affect my assay?

Yes, different CCD cameras give different pixel intensities based on the sensitivity of the camera. However, this will not affect assay performance or standard curve generation as the pixel intensities are relative values.

Do I have to use the entire 96 well plate in one assay?

Once the lyophilized reagents are reconstituted they should be used immediately. If the user desires to run several assays using the 96 well plate, we recommend the user purchase the Q-Plex Stripwell kits. These kits come with additional reagents for multiple testing periods. However, customers can use regular retail kits as long as the contents are stored properly. The reconstituted antigen standards should be immediately aliquoted and frozen at -20°C. The entire kit contents should be used within one week of reconstitution. Detailed information on kit storage after reconstitution can be found in the User’s manual.

Can I stop the assay once I start it?

No, for best results it is recommended that the assay be completed once started. After reading the results with a camera, the user has the option to delay data analysis to a convenient time. The IR plate may be read at any time after completion of the assay

What additional equipment (not provided in the kit) are required to run this assay?

The user will need to provide a pipette and imager. We also recommend an automatic plate washer and multichannel pipette for best results.

What imagers can be used to image the Quansys Multiplex ELISA plate?

Q-View™ Imager and Software:

Engineered for minimal optical distortion and automated via Q-View Software.  This is recommended for the acquisition of the chemiluminescent signal and quantification of spot intensity for the Q Plex™ multiplex ELISA arrays from Quansys Biosciences and PBL Assay Sciences.

How is the data gathered from the CCD imager analyzed?

The Q-View Software allows the user to open the plate image, mark the spots, input well assignements and select the product type. The software then automatically analyzes the pixel intensity of individual spots on the plate and process the data. All customers can download a free trial of the software and have full access for 20 days. After 20 days, the software becomes the trial version which will still process images and calculate raw data but will not perform regression analysis. Please contact us for more information on Q-View Software or visit this webpage.

What kind of samples can be run in the Quansys Multiplex ELISA Array?

The Q-Plex Array has been tested with serum, plasma, urine, and cell and tissue lysate. We have experienced no interference from FBS, 1% NP-40, 1% Tween, 1% Triton X-100, heparin (30 mg/ml), 1M urea, 20 mM EDTA, 20% citrate. SDS has been shown to interfere with the assay. Human samples containing human antibodies must be diluted 1:2 in the provided sample dilution buffer to remove potential false postives. If tissue homogenates or cell lysates are used, centrifuging is recommended to clarify samples prior to using in the assay. When using tissue homogenates, we recommend preparation in a protein-free buffer so that samples can be tested for total protein to normalize cytokine responses.

How much sample is required for the Quansys Multiplex ELISA Array?

The Q-Plex Array requires 30 µl—50 µl for mouse kits—total volume per well (sample plus diluent). Smaller sample volumes may be used when high levels of detectable proteins are anticipated. Samples containing antibodies MUST be diluted 1:2 in sample dilution buffer prior to running the assay.

How long does it take to complete the Quansys Multiplex ELISA protocol?

Most protocols require as little as two and a half hours for completion including analysis with the Q-View Software.

How much variance does the Quansys Multiplex ELISA array have?

The Quansys Multiplex ELISA assay has <15% CV between kit lots. Samples are usually linear out to a 1 to 64 dilution.

I don’t have access to a CCD camera system. Is there a testing service?

Yes, your samples can be mailed to tebu-bio where they will be tested using the Quansys Multiplex ELISA platform. Data, along with statistical analyses will be provided to the user within two weeks. Please call for shipping details and pricing.