Gyrolab automated platform – faster delivery of immunoassay data and more information per data point

Automated immunoassays enable robust running of assays with reproducible results and reduced hands-on time. The Gyrolab^® platform runs automated immunoassays with nanoliter sample volumes, replacing ELISA and other plate-based methods. Gyrolab method development is fast, the assay time is short and the automation allows for walk-away and overnight running. In addition, the small volumes save precious samples and expensive reagents. The output from the Gyrolab runs also provides extra information. Each data value is associated with a fluorescent column profile. Here we describe how the profiles can be used for method development, trouble-shooting and to detect true data outliers.

More data per data point

In the Gyrolab microfluidic platform samples and reagents are automatically delivered to miniaturized streptavidin columns (15 nL) on rotating discs. Biotinylated capture reagents bind to the columns and analytes are detected by Alexa Fluor™ 647 labeled detection reagents. The flow-through format makes the assays tolerant to various biological matrices. While the system is easy to use and can be run in an operator-independent manner, the output from the Gyrolab runs also provides extra information. Each data value is associated with a fluorescent column profile where profile shape and intensity give details on antibody affinity and a quality assessment of the results.

Column viewer profiles can for example be used for:

1.  Assay optimization and affinity characterization  

   The column profiles can guide the selection of antibody pairs, as it will inform on antibody-analyte interactions, or help optimize other assay parameters. In this example the column profiles were used to screen antibody clones to select candidates for the development of robust assays. High-affinity clones have a sharp dose response peak that is shifted to the left. Right shifted broad peaks represent lower affinity interactions.    

   
     

   Overlay of standard curves generated for multiple antibody clones using the same analyte concentrations. Example column profiles for each of the 6 clones assessed demonstrate the utility of the viewer profiles, identifying where the whole peak falls within the integration area (white square) 
   
   

2. Trouble shooting
   Replicates that fall outside assay criteria will be highlighted by the Gyrolab Evaluator software. The example below highlights the effect of a blocked column. This is most often caused by particles in the liquids passing through the capture column and can be solved by centrifugation or filtration of samples and other liquids. 
   
   
   Replicates of the same sample show a large deviation and this is highlighted by the software. Inspection of the column profiles indicates that one data point is of good quality (bottom), while the other data point has excess fluorescence at the top of the column (top), outside the area of detection (white square). This indicates a blocked column structure likely caused by particles in the solutions and can be excluded.  
   
   
3.  Identifying outliers  
   What do you do if duplicate or triplicate measurements of the same sample show large variation in response values? Can the outlier be excluded? The column profiles can reveal spikes caused by contaminations in sample, reagents and wash solutions, most commonly in the detection reagent. In the figure below, two samples show well behaved peaks and the third sample shows spikes. This outlier can be removed. 
   
   Montage showing a scenario where two out of three sample replicates are proper data points while the third (right) shows spikes from a contamination in one of the assay solutions. This identifies the third response value as a true outlier, allowing us to remove it 
   
   

Conclusions:

• The walk-away automation of Gyrolab immunoassays gives reproducible data, fast assay turnaround time, with small volume requirements
• Column profiles provide additional information and enable informed decisions
  
  

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