Technology - Screening Facility > Pin Transfer of Compounds... > Pin Array Technology

• Why use pin arrays?
• Pin Array Calibration
• Pin Array Selection

Why use pin arrays to transfer compound?

Pin arrays are preferred compound transfer tools at the ICCB-Longwood because they conserve reagents, are cost effective and are compatible with the types of assays carried out in our facility. Compound libraries are stored in DMSO. Typically, it is desirable that the amount of DMSO transferred to an assay well is less than 5% of the final well volume (in most cases, <1% is preferred). Since assay volumes range from 2µl (in 1536 well plates) to 50µl (in 384 well plates), 20nl to 100nl amounts of compound stock solution should be transferred to maintain the DMSO concentration in the desirable range. Most commercial pipetting systems cannot accurately pipette less than 100nl of compound and many of these systems are quite costly and slow. We have found that stainless steel pins can reliably transfer 20-100nl of small molecules in DMSO into assay plates. CVs are typically on the order of 20%, which is acceptable for conducting primary screening of compound libraries. The pin array can be rapidly washed and reused with less than 1% carryover. We have successfully used pin arrays to transfer compounds from 384-well compound storage plates (containing a minimum of 7µl of stock solution) into 96-well, 384-well or 1536-well assay plates. Another key advantage of the pin transfer system is cost effectiveness. Steel pin arrays are much less expensive than a corresponding array of pipet heads and do not require the purchase and disposal of pipet tips. Therefore, the only consumable cost for the entire system is the methanol used to wash the pin arrays between each compound transfer.

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Pin Array Calibration

To insure accurate and reproducible pin transfer of compounds to assay plates, the ICCB-Longwood pin arrays are calibrated routinely several times a year.  Calibration is also carried out when new pin arrays are received and when existing pin arrays are refurbished.  The calibration protocol uses rhodamine 110 (rhodamine green) dissolved in DMSO in the source plate (compound stock plate) and PBS in the target plate (assay plate).  Click here for the Calibration Protocol. 

The tables below show current calibration data for the ICCB-Longwood pin arrays.  Note that new pin arrays and new instruments require fine-tuning to optimize their performance and the below data represents work in progress for some instruments.

Seiko Pin Array Calibration Summary

Epson Pin Array Calibration Summary

CyBio Vario Pin Array Calibration Summary

* Calibration Pending

Pin Array Name: CyBio Vario Low Volume

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Pin Array Selection

Using a standard 384-well assay plate with 25-50µl volume per well, several pin array options are available to achieve a final compound concentration of approximately 10-50µM. We have found this concentration range to be reasonable for most cell-based and purified protein assays. If a higher compound concentration is required, multiple iterations of pin transfer may be performed.

The table below lists pin arrays, the volume of compound transferred, and the approximate final concentration at different assay volumes, assuming a 10mM compound stock solution (see the compound library page for actual concentrations of each library).

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