Assay miniaturization

Schullek JR, Butler JH, Ni ZJ, Chen D, Yuan ZY, A high-density screening format for encoded combinatorial libraries assay miniaturization and its application to enzymatic reactions, Anal. Biochem., 246 20-29, 1997. 

Assay miniaturization helps to reduce the consumption of very expensive assay reagents. The problems encountered as one attempts to miniaturize an assay relate to the change in surface-to-vol-ume ratio, lowered sensitivity, and low volume dispensing of materials. For instance, as one moves to smaller volumes, the surfaces available for unspecific binding increase relative to the volume. Furthermore, the smaller the volume, the less the amount of product-sensing material can be added thus the sensitivity of the assay is reduced. 

Technical, Biological, and Economical Limits for Assay Miniaturization in High-Density Plates... 

For cellular assays, miniaturized systems, such as EVOscreen, are capable of providing a superior solution the combination of sensitivity and miniaturization enables primary cells to be employed. The restrictions resulting from the availability of primary cells are overcome by the very small number of cells needed for each assay (100-1000 cells/nano-well). 

Key words Bacterial motility, Bacterial chemotaxis, Behavioral assays, Miniaturized plug-in-pond... 

The purpose of assay miniaturization is to stretch the reagent budget so more compounds can be screened with the same resources. If an assay can he scaled down from 200 pL to 50 pL, than four times the number of test compounds can be screened for the same reagent cost. 

The 384-well microplate is commercially available and several companies now supply instruments capable of reading 384-well plates. This has allowed experimentation with several homogenous assay methods to test the practicality and performance of assay miniaturization. The TopCount Microplate Scintillation and Luminescence Counter... 

The author wishes to recognize the contributions of the following Dr. s K. Neumann, M. Mercier for their work in assay miniaturization of SPA and HTRF, respectively Dr. E. Gjerstad of Roche Bioscience for sharing the data on the miniaturization of the luciferase reporter gene Dr. Gerard Mathis of CIS bio international for discussions on HTRF and J. Sitko and S. Rosen for their patience in the preparation of this manuscript. 

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