Noncell-Based Assays Parallel Artificial Membrane Permeability Assay

Noncell-Based Assays Parallel Artificial Membrane Permeability Assay 

In contrast to cell-based assays, noncell-based permeability assays using artificial membranes supported on filters are fast, flexible, cheap, and fully automatable. They are therefore ideally placed for use in high throughput. There have been many variations of this assay in terms of the fine details of the experiment and these will be discussed in due course however, the basic principles remain the same, based on a 96-well microtiter plate format. 

A sandwich is formed from two plates, a donor plate and a receiver plate. The donor plate is usually of a specially designed geometry, available from pION Inc. for use with its Evolution system and GUT box or from Millipore Inc. These plates are machined to minimize vortexing during shaking so that the buffer solution remains in contact with the lower surface of the receiver plate at all times without the formation of a meniscus. The receiver is a 96-well microfilter plate. The filters are generally 125 pm thick with 0.45 pm pores and 0.3 cm2 cross-sectional area with 70% 

Assembled PAMPA sandwich, solute begins to permeate 

After the samples have been incubated for the chosen time, the plates are separated and aliquots removed from both donor and receiver wells and the concentration of the solute determined. This is most commonly carried out by using H P LC, LC/ M S, or UV plate reader detection. 

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