Permeation Device Stirring Member Reduces Boundary Layer Thickness
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Solution Overview
Problem
Conventional in vitro drug absorption and transport assays, such as Caco-2 type cell assays and PAMPA, face challenges in accurately measuring permeability due to thick aqueous boundary layers, which are not adequately reduced by existing agitation methods, especially in high-density microtitre plates, leading to biased results for lipophilic compounds.
Innovation Solution
A permeation device with a receiving vessel and insert well, equipped with a stirring member that agitates the solution to reduce boundary layer thickness adjacent to the porous support, allowing for adjustable control of agitation to approximate in vivo conditions, with achievable boundary layer thicknesses as low as 15 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional agitation methods (orbital or linear plate shakers) are used to reduce aqueous boundary layer thickness, then boundary layer thickness is reduced to some extent, but the reduction is insufficient (cannot achieve below 300 to 500 μm) and anisotropy remains across microtitre plates
Solution Approach 1:
The invention divides the single-compartment system into two separate compartments (donor and acceptor), each with its own stirring mechanism. This segmentation allows independent control of boundary layers in each compartment, eliminating the anisotropy problem where edge compartments were better agitated than center compartments in conventional single-compartment systems.
Solution Approach 2:
The invention employs magnetic stirring members that can be dynamically controlled to provide adjustable agitation intensity in each compartment. The magnetic stirring members can be positioned at different locations and operated at different speeds, allowing dynamic adjustment of boundary layer thickness to achieve consistent results across all compartments of the microtitre plate.
2Productivity
If high-density microtitre plates are used to conduct numerous assays simultaneously, then productivity increases, but aqueous boundary layer thickness cannot be sufficiently reduced due to increased anisotropy and space constraints
Solution Approach 1:
By separating the assay system into two independent compartments with independent magnetic stirring, the invention enables effective boundary layer control in high-density plates where space is limited. Each compartment can be optimized independently, allowing accurate measurements even in the constrained geometry of high-density plate formats.
Solution Approach 2:
The invention replaces conventional mechanical plate shaking with magnetic stirring members that can be precisely controlled within each compartment. This substitution allows for more effective and uniform agitation in the limited space available in high-density microtitre plates, overcoming the anisotropy problem that plagues conventional mechanical shaking methods.
3Measurement precision
If solution agitation is increased to reduce aqueous boundary layer thickness, then boundary layer thickness decreases, but device complexity increases due to additional stirring mechanisms
Solution Approach 1:
The invention replaces complex mechanical stirring mechanisms (such as orbital or linear plate shakers) with simple magnetic stirring members that can be easily incorporated into each compartment. The magnetic stirring members are actuated by magnetic fields, eliminating the need for complex mechanical linkages and reducing overall device complexity while achieving effective boundary layer control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device effectively reduces aqueous boundary layer thickness, enabling more accurate permeation measurements that closely model in vivo absorption and transport conditions across the GIT and BBB, improving the reliability of drug absorption studies.
Implementation Method 1
A stirring member is disposed in the receiving vessel. The stirring member is operable to agitate a solution in the receiving vessel.
Implementation Method 2
The thickness of the aqueous boundary layers can be reduced by, for example, reducing the portion of solution that is substantially stagnant and adjacent to the porous support.
Data Source
AI summary
The invention provides a permeation device (2) comprising a receiving vessel (6) having an aperture adapted for receiving an insert well (4). Both the vessel (6) and well (4) are used as either donor or acceptor compartments for permeability assays. The vessel (6) or well (4) comprises a porous suppor (8)t, which may comprise biological or biomimetic materials, adapted for a molecular entity to permeate therethrough. In one embodiment, a stirring member (24) disposed in the vessel (6) can provide solution agitation to reduce aqueous boundary layer thickness adjacent to the support (8). Boundary layer thicknesses can be reduced by a device (2) of the invention to less than about 15 um such that a molecular entity permeating the support closely approximates in vivo absorption and transport conditions.