Patent ID: 7556928

Claim:
A method of screening a population of cells for a sub-population having a desired property, comprising: (a) encapsulating a population of cells in microdrops at a first ratio of average number of cells per occupied microdrop, wherein the microdrop is a biotinylated microdrop comprising matrix component molecules, first biotin molecules linked to the matrix component molecules, capture molecules with affinity for a molecule secreted by a cell linked to second biotin molecules, and streptavidin linking the first and second biotin molecules, the first biotin molecules and the matrix component molecules being in a molar ratio of from 0.2 to 0.01 moles biotin per mole matrix component molecules, and wherein the molecule, if any, secreted from the cell binds to the capture molecules thereby being retained within the microdrop; (b) screening the encapsulated cells to detect the secreted molecule and identify a first sub-population of microdrops encapsulating cells having the desired property; (c) isolating the cells from the microdrops resulting from the screening step; (d) encapsulating the isolated cells from the screening step at a second ratio of average number of cells per occupied biotinylated microdrop, the second ratio being smaller than the first ratio; and (e) screening the encapulsated cells to detect the secreted molecule and identify a second sub-population of microdrops encapsulating cells having the desired property.