For this experiment, three populations of cells were used: (1) EpCAM+ MCF-7 cells adhered to glass coverslips; (2) CFSE-labeled Raji cells sequentially modified with DSPE-PEG2000-biotin and mSA/Fn3 CSANs; and (3) a second population of Raji cells labeled with CellTrace Far Red, DSPE-PEG2000-DBCO, and mSA CSANs oligomerized with azide-bisMTX, granting them the ability to target unoccupied biotin moieties on the CFSE-labeled Raji cells. (A) In the absence of CSANs, neither Raji cell population is able to adhere to the MCF-7 cell monolayer. (B) When functionalized with the CSANs, the two Raji cell populations are able to interact with each other and with the MCF-7 cell monolayer. (C) The cell-cell interactions are largely reversed when the CSAN scaffold is disassembled with trimethoprim. (D) As the Far Red-labeled Raji cells only have the capability of targeting biotin, they are unable to adhere to the MCF-7 cell monolayer in the absence of the CFSE-labeled Raji cells that were modified with DSPE-PEG2000-biotin. Scale bars represent 100 μm.