Controlled cell adhesion using a biocompatible anchor for membrane-conjugated bovine serum albumin/bovine serum albumin mixed layer.

We report here a method for controlling cell adhesion, allowing simple yet accurate cell detachment from the substrate, which is required for the establishment of new cytometry-based cell processing and analyzing methods. A biocompatible anchor for membrane (BAM) was conjugated with bovine serum albumin (BSA) to produce a cell-anchoring agent (BAM-BSA). By coating polystyrene substrates with a mixture of BAM-BSA and BSA, controlled suppression of the substrate's adhesive properties was achieved. Hook-shaped nanoneedles were used to pick up cells from the substrate, while recording the cell-substrate adhesion force, using an atomic force microscope (AFM). Due to the lipid bilayer targeting property of BAM, the coated surface showed constant adhesion forces for various cell lines, and controlling the BAM-BSA/BSA ratio enabled tuning of the adhesion force, ranging from several tens of nano-Newtons down to several nano-Newtons. Optimized tuning of the adhesion force also enabled the detachment of cells from BAM-BSA/BSA-coated dishes, using a shear flow. Moreover, the method was shown to be noncell type specific and similar results were observed using four different cell types, including nonadherent cells. The attenuation of cell adhesion was also used to enable the collection of single cells by capillary aspiration. Thus, this versatile and relatively simple method can be used to control the adhesion of various cell types to substrates.