Photoinduced detachment of cells adhered on 2-methacryloyloxyethyl phosphorylcholine polymer with cell binding molecule through photocleavable linkage

We prepared a novel substrate that its surface properties, e.g., cell adhesivity can be precisely and independently controlled by photoirradiation. The control of surface properties was achieved through an amphiphilic photoresponsive polymer; poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)-co-4-[4-(1-hydroxyethyl)-2-methoxy-5-nitrophenoxy]butyric acid (PL)) (PMB-PL). The PL unit can be cleaved into two parts via the external photoirradiation, which allows a successful detachment of cells adhered on the material surface. We immobilized epidermal growth factor (EGF) onto PMB-PL surface through a condensation reaction with carbonyl group on PL units to increase binding ability to specific cells. The EGF receptor overexpressed human skin epidermoid carcinoma epithelial cells (A431 cells) were used as a model cell line. The number of adhered cells was significantly increased on the EGF conjugated surface comparing to bare PMB-PL surface, although there was no cell attachment observed on poly(MPC-co-BMA) surface. The surface immobilized EGF also helped to enlarge the adherent areas of cell morphologies on surface, in contrast with an observation of round-shaped morphologies of adhered cells on bare PMB-PL surface. A simple photoirradiation procedure caused a successful detachment of adherent cells from the surface both PMB-PLs without and with immobilized EGF. The detached cells by photoirradiation were exhibited a very high cell viability and active proliferation rate as well as the non-irradiated control cells. Here, we demonstrated an easy way to immobilize biologically active molecules onto PMB-PL surfaces. We observed that immobilized bioactive molecules clearly affect the cellular morphologies and increase the efficiency of photoinduced detachment from the surface. We believe that the PMB-PL substrate can be a promising cell-collection platform for cell-based analysis through immobilized bioactive molecules, e.g., EGF that controls cellular behavior on 2D surface.