Abstract
Protein-based cell microarray is a powerful tool used in both clinical diagnostics and fundamental researches. Protein such as antibodies were immobilized on the surface through covalent bond and the composition of cell mixture and characteristic of surface proteins could be determined in single assay within several minutes using this technology. However, the cell of interest after screening could not be released from cell microarray chip due to the unchangeable property of the microarray chip substrate. An intelligent surface with intrinsic thermoresponsive property could be used to improve surface property for cell release. Poly N-isopropylacrylamide (pNIPAAM) is a temperature sensitive hydrogel, which have been extensively studied in grafting on many kinds of surfaces due to its unique properties, such as its lower critical solution temperature (LCST) around 32-33℃ in aqueous solution, and the anti-fouling characteristic in room temperature. Poly N-isopropylacrylamide has been applied to the separation of biomolecules in the form of chromatographic matrices and cell substrates. Temperature dependent hydrophobic-hydrophilic changeable surface which is grafted by pNIPAAm (Poly N-isopropylacrylamide) have also been used for controllable capture and release of proteins in microfluidic devices. In this paper, a surface was fabricated by grafting thermo-responsive polymer to PDMS (Polydimethylsiloxane) for cell capture and release, and the difference in surface hydrophobicity were demonstrated by contact angle change and the binding of hydrophobic polystyrene beads to the surface. Furthermore, polystyrene beads that were modified with antibodies for cell recognition also showed activity to bind to cell surface through antibody-antigen interaction. The cells stained with conjugates of the antibody and polystyrene beads were applied to the surface to test the capture and release at different temperature. Polystyrene beads show the capability of both selection of specific cells and assisting the binding of cells to pNIPAAm surface through hydrophobic interaction. This research presents the idea of utilizing temperature-controlled hydrophobic interaction for capturing and releasing cells. It seeks to combine antibody-antigen interaction and cell sorting system to improve the specificity. This platform can be optimized and applied to provide further collection of cells of interest from protein-based cell microarray.