Protein Adsorption and Cell Adhesion/Detachment Behavior on Dual-Responsive Silicon Surfaces Modified with Poly(N-isopropylacrylamide)-block-polystyrene Copolymer

Abstract

Diblock copolymer grafts covalently attached to surfaces have attracted considerable attention because of their special structure and novel properties. In this work, poly(N-isopropylacrylamide)-block-polystyrene (PNIPAAm-b-PS) brushes were prepared via surface-initiated consecutive atom-transfer radical polymerization on initiator-immobilized silicon. Because of the inherent thermosensitivity of PNIPAAm and the hydrophobicity difference between the two blocks, the modified surfaces were responsive to both temperature and solvent. Moreover, the diblock copolymer brushes exhibited both resistance to nonspecific protein adsorption and unique cell interaction properties. They showed strong protein resistance in both phosphate-buffered saline and blood plasma. In particular, fibrinogen adsorption from plasma at either room temperature or body temperature was less than 8 ng/cm(2), suggesting that the surfaces might possess good blood compatibility. In addition, the adhesion and detachment of L929 cells could be "tuned", and the ability to control the detachment of cells thermally was restored by block polymerization of hydrophobic, cell-adhesive PS onto a thicker PNIPAAm layer. In addition to providing a simple and effective design for advanced cell-culture surfaces, these results suggest new biomedical applications for PNIPAAm.

Surface Modification to Control Protein/Surface Interactions

“…PS was chosen as the second block because it is a typical hydrophobic polymer and is widely used in cell culture applications (Scheme 3B). [63] As expected, we found that the adhesion and detachment of L929 cells could be more finely ''tuned'' using these materials. Thermoresponsive control of the adhesion/detachment of cells was again seen on block copolymer surfaces where initial PNIPAAm blocks (attached to the surface) were coupled to distal PS blocks.…”

A Survey of Surface Modification Techniques for Next-Generation Shape Memory Polymer Stent Devices

“…These patterns either encourage or discourage protein adsorption and/or cell adhesion, depending on the polymers involved. For this reason, diblock copolymers have been investigated with regard to surface energy or topography, and are being explored for their potential uses in reference to bioactivity [56].…”

Controlled Surface Initiated Polymerization of N‐Isopropylacrylamide from Polycaprolactone Substrates for Regulating Cell Attachment and Detachment

“…[51] However, if the RGD was attached to the middle section of the PMAA brush, cells were found to adopt a rounded morphology and focal adhesions concentrated toward the internal part of the cell. [51] Besides the already mentioned non-biofouling and cell adhesive brushes, there are also brushes that can be used to tune the cellular behavior, for instance by employing thermoresponsive polymers such as, PNIPAM [4][5][52][53][54][55][56] and poly(2-(2-methoxyethoxy)ethyl methacrylate-cooligo(ethylene glycol) methacrylate) (P(MEO 2 MA-co-OEGMA)). [52][53][54][57][58][59][60][61][62][63] These two polymers trigger a different cellular response above and below their critical solution temperature (LCST) due to a change in chain conformation and variations in intra-and intermolecular interactions around the LCST in these polymers.…”