Surface Modification of a Polycaprolactone Nanoporous Membrane with Poly(ethylene glycol) by Using Oxygen Plasma to Prevent Fibroblast Adhesion

The adhesion and proliferation of fibroblast onto the surface of an implant drug delivery device can lead to fibrous tissue encapsulation and limit the performance. Therefore, the development of an anti-biofouling surface is necessary for the implantable biomedical devices.

Poly(ethylene glycol) (PEG) is a nontoxic and nonimmunogenic polymer. PEG has the ability to inhibit cell adhesion on a surface due to its hydrophilicity, steric hindrance, and chain mobility. To produce a nonfouling surface, a simple and efficient method was proposed for grafting PEG on the polycaprolactone (PCL) nanoporous membrane surface. In this study, PEG-monoacrylates were pre-coated on the PCL membrane surface by soaking the membranes into the PEG-monoacrylate solutions. After complete drying, PEG could be successfully bonded on the PCL membranes with the aid of oxygen plasma treatment.

Initially, plasma treatment conditions have to be optimized to prevent cell adhesion. X-ray photoelectron spectroscopy (XPS) revealed that the surface composition of each membrane can be changed by using different plasma powers and treatment times. With application of lower plasma power and shorter treatment time, higher quality of PEG grafting can be obtained.

Different grafting densities, PEG chain lengths and several parameters in the precoating process were investigated. Upon the treatment, the water contact angle was decreased, suggesting the existence of hydrophilic PEG on the surface. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) spectra indicated that PEG was successfully grafted onto the PCL membrane with the appearance of the PEG characteristic peaks (1100cm-1). Cell morphology on the membranes was observed by using a fluorescent microscopy.