Structural effect of poly(ethylene glycol) segmental length on biofouling and hemocompatibility

Abstract

Although numerous studies have focused on poly(ethylene glycol) methyl ether methacrylate (PEGMA) hydrogels, the effect of the molecular weight and crosslinking of the monomer in its nonfouling properties remains poorly understood. Here, we prepared a series of PEGMA hydrogels from monomers of various chain lengths and identified structure/property correlations. The results revealed that the hydrogel hydration capacity depended on the chain length and crosslinking (from X-ray photoelectron spectroscopy analysis): for a similar initial amount of crosslinker, a lower monomer molecular weight resulted in a higher degree of crosslinking and a lower level of hydration. Protein (fibrinogen, lysozyme, human and bovine serum albumin) adsorption and bacterial attachment tests indicated that the structure of the PEGMA 500 hydrogel was suitable (chain length, crosslinking) to minimize biofouling. A higher monomer molecular weight (as in PEGMA 950) was associated with a higher hydrophilicity, but excessive free water in the cavities likely mediated foulant diffusion and trapping in the network. Conversely, a lower monomer molecular weight did not permit sufficient hydration to form a protective layer against fouling. These results were supported by blood cell (erythrocytes, leukocytes and thrombocytes) adhesion tests, suggesting that hemocompatibility can also be finely tuned by carefully selecting the monomer that constitutes the hydrogels.