Phase Transition Behavior, Protein Adsorption, and Cell Adhesion Resistance of Poly(ethylene glycol) Cross-Linked Microgel Particles

• Published in: Biomacromolecules Vol. 6; no. 4; pp. 2032 - 2039
• Main Authors: Nolan, Christine M, Reyes, Catherine D, Debord, Justin D, García, Andrés J, Lyon, L. Andrew
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-07-2005
• Subjects: Adsorption; Animals; Applied sciences; Biocompatible Materials; Cell Adhesion; Exact sciences and technology; Magnetic Resonance Spectroscopy; Mice; NIH 3T3 Cells; Organic polymers; Physicochemistry of polymers; Polyethylene Glycols - chemistry; Properties and characterization; Proteins - chemistry; Solution and gel properties; Biological properties; Cell culture; Liquid solid adsorption; Adsorption capacity; Temperature effect; Acrylamide derivative copolymer; Serum albumin; Ethylene oxide copolymer; Experimental study; Adhesion; Phase transitions; Protein; Ethylene oxide polymer; Biofouling; Preparation; Biocompatibility; Microgel; Acrylate copolymer; Prepolymer; Radical copolymerization; Fibroblast
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm0500087

Thermoresponsive poly(N-isopropylacrylamide) (pNIPAm) microgel particles cross-linked with various concentrations of PEG diacrylates of 3 different PEG chain lengths were synthesized via free-radical precipitation polymerization in order to investigate the phase transition and protein adsorption behavior as the hydrophilicity of the network is increased. Photon correlation spectroscopy (PCS) reveals that, as the concentration of PEG cross-linker incorporated into the particles is increased, an increase in the temperature and breadth of the phase transition occurs. Qualitative differences in particle density using isopycnic centrifugation confirm that higher PEG concentrations result in denser networks. The efficient incorporation of PEG cross-linker was confirmed with 1H NMR, and variable temperature NMR studies suggest that, in the deswollen state, the longer PEG cross-links protrude from the dense globular network. This behavior apparently manifests itself as a decrease in nonspecific protein adsorption with increasing PEG length and content. Furthermore, when electrostatically attached to a glass surface, the particles containing the longer chain lengths exhibited enhanced nonfouling behavior and were resistant to cell adhesion in serum-containing media. The excellent performance of these particulate films and the simplicity with which they are assembled suggests that they may be applicable in a wide range of applications where nonfouling coatings are required.