Functional, uniform, and macroporous latex particles:: Preparation, electron microscopic characterization, and nonspecific protein adsorption properties

A series of uniform, macroporous particles with different surface chemistries were prepared with different acrylic comonomers [methyl methacrylate (MMA), butyl methacrylate (BMA), epoxypropyl methacrylate, (EPMA), 2-hydroxyethyl methacrylate (HEMA), and methacrylic acid (MAA)] with styrene-divinylbenzene (S-DVB) in a multistep seeded polymerization. In the synthesis, uniform polystyrene seed particles 6.2 mum in size were swollen first with a low molecular weight organic agent and then with a monomer phase including an S-DVB mixture and a relatively polar acrylic monomer. Final macroporous particles approximately 10 gm in size were obtained by the repolymerization of the monomer phase in the swollen seed particles. Surface and bulk morphologies were investigated with scanning and transmission electron microscopy, respectively. Although highly porous particles could be achieved with relatively hydrophobic monomers such as styrene, BMA, MMA, and EPMA, the use of hydrophilic monomers such as HEMA and MAA led to the synthesis of uniform particles with lower macroporosity. A comparison of Fourier transform infrared and Fourier transform infrared/diffuse reflectance spectroscopy spectra indicated that the concentration of polar acrylic monomer on the surface was higher than in the bulk structure. The nonspecific protein adsorption behavior of uniform, macroporous particles was investigated with albumin as a model protein. The highest nonspecific albumin adsorption was observed with plain poly(styrene-co-divinylbenzene) [poly(S-DVB)] particles. The particles produced with MMA and EPMA also exhibited albumin adsorption capacities very close to that of plain poly(S-DVB). Reasonably low nonspecific albumin adsorption was observed with the particles produced in the presence of MAA, HEMA, and BMA. Poly(S-DVB) particles functionalized with poly(vinyl alcohol) provided nearly zero nonspecific albumin adsorption, For nonspecific albumin binding onto the particles via a physical adsorption mechanism, desorption ratios higher than 80% could be achieved. The desorption ratio with the EPMA-carrying particles was only 5% because the albumin adsorption onto EPMA-carrying particles occurred predominantly with covalent-bond formation. (C) 2002 John Wiley Sons, Inc.