Cooperative adsorption of lipoprotein phospholipids, triglycerides, and cholesteryl esters are a key factor in nonspecific adsorption from blood plasma to antifouling polymer surfaces.

Nonspecific protein adsorption is a central challenge for the use of polymeric materials in biological media. While the quantity of adsorbed protein can be lowered, very few surfaces are protein resistant when exposed to undiluted serum or plasma. The underlying principles of this fouling and the adsorbing proteins remain to be identified. Here, we investigated adsorption from undiluted human blood plasma to three different polymer brushes. Our study showed that the polymer structure does not influence which proteins adsorb. Further, we identified 98 plasma proteins that still foul current "protein-resistant" polymer brushes. Detailed studies into the major adsorbing protein revealed the central role that lipoproteins and low density lipoprotein in particular play in fouling of plasma to polymeric biomaterials. However, although apolipoprotein B100 is found as a major fouling protein in our mass spectrometry screening, studies on individual components of lipoproteins show that it is not apoB100 but a mixture of phospholipids, triglycerides, and cholesteryl esters that plays a major role in lipoprotein adsorption.

Tandem Coordination, Ring-Opening, Hyperbranched Polymerization for the Synthesis of Water-Soluble Core-Shell Unimolecular Transporters.

A water-soluble molecular transporter with a dendritic core-shell nanostructure has been prepared by a tandem coordination, ring-opening, hyperbranched polymerization process. Consisting of hydrophilic hyperbranched polyglycerol shell grafted from hydrophobic dendritic polyethylene core, the transporter has a molecular weight of 951 kg/mol and a hydrodynamic diameter of 17.5 ± 0.9 nm, as determined by static and dynamic light scattering, respectively. Based on evidence from fluorescence spectroscopy, light scattering, and electron microscopy, the core-shell copolymer transports the hydrophobic guests pyrene and Nile red by a unimolecular transport mechanism. Furthermore, it was shown that the core-shell copolymer effectively transports the hydrophobic dye Nile red into living cells under extremely high and biologically relevant dilution conditions, which is in sharp contrast to a small molecule amphiphile. These results suggest potential applicability of such core-shell molecular transporters in the administration of poorly water-soluble drugs.

Effect of polymer brush architecture on antibiofouling properties.

Polymer brushes show great promise in next-generation antibiofouling surfaces. Here, we have studied the influence of polymer brush architecture on protein resistance. By carefully optimizing reaction conditions, we were able to polymerize oligoglycerol-based brushes with sterically demanding linear or dendronized side chains on gold surfaces. Protein adsorption from serum and plasma was analyzed by surface plasmon resonance. Our findings reveal a pronounced dependence of biofouling on brush architecture. Bulky yet flexible side chains as in dendronized brushes provide an ideal environment to repel protein-possibly through formation of a hydration layer, which can be further enhanced by presenting free hydroxyl groups on the polymer brushes. A deeper understanding of how brush architecture influences protein resistance will ultimately enable fabrication of surface coatings tailored to specific requirements in biomedical applications.