Hemocompatibility of pseudozwitterionic polymer brushes with a systematic well-defined charge-bias control

Abstract

In this study, a pseudozwitterionic surface bearing positively and negatively mixed charged moieties was developed as a potential hemocompatible material for biomedical applications. In this work, hemocompatility of pseudozwitterionic surface prepared from copolymerization of negatively charged 3-sulfopropyl methacrylate (SA) and positively charged [2-(methacryloyloxy)ethyl] trimethylammonium (TMA) was delineated. Mixed charge distribution in the prepared poly(TMA-co-SA)-grafted surface can be controlled by regulating TMA and SA monomer ratios via surface-initiated atom transfer radical polymerization. The effects of grafting composition and charge bias variations on blood compatibility of poly(TMA-co-SA)-grafted surface were reported. The protein adsorption on different poly(TMA-co-SA)-grafted surfaces from human plasma protein (fibrinogen, HSA, and γ-globulin) solutions was evaluated using an enzyme-linked immunosorbent assay. Blood platelet adhesion and time measurements on plasma clotting were conducted to determine the platelet activation on the grafted surface. It was found that the protein resistance and anti-blood cell adhesion of prepared surface can be precisely controlled by controlling the charge balance of TMA/SA compositions. In addition, different charge bias variations on the poly(TMA-co-SA)-grafted surface would induce electrostatic interactions between plasma proteins and prepared surfaces which lead to adsorptions of interfacial protein and blood cells, plasma clotting, and blood cell hemolysis. Results from this study suggest that the hemocompatility of mixed charged poly(TMA-co-SA)-grafted surface depends on the charge bias level. This provides a great potential for designing biomaterial with unique surface chemical structure which could be used in contact with human blood.

Underwater Superoleophobicity of Pseudozwitterionic SAMs: Effects of Chain Length and Ionic Strength

“…The increasing content of −N­(CH 3 ) 3 + in mixed-charged SAMs can change the hydrophilic surface (water CA of about 20° in ratio 1:1 of oppositely charged components) into a hydrophobic surface (a completely positive charged component of −N­(CH 3 ) 3 + ) with over 60° CA for a water droplet in air . This conclusion supports the result that an outer −N­(CH 3 ) 3 + group in a long chain weakens the hydrophilicity of SAMs to some extent.…”

“…On the basis of the interactions and conformational change of mixed-charged monomers, it is not difficult to explain the reason for distinguishing underwater OCAs (DCE droplet) on different SAMs. The hydration strength of the −COO – group and the interchain interaction effect on hydration were taken into consideration in the following section, for the hydrophilic characteristic of the pseudozwitterion mainly appearing on the negatively charged monomer affirmed in a previous experimental work . The distance between two charged groups in a polymer chain can have effects on their inter- and intramolecular interactions, which can promote or inhibit the hydration of the charged groups; this experimental conclusion could also be understood at the molecular level from our work.…”

“…The increasing content of −N(CH 3 ) 3 + in mixed-charged SAMs can change the hydrophilic surface (water CA of about 20°in ratio 1:1 of oppositely charged components) into a hydrophobic surface (a completely positive charged component of −N(CH 3 ) 3 + ) with over 60°CA for a water droplet in air. 43 This conclusion supports the result that an outer −N(CH 3 ) 3 + group in a long chain weakens the hydrophilicity of SAMs to some extent. We combined the interchain interaction among SAMs expressed by RDF in Figure 10a, and the coordination number of the water molecule in the first hydration layer of the −COO − groups in Figure 8a and that of a −N(CH 3 ) 3 + group in Figure S6a to elucidate the internal cause, and unified the above In our systems, the length difference of mixed-charged monomers is a factor that cannot be ignored.…”

“…To date, the zwitterionic systems have been highly applied in biomaterials. − Nevertheless, in the way of designing superoleophobic materials with zwitterions, there are a few zwitterionic systems whose behavior can be altered between superoleophilicity and superoleophobicity, whereas there is a myriad of studies − regarding the fact that ion-responsiveness and the space effect are coexisting in a zwitterionic/pseudozwitterionic system for their applications in controlling protein adsorption and antifouling. In Chang et al’s work, , mixed-charged copolymer brushes and its protein-fouling resistance were systematically evaluated, especially with respect to the effect of ionic strength on the intra- and intermolecular interactions of the poly­(TMA- co -SA) with proteins. They found that the distance between oppositely charged groups in a polymer chain had effects on their inter- and intramolecular interactions, which would promote or inhibit hydration of the charged groups.…”

Molecular Understanding on the Underwater Oleophobicity of Self-Assembled Monolayers: Zwitterionic versus Nonionic

“…Besides, with grafting mode (a), a few hydrophilic SO 3 groups stand out the SAMs to serve as hydrophilic topology, ameliorating the overall underwater oleophobicity to some extent. Jhong et al 70 prepared mixedcharged polymer brushes consisting of sulfonate and quaternary ammonium ions and found that the hydrophilicity of the polymer became stronger with an increasing content of polysulfonate. In their opinion, the cationic quaternary ammonium groups were surrounded by three methyl groups, causing it to have some degree of hydrophobicity.…”