Heparin-Coupled Poly(poly(ethylene glycol) monomethacrylate)-Si(111) Hybrids and Their Blood Compatible Surfaces

Abstract

Well-defined (nearly monodispersed) poly(poly(ethylene glycol)monomethacrylate)-Si hybrids were prepared via surface-initiated atom transfer radical polymerization (ATRP) of the poly(ethylene glycol)monomethacrylate (PEGMA) macromonomer on the hydrogen-terminated Si(111) surface (Si-H surface). Both the active chloride groups at the chain ends (from the ATRP process) and the chloride groups converted from some ( approximately 32%) of the -OH groups of the Si-C bonded PEGMA polymer, or P(PEGMA), brushes were used as leaving groups for the covalent coupling of heparin. For the heparinized P(PEGMA)-Si hybrid surfaces, protein adsorption and platelet adhesion were significantly suppressed. The well-defined and dense P(PEGMA) brushes, prepared from surface-initiated ATRP, had allowed the immobilization of a relatively high concentration of heparin (about 14 mug/cm(2)). The resulting silicon surface exhibited significantly improved antithrombogenecity with a plasma recalcification time (PRT) of about 150 min. The persistence of high bioactivity for the immobilized heparin on the hybrid surfaces can be attributed to the biocompatibility of the PEGMA units, as well as their role as spacers in providing the immobilized heparin with a higher degree of conformational freedom in a more hydrophilic environment. Thus, the heparin-coupled P(PEGMA)-Si hybrids with anti-fouling and antithrombogenic surfaces are potentially useful in silicon-based implantable devices and tissue engineering.

Surface Modification to Control Protein/Surface Interactions

“…Similarly, Xu et al prepared a series of POEGMA or PHEMA modified silicon surfaces by SI-ATRP and coupled bioactive molecules including collagen (for cell adhesion), heparin (for antithrombogenicity), and IgG (for antigen binding) to the pendant hydroxyl groups by chemically bifunctional molecules such as thionyl chloride, 1,1 0 -carbonyldiimidazole and succinic anhydride. [44][45][46] This strategy also favors a high signal-to-noise ratio in biosensor and microarray applications. Xu et al reported recently on binary brushes of poly(poly(ethylene glycol) methacrylate-co-poly(ethylene glycol)methyl ether methacrylate) (P(PEGMA-co-PEG-MEMA)) and poly(poly(ethylene glycol)methyl ether methacrylate)(PPEGMEMA) prepared by consecutive ATRP from a resist-microdomained silicon wafer surface.…”

Protein Immobilization onto Poly(acrylic acid) Functional Macroporous PolyHIPE Obtained by Surface-Initiated ARGET ATRP

“…1,2 Polymer brushes are particularly suited for covalent immobilization of biomolecules because they possess a well-defined structure, excellent mechanical stability and dense functional groups. 3,4,5,6,7,8,9,10 Moreover, the number of binding sites for biomolecules can be controlled by the polymer chain length. While this concept is particularly successful for planar and inorganic substrates, the decoration of there-dimensional macroporous polymeric substrates with polymer brushes provides a significantly bigger challenge.…”

Heparin-immobilized polymers as non-inflammatory and non-thrombogenic coating materials for arsenic trioxide eluting stents

“…A bicinchoninic acid protein assay (MicroBCA) was performed to determine the total amount of protein adsorbed onto the polymer surface from PPP [23]. Prewetted polymer films (12  0.3 mm, diameter  thickness) were incubated in 24-well plates containing 2 ml of PPP at 37°C for 5, 15, 30, 60 and 120 min, respectively.…”

“…Plasma recalcification time and thromboplastin time are two parameters for evaluating the in vitro hemocompatibility of materials [23,26]. When Ca 2+ (factor IV) is complemented to the antico- agulated PPP, prothrombin (factor II) will be activated by the endogenous blood coagulation system and converted to thrombin [30].…”