Biomedical subjects

K G Neoh

Publications and source records attributed to K G Neoh.

38 records · Page 3Linked to original sources

PubMedDate not supplied

Heparin-coupled poly(poly(ethylene glycol) monomethacrylate)-Si(111) hybrids and their blood compatible surfaces.

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.

Acrylates↗

PubMedDate not supplied

Collagen-coupled poly(2-hydroxyethyl methacrylate)-Si(111) hybrid surfaces for cell immobilization.

To improve the biocompatibility of silicon-based implantable micro- and nanodevices, and to tailor silicon surfaces for controlled cell immobilization, well-defined functional polymer-Si(111) hybrids, consisting of nearly monodispersed poly(2-hydroxyethyl methacrylate [P(HEMA)] with covalently coupled collagen and tethered (Si-C bonded) on the silicon surfaces, were prepared. HEMA was graft polymerized on the hydrogen-terminated Si(111) surface (Si-H surface) via surface-initiated atom transfer radical polymerization (ATRP) to give rise to the Si-g-P(HEMA) hybrid. The active chloride end groups preserved throughout the ATRP process and the chloride groups converted from some (approximately 20%) of the OH groups of the P(HEMA) brushes were used as the leaving groups for nucleophilic reaction with the -NH2 groups of collagen to give rise to the Si-g-P(HEMA)-collagen surface conjugates. These hybrid surfaces were evaluated by culturing 3T3 fibroblasts. The biocompatible Si-g-P(HEMA) hybrid surface resisted attachment and growth of this cell line. The Si-g-P(HEMA)-collagen hybrid surfaces, on the other hand, exhibited good cell adhesion and growth characteristics, and the extent of cell immobilization could be controlled by adjusting the amount of immobilized collagen. Thus, incorporating the collagen-coupled P(HEMA) onto silicon surfaces via robust Si-C bonds may endow the silicon substrates with new and interesting properties for potential applications in silicon-based implantable devices, such as molecular sensors and biochips.

3T3 Cells↗