NEOH, Koon Gee

Professor

ScD (Chem. Eng.) MIT, 1980
BSc (Chem. Eng.) MIT, 1976

Contact information
Blk E5, 4 Engineering Drive 4, #02-34, Singapore 117576
Tel: (65) 6516 2176   Fax: (65) 6779 1936
Email: chenkg@nus.edu.sg

RESEARCH

(in collaboration with Prof. E. T. Kang)

Functionalized Surfaces for Biomedical Applications

The interactions of biomolecules with surfaces is a critical issue in many biochemical/biomedical applications, e.g. in the immobilization of enzymes on electrode surfaces for the development of biosensors, or the attachment and growth and attachment of cells on scaffolds. Through  proper molecular tailoring of the surfaces, substrates can be imparted with various functionalities such as antibacterial properties or biocompatibility. Our research also addresses the use of electroactive polymers for establishing electrical communication with biomolecules. Protein adsorption and interactions with the surface are selectively changed through electrical stimulation of the electroactive polymers. Since the redox center of an enzyme is usually located deep within the protein shell, the use of a redox mediator for wiring enzymes to electroactive polymers has  resulted in biosensors of enhanced sensitivity.

Stimuli-responsive and Smart Materials

Through the immobilization of photosensitive redox-active groups on polymeric substrates, flexible smart windows can be prepared to darken upon exposure to UV irradiation. Similarly, through the graft copolymerization of membranes with redox-active groups, the membranes can be imparted with reversible redox-controllable permeability. A controlled release system based on a conducting polymer film actuator has been developed. The release of the target species can be controlled either in a pulsatile or continuous fashion through electrical stimulation of the polymer.

Nanostructured Metal-Polymer Systems

Different techniques for the preparation of nanosized clusters of  metal, and metal - polymer nanocomposites have been developed. Electroless metal deposition on substrates can be accomplished through surface grafted electroactive or redox-active polymers. The appropriate use of masks coupled with UV-induced or plasma polymerization allows the formation of micro/nano conductive patterns on inert substrates. The deposition of silver nanoparticles on surfaces functionalized  with pyridinium groups greatly enhanced the bactericidal properties of these substrates. The development of magnetic nanoparticles with polymeric shell for attachment of functional groups is currently in progress.

SELECTED PUBLICATIONS

K. G. Neoh and E. T. Kang, “Functionalized Conducting Polymers for Biosensing” in Encyclopedia of Sensors (Eds: C. A. Grimes, E. Dickey and M. V. Pishko), American Scientific Publishers, USA, Vol 4, p121 (2006).

F. X. Hu, K. G. Neoh and E. T. Kang, “Antibacterial and Antifungal Efficacy of Surface Functionalized Polymeric Beads in Repeated Applications”, Biotechnology and Bioengineering 89, 474 (2005).

Y. L. Li, K. G. Neoh and E. T. Kang, “Controlled Release of Heparin from Polypyrrole-Poly(vinyl alcohol) Assembly by Electrical Stimulation”, J. Biomedical Materials Research A 73, 171 (2005).

F. X. Hu, K. G. Neoh, L. Cen and E. T. Kang, “Cellular Response to Magnetic Nanoparticles “PEGylated” via Surface-initiated Atom Transfer Radical Polymerization”, Biomacromolecules, 7, 809 (2006).

Z. L. Shi, K. G. Neoh, E. T. Kang and W. Wang, “Antibacterial and Mechanical Properties of Bone Cement Impregnated with Chitosan Nanoparticles”, Biomaterials, 27, 2440 (2006).

L. Cen, K. G. Neoh and E. T. Kang, “Gold Nanocrystal Formation on Viologen Functionalized Polymeric Nanospheres”, Advanced Materials, 17, 1656 (2005).