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Polymers for BioApplications Lab
PI: Assistant Professor Tong Yen Wah
(65) 6516-8467 (tel), (65) 6779-1936 (fax)
chetyw@nus.edu.sg
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The major expertise of our research group is in the field of polymers, in synthesizing monomers, in polymerization reactions and methods, in post-polymerization chemical modification, and in processing. Our interests in polymers are for their applications in any biological field, from biomolecular engineering (bioseparations, cell culture and expansion etc) to biomedical engineering (tissue engineering, drug delivery etc) to bioprocessing and pharmaceutics. We aim to integrate our knowledge of polymer science and engineering to multi-disciplinary fields, so that we can develop our strengths in all areas. |
 As part of our continual efforts in polymer research for bioapplications, one of the major research scopes of the group involves the development of polymeric microsphere as 3-D scaffold for cell attachment in growing an organ in vitro. As a promising scaffolding material for tissue engineering, such microspheres also offer versatility in combining drug delivery with surface modification, and also ease of synthesis with ease of multiple cell type co-culture. The surfaces of the polymeric microspheres have been modified to enhance their biocompatibility and bioactivity as effective extracellular matrix (ECM) mimics, and growth factors such as hepatocyte growth factor and fibroblast growth factor have been encapsulated into the microspheres for direct delivery to the cells. One of the organs we are targeting is the liver, and liver cells like hepatocytes and endothelial cells have been co-cultured together in this respect. Major advances in our group were lead by Dr Zhu Xinhao who has recently graduated with his PhD in June 2008. Another GPBE PhD student, Mr Chen Wenhui is also working on neural tissue engineering using this unique tissue engineering system. He was previously an NUS undergraduate research student working on his final-year research project in our laboratory. Upon graduation in 2007, he joined us for his pursuit of a PhD degree.
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| Figure 1. Cells can grow on microspheres for up to 28 days. The left image is a 3-dimensional laser confocal scan showing the cells spreading on the microspheres, while the right image is a light microscope image. |
Figure 2. Chen Wenhui working on growing neural cells on microspheres.
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The group’s research interests also include establishing a molecular strategy for engineering a collagen-like biomaterial, namely a biomimetic collagen that exhibits enhanced triple-helical stability, cell-binding activity, and substrate specificity for tissue transglutaminase (tTGase)-mediated cross-linking. We aim to convey collagen-like functionality to synthetic polymers to contribute to a better understanding of the cell-ECM interaction. This novel research was led by Dr Khew Shih Tak, a Malaysian who graduated from Universiti Teknologi Malaysia in 2003. He has also recently graduated with his PhD in June 2008. |
  
Figure 3. The collagen mimetic peptide triple helix on the left were synthesized and coated onto petri dishes. Cells cultured on the peptide (right most image) shows a similar morphology to cells cultured on natural collagen (middle image). |
In addition to the above, our group has developed synthetic polymers to mimic biological proteins for bioseparations. This is being realized through the innovative technique of molecular imprinting. It is a state-of-the-art technique that can be employed to prepare polymeric materials that possess recognition and selectivity towards pre-determined template molecules. We are particularly interested in synthesizing protein-imprinted nanoparticles that possess molecular affinity towards targeted protein molecules in an aqueous environment. The material represents a new class of material with a vast field of potential applications in biosensing, bioseparation and bioanalytical chemistry. The pioneering work was done by Dr Tan Chau Jin who successfully defended his PhD thesis in May 2008 and will graduate in July 2008. Other students involved include Mr. Shalom Wangrangsimakul and Ms. Niranjani Sankarakumar. Shalom, who comes from Thailand, was previously an undergraduate student in NUS and underwent a 2-year exchange programme to Ecole Centrale Paris, France in 2004-2006. He subsequently joined the group in 2007 as a Masters’ student. Niranjani had her undergraduate days back in her hometown in A.C. College of Technology, Anna University, India. She obtained her bachelor degree in 2006 and joined our group in 2007 for her PhD pursuit.
 
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