YUNG, Lin-Yue Lanry

Assistant Professor

PhD (Chem. Eng.) Univ. of Delaware, 1998
B.Ch.E., Univ. of Minnesota, 1993

Contact information
Blk E2, 5 Engineering Drive 2, #02-04, Singapore 117576
Tel: (65) 6516 1699    Fax: (65) 6779 1936
Email: cheyly@nus.edu.sg

RESEARCH

Nanobiomolecular assembly

Functionalized materials with unique structural, electronic and optical properties can be fabricated using micro/nanostructured assemblies. Instead of the conventional microfabrication technique, more research studies are focusing on the use of nanoparticles (NPs) as building blocks since they can be used to fabricate the assemblies under relatively straightforward and inexpensive experimental conditions. DNA possesses unique and spontaneous recognition characteristics and can be used to tailor new nano-assemblies with meticulous molecular patterns. We are currently developing different strategies to manipulate the number, size, and sequence of DNA conjugated on NPs. These NP-DNA conjugates, which can be assembled at precise position, will be a reliable building blocks for building nano-assemblies of different patterns robustly.

Nanoparticle-antibody targeting

Despite the effort for the development of NP-antibody related applications, fundamental studies on the interaction between antibodies and NPs are still very limited. For instance, the actual number and the corresponding conformation of antibody molecules on the NP surface have not been characterized. The lack of knowledge like this impedes the further development of NP-antibody related applications. We are currently attempt to elucidate the adsorption characteristics of IgG on NPs using fluorescence spectroscopy. The data collected from adsorbing IgG molecules onto NPs allows us to quantify the saturation surface coverage as well as to determine possible conformation of the adsorbed antibodies on different sizes of NPs.

Corneal tissue engineering with collagen nanofibers

Most of the engineered corneal substitutes are currently composed of three layers: the epithelium, stroma, and monolayer endothelium. The stroma layer, which constitutes to 90% thickness of a native cornea, is the key structure providing the optical refraction and mechanical strength of a cornea. The construction of engineered stromas is typically formed by random cross-linking of the collagen, resulting in an anisotropic polymeric network made of collagen very different from the collagen network found in a native cornea. The native corneal stroma is composed of multiple sheets of collagen fibrils aligned in same direction within each layer. This heterogenic alignment of the collagen fibrils has been attributed to the high mechanical strength. To obtain stronger mechanical strength, we are constructing a scaffold based on sheets of aligned collagen nanofibers via electrospinning. Human keratocytes, epithelial, and endothelial cells are being seeded and cultured on the scaffold for the formation of a complete engineered cornea.

Folated conjugated polymer micelles for drug targeting

Folate receptors have been known to be vastly overexpressed in several human tumors. As the result, folate (FOL) has been popularly employed as a targeting moiety of various anticancer agents to minimize their non-specific attacks on normal tissues as well as to increase their cellular uptake within target cells. We fabricated PLGA-PEG-FOL copolymer to form micelles for encapsulating anticancer drug. The cytotoxicity of the PLGA-PEG-FOL micelles loaded with drug was much higher to cancer cells than to healthy fibroblast cells, demonstrating that selectivity power of the folate conjugated micelles. Such micellar formulation for cancer drugs can be used as a new drug carrier for tumor targeting chemotherapy.

Toxicity of nanomaterials

The potential toxicity of nanoparticles on human and environment has been an immerging topic in recent years following the booming of the use of nanomaterials in commercial products. The recent nanoparticle-containing product recall may recruit more scientific, social, and political attention on this issue. Our current effort focuses on the studies of potential toxicity effects of nanoparticles on immune and circulatory systems as well as the underlying interaction mechanism between the nanoparticles and these two systems. Current data show that nanoparticles can enter cells via not only endocytosis but also by diffusion. Animal exposure study also shows that nanoparticles can reach different organs by respiration.

SELECTED PUBLICATIONS

W.J. Qin and L.Y.L. Yung, “Nanoparticle-DNA conjugates bearing specific number of short DNA strands by enzymatic manipulation of nanoparticle-bound DNA,” Langmuir, 21, 11330 (2005)

S.P. Zhong, W.E. Teo, X. Zhu, R. Beuerman, S. Ramakrishna and L.Y.L. Yung, “Formation of collagen-GAG blended nanofibrous scaffolds and their biological properties,” Biomacromolecules, 6, 2998 (2005)

Z.L. Shi, K.G. Neoh, S.P. Zhong, L.Y.L. Yung, E.T. Kang and W.E.J. Wang, “In-vitro antibacterial and cytotoxicity assay of multilayered polyelectrolyte functionalized stainless steel,” J. Biomed. Mater. Res. A, 76A, 826-834 (2006)

.J. Xu, S.P. Zhong, L.Y.L. Yung, E.T. Kang and K.G. Neoh, “Surface-active and stimuli-responsive polymer-Si(100) hybrids from surface-initiated atom transfer radical polymerization for control of cell adhesion,” Biomacromolecules, 5, 2392 (2004)

L.Y.L. Yung, F. Lim, M.M.H. Khan, S.P. Kunapuli, L. Rick, R.W. Colman and S.L. Cooper, “High molecular weight kininogen preadsorbed to surfaces markedly reduces neutrophil adhesion,” Biomaterials, 21, 405-414 (2000)

L.Y.L. Yung, R.W. Colman and S.L. Cooper, “Neutrophil-surface interactions on polyurethanes preadsorbed with high molecular weight kininogen,” Blood, 94, 2716-2724 (1999)

L.Y.L. Yung and S.L. Cooper, “Neutrophil adhesion on phosphorylcholine containing polyurethanes,” Biomaterials, 19, 31-40 (1998)