Ashlynn Lee, Nikken Wiradharma, Zhan Yuin Ong, Chuan Yang, Majad Khan, Wei Cheng, Pei Yun Teo, Shujun Gao and Yi Yan Yang

This research focuses on the development of novel biodegradable cationic nanoparticles with a hydrophobic core and a positively charged shell for the co-delivery of drugs and genes to combat multi-drug resistant cancers. IBN researchers have designed and synthesized biodegradable amphiphilic polymers/peptides of varying degrees of positive charge. These polymers/peptides are able to self-assemble into core-shell nanoparticles in aqueous solutions before or after DNA binding. The core is able to encapsulate hydrophobic drug molecules, while the positively charged shell binds negatively charged gene/protein molecules. These nanoparticles have attained high efficiency in protein and gene delivery to various types of cells such as breast and prostate cancer cell lines as well as bone marrow stem cells. By enabling the co-delivery of drugs and genes/proteins in a single system, synergistic therapeutic effects have been achieved in suppressing tumor growth.

Jieming Zeng, Ying Zhao, Xiao Ying Bak and Shu Wang

Genetic manipulation of stem cells in vitro is one of the critical approaches for realizing the potential of stem cells in regenerative medicine and basic research. Possible issues in genetic manipulation include controlling the differentiation of stem cells, isolating pure populations of specific types of differentiated cells, overcoming immune rejection after stem cell transplantation, and providing cell sources for ex vivo gene therapy. The main objective of this project is to establish the proof of principle of using baculoviral vectors for genetic modification of human embryonic stem (hES) cells and hES-derived cells without jeopardizing their stem cell properties. This research aims to develop effective gene transfer systems that may offer flexible control of transgene expression, for either short- or long-term, during stem cell differentiation, and to use the genetically modified stem cells for regenerative medicine.

Motoichi Kurisawa, Joo Eun Chung, Fan Lee, Li Shan Wang, Keming Xu and Kun Liang

Hydrogels have been used extensively for the controlled release of bioactive molecules and the encapsulation of cells. In particular, the use of hydrogels as scaffolds for tissue engineering has shown potential for achieving tissue repair or tissue regeneration in the body. However, most existing hydrogels require surgical implantation, which often results in tissue irritation and damage. This study proposes an alternative involving a biocompatible in situ gel-forming system composed of hyaluronic acid-tyramine (HA-Tyr) conjugates. Using a simple peroxidase-catalyzed oxidation reaction, this novel system allows hydrogels to be formed without any inflammation or reactions to the bioactive agents loaded. Enzyme-mediated HA gel formation in vivo shows promise for achieving effective drug therapy and tissue regeneration. The new materials are being examined for controlled protein release, immunocancer therapy, and tissue engineering.

Yukti Choudhury, Jiakai Lin and Shu Wang

RNA interference is a process in which the recognition of double-stranded RNA ultimately leads to the post-transcriptional suppression of gene expression. This suppression is mediated by short (21- to 22-nt), small interfering RNAs, which induce the degradation of mRNA based on complementary base pairing. Small interfering RNA technology is emerging as a potentially useful method to develop highly specific double-stranded RNA-based gene silencing therapeutics. This project aims to identify targets in brain tumors where gene silencing is likely to have therapeutic benefit. Small interfering RNA technology, in particular its delivery into specific cells, will also be optimized with the objective of developing a clinical solution.

Shona Pek, Siti Thaharah Mohamed, Wu Hong and Jackie Y. Ying

We have developed several methods of synthesizing nanocomposite biomaterials with controllable microstructure and composition. This enables us to incorporate and deliver substances such as drugs, proteins, growth factors, cells and organic dyes via membrane or scaffold platforms. For example, we have developed microspheres for sustained and/or delayed release of small drugs and growth factors. We have also developed transparent microemulsion-based membranes with tunable properties as the world’s first photochromic contact lenses.

Amalina Bte Ebrahim Attia, Shujun Gao and Yi Yan Yang

IBN researchers have developed transparent nanostructured polymeric membranes by the polymerization of bicontinuous microemulsions using a polymerizable surfactant. The membranes have temperature-dependent swelling properties. At lower temperatures, they swell, thereby reducing adhesion and allowing the dressing to be removed from the skin easily and without pain. In addition, these transparent membranes facilitate observation of the wound, while providing a moist wound-healing environment without an adhesive coating layer. When applied to an exuding wound, the membrane would rapidly absorb moisture and adhere to the surface without secondary retention materials. Therapeutics can be encapsulated within the membranes to accelerate the wound healing process. Cells can also be attached onto the thermo-sensitive membranes at 37°C, and would detach at 15°C and resume normal growth. In addition, the membranes have excellent durability and flexibility, demonstrating a great potential to be used as wound dressing or support for cell grafting. Animal studies will be conducted to evaluate the healing efficacy of burn wounds using the membranes with and without human dermal fibroblasts.

Shrinivas Venkataraman, Jeremy Tan, Chuan Yang, Amalina Bte Ebrahim Attia, Sangeetha Krishnamurthy, Shujun Gao and Yi Yan Yang

This research aims to develop smart and safe polymer-based carriers to target small molecular anticancer drugs specifically to tumor cells. Novel core-shell polymer nanoparticles are designed with pH-dependent lower critical solution temperatures (LCST). This value is above the nominal physiological temperature of 37°C at pH 7.4, but decreases to a temperature below the physiological temperature with a small decrease in pH. The resulting change in LCST causes the core-shell nanoparticles to deform and precipitate in an acidic environment, triggering the release of chemotherapeutics at low pH. Stimuli-sensitive nanoparticles are being synthesized with a narrow size distribution by novel approaches. A biological signal that can recognize tumor cells is chemically attached to the core-shell nanoparticles. These carriers may be employed to target drugs to tumor cells and release the drugs intracellularly.

Chunxiao Wu, Seong Loong Lo, Ying Zhao, Jiakai Lin, Esther Lee and Shu Wang

Recent studies have shown that the recombinant baculovirus Autographa californica and multiple nuclear polyhedrosis viruses with a mammalian expression promoter show great promise as the new generation of gene therapy vehicles. Baculoviruses display a broad tropism in both proliferating and non-proliferating, quiescent mammalian cells. They do not replicate in vertebrate cells, and produce little to no cytotoxicity. The focus of this project is to investigate the possibility of using baculovirus vectors for gene transduction in the nervous system. Engineering the viral vector to enhance its capability in transducing specific types of neural cells has been explored. This research aims to develop safe and effective DNA delivery systems applicable to the gene therapy of neurological disorders and brain cancers.

Joo Eun Chung, Motoichi Kurisawa, Susi Tan and Jackie Y. Ying

This research aims to develop smart and safe polymer-based carriers to target small molecular anticancer drugs specifically to tumor cells. Novel core-shell polymer nanoparticles are synthesized from functional biodegradable polymers with well-defined molecular weights and functionalities. The nanoparticles have nanosize and a narrow size distribution, and are tailored for high loading of various types of drug molecules. The shell of the nanoparticles contains biological ligands that can specifically recognize receptors over-expressed on cancer cell surfaces. These nanoparticles provide a platform for controlled delivery of a variety of anticancer drugs.

Shona Pek, Shujun Gao, Shariff Arshad and Jackie Y. Ying

Large amounts of lost bone are usually replaced by a variety of grafts or permanent alloy implants. The aim of this project is to create a composite bone scaffold material that has sufficient strength to support patients' lifestyles, and bioactivity to promote cell attachment and proliferation. This scaffold would be resorbable by natural tissue, with tunable mechanical properties and degradation rates. Two research challenges are the introduction of macroporosity and mechanical strength for load-bearing applications. IBN's research strategy involves creating a nanocomposite foam of collagen fibers and apatite nanocrystals. Preliminary in vitro studies with MC3T3 osteoblast cells indicate excellent cell attachment and proliferation on this scaffold. Ectopic in vivo implantation on SCID mice shows evidence of bone, tissue and blood vessel formation in the scaffold material. In addition, in vivo implantation of this scaffold material into critical-sized defects in the femur of Wistar rat and the tibia of Yorkshire-Landrace pigs resulted in successful healing and functioning of the defect area without the need for an external supporting cast.

Farah Tasnim, Yar Oo Zay, Mohammed Shahrudin Ibrahim, Ming Ni, Daniele Zink and Jackie Y. Ying

Commercialized in 1956, hemodialysis has been widely used to treat patients suffering from chronic renal failure. With hemodialysis, millions of renal failure patients in the world have not only survived, but also successfully demonstrated certain levels of social activities. However, hemodialysis is still inefficient as a renal replacement therapy. It only provides intermittent blood filtration and is unable to replicate the important absorptive, metabolic, endocrine, and immunological functions of the natural kidney. At IBN, we are developing an extracorporeal filtration and reclamation device consisting of composite hollow fibers made at IBN. This portable device will be able to continuously remove excess water and toxic wastes from the blood. By incorporating living epithelial cells of the kidney proximal tubule into the hollow fibers, the device will also be able to provide certain functions that are absent in conventional hemodialysis. As a result, the quality of life of the renal patients could be significantly improved by this biomedical device.

Dean Tai, Alvin Kang, Yuting He, Shuoyu Xu, Baixue Zheng, Qiwen Peng and Hanry Yu

We have developed optical imaging modalities to quantify liver fibrosis in tissues. The instruments and image-processing/feature analysis algorithms developed are being applied to automate and improve the pathological examinations related to fibrosis (FIBRO-C INDEX), and cancer-stroma interactions, which shed lights into the etiology of the diseases in quantitative manners. We are also developing a high throughput tissue imaging platform to quantify tissue/cell and ECM features of the whole organ in mice or the entire biopsy sample at molecular and cell resolutions. We are establishing the molecular and cellular basis of clinical imaging modalities such as MRI through the high resolution organ imaging of disease models. We utilize these quantitative tissue imaging modalities, and have also developed high-content analysis platform to be interfaced with robot-based liquid handling systems to evaluate efficacy of compounds against liver fibrosis in vitro and in vivo.

Abhishek Ananthanarayanan, Ciprian Iliescu, Deepak Choudhury and Hanry Yu

Cell-based assays for evaluation of the hepatotoxicity are attracting increasing attention from institutions and companies undertaking drug development. The major bottlenecks in employing these assays reside primarily in the lack of stable human hepatocytes as well as cell-culture models that recapitulate the in vivo physiological responses to the tested compounds. Academically, many cell-based models have been proposed with the promising ones based on sandwich, spheroid, and co-culture. So far, only the sandwich model is accepted by the Federal Drug administration (FDA) for routine hepatotoxicity testing of drugs. To improve the cell-based assays, we have developed 1) a much improved sandwich model, 2) a much improved spheroid model, 3) a culture supplement that substitutes the role of co-culture, and 4) three perfusion-based models. We are evaluating the strengths and limitations of these models in hepatotoxicity testing of paradigm compounds and improving the performance of these platforms for throughput. We also are developed microfluidic chips to predict the physiology-based pharmacokinetics properties of compounds.

Bramasta Nugraha, Cipian Iliescu and Hanry Yu

Complex tissues with multiple cell types will be engineered by controlling cell-cell interactions through manipulating cell-surface molecules, delivering growth factors precisely with controlled delivery devices, engineering cellular response to the chemical and mechanical signals using suitable hydrogels, and fabricating relevant 3D microfluidics and networks of channels. This project integrates biomaterials and novel microfabrication technologies to generate precisely controlled cell-containing structures that preserve the functions of liver cells as prototype microliver tissues. This project establishes the fundamental principles, toolboxes and devices to precision-engineer complex tissues and interfaces for drug testing and therapeutic applications.

Karthikeyan Kandasamy and Daniele Zink

The transcriptional activity of mammalian genes is regulated by a complex network of multiple variables. These include the binding of transcriptional regulators to cis-regulatory DNA elements as, for example, enhancer elements and promoters. In addition, epigenetic mechanisms involving DNA methylation, histone modifications, and the spatial organization of gene loci in the nucleus contribute to the transcriptional regulation of gene loci. Currently, it is unclear how the different levels of regulation interact and become integrated. Furthermore, it is not understood how the spatial organization of gene loci in the nucleus is regulated. Experimental evidence obtained during our previous studies suggested that the patterns of histone modifications not only regulate local chromatin structure, but also impact the spatial positioning of gene loci. These studies used the human cystic fibrosis gene (CFTR) and adjacent genes as model system. Using high-resolution light microscopy and ChIP/chip analyses, we will further explore this model system in order to address the functional relationships between the regulation of gene-specific patterns of histone modifications and the regulation of the nuclear positioning of corresponding loci.

Benjamin Tai, Shona Pek, Karthikeyan Narayanan, Chan Du, James Hsieh, Meng Fatt Leong, Jerry Toh, Serina Ng, Hongfang Lu, Andrew Wan and Jackie Y. Ying

Tissue engineering requires the use of a structural framework to support the adhesion and growth of cells. In addition to acting as a structural template, scaffolds provide the opportunity for the presentation of biological molecules that regulate the proliferation and differentiation of cells into tissue structures. This is especially important in conjunction with the use of stem and progenitor cells. Most of the current processes for the production of tissue scaffolds are incompatible with the incorporation of biological molecules, specifically proteins, due to the severity of conditions involving the use of high temperatures and organic solvents. We are developing procedures for making scaffolds by polyelectrolyte complexation, which is inherently more suitable for the presentation of biologics due to the milder, aqueous-based synthesis. The characteristics of these scaffolds are optimized to capitalize on the activity of various biological factors with respect to tissue development. By culturing differentiated embryonic and mesenchymal stem cells on these scaffolds, we are working towards therapies for liver failure and diabetes Type I. Another important effort in our group is the development of 3D matrices, to more closely mimic the natural environment of the cell for in vitro models.

Nandanan Erathodiyil, Yong Wang, Karthikeyan Narayanan and Jackie Y.

Cell separation has become an essential tool for a wide variety of biomedical applications. It is important to attain high-purity cell populations of interest from mixed cell populations for use in therapeutics and diagnostics. Antibodies can serve as molecules targeting specific membrane proteins on certain cell types. Our approach in cell separation was achieved by utilizing targeting ligands with magnetic nanoparticles and quantum dots. We have used glucosamine in the separation of insulin-secreting beta cells. The differential binding affinity of Glut2 towards glucosamine is employed to target and separate insulin-secreting beta cells from a mixed population of cells. Cell sorting was achieved by magnetic cell manipulation or FACS. We are currently developing a variety of small molecules to target other cell types such as neurons.

Xia Lei, Yan Wang, Wenhao Tong, and Hanry Yu

We have developed a greatly improved sandwich culture based on synthetic membranes and novel laminar-flow bioreactors at mini- or micro-scales. Controlling the mass transfer properties through these membranes and the environments to stimulate cellular functions, we are scaling these culture configurations into a higher throughput system for drug testing applications; and applying it to develop a renewable hybrid liver device to support patients with liver failure, at reduced cost and improved effectiveness. The key feature of these cultures are their abilities to maintain hepatocyte polarity and enhance secretory functions that allow the devices to be regenerated after exposure to toxic substances in patients with failed liver.

James T. M. Hsieh, Karthikeyan Narayanan, Meng Fatt Leong, Jerry Toh, Andrew Wan and Jackie Y. Ying

It has been discovered that cells behave differently in a flat layer than in complex, three-dimensional tissue. Cell studies in 3D may be more physiologically relevant as the 3D environment more closely resembles living tissue. However, few existing methods have been able to provide the required degree of control to spatially pattern cells in 3D. IBN is developing various new bioartificial devices using the 2-photon stereolithography laser system. These new devices are designed to closely resemble the natural cell architecture by incorporating biochemical cues onto material surfaces. In addition, these miniaturized devices are made from biodegradable materials, thus offering the potential for implantation.

Guolin Xu, Daniel Lee, James T. M. Hsieh, Chunyan Zhang, Bruce Yu, Emril Mohamed Ali, Hong Xie, Zhiqiang Gao and Jackie Y. Ying

This research aims to study and develop a fully integrated, automated, high sensitivity, low-cost molecular diagnostic that can be used in clinics and for point-of-care applications. We have designed a microfluidic system that can rapidly dissociate tumor tissue, isolate and lyse target cells, extract and purify mRNA, amplify genes, and detect the amplified genes. This biochip device provides for the possibility of early cancer diagnosis using solid tumor tissue samples.

Mo Chao Huang, Wai Chye Cheong, Jiashen Wei, Jackie Y. Ying and Mo-Huang Li

Synthetic genes with intact, biological functions can be used for a variety of purposes such as protein overexpression in heterologous systems, engineering proteins with specific functions, and gene vaccine. The objective of this project is to develop an integrated microsystem to perform parallel and automatic gene assembly with fast turnaround at reduced cost to create synthetic genes. Short synthetic oligonucleotides will be assembled into a DNA sequence of suitable size for encoding genes and genomes based on polymerase chain reaction (PCR) or ligase chain reaction (LCR) assembly methods. Components required for performing gene assembly will be developed, miniaturized and integrated into a chip to transform gene assembly into an inexpensive, rapid process for commercial applications.

Jaehong Lim, Jessica Shan Oon, Joo-Eun Jee and Su Seong Lee

The overall research goal lies in developing high-throughput screening tools for membrane cancer biomarkers, capitalizing on our novel peptide libraries as an arsenal of capture agents. One-bead-one-compound peptide libraries are screened for binding to intact cancer cells, while novel technologies are developed for the validation of the capture agents that interact with the targets on the membrane with high fidelity. These capture agents can be used for immunohistochemistry of tumor tissues. The new technologies can also be applied to screen other types of intact cells

Jaehong Lim, Yi Li Ang, Jessica Shan Oon, Joo-Eun Jee and Su Seong Lee

This research effort aims to develop high-affinity and high-specificity capture agents for serum cancer biomarkers. With our novel technologies, protein capture agents can be developed by screening bead-based peptide libraries in a high-throughput platform. The entire process may take merely a week. Compared with antibodies, these synthetic peptides are attractive as protein capture agents for a variety of applications such as in vitro diagnostic devices, due to their low cost and high stability.

Ciprian Iliescu, Guolin Xu and Hanry Yu

Gene extraction using conventional immuno-magnetic beads requires a large sample size and a large number of beads. It cannot be used to isolate target genes when the sample is too small. This research uses dielectrophoresis to bind target cells and beads, so that fewer beads are required to capture the target. This greatly improves the target gene extraction efficiency and reliability. IBN's device consists of a sandwich of silicon electrodes and microchannels. Electroporation and in situ PCR techniques are applied on the bead-binded cells for cell lysis and amplification of the target genes. The biochip is targeted at applications involving very small samples (< 10 ml) for molecular diagnostics, such as those for the early detection of cancer, and the identification of rare bacteria and virus.

Kwong Joo Leck, Xinlei Qian, Shuguang Zhang and Charlotte Hauser

G-protein coupled receptors (GPCRs) belong to one of the most important protein classes responsible for signaling. GPCRs are able to signal through several G-protein pathways and through G-protein-independent pathways mostly in a ligand-specific manner. They are directly involved in a variety of physiological processes such as sensing, learning and memory, but they are also coupled to body functions such as cardiac, urinary, gastrointestinal and endocrine functions. Therefore, GPCRs are one of the most attractive classes of receptors for drug design and are direct targets of more than 50% of clinically prescribed medicine. Our laboratory is focused on the study of human serotonin receptors, water-based smell receptors from zebrafish, and Wnt receptors, FZDs (frizzled). The goal of our studies is to develop ultrasensitive devices for very early non-invasive medical diagnosis, as well as for drug targeting. Detailed structural knowledge of the GPCRs is needed to design these ultrasensitive devices. In addition, we are interested in the design and use of novel biological materials based on a new class of very short self-assembling peptides, which have potential applications in drug and gene delivery, as well as regenerative medicine.

Xiaojun Chen, Yanbing Zhu, Hua Wang, Somenath Roy, Jun Hui Soh and Jackie Y. Ying

This project aims to develop biosensors for specific biomarkers. The biosensors are based on the assembly/immobilization of biological sensing molecules onto the electrode surface, and the detection of the bound biomarkers using electrochemical techniques. The sensing molecules of the biosensors are designed to meet three requirements: (i) selective binding for specific biomarkers, (ii) stable attachment to conducting surface (electrodes), and (iii) self-assembly as and immobilization on densely packed monolayer/multilayers. High specificity will be attained using bioaffinitive interactions, while high sensitivity will be achieved by combining the bioaffinitive events with a signal amplifier such as enzyme and nanoparticulate catalyst. The biosensors are integrated with microfluidic systems as compact and portable devices for point-of-care applications.

Nandanan Erathodiyil, Nor Lizawati Ibrahim, Yong Wang, Leng Leng Chng and Jackie Y. Ying

The reproducible growth and differentiation of pluripotent stem cells are one of the frontiers in modern tissue engineering and regenerative medicine. Of prime importance is the development of functional scaffolds that present the appropriate chemical, physical and biological cues so that they can interact effectively with living cells and encourage the development of new tissues. The heterogeneity of animal-derived cell culture substrates leads to variability in the responses of cultured cells, and the carryover of pathogens or immunogens complicates the use of human cells in therapeutic applications. The ideal scaffold should be biocompatible, non-immunogenic, pathogen-free, biochemically defined and support the regeneration of specific tissue types. We are developing chemically well-defined synthetic functional substrates that support embryonic stem cell passage or differentiation, with the aim of overcoming the disadvantages of current cell culture substrates. These synthetic polymer-based materials would offer great versatility in controlling chemical structure, molecular weight, mechanical strength and specific functions to mimic cellular environments. This new family of synthetic biomaterials is safe, versatile and may replace complex biological matrices of animal origin for applications in cell culture, tissue engineering, drug delivery, biosensors and regenerative medicine.

Yugen Zhang, Michael Reithofer, Liuqun Gu, Dingyi Yu, Siti Nurhanna Riduan, Mei Xuan Tan, and Jackie Y. Ying

Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. To achieve this target, we are interested in the development of novel green and environmentally friendly technology for organic synthesis and the pharmaceuticals industry. Our research is focused on metal-free organo catalysis, sustainable resources (e.g. using CO₂ as C1 resource), and environmentally benign catalysis (e.g. non-toxic, inexpensive iron catalysts and water-mediated reactions). We are also interested in the development of alternative and renewable energy resources and technologies through the use of novel catalyst systems. This includes creating highly efficient and highly selective catalyst systems for the dehydration of biomass into chemicals, fuels and materials. We are also working on transforming greenhouse gases such as carbon dioxide into useful chemicals or fuels such as methanol.

Yugen Zhang, Ting Lu, Liuqun Gu, Siti Nurhanna Riduan, Leng Leng Chng, Nandanan Erathodiyil and Jackie Y. Ying

Heterogeneous catalysis has many advantages over homogeneous catalysis. However, there are certain limitations on current protocols for producing heterogeneous catalysts via the immobilization of homogeneous catalysts onto inorganic or organic solid supports. This project aims to develop a new type of supported catalysts based on mesoporous silica and polymers, and organic-inorganic nanocomposites. This research will focus on the development of new materials and new chemistry. Organocatalysts, organometallic catalysts or biocatalysts will be investigated. The aim of this study is to build new catalyst support platforms to develop highly efficient catalyst systems. The target heterogeneous catalysts will allow for the synthesis of pharmaceuticals with superb activity, excellent enantioselectivity and recyclability. They will also enhance efficiency in the production of pharmaceuticals and specialty chemicals.

Jaehong Lim, Jian Liang Cheong and Su Seong Lee

This research tackles the major issues in ring-closing metathesis (RCM) associated with the synthesis of macrocycles. The homogeneous catalysts are effectively immobilized on mesoporous silica support, allowing for catalyst recycling and the use of continuous flow reactors. The reaction chemistry is also optimized by modifying the architecture of the catalytic species on the mesoporous supports.

Jinhua Yang, Xianfeng Yang, Xiaojun Chen and Jackie Y. Ying

Fuel cells and batteries based on nanocomposite materials have attracted significant attention. This research focuses on the synthesis of a variety of inorganic nanostructures with designed compositions and morphologies for fuel cell and battery applications. These novel materials possess excellent catalytic activity, and are promising for use in highly efficient and low-cost fuel cell and battery systems.