National University of Singapore homepage

Research Proposals arising from NUSNNI YOUNG INVESTIGATORS CLUB meeting under NUSNNI YOUNG INVESTIGATORS’ RESEARCH SCHOLARSHIPS (2002)

Application for graduate research is now open. Prospective graduate students can download application forms from the Faculty of Engineering or the Faculty of Science websites.

Students will need to register with either the Faculty of Engineering or the Faculty of Science. To apply for NUSNNI scholarships, send the completed application forms to:

**********************************************************************************
Engineering                                                     Science
Ms Jasmin Lee                                                    Ms Amanda Lee
NUS Nanoscience and Nanotechnology Initiative,      NUS Nanoscience and Nanotechnology Initiative
c/o Faculty of Engineering,                                   c/o Faculty of Science,
E3-05-29, 2 Engineering Drive 3, Singapore 117576.  S13-02-12A, 2 Science Drive 3, Singapore 117542.
Email: nnilsf@nus.edu.sg                                      Email: nnilml@nus.edu.sg

More details on Programme available in:
Faculty of Engineering: http://www.gse.nus.edu.sg/
Faculty of Science: http://www.science.nus.edu.sg/graduates/researchprog/

********************************************************************************************

The following list of research projects are now available for graduate students:-

* Thematic Strategic Research Programme, (Nanomanufacturing:- Nanoelectronics - The Next Wave) - SERC (A*STAR) Projects

Photoemission and X-ray absorption studies on organic/inorganic interfaces

Main Supervisor: Prof Seeram Ramakrishna (Department of Mechanical Engineering)

Co-Supervisor: Dr Teik-Cheng Lim (nnilimtc@nus.edu.sg) (NUS NNI)

The electrospinning process is the most effective method for the production of polymeric nanofibers – fibers with diameter less than 100nm. The effectiveness lies in the charged droplet which is electrically forced by an electrical field, coupled with the bending instability of the jet flow. The objective of this project is to develop some user-friendly theoretical models which can predict key flow characteristics based on input parameters such as processing conditions and raw material properties. The second objective is to correlate these input parameters with the final dimension, surface morphology, and physical properties of the electrospun nanofibers as a function of the input parameters. Results of this project will be beneficial for optimization purposes whereby a set of guideline will be generated for practitioners of the electrospinning process.

Please use the application forms of the Faculty of Engineering.

Development of Electrochemical Carbon Nanotubes Micro Sensors and Device
(Nanoscience and Nanotechnology is intrinsically an interdisciplinary research. Students with background in Biochemistry and
other Natural sciences such as Physics and Materials Science Engineering are in advantage for admission)

We propose to develop real-time chemical and biological sensors based on carbon nanotubes optimized to selectively detect a given molecular species from a gaseous or liquid mixture containing many other components. The sensor will be based on an array of carbon nanotubes functionalized non-covalently with conjugated ligands. The rationale of choice of the ligand will optimize both the speed and the reliability of the sensor. Our long-term goal is to select, design and fabricate sensing elements to be deployed in a detection chip that is able to identify nanomole quantities of targeted contaminants.

Development of Controlled Drug Delivery System Using Uniform Nanoporous Materials

Main supervisor: A/P Sibudjing Kawi (Dept of Chemical & Biomolecular Engrg, FOE)

Controlled drug delivery technology represents one of the most rapidly advancing areas of biomedical science contributed by chemists and chemical engineers for humans and mammal’s health care. The controlled delivery systems have the significant advantages compared to conventional dosage forms, as the efficiency of medicine is enhanced, and patient compliance and convenience are improved. The method by which a drug is delivered can have a significant effect on its therapeutic efficacy because some drugs have an optimum range of concentration within which the maximum therapeutic benefit is derived.

The objective of this project is to develop uniform nanoporous materials with proper internal surface chemical properties and tunable pore opening for application in dual-controlled drug delivery system. The chemically-modified surface will provide moderate interaction with molecules of target drugs to control the desorbing release rate. The tunable nanopore-opening results in dual-efficiency to control diffusion of drugs from pore channels of nanoporous materials. These nano-scaled controlled drug delivery materials will be tested to control the release of certain drugs with constant desired concentration. Equipments (such as HPLC, XRD, TGA-DTA, FTIR, TPD/TPR/TPO, GC-MS, UV-Vis, BET) are available in our lab for this research program. PhD and Master students are welcome to join this interesting research project.

Development of Nanoimprint Lithography for the Fabrication of Nanodevices

In the fabrication of nanodevices, a key step is in the fabrication of nanostructures and electrodes with features down to 10 nm in size. The key idea behind nanoimprint lithography is that one can produce desired patterns by stamping rather than the conventional multi-step photolithography or e-beam lithography techniques. The fabrication of such nanostructures and nanoelectrodes can then facilitate the subsequent fabrication of nanodevices using nanotubes, macromolecules, nanoparticles or other novel nanomaterials and structures.

Detection of Micro-Organisms Using Quantum-Dot Labelled Probes

Rapid and sensitive molecular techniques of the detection of interested microorganisms (e.g. pathogens and biological warfare agents) in environmental sources serve as an important means of warning and prevention. Fluorescence reporting systems are the most commonly used means for the current methods, but are limited to the availability of specific and expensive equipment with fluorescence detection capability, and the number (4 maximum) of targets simultaneously examined. The use of nanoprobes (<30nm in diameter) as the reporting system has emerged as a promising approach since it provides better specificity than fluorescence dyes, can be seen under visible light (low equipment cost), and provide multiple targets (>10) to be examined at the same time. In the proposed research, oligonucleotide, peptide and antibody-based probes will be initially synthesized with quantum-dot labeling at different level of specificity to different phylogenetic microorganisms and specific functional genes, proteins and cellular antigens of model microorganisms. The synthesized probes will be used to detect the model microorganisms separately and in combination. The results will be compared to those using fluorescence reporters. Techniques will involve cell hybridization, DNA/DNA or DNA/RNA hybridization and antibody/antigen reaction using for example real-time PCR and fluorescence microscope. The outcome should serve as a solid base for further applications into DNA microchip and lab-on-a-chip devices in life science research.

Design & Self-Assembly of DNA-Peptide Nanoparticles for Nonviral Gene Delivery
(Students with background in Biology, Biochemistry or Materials Science Engineering)

Nonviral gene delivery systems based upon plasmid DNA/chemical complexes have gained increasing attention for their potentials in avoiding problems inherent in viral gene vectors. In view of biocompatible and biodegradable natures and flexibility in design and fabrication with chemical or molecular biology methods, peptides provide an excellent and relevant material to form DNA nanoparticles through self-assembly of oppositely charged polymers. We propose to design and produce peptides with multiple functional domains that may act for DNA binding, DNA condensation and cell targeting. Endosomal lysis and nuclear uptake domains may be included for further improvement in the efficiency of DNA nanoparticle-based gene therapy. We will focus on peptides that may target the neurons with TrkB receptors, which are involved in Parkinson’s disorders, at the first stage of the work.

Please use the application forms of the Faculty of Science.

Design & Test of Molecular Bearings for Nano-Devices

Nano scale devices such as nano-electromechanical systems (NEMS) are limited in their performance by the tribological properties (such as adhesion, friction and wear) between two dynamically interacting surfaces. For atomically smooth surfaces, surface modification is one way of changing and controlling the tribology. In this project, the concept of molecular bearing will be utilized to design a surface with embedded molecular size bearings. Atomically smooth substrate will be modified to include patterned nano-particles. Polymeric nano-particles and carbon nano-tube will be deposited on the surface such as that they provide free rotational motion when another moving surface comes in contact, providing very low interfacial friction. The presence of nano-particles on the surface will be tested for the tribological characteristics such as friction, adhesion and wear. A successful design of molecular bearing surface will have great technological applications in the nanotechnology area.

Design & Manufacture of Wear-Resistant Surfaces

Coatings and thin layered materials have shown great promise not only in enhancing the appearance but also the durability and functional properties of products. With current technology, thin films used in many technologies can be extremely thin, such as in hard disc drives. Meaningful characterization must involve nanometer scale measurements. With advances in microscopy, qualitative information of surface properties at such length scale has now been made available. However, there are technical problems in the measurement of important mechanical properties such as hardness, elasticity, and friction of such thin films. Quantitative evaluation of Scanning Probe Microscopy data usually gives large errors (~50%) and controlled surface environments are required. An effort will be made to use molecular scale simulations to analyze data derived from such tests. The objective is to direct efforts at improving the tribological properties of surfaces and thin films. The project will require interdisciplinary expertise in fabrication, testing and characterization and simulation."

Dip-Pen-Nanolithography: Development of Novel Ink & Improved Printing Methods

This is a new technique and has a great of promise for printing small features at a fast rate as well as without the assistance of complicated optics. Here a small "pen" such as AFM tip can be used to write or deposited multilayers of molecules on a substrate. This would allow us to develop interesting nanostructures and nanodevices. So far a few molecules have been tried as ink and the technology appeared to be successful. However, the complete potential of this technology has not yet established due to the lack of interesting compounds or inks. We will try to explore this missing link and work towards designing a "nanoptrinter" or other devices.

Computer Modeling of spin-dependent charge transport and spin electronic devices
(Students should preferably have some background in physics)

Main supervisor: Dr Mansoor B. A. Jalil (Dept of Electrical and Computer Engineering, FOE)

Spin electronics or "spintronics" devices is a new class of nanoscale devices which exploit both the charge and spin properties of carriers. This class of devices promises a manifold increase in processing speed and power efficiency over conventional semiconductor devices. For instance, device speed can theoretically reach the THz range of spin precessional frequency. The first generation spintronics devices such as the magnetic RAM chip, utilize "passive" spin control, in which spin filtering and spin-dependent conductivity arise from material and interfacial properties of the device. The next generation of devices makes use of active spin control in which the individual spins of carriers are controlled by electrical, magnetic and optical means.

Computer simulation of spin transport is a new and rapidly developing area of research. A vast majority of present carrier transport theories and models have completely ignored the spin property, and needs to be revised substantially. At a fundamental level, we aim to develop spin transport models which can describe novel phenomenon such as spin-orbit (Rashba and Dresselhaus) effects, spin transfer torque, carrier-moment RKKY exchange in diluted magnetic semiconductor and interplay between spin and charge quantization. The models will range from simple effective mass approximation to more refined techniques of second quantized form, and non-equilibrium Green's function approach. At a more practical level, new computational models need to be developed for novel devices such as the spin-FET, spin injector, magnetic tunneling transistors, and spin qubit devices. A successful development of this model will have a significant impact in this emerging field of computational research.

Computer Modeling of Magnetic Nanoparticles
(Students should preferably have some background in engineering, physics or material sciences)

Main supervisor: Dr Mansoor B. A. Jalil (Dept of Electrical and Computer Engineering, FOE)

Magnetic nanoparticles have important applications for storing information and as advanced nanosensors. It is thus important to model the magnetization dynamics of these particles when they are subjected to an external field and/or in the presence of thermal fluctuations. Theoretically, the study of stochastic magnetization dynamics is divided into two broad areas, i.e. via the Langevin dynamics/Landau-Lifshiftz-Gilbert (LD/LLG) or the Monte-Carlo/Master Equation (MC/ME) method, each having their own advantages. However, the linkage between the two distinct methods has proved problematic. From a theoretical standpoint, this situation is unsatisfactory because results obtained from one method cannot be analytically confirmed with the other method. More crucially, a link will help overcome a major weakness of the MC/ME method, where time evolution is calibrated in arbitrary MC steps rather than real time step as in the LD approach. A successful computer model combining both methods, will be extremely useful in modeling the switching behavior and thermal stability of perpendicular magnetic recording (PMR) media and heat-assisted magnetic recording (HAMR). PMR and HAMR can attain storage densities in excess of 1 Tb/in2 (> 10 times more than the bit density of present hard-disks) and are expected to be the dominant storage media for the next 10-15 years. Magnetic nanoparticles are also increasingly being used in biomedical applications such as bead-array counters and targeted drug delivery.

Computer Simulations of Interactions between Nanoparticles and Living Cells

Nano-entities have a great impact on living cells. A typical example is the entry of viruses into a host cell, followed by the viral replication and virions exit. The entry and exit involve cell membrane wrapping and budding, thereby leading to a substantial deformation of the lipid bilayer membrane, depending on the entity size and the interaction with the membrane. Due to the complex nature of living cells, the underlying biophysics is not easy to resolve and remains a challenge to date. Computer simulations are a powerful tool that has been widely used in polymer science and appears promising to study the interactions, dynamics and kinetics for nano-entities in the vicinity of a living cell. Coarse-grained Monte Carlo and Brownian dynamic simulations will be applied to investigate the particle (to model a virus, for instance) induced cell fusion and fission, and the corresponding morphological changes of the membrane. It is aimed to gain a better understanding of underlying physics for biological processes.

Cell-Substrate Interactions

The primary goal of this project is to conduct a systematic study to understand, predict and control the effects of nano-scale changes in the synthetic ECM on cell morphology and functions. Hence, this research will directly test the underlying hypothesis that the interplay between cells and nano-scale synthetic ECM is critical to the morphological and functional development of cells. Although it is well characterized that gross changes in ECM impact on cell behavior, little is know on how cell morphology and functions would be affected by fine changes (at the nanometer scale) in the synthetic ECM. An in-depth understanding of the molecular effects of synthetic nanofiber ECM on cell behavior will aid in designing superior biomaterials for tissue engineering with specific applications.

Biomimetic Nanomaterials

Bone grafting and tissue engineering is a subject of intensive investigation in human health care as it directly affects the quality and length of the human life. Need for the development of biomaterials for bone grafting and tissue engineering is continuously stimulated by the unsatisfactory performance of available materials and, of course, lacking appropriate technique to fabricate bone-resembling substitutes. Reconstruction of bone tissue using biomaterials having structure, composition, and biological features that mimic the natural bone is a goal to be pursued.