Effect of amino acid composition on the antibacterial properties of peptide polymer antimicrobial agents
In 2016, the Polymer Science Group (PSG) at the University of Melbourne reported in Nature Microbiology on the development of a new class of antimicrobial agents, termed “Structurally Nanoengineered Antimicrobial Peptide Polymers” (SNAPPs), in the form of star-shaped polypeptide nanoparticles containing cationic lysine and hydrophobic valine amino acid residues. These SNAPPs demonstrated high efficacy against a range of ‘gram-negative’ bacteria and some of their concerning multidrug resistant (MDR) strains. Importantly, these SNAPPs demonstrated low toxicity towards mammalian cells and no bacterial resistance to the SNAPPs was detected due to their suspected multimodal mechanism of action. This study will look at preparing star-shaped SNAPPs using alternative cationic (e.g. ornithine, arginine) and hydrophobic (leucine, phenylalanine) amino acids to determine their effect on the antibacterial properties of SNAPPs. The results will potentially lead to the optimisation of SNAPP activity against gram-negative and other untested classes of bacteria.
Group webpage: Polymer Science
Application of iron MOF@GOx in RAFT polymerization technique
Fenton chemistry describes generation of hydroxyl radicals via reduction process of hydrogen peroxide (H2O2) by iron ferrous (Fe2+). According to our previous study, this reaction can initiate aqueous RAFT polymerization by using either chemical or biological Fenton reaction’s reagents at room temperature. In chemical Fenton-RAFT system, the challenge is that the polymerization stops after a few minutes, and we are not able to achieve high monomer conversions (> 95%) as H2O2 runs out instantaneously.
To overcome this, we have employed an enzyme (ie: glucose oxidase (GOx)) to slowly generate H2O2, which has resulted in well-defined polymers with near-quantitative conversion values. However, in this biologically activated RAFT polymerization the isolation of polymer is not easily achievable.
On the other hand, these Fenton-RAFT processes work in only aqueous media. In this project, we aim to overcome the drawbacks of above-mentioned Fenton-RAFT processes by conjugation of GOx and iron metal organic framework (MOF) particles, termed as MOF@GOx. Use of MOF particles will make it feasible to use organic solvents in order to make water-insoluble polymers. Likewise, these conjugates could be easily removed from the polymer media by filtration.
Group webpage: Polymer Science
Novel active and intelligent packaging for the meat industry
The Polymer Science Group as part of an industry funded collaboration with Meat and Livestock Australia, are looking at developing novel packaging solutions for the Australian meat export market. Packaging methods that provide extended shelf life; Australian brand labelling which invokes assurance of quality, integrity and provenance will increase demand at premium prices in the domestic and export markets. The recommendations from a preliminary study which will determine the scope of the research is currently underway. Potential packaging solutions may include either antimicrobial packaging, oxygen scavenger films or time temperature indicators.
This research project will involve conjugation of small organic compounds (antimicrobials, oxygen with a polymer precursor which will then be incorporated into a suitable packaging matrix. The student will learn synthetic chemistry, polymer chemistry and processing skills as well as develop skills in analytical instrument skills including, UV-Vis, FTIR, NMR, MALDi-ToF, DSC and tensile/compression testing.
Group webpage: Polymer Science
Flexible supercapacitors with piezoelectric separators
Supercapacitors are an interesting subclass of power sources aimed to complement or replace batteries in various applications. With the current trend of integrating power sources onto various wearable and portable devices, the need arises for the development of flexible supercapacitors that can be functional while bent or folded and remain an integral part of a portable or wearable device without compromising their charge storage performance.
This project aims to look at employing piezoelectric materials (that is, materials that can generate an electrical potential upon deforming) as components of supercapacitors. Piezoelectric polymers will be integrated into flexible supercapacitors as separators, and the ability of such an innovative device to self-charge via deformation will be investigated. The student(s) will be involved in the design of a flexible supercapacitor, its practical implementation and performance testing. Knowledge on polymer science, piezoelectricity and energy storage will be obtained by the person(s) in the course of this research project. The project has industry links with the Reserve Bank of Australia.
Building a cross flow system and testing for seawater desalination
Supervisors: Prof Amanda Ellis
Seawater reverse osmosis (SWRO) desalination is affected greatly by membrane biofouling which reduces membrane lifetimes and increases cost of permeate production.
This project has three parts. (1) the design and building of a 3-tiered desalination cross-flow system. All equipment is in place for assembly. (2) measurement of flux/permeate and salt rejection through industrial RO membranes and (3) chemical modification of membranes to improve biofouling resistance. This work is part of a broader project with DOW Chemicals USA.
One worm per drop: benchmarking a novel microfluidic device for drug discovery using C. elegans
The resistance of Alzheimer’s disease (AD) to effective therapeutic intervention coupled with the increasing costs of drug development demand new, cost-effective technologies better able to identify which “hits” emerging from drug discovery pipelines will show efficacy in the clinic. Caenorhabditis elegans (a simple nematode worm) is a powerful model system enabling the processes occurring within ageing neurons to be studied within the physiological context of a whole organism. The project aims to benchmark and evaluate a prototype of an automated microfluidic platform able to quickly and consistently immobilise C. elegans worms, ie: placing one animal per drop in a flowing stream of water drops in oil, for allow high-resolution imaging as a means to assay uptake, distribution and efficacy of compounds with potential for therapeutic benefit in AD. A prototype microfluidic device has been developed and this project aims to test the dosing of drugs via the coalesce of drops within the device as well as the consistency of obtaining one drop per worm. The initial early stages of the work will be undertaken within chemical engineering and focussed on learning how to use the microfluidic device and performance testing without worms. This will be followed by the chance to work with our research collaborates in the Flory Institute of Neuroscience and Mental Health actually running animals through the device, dosing them compounds under active development for treating AD.
Group webpage: Dagastine Group
Quantitative models of the microparticle indentation process
Atomic Force Microscopy (AFM) has been used with great success to measure the strength of microscale objects, including cells, microparticles and microcapsules. This type of measurement is of fundamental importance in many biological, pharmaceutical, personal-care products and food processing applications. Accurate measurements of stiffness are crucial to determine if drug-delivery capsules are bio-compatible, or to define robustness in various processes associated with fragrance or flavour delivery and newer technologies such as self-healing materials.
This project will focus on developing and applying computational models of a micro-particle being compressed by an indenter. Specifically, the project will examine the effect of adhesion between the particle and the substrate on the accuracy of the measurement, and develop quantitative tools to correct experimental data from typical AFM measurements. The effect of particle size & shape, indenter size & shape, and adhesion strength will be investigated.
Group webpage: Dagastine Group
Ion transport in charged polymer membranes
Charged polymer membranes, often referred to as ion exchange membranes (IEMs), play a prominent role in addressing global energy and environmental challenges. They have great potential in a variety of applications including water desalination, wastewater treatment, energy storage and food and beverage processing. Electromembrane processes (e.g. electrodialysis, fuel cells, and membrane capacitive deionisation) are based on ion migration across ion exchange membranes from one solution to another under the influence of a potential gradient. To improve separation performance and energy efficiencies of these processes, a sound understanding of water and ion transport in charged polymer membranes is required to develop high throughput and chemically stable membranes. This project will investigate the transport of monovalent and divalent ions through charged polymer membranes across a range of ionic strengths. During this project, the student will acquire hands-on experience in membrane preparation and characterisation, as well as advanced analytical techniques such as ion chromatography and zeta potential analysis.
Incineration chemistry of chemical warfare agents
Supervisor: Dr Gabriel da Silva
The threat of chemical weapons (CW) attacks is a persistent one, despite being internationally outlawed. Huge stockpiles of nerve agents and other CWs remain in existence, and their safe and complete destruction is an ongoing concern. To aid in the destruction of CWs and in the investigation of suspected CW usage we need to understand how they decompose in incinerators and the residual products of their combustion. This is a computational project, which will use quantum chemical and statistical mechanical methods to predict the mechanism and energetics of CW decomposition reactions. Training will be provided to use the university high performance computing cluster and appropriate molecular modelling and quantum chemistry software packages.
Group webpage: Group da Silva
Improving the efficiency of extraction of biofuels from microalgae slurries using standing wave ultrasound treatment
Microalgae are a promising new feedstock for sustainable production of protein feeds, nutraceuticals and biofuels. However, the cost of producing biofuels from microalgae must be reduced to become competitive with fossil fuels.
The ultimate goal of the project is to improve the extraction efficiency of biofuel feedstock lipids from viscous slurries of ruptured microalgae cells. This is an important bottleneck in the processing of microalgal to produce fuels.
This viscous algal biomass slurry is a very complex mixture, consisting of proteins, carbohydrates, cell debris along with valuable lipids. During the solvent extraction of lipids from this mixture, solvent with dissolved lipids in it forms a very stable emulsion. The stability of emulsion is due to the adsorption of various components from the biomass onto the oil-water interface.
The standing wave ultrasound treatment is a promising new option that we are exploring to help separate the emulsion from the viscous slurry. The initial study involves developing optimal ultrasound parameters using model emulsions of hexadecane in water/glycerol mixtures of various viscosities. Once the ultrasonic parameters are established to separate oil from various model viscous solutions, these parameters will be applied to the actual extraction of biofuel feedstock lipids from a microalgae slurry.