The catalytic action of proteolytic enzymes on proteins has wide industrial applications in many industries, i.e. food, pharmaceuticals, diagnostics, waste treatments, and the textile industry. However, the use of soluble proteases has limitations such as high costs, poor stability, and lack of multiple utility – all of which hampers their implementation at industrial scale. A quest for optimum enzyme performance has therefore made enzyme immobilization the preferred technology for designing industrially feasible and stable biocatalyst. This project is being achieved by exploiting the proteolytic activities of cell-envelope proteinases (CEPs) from Lactobacillus delbrueckii subsp. lactis 313. Optimization of culture conditions and bioprocessing of CEPs has been achieved and stable forms of these enzymes are prepared via immobilization techniques. Covalent enzyme attachment on various supports such as nanoparticles and synthetic polymers fibres is being studied. Another immobilization technology being explored is cross-linking enzyme aggregates (CLEA). It is anticipated that the integrated bioprocess, involving expression and immobilization of CEPs will yield stable biocatalysts that are cheap, simple and scalable, giving them the potential for various industrial applications in protein degradation.
The immobilisation of enzymes has always been an approach to efficiently re-use and recycle enzymes from reactant mixtures. It is also a way to ensure the complete removal of enzymes from the product stream. Research on enzyme immobilisation technique has progressed rapidly in the past decade, with the current trend being to achieve the immobilisation at nanoscale. This offers several benefits over conventional techniques namely higher surface area, increased enzyme loading, lower mass transfer and reduced fouling effects. However, it is a challenge to separate these nanoparticles at industrially relevant scale. This project aims to overcome this challenge by developing a peptide scaffold that responds to external stimuli on which the enzyme can be immobilised. Self-assembling peptides are known to spontaneously form nanostructures that translate to macroscopic forms like hydrogels and aggregates. Such macrostructures are relatively easy to separate with existing separation process at large scale. The research would focus on utilising such self-assembling peptides for developing a responsive peptide scaffold for enzyme immobilisation.
Stimuli-responsive peptides or proteins that are able to self-assemble at air-water interface can be used for function control of foams for widespread applications. However, production and application of such materials are cost ineffective. This project aims at developing knowledge for application of these promising designed protein surfactants at reduced cost while maintaining their high performance, by understanding the link between interfacial properties and foam functions. Research includes developing low cost process for production and purification of designed proteins, identifying key factors for foam function control, as well as developing formulation systems with low cost and high performance.
RNA interference (RNAi) is a promising approach for treatment of many protein related diseases. However, the development of RNAi into successful therapeutical application is hindered by low efficiency of existing delivery systems. The PhD project focuses on the development of a novel delivery system for in vivo application of RNAi. The work combines nanoparticle technology and design of new peptides to engineer advance delivery system that does not require chemical modification for nanoparticle functionalization. In the preliminary research, two novel bifunctional peptides were designed to conjugate the large pore mesoporous silica nanoparticles (LP-MSN) and nucleic acids in the absence of chemical reagents. Our preliminary data shows that bifunctional peptides-modified LP-MSN delivery system is a promising tool for RNAi-based therapy.
The properties of clean, healthy, high specificity and high efficiency biocatalysts have wide application ranging from food processing to biofuel and medical diagnostics. However, biocatalysts from natural sources are sensitive towards heat, solvent, proteinase and other extreme conditions. High cost of biocatalysts also impedes its broad application. These weaknesses limit the application of biocatalysts. Enzyme immobilization is utilized by engineers to improve their stability and reusability as advanced biocatalysts. Especially, immobilizing enzymes on nanoparticles with various properties have been intensively studied. This research aims to increase enzyme functions by developing new immobilisation methods that are environmental friendly and don’t require chemical modification at nanoparticle surface. This project is expected to engineer advanced biocatalyst that can be used to produce fine chemicals and drug intermediates.