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We are pleased to present Asep Nugraha to speak on Wet chemical process for the preparation of mesoporous gold-based nanomaterials and Yilun Weng on Alginate-based Materials for Enzyme Stabilization using Spray Drying.

Time:    11am

Date:     30 March 2023

Where:  AIBN Level 1 Seminar Room (#132)


Asep Nugraha

Title:  Wet chemical process for the preparation of mesoporous gold-based nanomaterials

Abstract:  Since the discovery of the high catalytic activity of unsupported gold (Au) nanoparticles for CO oxidation, gold-based nanocatalysts have emerged as a new class of highly active catalysts that drives numerous chemical reaction processes. Au-based nanocatalysts have found applications in various fields including environmental remediation, biosensor, chemical synthesis, and energy conversion. In order to enhance the efficiency of material utilization and reduce costs of Au-based nanocatalyst, researchers are exploring methods either to increase surface area or incorporate less expensive metals through alloying process. Among various approaches, adding mesoporosity in Au-based nanomaterials have attracted great interest as it can improve catalytic activity by providing large surface area with highly abundant of active sites and create pathways for mass and electron transport in the porous structure. In addition, pores in Au-based nanomaterials can impose electromagnetic (EM) boundary conditions that generate intense and highly contorted EM fields via surface plasmon resonances that is beneficial in optical applications. Although various synthesis approaches, including soft- and hard-templating, have been employed to fabricate mesoporous Au-based nanomaterials, the fabrication process to produce the mesoporous Au-based nanomaterials with uniform and well-defined porous construction is still great challenge to address due to the high mobility of the Au+3, and significant positive reduction potential. Therefore, in this study we develop the simple approach to fabricate mesoporous Au-based nanomaterial with high uniformity in shape and a narrow range of pore size distribution via precursor reduction in the presence of polymeric micelle templates and thiol capping agents. This strategy allows for easy control over the dimensional aspects of the nanoarchitecture (e.g. pore size, and particle size), enabling the tunability of electrocatalytic activity and the electric field modification upon LSPR excitation. Our study provides an understanding of the well-controlled structural features for the meso-Au NPs, which hold promise for the improved performance in the optical application and electrocatalyst.

Bio:  Asep Nugraha is a PhD student at the Yamauchi group in AIBN at the University of Queensland. He obtained his Bachelor's degree from Padjadjaran University in Indonesia and Master's degree in Nanoscience and Nanotechnology from Waseda University in Japan. His research focuses on the synthesis of advanced inorganic nanomaterials with porous architecture and their application in the field of energy and biosensors.

Yilun Weng
Title:  Alginate-based Materials for Enzyme Stabilization using Spray Drying
Abstract:  Enzymes are important biocatalysts for industries. However, many enzymes are sensitive to high temperatures involved in common industrial processes which could decrease or even completely destroy the enzyme activity. To address this issue, many approaches have been developed to improve enzyme thermal stability. Our previous study has demonstrated that enzyme encapsulation using alginate microparticles is effective in improving enzyme thermal stability. However, it remains a challenge to improve not only enzyme thermal stability, but also bioavailability. Bioavailability is critical for encapsulated enzymes, especially in food and feed industries when enzymes are used as food additives. We optimized the overall enzyme encapsulation efficiency using a three-fluid nozzle spray drying process, and achieved a high enzyme loading of 48 wt% with a high enzyme thermal stability. The encapsulated enzyme showed much less conformational structural changes when subjected to heat treatment, compared with native enzymes. Furthermore, an in vivo animal trial of the encapsulated enzyme demonstrated an excellent bioavailability. Compared to free enzyme, the encapsulated enzyme was able to promote the absorption of phosphorus and calcium, further enhancing the animal overall performance.

Bio:  Yilun obtained a BE in Energy and Environmental Engineering at Zhejiang University (China) and a ME in Chemical Engineering at the University of Queensland before starting his PhD in AIBN. Yilun's research project is focused on developing a scalable enzyme encapsulation technology aimed at enhancing enzyme stability. His work is supervised by Prof Chun-Xia Zhao, Dr Hao Song, and Dr Wendy Chen. The project is of significant interest to the industry, and it is being conducted in collaboration with Bioproton Pty Ltd.

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