Nanyang-SNIC Distinguished Lectureship Series

Lecture Archives (2020 and before)

 

Title:Mitochondrial Metabolite Signalling in Health and Disease
Speaker:Professor Mike Murphy
Date:6th February 2020
Time:3.00pm-4.30pm
Venue:SPMS Lecture Theatre 3
Host:Assistant Professor Felipe Garcia
Abstract:Mitochondrial redox metabolism is central to the life and death of the cell. For example, mitochondrial production of free radicals and subsequent oxidative damage has long been known to contribute to damage in conditions such as ischaemia-reperfusion (IR) injury in stroke and heart attack. More recently mitochondrial redox changes have also been implicated in redox signalling. Over the past years we have developed a series of mitochondria-targeted compounds designed to ameliorate or determine how these changes occur. I will outline some of this work, which suggested that ROS production in IR injury during stroke was mainly coming from complex I. This led us to investigate the mechanism of the ROS production and using a metabolomic approach we found that the ROS production in IR injury came from the accumulation of succinate during ischaemia that then drove mitochondrial ROS production by reverse electron transport at complex I during reperfusion. This surprising mechanism led up to develop further new therapeutic approaches to impact on the damage that mitochondrial ROS do in pathology and also to explore how mitochondrial ROS can act as redox signals. I will discuss how these unexpected mechanisms may lead to redox and metabolic signals from mitochondria in a range of conditions under both healthy and pathological conditions.

 

 

Title:Dynamic Molecular System
Speaker:Professor Ben Feringa
Date:13 January 2020
Time:4.00pm-5.30pm
Venue:SPMS Lecture Theatre 3
Host:Assistant Professor Felipe Garcia

 

Title:Chemical Design of Nanoplasmonic Sensors
Speaker:Professor Luis Liz-Marzan
Date:25th September 2019
Time:2.30pm-4.00pm
Venue:SPMS Lecture Theatre 2
Host:Associate Professor Ling Xing Yi
Abstract:

Nanoplasmonics can be defined as the science studying the manipulation of light using materials of size much smaller than the radiation wavelength. This technology finds applications in various fields including sensing and diagnostics. An essential component of nanoplasmonics are the nanostructured materials, typically noble metals, which can very efficiently absorb and scatter light because of their ability to support coherent oscillations of free (conduction) electrons. Although the remarkable optical response of “finely divided” metals is well known since more than 150 years ago, the recent development of sophisticated characterization techniques and modeling methods has dramatically reactivated the field. An extremely important pillar supporting the development of nanoplasmonics has been the impressive advancement in fabrication methods, which provide us with an exquisite control over the composition and morphology of nanostructured metals. Colloid chemistry methods in particular have the advantages of simplicity and large scale production, while offering a number of parameters that can be used as a handle to direct not only nanoparticle morphology but also surface properties and subsequent processing. This talk will present a selection of fabrication methods that allow fine tuning of the morphology of nanoplasmonic building blocks, with the ultimate goal of improving their optical properties and their performance in sensing applications. Several examples will be presented in which nanostructured materials comprising gold nanoparticles were used as substrates for ultrasensitive detection of biorelevant molecules.

References 1. M. Grzelczak, J. Pérez-Juste, P. Mulvaney, L.M. Liz-Marzán, Chem. Soc. Rev. 2008, 37, 1783-1791 2. L.M. Liz-Marzán, M. Grzelczak, Science 2017, 356, 1120-1121. 3. G. González-Rubio et al., Science 2017, 358, 640-644. 4. G. Bodelón et al., Nature Mater. 2016, 15, 1203-1211. 5. J. Kumar, H. Eraña, E. López-Martínez, N. Claes, V.F. Martín, D.M. Solís, S. Bals, A.L. Cortajarena, J. Castilla, L.M. Liz-Marzán, PNAS 2018, 115, 3225-3230.

 

Title:A Future for Unconventional Carbon Nanostructures
Speaker:Professor Feng Xinliang
Date:8th May 2019
Time:11.00 am – 12.30 pm
Venue:SPMS Lecture Theatre 4
Host:Assistant Professor ITO Shingo
Abstract:

Carbon is intimately connected to almost everything we deal with in a daily basis. Scientists have realized two allotropes of carbon two hundred years ago, which are the most well-known diamond and graphite. These allotropes, with their vastly different structures, reveal that the structure and alignment of carbon atoms have profound effects on the material properties. In the past four decades, nanometre-sized allotropes of carbons, such as fullerenes, carbon nanotubes and graphene have emerged that have completely changed the landscape of carbon-based materials, and their discoveries have opened doors to enable the development of new physical sciences and technologies.

Nowadays, many carbon nanostructures have been theoretically predicted but are yet to be developed experimentally. Strategies like “top-down” and “bottom-up” approaches are established towards their syntheses. In general, “top-down” approach starting from graphitic precursors often leads to a mixture of molecules/polymers with a broad range of carbon nanostructures and thus a variety of properties. “Bottom-up” step-wise synthesis represents a promising approach to achieve structurally defined carbon nanostructures with molecular-level design. In this presentation, I will firstly introduce the rationale for using bottom-up chemistry for the precise synthesis of various graphene nanostructures ranging from arm-chair to zig-zag edge structures. In addition to the planar nanocarbons, curved carbon nanostructures as promising next-generation carbon materials will be next discussed. The curvature has important ramifications on the inherent physical behavior of carbon materials. Third, the implementation of combinations of heteroatoms, such as nitrogen and boron, for example substituting a C=C unit with an isoelectronic B-N moiety or the NBN-fragment at the zig-zag edges which can be selectively oxidized into the radical cation, will be presented. Finally, to bridge the molecules and devices, structurally well-defined graphene nanoribbons will be particularly introduced. Over the past few years, a variety of GNRs with different width and edge structures have been accessed by solution-phase and on-surface syntheses, as well as CVDbased method, which are essential for the development of future graphene-based nanoelectronics and spintronics.

 

Title:Interfacing Nature’s Catalytic Machinery with Synthetic Materials for Semi-artificial Photosynthesis
Speaker:Professor Erwin Reisner
Date:25th February 2019
Time:11.00 am – 12.30 pm
Venue:SPMS Lecture Theatre 4
Host:Assistant Professor Soo Han Sen
Abstract:

Semi-artificial photosynthesis interfaces biological catalysts with synthetic materials and aims to overcome the limitations of natural and artificial photosynthesis.1 It also provides an underexplored strategy to study the functionality of biological catalysts on synthetic scaffolds through a range of techniques. This presentation will summarise our progress in integrating biocatalysts in bespoke hierarchical 3D electrode scaffolds and photoelectrochemical circuits.2 We will first discuss the fundamental insights gained into the function of the water oxidation Photosystem II, where (i) unnatural charge transfer pathways have been revealed at the enzyme-electrode interface, and (ii) O2 reduction that short-circuit the water-oxidation process has been discovered.3-4

The wiring of Photosystem II to a H2 evolving hydrogenase or a CO2 reducing formate dehydrogenase has subsequently enabled the in vitro re-engineering of natural photosynthetic pathways. We have assembled efficient H2 evolution and CO2 reduction systems that are driven by enzymatic water oxidation using semi-artificial Z-scheme architectures.5-7 In contrast to natural photosynthesis, these photoelectrochemical cells allow panchromic light absorption by using complementary biotic and abiotic light absorbers. As opposed to low-yielding metabolic pathways, the electrochemical circuit provides effective electronic communication without losses to competing side-reactions. Progress in the integration of robust live cyanobacteria in 3D structured electrodes will also be discussed.8

References (1) Kornienko et al., Nature Nanotech., 2018, 13, 890–899 (2) Mersch et al., J. Am. Chem. Soc., 2015, 137, 8541–8549 (3) Zhang et al., Nature Chem. Biol., 2016, 12, 1046–1052 (4) Kornienko et al., J. Am. Chem. Soc., 2018, in print (DOI:10.1021/jacs.8b08784) (5) Sokol et al., Nature Energy, 2018, 3, 944–951 (6) Nam et al., Angew. Chem. Int. Ed., 2018, 57, 10595–10599 (7) Sokol et al., J. Am. Chem. Soc., 2018, 140, 16418–16422 (8) Zhang et al., J. Am. Chem. Soc., 2018, 140, 6–9

 

Title:Conversion of Oxygenated C1 Feedstocks to C2 Products: Mechanism and Electrochemistry with Molecular and Heterogeneous Systems
Speaker:Professor Theodor Agapie
Date:16th January 2019
Time:10.30am to 12.00pm
Venue:SPMS Lecture Theatre 3
Host:Assistant Professor Jason England 
Abstract:

Toward utilizing CO2 as a carbon source for the generation of liquid fuels and other value-added chemicals using renewable energy, the development of chemical transformations for the preparation of multicarbon products is desirable. From the perspective of organometallic complexes, CO reductive coupling chemistry has been demonstrated with Mo supported by multidentate terphenyl diphosphine ligands. Low temperature synthetic, kinetics, and isotopic labeling studies have been performed to gain mechanistic insight into CO activation and coupling. The redox non-innocent and labile pendant arene donor is instrumental for the observed reactivity. From the electrochemical perspective, organic additives have been employed to tune the selectivity of CO2 reduction on polycrystalline Cu electrodes. Addition of N-aryl pyridinium results in almost complete suppression of methane formation and decrease in hydrogen generation, for a combined selectivity for C2 and C3 products of ~80%. The formation of an organic film consisting of the product of reductive dimerization of N-aryl pyridinium is required for improved selectivity of CO2 reduction to multicarbon products.