Atomic Force Microscopy and Food Workshop

afm-workshopImmediately following DOF17 there will be a 1.5-day workshop at the University of Auckland on the use of Atomic Force Microscopy in food and nutrition research. The workshop aims to attract 20-30 participants across a broad range of research areas.

The main focus is to provide participants with practical experience of analysing food materials using the latest AFM techniques and equipment. In addition, participants will learn about recent progress in the field from leading international AFM experts working in the areas of foods, biomaterials, and soft matter systems.

The workshop will cater for beginners and AFM experts alike. We also anticipate involvement of advanced users seeking exposure to new analytical approaches.


Confirmed Keynote Speakers

Patrick Gunning
Scanning Probe Microscopy Group
Institute of Food Research, Norwich, UK

Raffaele Mezzenga
Laboratory of Food and Soft Materials
ETH Zürich, Switzerland

Jenny Malmstrom
Chemical & Materials Engineering
The University of Auckland, New Zealand

Gleb Yakubov
Centre of Excellence in Plant Cell Walls
The University of Queensland, Australia

Rico Tabor
School of Chemistry
Monash University, Melbourne, Australia

Bill Williams
Institute of Fundmental Sciences
Massey University, New Zealand

Malcolm Lawn
Nanometrology Section
National Measurement Institute, Australia

Keynote Speakers Abstract and Bios

Unique aspects of force included within microscopy

Patrick Gunning, Quadram Institute Bioscience (f. Institute of Food Research), Norwich, United Kingdom

The combination of high-res visualisation of ultrastructure with force measurement is the major impact of AFM. The potential of force spectroscopy to probe the specifics of receptor-ligand interactions at the single molecule level is promising. For example, factors such as bond lifetimes, distances, and the number and nature of the energy barriers involved in single receptor-ligand interactions, are all within the realm of AFM measurement. My presentation will include explanations of the fundamental aspects of AFM’s force spectroscopy and demonstrate the ability that this combination has successfully enabled exploration of structure-function relations in food science. It features several aspects; food material science, digestion, satiety, bioactivity and my most recent investigation of the role of the gut microbiome.

Patrick Gunning has worked on the development of scanning probe microscopy (SPM) of biological systems at the Quadram Institute Bioscience (former Institute of Food Research) in Norwich for over 22 years. His group were one of the first in Britain to use the original form of scanning probe microscopy, the scanning tunnelling microscope (STM) and their research has now moved on to atomic force microscopy (AFM). Patrick is a recognized expert in field of biological AFM and has co-authored an internationally best-selling book on the subject (currently in its second edition). His research areas range from the material science of food ultrastructure to the physiological and biological interactions between food components, the GI tract and the microbiota which inhabit it.

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Analyzing Polymers, Filaments, Biomacromolecules and Fibrous Objects via the open-source code FiberApp

Raffaele Mezzenga, ETH Zurich, Department of Health Science & Technology, Schmelzbergstrasse 9, LFO E23, 8092 Zurich

Biological semiflexible polymers and filaments such as collagen, fibronectin, actin, microtubules, coiled-coil proteins, DNA, siRNA, amyloid fibrils, etc. are ubiquitous in nature. In biology, these systems have a direct relation to critical processes ranging from the movement of actin or assembly of viruses at cellular interfaces, to the growth of amyloid plaques in neurodegenerative diseases. In technology and applied sciences, synthetic macromolecules or fibrous objects such as carbon nanotubes are involved in countless applications. Accessing their intrinsic properties at the single molecule level, such as their molecular conformations or intrinsic stiffness, is central to the understanding of these systems, their properties, and the design of related applications. In this talk I will discuss the features and potential of FiberApp in analyzing polymers, fibrils and filamentous objects. FiberApp is a new open-source tracking and analysis software based on a cascade of algorithms describing structural and topological features of objects characterized by a very high length-to-width aspect ratio, generally described as “fiber-like objects”.

Raffaele Mezzenga received his master degree (Summa Cum Laude) from Perugia University, Italy, in Materials Science and Engineering, while actively working for the European Center for Nuclear Research (CERN) and NASA on elementary particle-polymer interactions (NASA Space Shuttle Discovery mission STS91). In 2001 he obtained a PhD in Polymer Physics from EPFL Lausanne, focusing on the thermodynamics of reactive polymer blends. He then spent 2001-2002 as a postdoctoral scientist at University of California, Santa Barbara, working on the self-assembly of polymer colloids. In 2003 he moved to the Nestlé Research Center in Lausanne as research scientist, working on the self-assembly of surfactants, natural amphiphiles and lyotropic liquid crystals. In 2005 he was hired as Associate Professor in the Physics Department of the University of Fribourg, and he then joined ETH Zurich on 2009 as Full Professor. His research focuses on the fundamental understanding of self-assembly processes in polymers, lyotropic liquid crystals, food and biological colloidal systems.

Prof. Mezzenga has been a visiting Professor from Helsinki University of Technology (now Aalto University), a Nestlé Distinguished Scientist, and recipient of several international distinctions such as the Biomacromolecules/Macromolecules Young Investigator Award (2013, American Chemical Society), the John H. Dillon Medal (2011, American Physical Society), the Young Scientist Research Award (2011, American Oil Chemist Society) and the 2004 Swiss Science National Foundation Professorship Award.

Imaging challenges in bionanotechnology

Jenny Malmstrom, Department of Chemical and Materials Engineering, University of Auckland, New Zealand

In our research group we are interested in the interface between materials and biological systems – such as proteins and cells. Structured or organised surfaces with nanoscale features are important in a range of fields ranging from energy and computing to controlling cellular adhesion. The precise organisation of proteins at surfaces is one route to creating such engineered interfaces. Proteins exist with an enormous structural and chemical versatility and lend themselves well to be functionalized with different moieties. The ability to rationally engineer proteins enables the use of proteins as carefully designed nanometer sized building blocks.

I will present work from our group focussed on using protein-protein interactions to build up higher order structures, and in particular to order these structures. Proteins like Lsmα and peroxiredoxin self-assemble into robust doughnuts whose pore size can be tuned specifically to encapsulate metal complexes or nanoparticles and then assemble further into tunnels to create magnetic, electrical or optical nanorods. This work describes how we are harnessing this potential to create functional arrays of these self-assembling protein rings. We have explored ways of arranging these protein rings, for example through templating using a self-assembling block copolymer, or through specific binding to a patterned surface. Furthermore, the protein core has been used to template the synthesis of small (~3 nm) magnetic nanoparticles. Throughout all of this work, imaging is an important characterisation tool and I will show how we use AFM (including magnetic force microscopy) and other techniques to understand our systems.

Jenny Malmström joined the Department of Chemical and Materials Engineering in 2016. She received her MSc degree in Bioengineering at Chalmers University of Technology, Gothenburg, Sweden (2004) and a Ph.D. in Nanoscience at the University of Aarhus, Denmark (2010). From Denmark she moved to Auckland, where she joined the School of Chemical Sciences (UoA) as a post-doctoral research fellow. Her research is very interdisciplinary and focusses on the interface where biological molecules or cells meet novel materials. Her expertise lies in characterising and understanding the material-biomolecule interactions and the influence of surface properties that underpin cell adhesion onto substrates. This detailed understanding can be applied to emerging and exciting areas such as the creation of smart materials to help understand or control cellular behaviour, or to create ordered functional patterns of biomolecules.

Nanoindentation of hierarchical biological materials: from polysacchride gels to living cells

Gleb Yakubov, ARC Centre of Excellence in Plant Cell Walls, School of Chemical Engineering, The University of Queensland, Australia

Atomic Force Microscopy is widely used to characterise the micromechanics of complex biological systems including cells. The attraction of using AFM for nanoindentation is its ability to measure very low forces and its operational versatility, as well as the potential to include in situ imaging. However, interpretation of force indentation curves may present a significant challenge especially for biological materials and systems that are heterogeneous and comprise a number of morphological features, each having a unique set of micromechanical properties.

Here, I present a novel Multi Regime Analysis (MRA) algorithm that tackles these challenges enabling deconvolution of highly complex force indentation profiles. The MRA approach combines both well established and semi-empirical theories of contact mechanics within a single framework. The fundamental finding is that each structural contribution to the mechanical response can be incorporated in series with other ‘mechanical resistors’ using a vector field of deformations mapped onto the experimental values of force. This simplification enables interpretation of the micromechanical properties of materials with hierarchical structures as well as automated processing of large data sets, which is particularly indispensable for biological systems.

Further, I will illustrate the applicability of MRA for characterising the micromechanics of a broad range of soft materials including plant cell and polysaccharide microgels. In particular, I will show the unique capability of MRA to map micromechanical properties and to evaluate elastic moduli of anisotropic materials with complex hierarchical structures.

Gleb Yakubov joined The University of Queensland in 2012, where he leads Biointerface and Biocolloid engineering group, with a strong focus on glycoprotein/mucin adsorption, saliva interactions, as well as tribological and mechanical properties of hydrocolloid and hydrogel systems including plant cell walls, polysaccharide gels, and complex foods. Prior to joining UQ, Gleb spend 9 years working in industrial R&D roles at one of the global fast-moving consumer goods companies. During this period, he developed and delivered a number of innovations across several food and personal care categories.

AFM with soft colloidal probes – understanding droplet and bubble interactions

Rico Tabor, School of Chemistry, Monash Univeristy, Melbourne, Asutralia

Understanding the interactions between droplets of oil and gas bubbles is central to tuning the desired properties of foodstuffs such as ice cream and mousse, cosmetics and pharmaceuticals, and in mineral flotation and separation. Fundamentally, the interaction between dissimilar fluid interfaces is an interesting problem, as they may charge and deform to different extents, and can potentially experience a range of exotic forces due to the composition of the intervening fluid.

We have developed new methods to use the atomic force microscope (AFM) to analyse collisions between pairs of bubbles and oil droplets – of around 100 microns diameter – in various conditions.1,2 From surfactant-free interfaces where the native charge of the air–water and oil–water interface can be examined, to complex fluids where the granularity of the background fluid creates hysteresis and structural forces, almost all combinations of soft colloid can be interrogated.

Crucially, by combining the data obtained from AFM with other techniques such as confocal microscopy and small-angle neutron scattering,3 a complete picture of the role of solution structure and droplet interacts can be obtained. Now we seek to delve further into the realms of macroscopic and microscopic rheology to better understand the relationships between the rarefied single interaction forces measured using AFM and the bulk properties of the complex and multicomponent fluids that are central to food processing.

Rico Tabor is an ARC Future Fellow and Senior Lecturer at Monash University. He completed his undergraduate degree at the University of Bristol, UK, and went on to undertake a PhD in the surfactant lab of Prof. Julian Eastoe, graduating in 2009.

In 2012, Rico took up a lectureship in the School of Chemistry at Monash University, where he leads the Soft Materials and Colloids Laboratory.His group’s research is focused on several key areas of soft materials and colloidal systems:

o Applications of small-angle neutron scattering, light scattering and atomic force microscopy in studies of soft and self-assembled systems.
o Novel surfactants and their properties, including pH and photo-responsive molecules;
o Carbon nanomaterials (especially graphene oxide) with particular focus on colloidal and interfacial properties;

Rico has published 75 papers across a range of topics in surface and colloid science, and works extensively with industry on applications of colloidal systems to practical problems.

Us and Them: Inhomogeneities in Polysaccharides and their Gels Studied by AFM

Bill Williams Institute of Fundmental Sciences, Massey University, New Zealand

The emergence of patterning in biological systems is of fundamental interest. Here we first describe how the molecular patterning of a polysaccharide substrate influences its single molecule stretching behaviour and describe work designed to facilitate such AFM experiments by the end-tethering of species of interest. Secondly .we briefly review AFM work on the moduli mapping of plant tissues and describe our parallel studies on biomimetic gels that reveal large length-scale inhomogeneities in mechanical properties.

Bill Williams obtained an Honours degree in Physics with Astrophysics from Leeds University, UK and then undertook a PhD in NMR relaxation behaviour at the Open University. He went on to spend a number of years as a Postdoctoral Fellow in The Chemistry Department at York University, UK, working on various aspects of biological polymers. Subsequently he spent 4 years with Unilever Research, before returning to academia in March 2003, with a position in The Institute of Fundamental Sciences at Massey University, NZ, where he is working on biophysics and soft-matter.

Look, but don’t touch: The influence of imaging induced deformation on nanoparticle metrology with AFM

Malcolm Lawn, Nanometrology Section, National Measurement Institute, Australia

Experienced AFM operators will be familiar with common imaging artefacts arising, for example, from tip blunting and contamination, sub-optimal feedback gain settings, and sample drift. Imaging induced sample deformation, however, can be less obvious, and therefore may be routinely overlooked. Results from recent inter-laboratory comparisons of nanoparticle size distributions based on measurements of apparent particle heights derived from AFM imaging and measurements of particle diameter obtained using other nanoparticle characterisation techniques typically show the AFM height measurements to be smaller than measurements with these other techniques.

Imaging induced particle deformation is a likely contributor to this method divergence. With the aim of improving the accuracy of the measurements derived from AFM imaging, we have undertaken an investigation of how nanoparticle deformation varies with imaging parameters and particle properties and how it can influence measurement reproducibility. The results suggest that imaging induced deformation can significantly influence AFM studies of soft nanomaterials. We suggest guidelines to assist AFM operators in achieving greater accuracy and comparability in nanomaterial imaging and characterisation.

Malcolm Lawn is one of the founding staff members of the Nanometrology Section, established in 2007, at the National Measurement Institute Australia (NMIA). Prior to this, Malcolm had been with the NMIA Time and Frequency Section since 1991, working on trapped-ion frequency standards and precision satellite time-transfer. With the Nanometrology Section, his research interests include contributing to establishing traceability to the realisation of the SI metre through NMIA’s metrological scanning probe microscope, AFM calibration, along with image processing and analysis for metrology. More recently, his research has focussed on nanomaterials metrology with AFM, to understand and reduce method divergence between AFM and other nanoparticle characterisation techniques.