Maria Murace (University of Cambridge, UK), Supervisor: Prof. Silvia Vignolini: Understanding Light management in marine organisms.
The aim of this task is to understand light management strategies in seaweeds. In tight collaboration with the Natural History Museum of London (NHM), we will study the structural colour of some green and red seaweeds. Specifically, we will work on two species of green algae, Valonia ventricosa and Chaetomorpha melagonium, and two species of red algae, Chondria scintillans and Chondria coerulescens. By means of optical and electron microscopy, swe will characterise the cell wall architecture in these species. We plan to investigate the formation and development of the cell wall in such algae under different light conditions, to understand how different geometries could help improving the photosynthesis. We will also expand the study to different green species that grow in different environments. Additionally, the morphology and distribution of photonic structures among different families of green algae is interesting on an evolutionary point of view. In the same context, we will also study the origin and function of structural colour in red algae. Another marine organism we work on is the sea slug Elysia viridis, which is able to maintain functional chloroplasts from the algae she feeds on inside its body for over 3 months. Another feature of this organism is the presence of structurally coloured spots scattered across the body. Since they form part of a complex symbiotic system, understanding their function is an important step in elucidating further the symbiosis as a whole, and the role of colour in symbioses more generally.
For further details please contact sv319@cam.ac.uk
Arianna Rizzo (Université de Nantes, FR), Supervisor: Prof Bruno Jesus: Diatom biophotonics in hydrogels and natural microphytobenthic communities, effect of biofilm structure.
Coastal tidal sediments are highly productive systems at the land-sea interface. Their productivity is in most cases fuelled by benthic microalgae embedded in a biogenic polymer matrix forming biofilms at the sediment surface and supporting multiple ecosystem functions and services. These biofilms are dominated by benthic diatoms that are highly efficient at photo regulating albeit being exposed to extreme light variations during tidal cycles. They use a complex mixture of mechanisms to photo-regulate, including vertical movements within the sediment matrix and species cycling/stratification at the sediment surface. These movements modulate the light environment inside the sediment but are extremely difficult to investigate under natural conditions. The objective of this task is to study how biofilm structure and biofilm movements mediate light environment within artificially built biofilms. In collaboration with UMIL we will build biofilms within structured hydrogels with the aim of: (i) understanding the effect of species stratification on the biofilm light environment, and (ii) investigating if cell orientation in relation to the surface has a photonic effect on the light distribution within the biofilm, in collaboration with IIT. We will manipulate biofilm composition using a variety of benthic species (e.g. Entomoneis paludosa, Biremis lucens, Pleurosigma angulatum) embedded in the hydrogels and we will measure the effect on light (with UCPH) and photosynthetic efficiencies using a combination of PAM fluorescence, O2 microsensors and PAR microsensors. This highly novel approach will allow understanding how light is transmitted and regulated so efficiently in benthic microalgae biofilms, and how such mechanisms can be applied in the development of new membrane based bio-photo reactors (UMIL).
For further details please contact bruno.jesus@univ-nantes.fr
Ariel Garcia Fleitas (POLIMI Milano, IT), Supervisor: Prof. Guglielmo Lanzani: Photosynthetic processes in algae via time-resolved spectroscopy.
Recently it has been shown that seaweeds use complex photonic structures for photoprotection. The aim of this task is to exploit time-resolved spectroscopy/imaging to study the photophysical properties of seeweeds. We will exploit transient absorption with femtosecond temporal resolution (amplified Ti:sa laser with pulse duration ~200fs and rep. rate of 250KHz), time-resolved fluorescence spectroscopy (tunable excitation over the spectral range 300-1500 nm, and streak camera detection system with a time resolution of ≈3 ps), and fluorescence lifetime imaging with ns temporal resolution, to characterize seweeds photosynthesis in vivo. In particular this task is focused on two topics. The task regards the study of photoprotection mechanisms in the algae (Chondrus crispus), provided by the NHM, which we hypothesize is the main function of its structural color changes. Measurements will be carried out in different environmental conditions with respect to irradiance, water turbidity, and temperature. Photoprotection mechanisms will be correlated with biological studies of seaweed photosynthesis performed by teams at the NHM, UCPH and UN. The second part of the task regards the study of the interaction of light sensitive materials (polymer nanoparticles, molecular chromophores, also in collaboration with UNIBA) with diatoms (provided by UN), that are simple unicellular organisms whose photosynthetic apparatus is able to convert solar energy into chemical energy with high efficiency. In particular we aim to investigate the changes induced by the photoactive molecules in diatoms photosynthetic pathways in order to enhance their performances in vivo (e.g. light harvesting capability) and hence to increase biomass production. Spectroscopic information will be correlated with biological characterization such as the growth rate.
For further details please contact guglielmo.lanzani@iit.it
Margot Minjiu Arnould Petré: (The Natural History Museum London, UK), Supervisor: Prof. Juliet Brodie: Light management strategies in seaweeds.
Seaweed are marine macroalgae that represent a large and diverse group >24,700 species, several of which exhibit complex optical properties using different structures and materials to optimize photosynthesis. The aim of this task is to study how structural colours (iridescence) in seaweeds affect photosynthesis. We will first look at the distribution of structural colour in seaweeds, as little is known about this phenomenon. Then we aim to: (i) study the optical response of structurally coloured seaweeds and relate it to their morphological response and photosynthetic activity (with UCAM and UCPH), and (ii) correlate these observations to the phylogenetics of the groups. We will study red (Rhodophyta), green (Chlorophyta) and brown (Phaeophyceae) macroalgal species, representatives of which are present in the UK, as well as green (Chlorophyta) macroalgal species available via colleagues from e.g. the Mediterranean and Australia. The bacteriosome of these species will be studied by HOEKMINE. The optical response of structurally coloured algae will be measured along with analyses of the anatomy of their tissues via electron microscopy (SEM/TEM). Finally, we will perform comparative studies to measure if different mechanisms are produced to achieve the same optical effects. With the data collected from all the different species analyzed, we will compile a publically available database enumerating the different iridescent species. Moreover, to understand if structural colour influences photosynthesis, we will perform photophysiological experiments focusing mainly on variable chlorophyll fluorescence (PAM) imaging PAM (with UN and UCPH).
For further details please contact j.brodie@nhm.ac.uk
Michele Pompilio (University College London, UK), Supervisor: Prof. Franco Cacialli: Exploitation of bio-inspired light-management strategies.
It has been proposed that evolved photonic photonic nanostructures in certain corals and diatoms provide photo-protection of chromophores/pigments susceptible to bleaching. In this task, we will leverage nanoscale characterizations facilities at the LCN and availability of diatoms and corals to obtain accurate nanomorphological characterization (via FIB-assisted SEM/TEM tomography), so as to build "digital" representations of coral skeletons and diatom frustules. These will then be used in detailed modeling of the optical properties with UCAM, both to i) achieve deeper understanding of the organisms photosynthetic/photoprotection functions, and ii) allow potential replication (and scale-up) via nanolithograhy of either the original structures or of their negatives (e.g. via FIB of silica substrates). "Masters" will then be used for large-scale nanoimprinting of substrates for printable solar cells and tested for UV-soaking stability at UCL. We will also develop "guided self-assembly" of bio-nano-photonic blocks (viz. diatomic exoskeletons), via self-assembly at the retracting meniscus of a mesostructured substrate with appropriately spaced banks, to achieve ordered arrays. Surface functionalisation will favor attachment of the elements to the substrates. Diatoms offer photoprotection by selectively scattering UV at the periphery of the exoskeleton, and the ridges will be engineered to waveguide away such damaging components. At a more fundamental level we will use coating/infiltration of the bio-photonic structures with fluorescent dyes (available from our work on organic semiconductors), to act as sensitive detectors of the radiation scattered/waveguided by and in the bio-elements (corals and diatom frustules), for example by monitoring the decay of the bleaching/photoluminescence efficiency of the chromophores at different locations on the skeletons/frustules. In addition to infiltration of the fluorophores on the skeletons we will also explore, with UNIBA (host for extended secondment of the UCL ESR), chemical functionalisation of dyes emitting/absorbing across the visible and NIR spectrum for their metabolic insertion into living diatoms during growth. This will also provide very interesting model systems to both deepen understanding and guide synthetic optimization of the naturally-occurring photosynthetic processes.
For further details please contact f.cacialli@ucl.ac.uk
Huixan Khang (University of Milan, IT), Supervisor: Prof. Luisa De Cola: Bio-inspired breathing hydrogels for self-sustaining bio-photoreactors.
Embedding of cells into hydrogel scaffolds of predesigned architecture has been intensively investigated with focus on tissue engineering and organ printing. However similar techniques have poorly been exploited to immobilise microalgae and rarely considered as a scaffold for bacterial growth. Co-immobilization of microalgae and bacteria in the same tissue can be a useful technique for effective environmental applications such as enhanced CO2 capture and production of biomass in bio-photoreactors, but also for the development of biosensors and production of clean energy. We will develop transparent micro-hydrogels, which are perfectly auto-sustainable and contain a combination of structurally colored bacteria and microalgae (in strong collaboration with HOEKMINE, UN and UCPH. We will use biocompatible polymeric systems that can cross link in water and can release nutrients for several weeks. The microalgae can be embedded in the water solution of the pre-gel for encapsulation in the µm-sized porous structures (20 µm or larger). In particular algae-containing hydrogel beads will be prepared by using a microstructured poly(dimethylsiloxane) (PDMS) slab. The pre-gel solution with the microorganisms will be poured in the slab, allowed to gel, making a negative copy of the microstructures surface, before being mechanically released from the PDMS master. The gelation requires only few seconds and occurs at room temperature and without the use of any catalyst. Nutrients for growth will be released by porous silica nanoparticles (developed in UMIL) that are immobilized in the hydrogels and able to break on demand slowly releasing small (bio)molecules over several days. The particles are covalently linked to the gels and uniformly distributed in the 3D network. They will act as a food supply for the microorganism. In addition the use of different sizes, shape and functionalization of the particles will allow introducing colors, scattering units and modification of the mechanical and elastic properties of the 3D structure. This will allow the study of the behavior of different organism (such as diatoms, with UN) in 3D under different light conditions, while maintaining the same chemical composition of the gels.
For further details please contact luisa.decola@unimi.it
Cesar Vicente Garcia (University of Bari, IT), Supervisor: Prof. Gianluca Farinola: Synthetic strategies for Bionic Diatoms.
Diatoms are single-celled photosynthetic microalgae dominating phytoplankton and ubiquitously distributed in both marine and freshwater ecosystems. Despite a huge diversity in size and shape among diatoms, a common structural feature lies in their micro- and nanopatterned exoskeleton (frustule) made of mesoporous biosilica, whose photonic properties play a key role in light management during photosynthesis. Such role and properties are not yet thoroughly explored by biologists and physicists on living diatoms, as such studies require interdisciplinary investigation to unravel diatom optics, and exploit such knowledge e.g. for enhancing photosynthetic activity of diatoms, or to develop new biohybrid organisms with similar photonic behavior. Potential application of such knowledge encompass many nanotechnological fields, ranging from photonics to solar energy conversion. We will study the photonic properties of diatom frustules by using tailored photoactive molecules and fluorophores as feeding agents for living diatoms (with UN). A great variety of organic and organometallic compounds with either intense light absorption, fluorescence or phosphorescence, will be designed and synthesized to improve algal light harvesting and photosynthesis, or to integrate the photophysical natural properties of the biosilica exoskeletons in novel bioninc systems (in collaboration with IIT, UCL and UCAM). These molecules will be endowed with proper functional groups to favour their physiological incorporation into living diatom cells and facilitate their integration into the biosilica frustule nanostructure. Such biotechnological strategy represents an extremely low cost, straightforward and promising route to bionic organisms with enhanced photosynthetic activity due to combination of the frustule nanostructure optical properties with the photo-physical properties of the integrated molecules.
For further details please contact gianlucamaria.farinola@uniba.it
Alvaro Escobar (Hoekmine BV, Utrecht NL), Supervisor: Dr. Colin Ingham: Light management with Bacteria - Sensors and pigments, genetics and ecology
The Flavobacterium IR1 is a robust Gram-negative bacterium and a genetic model system for structural colour in nature, with self-organising colonies forming a 2D photonic crystal. Physical and genetic modification of this microorganism to act as an environmental sensor will be undertaken in this task. Biosensors, with an external stimulus triggering reorganization of the bacterial colony via gene expression, or more direct impact on cell organization, will be designed in the task in collaboration with UMIL. Such cellular biosensors with a read-out of vivid colour, i.e. interpretable by a non-expert user in resource limited settings, are anticipated to find widespread applications in sensing. The capacity and applications of highly ordered IR1 colonies to reflect and modulate white light will be investigated optically both for diagnostics and as photonic pigments (with UCAM). Strategies will be developed to utilize the light output of bacterial colonies, including modulations of light output (e.g. lasing) will be measured (with UCL). The preservation of bacterial photonic structures will be improved, facilitating both sensor applications and structural determination for biomimetics, i.e. to support the manufacture of bio-inspired products such as sensors, responsive fabrics and advanced optical surfaces. The photonic interaction of IR1 with organisms with particular reference to photosynthesis is of particular importance, especially interactions with macroalgal hosts or other micro- or microorganisms studied with (NHM, UN, UCPH).
For further details please contact colinutrect@gmail.com
Gabriel Ferreira (University of Copenhagen, DK), Supervisor: Prof. Michael Kühl: The role of fluorescent host pigments for photosynthesis and optics in corals.
Green fluorescent protein (GFP)-like host pigments are responsible for the vivid colouration of many reef-building corals and have been proposed to have beneficial effects on coral photobiology, such providing photoprotection and modulating the radiative heating of corals. Host pigments may also modulate light propagation and photosynthesis in corals. While the spectral absorption and emissive properties of (GFP)-like host pigments have been studied in detail in vitro, the in vivo characterization and role of host pigments for light propagation and photosynthesis in corals remain weakly explored, as this requires a combination of biological methods with novel experimental approaches from outside biology. We will employ microsensors and novel non-invasive imaging tools for microscale analysis of photosynthesis, light fields and tissue structure in corals with and without GFP-like host pigments. Time-resolved fluorescence spectroscopy/imaging will be used (in collaboration with IIT) for spatio-temporal spectral characterization of GFP-like host pigments in corals both at macro and micro-scale using a femtosecond laser source (tunable over the spectral range 300-1500 nm) in combination with a streak camera (time resolution of ≈3 ps). Experimental data will also be used (with UCAM and UCL) to extract basic optical properties and to develop models for light propagation using approaches from tissue optics. This multidisciplinary approach aims to unravel mechanistic insight into how GFP-like host pigments optimize light exposure and photosynthesis in corals. Such information will inspire novels ways of modulating light capture and exposure in bionic materials and bioreactors for UMIL. In parallel phototrophic microbial communities and symbioses will be studied with HOEKMINE, UN and UCAM.
For further details please contact mkuhl@bio.ku.dk