 Office of warfare, this school of the very interesting and interdisciplinary ITN project. So when I decided what was the most appropriate subject for this lecture, I thought that the use of photosynthetic microorganism, of materials derived from photosynthetic microorganisms, which is really a new research area, ki je zelo vse objske, da je to vse objske. Vse je odlično in tezavodne občas, kjer drugi kemis, biologi, fotofis, ki se nekdo počeljali in zelo v komandri ljubi, zelo vse nekaj nekaj stvari materijov, kaj je bil, nekaj neč, kaj je, nekaj nekaj nekaj je vse občas, je vse nekaj nekaj nekaj šli občas, in z njega je najbolj zelo. Zato vse sem zelo, da je najbolj zelo, da se zelo v teželji, in nekaj nekaj, da se zelo na to, da je vse zelo, in da sem se zelo na to, in da sem se zelo na teželji, za 5-6 let. Zelo, da je vse zelo na to, da je zelo na to, tudi na svetu, da je posljeno vse materijale in komponente fotosintetice, kaj je materijale in komponente elektronika in fotonika sistem in devices. V ovom različenju ljudi, ki je zelo energija, tudi, ki je dobro dobro vse komponente, tudi, ki je zelo energija, dobro začu, zelo če, da je zelo, da je zelo, da se zelo, da je zelo. In tudi je skončenja materijala tudi, ki je zelo, da je zelo, ker je tudi, da je zelo vse fotosintetice. Tudi, ki je tudi, ki je tudi, ki je tudi, ki je tudi, ki je tudi, ki je tudi, ki je tudi, konveritivna vrjela v metaboliki, ki obržil neko karboidorov, z nju kot zlečen, in tega energia kaj je potrešnjeti linksi, in do zeločenjah se zeločijo, ki je zeločil na površetnih zeločenjah in taj vse je zeločil. These are two examples where actually in two research groups, one is my research group and the other is the research group in Sweden. We are both involved in a fat open European project relevant to the use of photosynthetic organisms for production of components for electronics. In the case of the group in Sweden, they are using part of the plants of the leaves essentially as a template for building circuits for organic bioelectronics. While in our case we are using microorganisms as essentially bacteria and microscopic algae to produce in one case materials for bioelectronic devices for photo conversion and in the other case components for photonics. So essentially this is a very synthetic time scale of the evolution of organic electronics, which have been largely determined by the development of materials. So the perspective of this lecture is essentially reasoning about the possibility open by designing and synthesizing materials in the production of energy through the sunlight. So essentially the organic electronics started with the possibility of building the first solar cells made out of organometallic materials like corporate talocyanines but then also organometallic complexes were used for LED devices as non-linear optics materials, as material for fluorescent electroluminescent devices and more recently heterocyclic chemist has been playing a big role in the production of polymers for plastic solar cells and also for modern organic light emitting driving transistors and also impacting on the possibility of using photonics in biomedicine. So the growth and development of organic electronics and exploitation of organic materials for energy collection and conversion has been, of course, largely determined by our possibility and ability of designing new materials. This has resulted in a big impact on technology with the growth of an entire new technological field called plastic electronics and also the possibility of using and scaling down electronics to the molecular scale with the molecular electronics. Some classes of materials that have been developed over the years, I've chosen examples from my work but I mean they are quite general classes of materials for electroluminescent devices where electrical energy is converted into light, these are conjugated polymers or organometallic complexes. A lot of work has been done, as I said, on conjugated polymers for plastic solar cells, which are essentially based on heterocyclic structures or molecules for organic electronic devices. The literature is impressive in terms of optimization of materials based on molecular design and in most cases the performances are the first goal and sometimes there is not that much attention to the cost of materials. So in many cases, for instance in plastic solar cells development, the literature has pointed out that many polymers which are reported in the literatures as record polymers in terms of efficiency for conversion of solar light into energy are actually materials which are just academic materials because there is no possibility to scale up those materials to industrial production because their cost would be much, much more than the cost that can be afforded by companies to produce those materials and devices on a practical scale. So the problem of making materials and incorporating in the molecular design of materials not only the efficiency but also the scalability and the synthetic feasibility is a major issue where organic chemists, synthetic chemists are, of course, playing a major role and all the people involved in this field should be conscious that designing materials means not only targeting efficiency but also targeting feasibility in terms of cost and environmental impact of production. So there are several research group who started to be interesting in the possibility of using biological materials or biomimetic materials as a source of materials for optoelectronic devices and for devices for conversion of light into energy. For instance, just to mention some example of those materials, melanins have been considered as polymers for optoelectronic devices or for memory devices. Melanins means both melanins that can be extracted from organisms, so natural melanins but also mimics of melanins that can be used very easily in laboratory by polymerization, oxidative polymerization of dopamine. Another example is silk, which can be produced on a larger scale and also dope. This is a fantastic material which has many interesting photonic properties and a very high level of compatibility and it can be also functionalized in many interesting ways. Another example is cellulose, which, of course, is a very abundant material and is also prone to easy chemical functionalization. It has been demonstrated that cellulose can be used for fabrication of organic and bio-organic optoelectronic devices, both as an inert support but also as an active material, as proper functionalized. This is the framework and here came the question that our group and also other groups worldwide are now investigated. The point that is now investigated and the point that I would like to discuss with you today. Can we envizage a general biotechnological route to optoelectronic and photonic materials from photosynthetic organisms and, in my case, I would say, from photosynthetic microorganisms for what we are going to discuss today. Essentially, photosynthetic organisms are organisms which have been evaluated by nature over billions of years to be able to interact with light, to collect light, to convert this light very efficiently into chemical energy. So, essentially, they have all the optimized machinery, which is very difficult to mimic, of course, because it's, as I said, optimized in billions of years for interaction with light and for conversion of light into several forms of energy. And they are there already. What I mean is that they are themselves produced by absorption of light. So, they are themselves materials made out from a process where the ultimate source of energy is sunlight. If you look at the structure that the microorganisms, photosynthetic microorganisms have developed for interaction of light with your highs of synthetic chemists who have been involved, as I did for 20 years of my scientific activity, in developing, designing, optimizing artificial materials for interaction with light, which means materials able to collect light and convert light into energy or the opposite convert energy, electrical energy into light, then you feel like hell is in the wonderland. There is in front of you a wonderful, immense source of structures, materials, systems that are already there waiting to be exploited or to be extracted for being used in our devices or for being treated as materials, with the artificial materials that we have been synthesizing for many years in our synthetic laboratories. Essentially, I will discuss this possibility with two examples, which are partially taken by the work that we have been carried out recently in my research group, but also partially taken from the literature because we have been not the only ones considering this possibility. Essentially, I will discuss the use of photosynthetic bacteria and photoenzymes extracted from photosynthetic bacteria as active material in optoelectronic and photonic devices. If we have time enough after this part, I will shortly discuss about the use of diatoms, microalgae, photonic structures as materials for photonics. Of course, as I said at the beginning, I am discussing those two subjects as a synthetic chemist. For me, those microorganisms are just a source of materials that I want to extract and purify and modify and eventually test into devices. This is a largely interdisciplinary subject, so microbiologists would discuss this point in completely different terms. A physicist and a photo physicist would be the same. I am discussing this with my language, which may be not a perfect one, but this makes also the game very stimulating from my point of view. So, let's start with photosynthetic bacteria and particularly what we have done for production and destruction from photosynthetic bacteria or photoenzymes that we have eventually tested as photoactive material in optoelectronic devices for solar energy conversion. Before starting, I would invite you to consider this like an extension of an approach which is very mature in pharmaceutical chemistry, for example. In pharmaceutical chemistry is, of course, well-known that you produce some drugs like antibiotics from fermentation processes. You extract them from the microorganism. Eventually, you can modify the molecules with synthetic processes to optimize their performances. But it's very uncommon that the same approach is used in materials chemistry. So, it's kind of a new paradigm. The bacterium that we have used is rhodobacter spheroides. I'm going to explain how rhodobacter spheroides photosynthetic apparatus is done because it may be not obvious for those in the audience who are not familiar with photosynthetic organisms. Rhodobacter spheroides is a very simple red bacterium, nonoxygenic bacterium. It is very well-known and very well-investigated because it's a model system for photosynthetic process because it's very easy to be cultivated in a laboratory to be chemically, to be genetically modified. And it has also a very simple photosynthetic apparatus, so it's not so difficult to, let's say, disassemble the photosynthetic apparatus, which would be much more challenging in the case of higher plants or superior photosynthetic organisms. In a very schematic way, we can say that the entire system for collection of light and production of the first high-energy chemicals that eventually fuel the entire photosynthetic machinery is all embedded into the cell membrane. So, this is the cell membrane and you can see all these colored structures, which are a very schematic way to represent the photosynthetic unit. The photosynthetic unit is the part of the photosynthetic apparatus which will collect light and convert light into charge-separated states, which are then used to fuel the biochemical part of the photosynthetic system. So, we can envizage these photosynthetic units as made of three components, the light-arvesting complex one, the green, the light-arvesting complex two, the red, and the reaction center. This is an example of how they are organized into the membrane and then the energies eventually conveyed to the ATP synthase complex. So, they are organized in a very precise way. The light-arvesting complex is one and two, which means the green and the red objects are protein pigment complexes, where the pigments, essentially chlorophylls and carotenoids, are kept in the proper orientation and position by the protein part, by the enzymes. While the blue object is the reaction center, which is the actual photoconverter, I mean, it is a photoenzyme, where the photons collected by the light-arvesting complexes one and two are converted into charge-separated states. This is a closer view, where you can see that the entire system is a complex supramolekular arrangement, which has to be kept in the proper position to work, otherwise it simply won't work. So, ideally, if we could take the system out of the cell membrane and put this onto an electrode or into an optoelectronic device, this would be an ideal system for conversion of photons into charge-separated states, because the system is able to convert photons into electron-ole couples with about 100% efficiency. This is not easy, because, as I said, that's a very delicate supramolekular system. So, if we just take it out from the cell membrane and put on an electrode, it would be quite a brutal approach, which would not work, because the system is subject to continuous photodegradation. So, in the living system, the antenna complex is continuously replaced, but it can't be done, of course, when we take the system out of the cell membrane. However, on the contrary, the reaction center, which is the actual photon enzyme in charge of conversion of photons into charge-separated states, is a quite robust system. It can be extracted from the cell membrane. It can be kept in solution if provided that you keep it in the presence of a tensioactive, which mantain the system in solution, preventing its precipitation. Then it can be handled and keep alive and active for weeks or even for months. So, it's a very robust system. Let's say in a very few words how the system is done, because, of course, this is a very complex transmembrane protein. So, if we have a look at the protec structure, it may be a little bit confusing, we are trying to minimize the complexity and to explain how the system works in a very simple words. So, let's imagine that the entire protec scaffold is just a scaffold, just kind of a basket, where the actual cofactors responsible of the generation of the charge-separated states are maintained. So, the protec scaffold is made of three subunits, M, L and H, which basically create a basket. The L and the M subunits are shaped like a cylinder, which a cavity inside and an hydrophobic surface. And the bottom is closed by this H subunit, which is a globular protein. So, overall it's a kind of a container. It's appropriately oriented into the cell membrane with this part, which is a cavity facing the periplasmatic side, while the part which is closed faces into the cytoplasmatic side. And into the cavity we have the cofactors, which are the actual system responsible of the generation of charge-separated states. Let's have a look at this very simplified cartoon where we observe that those cofactors, which are, in fact, quite complex structure, are simplified to their key components. So, we have two bacterioclorophyll molecules, which are arranged in functional dimers, two isolated bacterioclorophyll molecule, two bacteriophilofitin, which is the same as bacterioclorophyll, but without the central magnesium cation, two ubiquinon molecule and one non-Ame iron 2-plus cation. So, essentially when the photons are absorbed by the light harvesting complex, the excited state is generated on this bacterioclorophyll dimer, which is the primary energy acceptor. And then a cascade of electron transfer processes takes place, bringing the electron from the primary electron acceptor to the last electron acceptor, which is a quinone molecule. And this generates a charge-separated states, which is, of course, a huge dipole into the cavity of the protein. And essentially what is very interesting is that this charge-separated state is a long-living charge-separated state. It lasts from one to three seconds if you keep the system without the natural electron acceptor and electron donor, which in the living system would immediately quench these charge-separated states. But if you keep it out of the system, it will produce this charge-separated state, which is a long-living charge-separated state. As I said in the cell, this is fueling the photocycle, which means that the hole generated in the excited state on the functional dimer will be used to oxidize the cytochrome, while the electron will be released in the form of the reduced quinone into the internal environment of the cell, thus creating the transmembrane pH gradient, which is the fuel of the ATPase enzyme. So, the idea was can we demonstrate that this photoenzyme can be used outside the cell to generate charge-separated states, which can be eventually exploited into optoelectronic devices. Of course, if you have a look at the absorption spectrum of the reaction center, there are entire parts of the absorption spectrum, by the sunlight, of course. And this, because the system has been evaluated in nature not to absorb light, because it's always associated with the light-arvesting complexes 1 and 2, but it has been evaluated just to convert the photon subsorbent by the light-arvesting system. But as I said, we can't take the light-arvesting complexes out of the cell membrane because they are labile. So, to make the system work, we should replace all these complexes with very simple molecules, the same synthetic molecule that we use, for instance, for production of polymers, for plastic solar cells, small organic molecules, provided that they match well with the absorption spectrum of the reaction center and provided that we are able to locate those molecules, to affix those molecules to the primary energy acceptor. So, we started our investigation as a proof of principle. We thought, OK, let's try with a very simple molecule that can absorb light here where there is no absorption in the spectrum of the reaction center and that can emit light where there is a maximum of absorption in the absorption spectrum of the reaction center. And let's see if there is any kind of energy transfer. If we can, at least in principle, replace the antenna system with an artificial molecule. So, we started with this very simple building block, which we had in our laboratories, because this is a very classical building block. It's a bestiophene benzotaiadiazol building block that is largely used as a monomer for the production of polymers for plastic solar cells. I'm not going to give you synthetic details because I don't know if there are synthetic chemists in the audience that are extremely boring maybe for other people to listen to synthetic details. But I want to point out that this is a very important part of the work, although I'm not going to discuss it in details. But just to share with you the logic of the design of the molecule, why we choose this structure because it has a good absorption spectrum more or less matched with the minimum of absorption spectrum of the reaction center. The relative absorption of the reaction center takes place. And it has also a good stock shift. We can modulate the position by extending the conjugated system in order to match exactly with the absorption spectrum of the reaction center. So, we end out with the molecule which has an extended conjugation but we also need a flexible spacer because the molecule is a rigid rod molecule so if we just attach the molecule to the protein without a spacer it will intercalate into the alpha helix of the protein and it will denaturate the protein. The natural protein is a major issue if you want to use protein as active materials in optoelectronic devices. And of course we need reactive units that is able to covalently attach the molecule to precise position of the protein. This is engineering the position where you want to have the molecules in order to have energy transfer in photoenzyme. So, you see there is a good matching of absorption and emission and we can carry out the chemistry to attach our antenna using a very simple amide bond formation that will covalently affix the antenna molecule to the lys in residues of the protein. There are precise position which are indicated here as these blue dots which are the amino groups. We know exactly where the amino groups are in the protein so we know exactly where we are eventually going to bind the antenna molecule on the protein. And some of those positions are very useful because they are very close to the primary energy acceptor. What we did is to confirm that we in fact had functionalized the protein in the proper position so we could crystallize the photoenzyme which was not very simple. These are the crystals of the native enzyme and these are the crystals by your conjugated system and upon collecting x-ray data at the synchrotron facility in Grenoble we could figure out to have a map of the position where the photoenzyme is located and for instance we could demonstrate that this lys in residues has been functionalized which means that the antenna is close enough to the primary energy acceptor and also to the secondary energy acceptor to give foster energy transfer so that this small organic molecule replacing the huge antenna system can be attached in a proper position to collect light and give energy transfer to the reaction center. We can see a partial quenching of emission upon energy transfer, we can see a change in the fluorescent lifetime decay which indicates that effective energy transfer is occurring and that so energy transfer is a possible mechanism for transferring energy to the reaction center. What we find is that this is the absorption spectrum of the native reaction center the blue one, the red one is the spectrum of the functionalized reaction center so clearly there is an absorption here at 450 nanometers where the native system does not absorb which is due to the absorption of the antenna molecule and if we measure the generation concentration of charge separatist state shining light at 450 nanometer where only the functionalized system can absorb light we see a five-fold increase in the concentration of charge separatist states which is the final proof of the effective energy transfer we have effectively replaced the antenna system with this monochromatic absorber at 450 nanometers this is just a proof of principle of course because we want to replace all the wavelength of the absorption spectrum so we need different molecules and here we started to play our game because as I said I'm a synthetic organic chemist so we did a lot of molecules able to absorb light into the entire visible spectrum and transferring this energy to the primary energy acceptor I'm not going to discuss this part because I would just to discuss the principle behind it and I will show you just the final results out of one out of 10, 15 molecules that we have done this is a cyanine molecule it's quite a complex structure it is water soluble which is important if you want to play with enzymes especially again we see this reactive unit that you use to attach the antenna to the lysine residues and as you can see this molecule is a wide absorption spectrum so in this case just shining white light we could determine an increase of 90% of the generation of charge separatist states comparing the native photoenzyme with the functionalized photoenzyme so essentially it's kind of replacing the antenna complex with a simple molecule this is eventually an hybrid system which is working as the entire photosystem but only the reaction center is the natural component and the other component the antenna is a small simple let's say simple artificial antenna so now what we want to do with this photoenzyme because of course having the enzyme just floating in solution is completely useless we want to have the enzyme as an active material in a device and the question is can we use this functionalized reaction center on an electrode to do that we need to address somehow the reaction center on the electrode because of course that's not trivial it's very easy to denaturate a protein so we tested various approaches which are essentially examples of approaches taken from the literature that have been previously used to attach enzymes to electrodes or for instance to graph in layer or in any way to semiconductors that are able to interface a system able to produce charge separated states with an electronic circuitry so in the case of graphene we used a very simple approach that had been previously reported for functionalizing carbon nanotubes with glucose oxidase molecules in this case pi pi is taking interaction between pyrin molecules and graphene layers are used in the space and then the malimide group and the malimide group can react with the only accessible system on the protein so in this case there is only one accessible amino acid with SH group so we know exactly where the protein has been where is the chemical link to attach the protein to the substrate so this is nice but this is just a picture in my opinion of course we characterize the system but this is the way commonly represented in the literature where an enzyme is attached for instance to carbon nanotubes but that is simply not true because the hydrophobic surface of the protein will interact with the hydrophobic surface of graphene so most likely those photoenzymolexes will be lying flat on the surface rather than just standing up on it so we went to more classical approach at least more familiar for me as a synthetic organic chemist so what we did is again using lysine residues and using a bifunctional spacer one of the end of the spacer is reacting with lysine and the other is an azido group which opens up interesting possibilities in creating easily creating covalent bonds so we used this azido group to react with triple bond attached on graphene flakes doing click chemistry and so we functionalized these graphene oxide flakes with the enzyme using the spacer that have shown you of course it's not elegant as the one I showed you before because in that case we had only one aminoasis so we know exactly where the protein is bound to the graphene but it is much more effective the most interesting results were obtained by using hydrogen bond and organic semiconductors these very simple molecules have been demonstrated by the group of Serdar Sarichivchi in Lins to be very effective semiconductors they bound each other in a very ordered way through hydrogen bonds so they are very simple they can be casted in a very simple way but especially they work in aqueous condition which is a requisite to use the materials in when you want to use an enzyme and also especially from our point of view they have this nitrogen atom that can be functionalized using the chemistry as I showed you before so this is the linker again you can see the two activated carboxylic group one end is reacting with this nitrogen atom the other end is reacting with the lysine residues so this is the scheme of a very simple resistive device two gold electrodes a tin layer of the semiconductor is the epidine the only denone semiconductor as I said it works in water this is an AFM picture showing the multi crystalline surface we first react the system with the spacer and then we use the reactive end of the spacer to attach the reaction center molecule so at the end we have the surface of the semiconductor on the electrode completely functionalized with the reaction center and working in water this is a resistive device so if we shine light at 600 nanometers where no absorption takes place in the organic semiconductors but only the reaction center can absorb light it generates the charge separatist states and it can dope first of all we demonstrate that the enzyme is still active so it has not been denaturated and you can shine in light essentially the enzyme is photosensitizing the organic semiconductor creating charge separatist state which can eventually dope the organic semiconductor so it's acting like an enzymatic photosensitizer and you can see photo currents on and off, upon shining light on and off and since the system is covalently functionalized then you can get the electrode stable even after washing many times with different solutions and therefore principle that we can photosensitize the surface so it's basically a photo conductor device based on the use of photo enzyme but we can also go to a kind of a more sophisticated device which can be also light driven by the use of the reaction center this is a field effect transistor I think most of you in the audience is a field effect an organic field effect transistor is done but anyway I'm going to show a very simplified cartoon we have a conductive silicon substrate a dielectric with two electrodes on top of it and a thin layer of the organic semiconductor the source electrode is grounded and then we have a gate electrode which where this conductive silicon substrate is biased against the source electrode and this is gating the device so if we apply a voltage between the gate and the source electrode charges are collected at the very first interface between the organic semiconductors and the dielectric so this is the channel and depending on the intensity of this voltage we can accumulate an increasing amount of charges so essentially once we apply the voltage between the source and gate electrodes we have that the current flowing between those two electrodes is modulated by the gate electrode and these are the classical Ivo curves of an organic field effect transistor device so this is a very simplified cartoon as I said I'm not a device physicist but it's useful to understand how an electrolyte gate organic transistor works in an electrolyte gate organic transistor essentially the semiconductor channel here is closer to an electrolyte was potentially fixed by the gate dielectric so essentially the device is gated by the solution and the gate electrode is this electrode into the electrolyte solution so what we want to do is to use the light as the external stimulus to trigger and to modulate the current flowing into the device that would have been a light gated transistor to do so we need to accumulate our reaction center right here attached to a transparent ITO electrode and this is the channel but to make the system work we need to have the reaction center not only affixed on the electrode but also oriented so this is the let's say the most challenging point because if we have the samples randomly oriented of course they will cancel each other so you will not observe any effect so how can we orient the reaction center protein it's a delicate object it's not easy to orient we can exploit again it's biological role as I said in nature the system is considered to be reduced after having been photo excited by the cytochrome so if we randomly deposited the cytochrome C on the surface of the ITO electrode and only those cytochrome facing their selective docking site on the upper side will be able to capture the reaction center and to keep the reaction center by weak supramolecular interaction in the proper orientation so this is the way we addressed the reaction center molecules on the surface of the ITO electrode so again the device architecture we have the two source and drain electrode here and here this is the channel which is made out of a pentazine functionalized pentazine organic semiconductor then this is the light sensitive unit ITO oxidizes cytochrome user to address the reaction center this is the reaction center and this is how the device is assembled so essentially by shining light we generate dipoles in the reaction center which are oriented we generate an asymmetric distribution of ions into the solution and this distribution of ions that remind an accumulation of negative charges at the interface with the channel which eventually will dope the channel and modulate the current so what we see is that in this transistor device we are modulating the light on and off and also the intensity of the current flowing between these two electrodes by shining light so this is an ultimate demonstration of the possibility of using the reaction center which is a complex transmembrine protein from a photosynthetic organism as an active material able to generate a new kind of device where the transistor is photogated and of course the photogating is only visible when the reaction center is on there and when it is properly oriented otherwise we don't observe any response to light so to conclude where this part of the talk the reaction center can be functionalized first of all it can be produced on a large scale because this is a bacterium so it can be produced by fermentative process also in a large scale this is a way to produce materials which otherwise have to be done by classical synthetic chemistry reaction center can be functionalized so an unslide absorption can be covalently fixed in a semiconductor film can be oriented on an electrode surface and can be used as active material in bioelectronic devices this is a proof of principle I am not telling you that tomorrow we are going to produce on industrial scale electronics based on these photoenzymes because this is not true at least at the moment but this was the same kind of things that I would have seen 30 years ago talking about the possibility of making electronic devices on a commercial scale out of organic semiconductors the community of engineers would have been extremely skeptic and I personally experienced that when I was a PhD student presenting the results about organic polymers in photovoltaics in electro luminescence in front of audience of engineers they were skeptics because of the instability of materials and this would be the same issue in the case of biological materials so sure this is something worth to be investigated let me use the first I guess 10 minutes of my presentation to show you something different which is more simple but which goes in the same direction of using photosynthetic components to make materials for photonics out of them in this case the organism that we have used are diatoms microalgae diatoms are unicellular algae which are ubiquitoriously diffused in fresh water and ocean they are everywhere there is a wet environment and there are 10 to 100,000 species of diatoms that have been demonstrated and they are characterised by having their cell encased into a silica shell wall and this silica shell is actually not pure silica but this silica is a kind of a composite made of silica and the polyamine systems I made myself aware of the existence of those wonderful living structures because I was attending a discussion of a PhD thesis in environmental science where students had used diatoms as an environmental probe to collect the situation of pollution in my region in a very polluted town Taranto close to the place where I live where I use it to live and they were using diatoms to the structure of those cells to check the pollution by avimetals into the river at the same time I was working on silica nanostructures obtained via synthetic chemistry doped with light emitting organic molecules so I was particularly sensitive to the chemical method for the production of controlled production of silica nanostructures and I was amazed when I realised how beautiful those systems are and the features are on the nano scale the entire shell is on the micro scale but the features on the silica are on the nano scale and they are different for different species of diatoms each of them have their specific particular texture and structure of the pores which are very well regularly distributed on the surface there are many biological hypotheses about the role of these silica shells of course they are used by the cells for protection against predators for sorting food particles for protecting the cell against the intake of viruses but especially they have a photonic role because these very regular distribution of pores on the nano scale generate photonic nanostructures which has something to do with the biological cycles of the cell I'm not going to go into details but they somehow tell the cells the light elaboration coming from interaction of sunlight nanostructure tells the cells when the moment is to switch from a sexoid reproduction to sexoid reproduction and it has to be with elaboration of light I think it was a good idea I thought it would have been a good idea to investigate the possibility of making nanostructure at silica based materials out of those cells and when I went to the literature I found out that I was not the first one but the possibility though there would have been a lot of work still to do about about this before going I want to show you some microscopy pictures of those cells which are simply beautiful and you can see in polarizant microscopy their nanostructures these are taken from the web but then I will show you the pictures some of the pictures taken from our laboratory this is a very classical picture because all those silica nanostructures share a common feature which is they are made of essentially three components which are an epitec and an hypotheca which are like patrie dishes kept together by a sort of belt which is a girdle and the nanostructure which as I said is species specific is different on the epitec on the hypothec and on the girdle keeping the two parts together the advantages of these sorts of nanostructure silica is that they can be easily obtained by breeding those organisms which is by the way very well known because there is a wide industrial production of diatoms because they are used as food for fish in industrial cultivation of fish but moreover there are huge accumulation of fossil diatoms which are not chemically pure because metathetic processes has changed their composition from bio silica to essentially calcium carbonate or other oxide so they still keep their nanostructure features and the composition is different and they are also commercially available of course but we wanted to grow these cells in the laboratory, we did this with the help of PhD students in biotechnology because we would not have been able to do so because we are chemists, synthetic chemists and so these are some of the pictures of the Lacyociravis flogy, one of the species that can be easily grown in a laboratory scale and the laboratory of organic synthesis as you can imagine the easiest place to grow up diatoms but in spite of that they grow and so we could get two grams of nanostructured bio silica per liter just leaving the cells grow without doing anything contrary to the synthetic production of bio silica or we can grow them into a specific bioreactor system, these are some pictures of the nanostructure features of the diatoms, this is not the most regular species though it is easiest to cultivate and then coming to the point, we can functionalize of course this bio silica which is very easy because it's just silica, so we have all the chemical tools for the functionalization of silica by simply grafting a silicon alkoxide units to the surface of activated silica this is very easy, so we let's say kill the diatoms, we remove all the organic matters by an acidic oxidative treatment and then we can graft all the molecules we want in this case these are molecular semiconductor so we end up with red emitting semiconductor functionalized microscopic dots with nanostructured features what is more interesting is that we can also do that in vivo which means without doing chemistry on the silica shell previously extracted and purified and just dope in vivo the system by adding certain molecules properly functionalized to the growing medium of the diatoms, for instance we can dope the silica with iridium and with other main group metals by simply adding phosphorescent iridium complexes to the growing medium and then we can extract the silica and also eventually break down the silica shells and convert them to nanoparticles and this is an easy way to produce heavy metal doped silica nanoparticles by simply exploiting the solar sun the solar energy which is the energy fuel for growing algae and they do all the work for us it's interesting that we can also exploit instead of breaking them down as we did for doing silica nanoparticles in their photonic structure in this case we have introduced this molecule which is a blue emitter functionalized with the silicon alkoxide group the silicon alkoxide is the chemical message to tell diatoms ok, I'm food, so please eat me so at the end it will enter the metabolic chain of diatoms and it will be fixed into the silica shell this is the diatom still alive you can recognize the red emitting dots which are the photosynthetic organelles while the shell is dyed blue by the our molecule then if you remove all the living matter the molecule is still alive I still because it's embedded into the silica these are these are measured collected by Guglielmo Lanzania team in Milano this is the transmission map of a specific region of the diatoms you can see that there is a gap in the transmission which is not due to the absorption of the silica but it's due to the it's kind of a photonic band gap due to the alternation of refractive index regular alternation of refractive index into the cell due to the silicon voids and it depends on where you collect the data of course because it depends on the texture of the alternation of silicon voids if you do the same measurements that has been previously doped with the light emitting molecule so you can see the interaction of the light emission of the molecules with the photonic structure of the diatom so the red one is the emission spectrum of a team film of this pure molecule the blue spectrum is the transmission spectrum of the diatom the red spectrum is the emission spectrum of the diatom stoped with the light emitting molecule so you can see that z vrštima vrogu v krati, a zelo je to delil. Zelo jezda je modulirati vrog vkrati delajtevstvom moliku v pot craftingi delatom. Vzelo jezda je zelo, da je zelo vzelo v vrštima delatom, če jezda je intimatelj, in zelo jezda jezda jezda. In vzelo jezda jezda jezda jezda v vrštima delatom, neč nezelo,認ret, glas действительно ozpravlet. So, to zame naša boljga vzglasba, ali nevala pozdravljana, dela je nevala pozdravljana. Zelo, ker tako nega je vzglasba, da je začel se šega pricaja z extendirstvom z vzglasba izgleda vzašljenja. Tekajša je vzašljenja. Tekajša je začel izgleda, tko je vso obžarna du spostana. Nadjela se na koncluzijne. Pri p ㅋㅋㅋom misli na to 102. Pred below. Cock mm. As a synthetic chemist. Volim t.v. Od to. Discussi v debil. And they taught. If I go there, and I just start to tell about how we design and synthesize molecules. Organic molecules. And they give a lot. Of information about the organic synthesis method. Zato je nisak tudi izgledaj, ali to je vseh ponudoviti na ulasnih karmistših, da je tudi interdisciplinarne ulasnih, zato si je vseh še je menej komunity, ampak vseh in nasoje vseh počke, da ne vši pošli, da bila pošli na ročnju energiji. Zdaj, da sem imaš menej vseh izgledaj, da je pošli v malim laboratorij, do naših pošli vsi, bo poslutnje potreboj vsega fotosintetice, kaj je materij, kaj je vsega materij, kaj je zelo početnje, komvirnje, neč zelo vsega. To je zelo, da je vsega, ko početim, kaj je zelo. Vsega, ki sem izgleda, zelo je, da bomo moj rečen, da nekaj je počet, da bomo počet, da bomo počet, da sem izgleda, gaj drugi organizm. Ge začelim, da je vse to, pa je zelo vziv, da se zelo tako površa in ne vse, da je vse akademijne prave. In zelo je vse v Vangela Agostiano in Massimo Trohta, ki je ekspert v fotofiziki kot fotosynthetiki protein in vse vsežite in tudi zgodkili v Fábio Biscarini v Modena ker zelo je to, to samo po vzniku skupitev, ki je to neče povsem, zelo se bo ne potrebne in se da so počke vse. Čakaj, Cranski. Čakaj, Czarno, Kafa. V zelo všečenem učinu. In je bilo možno, da se nespešno zjavljati nekaj vzvečnih nekajh vzvečnih nekajh. Čakaj, kaj je tudi so učinil? that are also simplisized by I have to stress this much. This is possible to heal somehow using the structure, it's just degrading structure? I'm not sure if I understand what you mean. If you are wondering if there is a way to prevent photodegradation. Ej. To je najlej inšta. Kaj če se čekaj, da je poči, da je poslednje... ...mužel je poči, da je poči, da je poči, da je poči, da je poči, da je poči. Čekaj nekaj, ki je oksid. Or encapsulation has been... I mean, the degradation of materials is the issue with all organic electronics, which has been solved by many technological approaches, which are never discussed enough. I mean, most of the devices are encapsulated and there is an entire class of materials that is very seldom discussed in presentation, which is the getters, the materials who are in charge of collecting oxygen to prevent oxygen, to photoxidize the active molecules. So this would be the easiest approach. Of course, working with the living system, you can imagine much more. And this is one of the reasons why I think that this approach could enormously impact in the future technology, which is, of course, genetically modifying the organism in order to give you all the ingredients you need into the same structure without the need of manipulating it via chemical methods afterward or minimizing the chemical manipulation. So, of course, the development of this system is taking the entire part out of the cell membrane because extracting the photoenzyme is much more expensive than synthesizing a polymer for plastics or a cell. So I'm not selling here cheap materials or convenient material, but just a proof of principle. This would become competitive with practical approach or reasonable as a practical approach the day when we will be able to take all the system with the membrane and put the system on the electrode or even more making the bacterium, the living bacterium able to grow up on the surface of an electrode and developing class of materials that can collect electrons directly out of the bacterium instead of having so many interfaces. So that moment will be also the moment where we will be able to protect the entire system against photooxidation, make the system stable and so make the system meaningful in terms of production. So you can imagine all the possible situation between adding molecules that just prevent photooxidation, like getters, and making the living system able to behave as a material and with that bringing with it all the self-healing ability because what the bacterium does in fact and the plant does in fact is continuously self-healing because the molecules are continuously photooxidized. So they are continuously replaced by a living cell. So the entire genetic machinery is also in charge of self-healing the system. So that's the way probably. Yeah, they are out there during the group. Yeah, yeah, sure. Yeah, during the group. Yeah, yeah. What happens is that if you introduce this trialkoxis island group so the cell is always looking for a source of silicon. They can also grab the silicon from the glassware. So once they see this alkoxis island group, they immediately convey it to the siliconification vesicles where the bio silica is produced. So although I am not conclusive proofs, but I think that probably the molecules is eventually covalentely touched to the silica structure because of that trialkoxis island group. Yeah, yeah. That was the major issue in fact. So first of all when we do photo degradation on the molecules that has been just grafted by chemical matter, so if I take the silica shell purify from the living matter and then I graft the molecule, then if I do the oxidative acidic treatment again, all the organic molecule is bleached because it would not resist that aggressive treatment. When you do the same, once the molecule has been embedded in vivo through adding the molecule to the solution, we don't see significant changes in the emission spectrum and in the absorption spectrum which is an indirect indication that the molecules have survived the chemical treatment. Then we did also some mass spectrometry measurements on the doped silicon, so we have quite conclusive evidences that the molecule is intact. As organic chemists are quite picky about conclusive proofs, so it's reasonably demonstrated that the molecule has not been destroyed, which means that it's very intimately embedded into the silica. Yeah, yeah, yeah. Actually carotenoids, when the system is the entire living system, they are doing their antioxidant work in the classical metabolic way. When you take them out from the cell just adding carotenoids, I mean, we have not tried to do that, but it would be like an antioxidant. We have not tried that. To be honest, those are molecules which I think are commercially available, where the graph inflakes are already attached to the graphene. But there are plenty of methods where you can exploit because these are graphene oxide groups. Graphene oxide, of course, has many functional groups, epoxide groups that you can exploit for doing, for instance, a nucleophilic attach with also organometallic reagents to attach the aromatic ring, bearing the triple bond. So it's not pure graphene, which would make the functionalization much more difficult. It reduces the graphene oxide, so there are still functional groups around that you can exploit for doing chemistry on top of it. Thank you.