Physical investigation and understanding of biomineralisation proteins and their use for the synthesis of new nanomaterials

Scientific and economic interest in nanotechnology has grown in recent years. Within this the quest to produce tiny and highly tailored magnetic particles, or nanomagnets is crucial. Nanomagnets have a range of practical uses. Historically they have been used for information storage such as tapes and hard drives. Recently this has expanded, with the development of 3D information storage systems providing high density data storage. There is also much interest in the medical applications of nanomagnets. Magnetic particles are being developed to provide targeted medicine within the body. For example, if drugs are tied to nanomagnets at the molecular level then they can be directed by a magnet to specific sites within the patient. This allows a drug to be delivered to a specific area, without harming the rest of the body. Similarly, nanomagnets can be used in hyperthermic therapies. This is where, after being directed to specific tumour sites, magnetic particles are heated to either destroy a tumour or activate a drug. However, as nanotechnology grows, so too does the need to develop precisely engineered nanomagnets. Different applications demand different shapes and sizes of particles and different magnetic properties. Controlling the composition and dimensions of nanomagnets has therefore become a key goal of researchers. Biomineralisation is the process that occurs in living organisms to produce minerals such as bones. Because genetics control biomineralisation processes the materials produced exhibit very precise, uniform and intricate formations down to the nano-scale. Furthermore, if the genetics are understood it may be possible to change with precision the nature of biomineralised materials. Magnetotactic bacteria biomineralise high quality and uniform nanoparticles of the iron-oxide magnetite within biological fatty shells (or vesicles) within the bacterial cell (termed magnetosomes). Because magnetosomes exhibit considerable uniformity and precision they present a novel and attractive route to produce high quality nanoparticles. However, the biomineralisation method can be inefficient for commercial production and is restricted to the specifications imposed by the bacterial cell leaving little flexibility for further modifications. A protein found to be involved in making nanomagnets in the bacteria has previously been extracted, and mass produced (expressed) and used in a chemical precipitation of magnetic particles. The protein was found to control the particle's size and shape even in this chemical production outside the bacterial cell. This research will identify biomineralisation proteins from the genetic information we have about magnetic bacteria, and investigate these proteins individually by expressing then and using them in a chemical formation of nanoparticles similar to the previous study. From this we will study in detail how the protein physically controls the size and shape of the particles using microscopy, spectroscopy and diffraction techniques. These will study the proteins while they are making the particles, so we can identify which parts of the proteins are responsible for the control over formation. With this information we will develop a combined chemical/biological method of making nanomagnetic particles. The new method will combine the benefits of the precision offered by biomineralisation, with the higher yields and more malleable system with respect to variation, offered by chemical synthesis. Furthermore, once the specific role of each protein has been ascertained, particles can be designed and custom-made with the addition of a recipe of the specific proteins and metal ions. This will offer more control over the particles' characteristics than the biological system. This biomimetic synthetic method will allow for the production of particles on a larger, and more commercially viable, scale than if the bacteria alone were used.

Magnetic nanoparticles have many uses in nanotechnology (information storage, advanced electronics, targeted healthcare and medicine) and as these technologies increase in sophistication, so does the demand for more customised precision particles. I propose a novel route for magnetic nanoparticle production by utilising biomineralisation proteins that synthesise high quality and uniform particles in magnetic bacteria. Specifically I intend to exploit the precise genetic control biomineralisation offers to develop an in vitro biomimetic system to produce large yields of tailor-made nanomagnets for commercial nanotechnological and biomedical applications. The addition of biomineralisation proteins into an in vitro chemical precipitation of nanoparticles of magnetite has been shown to improve particle regularity and yield. I thus propose to expand on this work to identify novel candidate biomineralisation using comparative bioinformatics, particularly specific shape defining proteins. We will then express and purify these proteins and study their affect on the in vitro precipitation of nanomagnets. We will study in detail how the protein physically controls this process using microscopy, spectroscopy and diffraction techniques. These will study the protein and genetically mutated proteins while they control the particle precipitation, so we can identify the protein motifs responsible for the control over formation. With this information we will develop this combined chemical/biological method of making nanomagnetic particles. The new method will combine the benefits of the precision offered by biomineralisation, with the higher yields and more malleable system with respect to variation, offered by chemical synthesis. Furthermore, once the specific role of each protein has been ascertained, particles can be designed and custom-made with the addition of a recipe of the specific proteins and metal ions, producing high yields of superior nanomagnets.

The research proposed will investigate how proteins biomineralise nanomagnetic particles in magnetic bacteria, with the future long-term goal of using this knowledge to develop new commercial biomimetic methods, presenting an immediate and vastly improved solution to the synthesis of highly uniform magnetic nanoparticles for nanotechnological and biomedical applications. The biomimetic additives (proteins, peptides or molecules) identified and created here will potentially offer an ambient conditioned synthetic method of producing high yields of high-quality morphologically controlled nanoparticles. It can therefore be seen that the study proposed here has considerable long-term commercial implications, potentially benefiting industries producing nanomagnets for recording and information storage media, advanced electronics and healthcare nanotechnologies. By presenting a commercially viable route to high yields of precision particles this research could be further developed to make advanced technologies more cost efficient, thus more widely available, benefiting industries as well as governmental bodies such as the NHS and thus the general public with respect to quality of life. With this in mind I have planned a commercial exploitation strategy which will look to patent successful biomineralisation additives and to seek partnerships to exploit innovative industrial development of this biomimetic nanoparticle production. This will be done in consultation with the University of Leeds enterprise and innovations office and 'TechTran' and by seeking follow-on funding in the form of CASE and Industrial partnership awards. I also plan to work closely with other academics that have experience and expertise in this field of research and have developed this research commercially with spin-out companies. The project is inherently multidisciplinary and as such it aligns well with the BBSRC's roadmap and it specifically addresses the BBSRC strategic priority areas of 'synthetic biology' and 'nanoscience through engineering to application: bionanotechnology'. The multidisciplinary nature of the project also provides excellent cross-disciplinary training for both the PDRA and the technician. Furthermore the project offers additional interdisciplinary networking and knowledge transfer, not only for the PDRA and technician, but also for all the collaborators. I plan to increase the impact of this project through a wide range of dissemination methods. I have a strong track-record in publishing my results in the best high-profile journals and in gaining wide media coverage of my research to give my research maximum impact. I plan to follow a similar strategy for this project, disseminating my results promptly in the form of journal articles and conference papers, while simultaneously working with the press office to gain media coverage. The skills and methodologies developed in the work will also be disseminated to students in the form of material in advanced undergraduate courses and project based laboratory skills training. Further hands-on dissemination to the public will take the form of interactive workshops in the discovery zone of the Leeds science festival.