Magnetite synthesis in biomimietic nanovesicles: innovative synthetic routes to tailored bio-nanomagnets

近年来，人们对纳米技术的科学和经济兴趣有所增长。在这其中，制造微小且高度定制的磁性颗粒或纳米磁铁的探索至关重要。纳米磁铁有一系列的实际用途。从历史上看，它们被用于磁带和硬盘等信息存储。最近，随着提供高密度数据存储的3D信息存储系统的发展，这一点已经扩展。纳米磁铁在医学上的应用引起了人们的极大兴趣。人们正在开发磁性颗粒，以便在体内提供靶向药物。例如，如果药物在分子水平上与纳米磁铁捆绑在一起，那么它们可以通过磁铁定向到患者体内的特定位置。这使得药物可以被输送到特定的区域，而不会损害身体的其他部分。同样，纳米磁铁也可以用于热疗。在这里，磁性颗粒被定向到特定的肿瘤部位后，被加热以摧毁肿瘤或激活药物。这种颗粒也已经被用作诊断医学的图像增强剂。然而，随着纳米技术的发展，开发精确设计的纳米磁铁的需求也在增加。不同的应用需要不同形状和大小的颗粒以及不同的磁性。因此，生产高度可控的纳米磁铁，其成分、大小和形状足以用于这些行业，已成为研究人员的关键目标。生物矿化是指在活体中发生的产生骨骼等矿物的过程。因为基因控制着生物矿化过程，所以产生的材料表现出非常精确、均匀和复杂的结构，精确到纳米级。趋磁细菌使细菌细胞内称为磁小体的生物壳(或囊泡)中的高质量均匀的氧化铁磁铁矿纳米颗粒生物矿化。由于磁小体表现出相当的均匀性和精密度，它们为制备高质量的纳米粒子提供了一种新颖而有吸引力的方法。然而，生物矿化方法在商业生产中效率低下，而且灵活性不高，因为细胞严格控制形态和组成，因此粒子不容易改变(例如，最大钴掺杂1.4%)。为了合成精确的定制磁性纳米粒子，我们将探索一种仿生方法，从自然中获得灵感，在细胞外的人工磁小泡中开发纳米磁铁矿沉淀系统。我们将在纳米囊泡内进行简单的常温化学沉淀磁铁矿，以帮助控制颗粒大小，并将生物矿化蛋白质整合到囊泡内部，进一步将生物精确的形态施加在颗粒上。该系统将结合生物矿化的所有好处，如形态精确度和生物兼容涂层，以及化学沉淀的所有好处，如高产量和关于变化的更具延展性的系统，因此颗粒可以定制。此外，这种形成技术使用环境友好的条件，并且在颗粒中添加生物兼容的脂类涂层也非常有利于医疗保健应用。

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 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. Such particles also already have used as image enhancers for diagnostic medicine. 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. Producing nanomagnets with highly controlled; composition, size and shapes, in large enough amounts to be of use to these industries, 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 nanoscale. Magnetotactic bacteria biomineralise high quality uniform nanoparticles of the iron-oxide magnetite within biological shells (or vesicles) called magnetosomes, within the bacterial cell. Because magnetosomes exhibit considerable uniformity and precision they present a novel and attractive route to produce high quality nanoparticles.However, the biomineralisation method produces inefficient yields for commercial production and is also not very flexible, as the cell strictly controls morphology and composition, so the particles cannot be easily adapted (e.g. maximum cobalt doping 1.4%).In order to synthesise precision customised magnetic nanoparticles, we will explore a biomimetic approach where we take inspiration from nature to develop a nano-magnetite precipitation system within artificial magnetosome vesicles outside the cell. We will perform a simple ambient temperature chemical precipitation of magnetite within nano-vesicles to help control the particle size and incorporate biomineralisation proteins into the interior of the vesicles to further impose biologically precise morphology over the particles. The system will combine all the benefits of biomineralisation such as morphological precision and a biocompatible coating, with all the benefits of a chemical precipitation such as high yields and a more malleable system with respect to variation, so particles can be customised.Additionally this formation technique uses environmentally friendly conditions and the addition of a biocompatible lipid coating to the particles is also highly advantageous for healthcare applications.