Molecular interactions between proteins or between proteins and small molecules are pivotal events for selective binding of biological structures and, consequentially, for their correct function. In this scenario, the evaluation of kinetic parameters, characterizing a molecular interactions, is considered a crucial event to reveal the nature of binding processes. The focus on peculiar forces involved in the molecular recognition represents an opportunity to explore biological interactions in real time, and to develop a number of innovative biotechnological methods for diagnosis and/or therapy. Currently, optical biosensors, offering an increasingly effective technology to detect in real time molecular binding, are usually composed by a detector, a sensor surface and a sample delivery system: only definite substances, which are able to interact specifically with the biological part, lead to an optical or electrical signal of the physical transducer. In this review we want to highlight the exponentially-growing interest of Surface Plasmon Resonance (SPR) based optical biosensors for molecular binding analysis in different research fields.

In 2005 we reported for the first time on a chemical route aiming to synthesize stable magnetic carbon/graphite. By using the Nuclear Magnetic Resonance (NMR) technique we have verified that its magnetism is an intrinsic property of this synthesized material and not originated from ferromagnetic impurities of any kind. Through direct measurement of the local magnetic field using Carbon-13, we have concluded that its magnetism originated from defects in the structure. From its biocompatibility, we have been working on the use of magnetic carbon/graphite to deliver many compounds aiming to fight different diseases. Despite all the scientific and technological advances of the present day, cancer is a multifactorial and difficult-to-treat disease, killing hundreds of thousands of people a year worldwide. Therefore, the development of a new and efficient drug delivery system to fight cancer – among other diseases - is as important as the discovery of a novel active molecule. In this review of our own work, we show the drug delivery system named MAGUS® (an acronym for Magnetic Graphite Universal System) we have built based on nanostructured magnetic carbon/graphite. This is an innovative and promising system composed of a biocompatible nanostructured particle of magnetic carbon/graphite functionalized with different molecules and materials. MAGUS®, depending on what we link to its structure, is so versatile and can be used to detect a wide range of specimens, from tumors and cancers to chemical and biological agents used as non-conventional weapons. That is why we call it universal. In the present work, MAGUS® will be acting as a biosensor, where the magnetic carbon/graphite is functionalized with radioactive particles of Iodine-131 and antibodies of different types of cancer. Then, by focusing on both the antigen-antibody interaction and the spatial guiding through an external magnetic field we are providing our drug delivery system a double way to detect and reach just the target. Based on these strategies, the functionalized magnetic carbon/graphite will reach only the neoplasm and not the surrounding healthy cells around. In a general view, it means that we are giving specificity to the MAGUS® drug delivery system as a pioneering and effective way to detect and treat cancers. We are also working on this unprecedented and efficient drug delivery system using the principles of Boron Neutron Capture Therapy (BNCT) with Boron-10 instead of Iodine-131. BNCT technique uses neutrons as the external source and is frequently employed to treat specific tumors that are radio resistant or very difficult to kill using conventional radiation therapy. In summary, we show here for the first time that our Magnetic Graphite Universal System associated with nuclear techniques can be successfully used as a biosensor to detect and fight cancers and tumors with powerful features that conventional delivery drug systems and other treatments do not have at all.