Neuronanotechnology: from mind imaging to brain repair

Ever since the speculations of ancient philosophers and the first studies of the human nervous system, we have been fascinated by this mysterious black box that connects us to the surrounding world. The path to understanding how it functions has been arduous, and many scientists think that we are far from having discovered everything that this most astonishing of biological machines, with its countless cellular connections, is able to do. The human brain, however, is able to conceive and create tools to study and to heal itself.

One of these creations of the human mind is bionanotechnology, used in the fabrication of materials, composites, and machines with biocompatible structures no larger than 100 nanometers, to be used in medical diagnosis, therapy, and surgery, and offering more efficient and less invasive alternatives. Much of this technology has already been tested both in vitro and in vivo (on animals), but there is still much to learn and better understand about the processes of biological systems as complex as the human brain.

The brain does not only interconnect our entire body, but also connects us with the environment around us, drawing sensorial information from our surroundings, codifying it in an electronic language, and translating it on demand to enable us to interact with our environment and to survive within it. Marvelous as it is, however, our brain remains exposed to damage, deficiencies, and eventual death. Nanotechnology can be a tool for understanding how the brain functions, for treating pathologies and disorders in the brain, and possibly even for raising it to a higher cognitive level and taking it beyond the barriers of death.

Neuronanotechnology can be very effective in the early diagnosis of neural pathologies and tumors and in research on brain functions in general. A good example is “quantum dots,” which have proven effective in diagnosing diseases that are difficult to detect owing to their small concentrations of pathogens. For example, early-stage bacterial meningitis can be detected by means of this nanocomposite that reacts with a solution of quantum dots with various epitopes, locating the pathogen before serious symptoms appear, and when the disease is still treatable (Guo and Wei, 2005).

Other devices that can improve neuropathological diagnoses and provide help in researching the nervous system are implants of nanotechnology, such a platinum nanowires that can pass through the bloodstream without interfering with the circulation of the blood. In one experiment, these nanowires, guided by the neurovascular system, were used to detect the activity of neurons adjacent to the blood vessels (Llinás et al, 2005). Interactions between neurons can be more fully explained thanks to these nanowires, which broaden the scope of neurobiological research and shed light on both the biological causes of mental disorders and the diagnoses of lesions. Nanorobots are electromechanical machines assembled on an atomic scale, with the ability to detect and adapt to heat, rays, surfaces, sounds, and chemical substances, as well as to repair themselves and to self-replicate. Nanorobots can be used to locate and treat malignant brain tumors, through the use of focalization sequences and magnetic fields for the direction and concentration of particles.

Thanks to nanotechnology, neuroimaging for diagnosis will become more precise, sensitive, and localized. Positron emission tomography, which uses isotope labeling, could increase in scope, thanks to nanomaterials that provide better resolution. These same nanomaterials could even be built in nanorobots capable of eliminating cancerous tumors in the brain. The ultrasensitive properties of nanocomposites will allow for the mapping of neuronal networks and of the molecular processes that occur within the neurons to be improved. One such example is the laser luminescence technique used to detect gold nanorods (Wang et al., 2005).

Nanotechnologies can also be applied to therapeutics, from pharmacological nanomaterials to nanorobots used to repair brain tissue. In the area of pharmaceuticals, the use of guided nanorobots for the administration of drugs is being studied. Certain nanomaterials, such as nanoparticles of metal and metallic oxide, nanocapsules, and others coated with biocomposites, increase the bioavailability and multifunctionality of the pharmaceuticals (Fonseca-Santos et al., 2015).

For example, Buckminsterfullerene, also as known as “Buckyballs,” are hollow spherical molecules with specific ligands in their structure that can be guided to specific locations in order to release the drug over time. The nanocapsules protect the biological agent during the entire journey to the target cell or tissue (Ellis-Behnke et al., 2007). Another property of these nanomaterials and nanocapsules is that they can easily pass through the bloodbrain barrier, some of them even being able to pass through the cell membrane and modify the functioning of enzymes or genes. Thanks to these nanocomposites, dosages can be reduced by anywhere from ten to fifty orders of magnitude. Moreover, the therapy period is shortened and there are fewer side-effects, with increased efficiency of the drugs in the nervous system.

Another remarkable potential therapeutic application of neuronanotechnology is that of regenerating nerve tissue by means of nanofibers of self-assembling peptides, which may be able to repair axons and foster the propagation of the action potential. A study group in the United States is developing an endomyccorhizae-like interface as a neuronal nanoprosthesis made of interconnected nanofibers that form a hybrid network with neurons. These nanofibers are able to diffuse action potential where neural circuits have been damaged owing to cerebrovascular lesions or neurodegenerative disorders (Saniotis et al., 2018).

The task of deciphering the biological underpinnings of the mind is one of the most complex and fascinating riddles that human beings have ever faced. Many

scientists, researchers, and engineers agree that, although neuroscience is still in its early stages, nanotechnology is likely carry it into the future by leaps and bounds, as even the mind itself may be uploaded into computers to be studied, with the creation of a brain-computer interface. This is what is promised by IBM’s Blue Brain project, which is being developed in collaboration with companies and institutes all over the world. The project consists of creating an artificial brain that will reconstruct and simulate, with biological details, first of all the brains of rodents and finally the human brain itself. These reconstructions and simulations are mapped from a brain in vivo by means of nanorobots recording data through the interface of a supercomputer. Although the project is still at the laboratory stage, it may well open a window toward understanding the structure and function of the brain at many levels, particularly cognitive and mental, as it seeks to decipher the neural code (Ganji and Nayana, 2015; Poonia, 2019).

We need to ask ourselves, however, whether all this new technology, as impressive and promising as it is, may not have long-term disadvantages or repercussions. There are always challenges and obstacles to understanding complex natural phenomena, especially along the frontier separating the biological realm from the artificial world. Nevertheless, some authors, such as Ray Kurzweil, enthusiastically predict that, within ten years, much of this technology will already be in use, including even interfaces between computers and the human brain.

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Trilce María Fernanda Ortega Hernández

Biologist, neuroscientist, and researcher in neuroethology in non-human primates at the Instituto de Neuroetología of the Universidad Veracruzana