Applications of nanotechnology in neurosurgery

Εισαγωγή: Κάθε αντικείμενο, υλικό ή σωματίδιο με μία, δύο ή τρεις εξωτερικές διαστάσεις μικρότερες από 100 nm, μπορεί να χαρακτηριστεί ως νανο-αντικείμενο, νανο-υλικό ή νανο-σωματίδιο αντίστοιχα. Η νανοϊατρική είναι η εφαρμογή της νανοτεχνολογίας στην ιατρική και καθορίζεται από τη συνεργασία πλήθους επιστημών. Τα νανοσωματίδια αποτελούν τους δομικούς λίθους της νανοϊατρικής και οργανώνονται σε νανοσυστήματα, τα οποία κατηγοριοποιούνται περαιτέρω σε μοριακά, κολλοειδή και μεγαλομοριακά διαλύματα. Σκοπός: Ο σκοπός της παρούσας μελέτης είναι η παρουσίαση των πιο σύγχρονων επιτευγμάτων της νανοτεχνολογίας σε χρήση στους διάφορους τομείς της νευροχειρουργικής. Μέθοδος-Υλικά: Διεξήχθη μια συστηματική ανάλυση σύμφωνα με τις οδηγίες PRISMA. Κριτήρια εισόδου και εξόδου από τη μελέτη μας εφαρμόστηκαν για οποιοδήποτε νανοϊατρικό ή νανοτεχνολογικό επίτευγμα στα πλαίσια της νευροχειρουργικής. Η αναζήτηση πραγματοποιήθηκε χρησιμοποιώντας λογική Boolean στην προχωρημένη αναζήτηση της βάσης δεδομένων Pubmed καθώς και στη βιβλιογραφία των άρθρων που προέκυψαν. Αποτελέσματα: Η αναζήτηση παρείχε 1984 άρθρα, από τα οποία 190 πλήρη άρθρα ελήφθησαν για περαιτέρω έλεγχο. Σύνολο 78 άρθρων συμπεριλήφθηκαν στη μελέτη μας. Η πλειοψηφία των μελετών αφορούσε σε 43 άρθρα για τη νευρο-νανοθεραπεία, και 47 από το σύνολο των άρθρων αφορούσαν τη νευρο-ογκολογία. Συμπεράσματα: Ο εγκέφαλος είναι πιθανόν η μεγαλύτερη πρόκληση ως όργανο στόχος, με κύριο εμπόδιο τον αιματοεγκεφαλικό φραγμό. Η επίπτωση των εγκεφαλικών νοσημάτων αυξάνεται καθώς ο πληθυσμός γερνάει, και τα συμβατικά φάρμακα αποδεικνύονται ανεπαρκή για την αντιμετώπιση των περισσότερων νευρολογικών νοσημάτων. Η νανοτεχνολογία είναι ακόμη νέα επιστήμη, αλλά πολλά υποσχόμενη, και πολλά νανοσυστήματα αναπτύσσονται ήδη για την αντιμετώπιση των νοσημάτων του εγκεφάλου.Background: Any object, material or particle with one, two or three of the outer dimensions smaller than 100 nm can be defined as nano-object, nano-material, or nano-particle respectively. Nanomedicine is the application of nanotechnology to medicine and is defined by the collaboration of an interdisciplinary field of sciences. Nanoparticles are the building blocks of nanomedicine and they are organized in disperse nanosystems, which are further categorized in molecular, colloidal, and coarse dispersions. Objective: The objective of this study is to review the current developments of nanotechnology that are of use in different sections of neurosurgery. Methods and Materials: We conducted a systematic review according to the PRISMA statements. Inclusion and exclusion criteria were applied for any nanomedical or nanotechnological advances in terms of neurosurgery. The search was performed using the Boolean logic of the advanced search of the PubMed database and by scanning reference lists of the resulting articles. Results: The search yielded 1984 items and full texts of 190 articles were retrieved for further investigation. A total of 78 original studies were included in our review. Most of the studies, a total of 43, were about neuro-nanotherapy, while a total of 47 were about neuro-oncology. Conclusion: The brain is probably the most challenging target organ, with the main obstacle to overcome the blood-brain barrier (BBB). Incidence of brain pathology is rising as the population ages, and convectional medications prove to be insufficient for dealing with many neurological diseases. Nanotechnological research is still young, yet quite promising and many new nanosystems are nowadays under development against brain pathology

Carbon Fiber Electrode Arrays for Cortical and Peripheral Neural Interfaces

Neural interfaces create a connection between neural structures in the body and external electronic devices. Brain-machine interfaces and bioelectric medicine therapies rely on the seamless integration of neural interfaces with the brain, nerves, or spinal cord. However, conventional neural interfaces cannot meet the demands of high channel count, signal fidelity, and signal longevity that these applications require. I investigated the damage resulting from conventional Utah arrays after multiple years of implantation in the cortex of a non-human primate as a possible explanation for these limitations. The neuron density around the electrode shanks was compared to the neuron density of nearby healthy tissue, finding a 73% loss in density around the electrodes. The explanted arrays were imaged and characterized for degradation. Coating cracks, tip breakage, and parylene cracks were the most common degradation type. A significantly higher number of tip breakage and coating crack occurrences were found on the edges of the arrays as compared to the middle. In this work, I made clear the need for a minimally damaging alternative to the Utah electrode array. Neural interfaces composed of carbon fiber electrodes, with a diameter of 6.8 microns, could enable a seamless integration with the body. Previous work resulted in an array of individuated carbon fiber electrodes that reliably recorded high signal-to-noise ratio neural signals from the brain for months. However, the carbon fiber arrays were limited by only 30% of the electrodes recording neural signals, despite inducing minimal inflammation. Additionally, it was relatively unknown if carbon fibers would make suitable long-term peripheral neural interfaces. Here, I illustrate the potential of carbon fiber electrodes to meet the needs of a variety of neural applications. First, I optimized state-of-the-art carbon fiber electrodes to reliably record single unit electrophysiology from the brain. By analyzing the previous manufacturing process, the cause of the low recording yield of the carbon fiber arrays was identified as the consistency of the electrode tip. A novel laser cutting technique was developed to produce a consistent carbon fiber tip geometry, resulting in a near tripling of recording yield of high amplitude chronic neural signals. The longevity of the carbon fiber arrays was also addressed. The conventional polymer coating was compared against platinum iridium coating and an oxygen plasma treatment, both of which outperformed the polymer coating. In this work, I customized carbon fiber electrodes for reliable, long-term neural recording. Secondly, I translated the carbon fiber technology from the brain to the periphery in an architecture appropriate for chronic implantation. The insertion of carbon fibers into the stiffer structures in the periphery is enabled by sharpening the carbon fibers. The sharpening process combines a butane flame to sharpen the fibers with a water bath to protect the base of the array. Sharpened carbon fiber arrays recorded electrophysiology from the rat vagus nerve and feline dorsal root ganglia, both structures being important targets for bioelectric medicine therapies. The durability of carbon fibers was also displayed when partially embedded carbon fibers in medical-grade silicone withstood thousands of repeated bends without fracture. This work showed that carbon fibers have the electrical and structural properties necessary for chronic application. Overall, this work highlights the vast potential of carbon fiber electrodes. Through this thesis, future brain-machine interfaces and bioelectric medicine therapies may utilize arrays of sub-cellular electrodes such as carbon fibers in medical applications.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169982/1/elissajw_1.pd