A bilayered PVA/PLGA-bioresorbable shuttle to improve the implantation of flexible neural probes.
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Authors
Pas, Jolien
Rutz, Alexandra L
Quilichini, Pascale P
Slézia, Andrea
Ghestem, Antoine
Kaszas, Attila
Donahue, Mary J
Curto, Vincenzo F
O'Connor, Rodney P
Bernard, Christophe
Williamson, Adam
Malliaras, George G
Publication Date
2018-12Journal Title
J Neural Eng
ISSN
1741-2560
Publisher
IOP Publishing
Volume
15
Issue
6
Pages
065001
Language
eng
Type
Article
Physical Medium
Print-Electronic
Metadata
Show full item recordCitation
Pas, J., Rutz, A. L., Quilichini, P. P., Slézia, A., Ghestem, A., Kaszas, A., Donahue, M. J., et al. (2018). A bilayered PVA/PLGA-bioresorbable shuttle to improve the implantation of flexible neural probes.. J Neural Eng, 15 (6), 065001. https://doi.org/10.1088/1741-2552/aadc1d
Abstract
OBJECTIVE: Neural electrophysiology is often conducted with traditional, rigid depth probes. The mechanical mismatch between these probes and soft brain tissue is unfavorable for tissue interfacing. Making probes compliant can improve biocompatibility, but as a consequence, they become more difficult to insert into the brain. Therefore, new methods for inserting compliant neural probes must be developed. APPROACH: Here, we present a new bioresorbable shuttle based on the hydrolytically degradable poly(vinyl alcohol) (PVA) and poly(lactic-co-glycolic acid) (PLGA). We show how to fabricate the PVA/PLGA shuttles on flexible and thin parylene probes. The method consists of PDMS molding used to fabricate a PVA shuttle aligned with the probe and to also impart a sharp tip necessary for piercing brain tissue. The PVA shuttle is then dip-coated with PLGA to create a bi-layered shuttle. MAIN RESULTS: While single layered PVA shuttles are able to penetrate agarose brain models, only limited depths were achieved and repositioning was not possible due to the fast degradation. We demonstrate that a bilayered approach incorporating a slower dissolving PLGA layer prolongs degradation and enables facile insertion for at least several millimeters depth. Impedances of electrodes before and after shuttle preparation were characterized and showed that careful deposition of PLGA is required to maintain low impedance. Facilitated by the shuttles, compliant parylene probes were also successfully implanted into anaesthetized mice and enabled the recording of high quality local field potentials. SIGNIFICANCE: This work thereby presents a solution towards addressing a key challenge of implanting compliant neural probes using a two polymer system. PVA and PLGA are polymers with properties ideal for translation: commercially available, biocompatible with FDA-approved uses and bioresorbable. By presenting new ways to implant compliant neural probes, we can begin to fully evaluate their chronic biocompatibility and performance compared to traditional, rigid electronics.
Keywords
Brain, Animals, Mice, Inbred C57BL, Mice, Polyvinyl Alcohol, Biocompatible Materials, Electrodes, Implanted, Absorbable Implants, Electric Impedance, Male, Polylactic Acid-Polyglycolic Acid Copolymer
Sponsorship
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (732032)
Identifiers
External DOI: https://doi.org/10.1088/1741-2552/aadc1d
This record's URL: https://www.repository.cam.ac.uk/handle/1810/285116
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