Silk as a Multifunctional Biomaterial Substrate for Reduced Glial Scarring around Brain‐Penetrating Electrodes

Tien, Lee W.; Wu, Fan; Tang-Schomer, Min D.; Yoon, Euisik; Omenetto, Fiorenzo G.; Kaplan, David L.

doi:10.1002/adfm.201203716

Cited by 118 publications

(116 citation statements)

References 76 publications

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“…Flexible fibres have been inserted into tissue using dissolvable coatings such as gelatin, [19] silk, [20] and maltose. [21] Carbon nanotube bundle electrodes on flexible substrates have been inserted into the brain using a rigid gold wire carrier.…”

Section: Introductionmentioning

confidence: 99%

Soft, Flexible Freestanding Neural Stimulation and Recording Electrodes Fabricated from Reduced Graphene Oxide

Apollo

Maturana

Tong

et al. 2015

Adv Funct Materials

131

148

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. (2015). Soft, flexible freestanding neural stimulation and recording electrodes fabricated from reduced graphene oxide. Advanced Functional Materials, 25 (23), 3551-3559. Soft, flexible freestanding neural stimulation and recording electrodes fabricated from reduced graphene oxide AbstractThere is an urgent need for conductive neural interfacing materials that exhibit mechanically compliant properties, while also retaining high strength and durability under physiological conditions. Currently, implantable electrode systems designed to stimulate and record neural activity are composed of rigid materials such as crystalline silicon and noble metals. While these materials are strong and chemically stable, their intrinsic stiffness and density induce glial scarring and eventual loss of electrode function in vivo. Conductive composites, such as polymers and hydrogels, have excellent electrochemical and mechanical properties, but are electrodeposited onto rigid and dense metallic substrates. In the work described here, strong and conductive microfibers (40-50 μm diameter) wet-spun from liquid crystalline dispersions of graphene oxide are fabricated into freestanding neural stimulation electrodes. The fibers are insulated with parylene-C and laser-treated, forming "brush" electrodes with diameters over 3.5 times that of the fiber shank. The fabrication method is fast, repeatable, and scalable for high-density 3D array structures and does not require additional welding or attachment of larger electrodes to wires. The electrodes are characterized electrochemically and used to stimulate live retina in vitro. Additionally, the electrodes are coated in a water-soluble sugar microneedle for implantation into, and subsequent recording from, visual cortex. AbstractThere is an urgent need for conductive neural interfacing materials that exhibit mechanicallycompliant properties while also retaining high strength and durability in physiological conditions. Currently, implantable electrode systems designed to stimulate and record neural activity are comprised of rigid materials such as crystalline silicon and noble metals. While these materials are strong and chemically stable, their intrinsic stiffness and density induce glial scarring and eventual loss of electrode function in vivo. Conductive composites, such as polymers and hydrogels, have excellent electrochemical and mechanical properties, but are electrodeposited onto rigid and dense metallic substrates. In the work described here, strong and conductive microfibres (40-50 µm diameter) wet-spun from liquid crystalline dispersions of graphene oxide are fabricated into freestanding neural stimulation electrodes. The fibres were insulated with parylene-C and laser-treated, forming "brush" electrodes with diameters over 3.5 times that of the fibre shank. The fabrication method is fast, repeatable, and scalable for high density 3-D array structures and does not require additional welding or attachment of larger electrodes to wires. The electrodes are characterized electroch...

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Section: Introductionmentioning

confidence: 99%

Soft, Flexible Freestanding Neural Stimulation and Recording Electrodes Fabricated from Reduced Graphene Oxide

Apollo

Maturana

Tong

et al. 2015

Adv Funct Materials

131

148

View full text Add to dashboard Cite

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“…Glass is also very stiff and this mechanical mismatch can damage surrounding soft tissue due to either fiber motion or natural body motions such as heartbeat and breathing. The mismatch in stiffness between the tissue and the fiber can result in scar formation [2] which may limit light delivery to the desired target. Implanted glass fibers are currently used to deliver light for treatment of malignant brain tumors [3], but this technique is limited to severe cases due to the risks outlined above.…”

Section: Introductionmentioning

confidence: 99%

Biocompatible silk step-index optical waveguides

Applegate¹,

Perotto²,

Kaplan³

et al. 2015

Biomed. Opt. Express

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Biocompatible optical waveguides were constructed entirely of silk fibroin. A silk film (n=1.54) was encapsulated within a silk hydrogel (n=1.34) to form a robust and biocompatible waveguide. Such waveguides were made using only biologically and environmentally friendly materials without the use of harsh solvents. Light was coupled into the silk waveguides by direct incorporation of a glass optical fiber. These waveguides are extremely flexible, and strong enough to survive handling and manipulation. Cutback measurements showed propagation losses of approximately 2 dB/cm. The silk waveguides were found to be capable of guiding light through biological tissue. #246610Received 23

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“…For functional integration with host brain neurons it is desirable to induce guided neuronal/glial alignment and axon tract formation, such as by imparting structural anisotropy in the implant material [16] . Many biomaterials are being developed to support cell grafts in the brain [17] , or to facilitate chronic electrode implants as coatings [18] . However, a brain-implantable material to support neurons and electrodes as well as sustained neuron-electrode interfaces has not been realized.…”

Section: Introductionmentioning

confidence: 99%

Film‐Based Implants for Supporting Neuron–Electrode Integrated Interfaces for The Brain

Tang-Schomer

Hronik-Tupaj

et al. 2013

Adv Funct Materials

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Neural engineering provides promise for cell therapy by integrating the host brain with brain-machine-interface technologies in order to externally modulate functions. Long-term interfaces with the host brain remain a critical challenge due to insufficient graft cell survivability and loss of brain electrode sensitivity over time. Here, integrated neuron-electrode interfaces were developed on thin flexible and transparent silk films as brain implants. Mechanical properties and surface topography of silk films were optimized to promote cell survival and alignment of primary rat cortical cells. Compartmentalized cultures of living neural circuit and co-patterned electrode arrays were incorporated on the silk films with built-in wire connections. Electrical stimulation via electrodes embedded in the films activated surrounding neurons evoked calcium responses. In mice brains the silk film implants showed conformal contact capable of modulating host brain cells with minimal inflammatory response and stable indwelling for weeks. The approach of combining cell therapy and brain electrodes could provide sustained functional brain-machine interfaces with ex vivo control of neuron-electrode interface with spatial and temporal precision.

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Silk as a Multifunctional Biomaterial Substrate for Reduced Glial Scarring around Brain‐Penetrating Electrodes

Cited by 118 publications

References 76 publications

Soft, Flexible Freestanding Neural Stimulation and Recording Electrodes Fabricated from Reduced Graphene Oxide

Soft, Flexible Freestanding Neural Stimulation and Recording Electrodes Fabricated from Reduced Graphene Oxide

Biocompatible silk step-index optical waveguides

Film‐Based Implants for Supporting Neuron–Electrode Integrated Interfaces for The Brain

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