Efficient photocapacitors via ternary hybrid photovoltaic optimization for photostimulation of neurons

ACS Appl. Mater. Interfaces

Srivastava

Yıldız

et al. 2020

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Neural interfaces are the fundamental tools to understand the brain and cure many nervous-system diseases. For proper interfacing, seamless integration, efficient and safe digital-to-biological signal transduction, and long operational lifetime are required. Here, we devised a wireless optoelectronic pseudocapacitor converting the optical energy to safe capacitive currents by dissociating the photogenerated excitons in the photovoltaic unit and effectively routing the holes to the supercapacitor electrode and the pseudocapacitive electrode–electrolyte interfacial layer of PEDOT:PSS for reversible faradic reactions. The biointerface showed high peak capacitive currents of ∼3 mA·cm –2 with total charge injection of ∼1 μC·cm –2 at responsivity of 30 mA·W –1 , generating high photovoltages over 400 mV for the main eye photoreception colors of blue, green, and red. Moreover, modification of PEDOT:PSS controls the charging/discharging phases leading to rapid capacitive photoresponse of 50 μs and effective membrane depolarization at the single-cell level. The neural interface has a device lifetime of over 1.5 years in the aqueous environment and showed stability without significant performance decrease after sterilization steps. Our results demonstrate that adopting the pseudocapacitance phenomenon on organic photovoltaics paves an ultraefficient, safe, and robust way toward communicating with biological systems.

Section: Introductionmentioning

confidence: 99%

Organic Photovoltaic Pseudocapacitors for Neurostimulation

ACS Appl. Mater. Interfaces

Srivastava

Yıldız

et al. 2020

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“…[38] The responsivity corresponding to 156 mA W −1 and photovoltage levels (Figure 3c) are higher than the other dry-material-based interfaces made of nanorodcarbon nanotube, [10] silicon dioxide, [46] metal and p-n semiconducting organic nanocrystals, [11] polymeric donor-acceptor, and PEDOT:PSS based photovoltaic interfaces. [13,15,16,47]…”

Section: Photo-electrochemical Characterizationmentioning

confidence: 99%

“…The good biocompatibility exhibited by the biointerface is in good agreement with the previous studies examining each compound in our design separately. [16,53] Especially, hydrogel studies suggest that porous nature and microscale surface morphology supports the cell attachment. [27]…”

Section: Stability and Biocompatibility Testsmentioning

confidence: 99%

Tissue‐Like Optoelectronic Neural Interface Enabled by PEDOT:PSS Hydrogel for Cardiac and Neural Stimulation

Adv Healthcare Materials

Yıldız

Kaleli

et al. 2022

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Optoelectronic biointerfaces have made a significant impact on modern science and technology from understanding the mechanisms of the neurotransmission to the recovery of the vision for blinds. They are based on the cell interfaces made of organic or inorganic materials such as silicon, graphene, oxides, quantum dots, and 𝝅-conjugated polymers, which are dry and stiff unlike a cell/tissue environment. On the other side, wet and soft hydrogels have recently been started to attract significant attention for bioelectronics because of its high-level tissue-matching biomechanics and biocompatibility. However, it is challenging to obtain optimal opto-bioelectronic devices by using hydrogels requiring device, heterojunction, and hydrogel engineering. Here, an optoelectronic biointerface integrated with a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS, hydrogel that simultaneously achieves efficient, flexible, stable, biocompatible, and safe photostimulation of cells is demonstrated. Besides their interfacial tissue-like biomechanics, ≈34 kPa, and high-level biocompatibility, hydrogel-integration facilitates increase in charge injection amounts sevenfolds with an improved responsivity of 156 mA W −1 , stability under mechanical bending , and functional lifetime over three years. Finally, these devices enable stimulation of individual hippocampal neurons and photocontrol of beating frequency of cardiac myocytes via safe charge-balanced capacitive currents. Therefore, hydrogel-enabled optoelectronic biointerfaces hold great promise for next-generation wireless neural and cardiac implants.

Section: Quantum Dot Systems For Neural Stimulationmentioning

confidence: 99%

Optoelectronic Neural Interfaces Based on Quantum Dots

ACS Appl. Mater. Interfaces

Karatum

Nizamoğlu

2022

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Optoelectronic modulation of neural activity is an emerging field for the investigation of neural circuits and the development of neural therapeutics. Among a wide variety of nanomaterials, colloidal quantum dots provide unique optoelectronic features for neural interfaces such as sensitive tuning of electron and hole energy levels via the quantum confinement effect, controlling the carrier localization via band alignment, and engineering the surface by shell growth and ligand engineering. Even though colloidal quantum dots have been frontier nanomaterials for solar energy harvesting and lighting, their application to optoelectronic neural interfaces has remained below their significant potential. However, this potential has recently gained attention with the rise of bioelectronic medicine. In this review, we unravel the fundamentals of quantum-dot-based optoelectronic biointerfaces and discuss their neuromodulation mechanisms starting from the quantum dot level up to electrode−electrolyte interactions and stimulation of neurons with their physiological pathways. We conclude the review by proposing new strategies and possible perspectives toward nanodevices for the optoelectronic stimulation of neural tissue by utilizing the exceptional nanoscale properties of colloidal quantum dots.