Transparent microelectrodes have recently emerged as a promising approach for crosstalk‐free multifunctional electrical and optical biointerfacing. High‐performance flexible platforms that allow seamless integration with soft tissue systems for such applications are urgently needed. Here, silver nanowires (Ag NWs)‐based transparent microelectrode arrays (MEAs) and interconnects are designed to meet this demand. The nanowire networks exhibit a high optical transparency >90.0% at 550 nm, and superior mechanical stability up to 100,000 bending cycles at 5 mm radius. The Ag NWs microelectrodes preserve low normalized electrochemical impedance of 3.4–15 Ω cm2 at 1 kHz, and the interconnects demonstrate excellent sheet resistance (Rsh) of 4.1–25 Ω sq−1. In vivo histological analysis reveals that the Ag NWs structures are biocompatible. Studies on Langendorff‐perfused mouse and rat hearts demonstrate that the Ag NWs MEAs enable high‐fidelity real‐time monitoring of heart rhythm during co‐localized optogenetic pacing and optical mapping. This proof‐of‐concept work illustrates that the solution‐processed, transparent, and flexible Ag NWs structures are a promising candidate for the next‐generation of large‐area multifunctional biointerfaces for interrogating complex biological systems in basic and translational research.

Since being developed over 50 years ago, aromatic polyamides have been used industrially for numerous highperformance applications due to their heat resistance, chemical stability, and high strength. Despite this extensive time span, limited applications as surface coatings have been explored due to most aromatic polyamides being insoluble in organic solvents and their extremely high melting temperatures. However, new polymerization techniques have been developed to overcome this insolubility, allowing applications such as reverse osmosis membranes and gas separation membranes to be developed. With the recent advancement of substituent effect chain-growth condensation polymerization, controlled growth aromatic polyamides have been shown to grow from flat and curved surfaces. In this study, aromatic polyamides with a protecting side chain were grown from flat and curved surfaces to allow for post polymerization deprotection and the introduction of hydrogen bonding along the backbone of the polyamide. The aromatic polyamide brushes formed were then characterized using transmission electron microscope and atomic force microscopy to explore important physical properties of the polymer brushes, including grafting density and Young's modulus. The introduction of hydrogen bonding dramatically increased the Young's modulus of the aromatic polyamide brushes from 5−6 to 22−32 GPa. Our results demonstrate the tunability of the aromatic polyamide brushes to achieve high mechanical strength and pave the way for their application in areas such as high-performance coatings.

While the presence of organic macromolecules (or foulants) can exacerbate silica scaling of membranes, the effects of the types and physicochemical properties of macromolecules on silica scale formation remain poorly understood. We herein use a quartz crystal microbalance with dissipation monitoring to investigate the kinetics of silica mass deposition on sensors coated by lysozyme, bovine serum albumin (BSA), humic acid, or alginate. Our results show that deposited silica mass resulting from heterogeneous nucleation of monosilicic acid cannot be explained by the free energy barrier to nucleation but instead linearly correlated to the hydration energy of the macromolecule-covered surfaces. The most silica heterogeneous nucleation occurs on the most hydrophilic alginate-coated surface, which is likely due to the favorable interaction between silicic acid and alginate via hydrogen bonding and chemical reactions. For the deposition of silica aggregates formed from bulk nucleation, the deposited silica mass is the highest on the BSA-coated surface, consistent with the greatest adhesion force between BSA and silica measured using force spectroscopy. Finally, silica scaling on macromolecule-coated surfaces is promoted by calcium ions, and the deposition of silica is mostly irreversible upon rinsing with water.

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Transparent microelectrodes have recently emerged as a promising approach to combine electrophysiology with optophysiology for multifunctional biointerfacing. High-performance flexible platforms that allow seamless integration with soft tissue systems for such applications are urgently needed. Here, silver nanowires (Ag NWs)-based transparent microelectrodes and interconnects are designed to meet this demand. The Ag NWs percolating networks are patterned on flexible polymer substrates using an innovative photolithography-based solution-processing technique. The resulting nanowire networks exhibit a high average optical transparency of 76.1-90.0% over the visible spectrum, low normalized electrochemical impedance of 3.4-15 Ω cm2 at 1 kHz which is even better than those of opaque solid Ag films, superior sheet resistance of 11-25 Ω sq−1, excellent mechanical stability up to 10,000 bending cycles, good biocompatibility and chemical stability. Studies on Langendorff-perfused mouse and rat hearts demonstrate that the Ag NWs microelectrodes enable high-fidelity real-time monitoring of heart rhythm during co-localized optogenetic pacing and optical mapping with negligible light-induced electrical artifacts. This proof-of-concept work illustrates that the solution-processed, transparent, and flexible Ag NWs networks are a promising candidate for the next-generation of large-area multifunctional biointerfaces for interrogating complex biological systems in basic and translational research.