In this review, we focus on the contributions made to the bioelectronic field from various aspects of chemistry.

Optically-controlled non-genetic neuromodulation represents a promising approach for the fundamental study of neural circuits and the clinical treatment of neurological disorders. Among existing material candidates that can transduce light energy into biologically-relevant cues, silicon (Si) is particularly advantageous due to its highly tunable electrical and optical properties, ease of fabrication into multiple forms, ability to absorb a broad range of light spectrum, and biocompatibility. This protocol describes a rational design principle for Si-based structures, general procedures for material synthesis and device fabrication, a universal method to evaluate material photo-responses, detailed illustrations of all instrumentation used, and demonstrations of optically-controlled non-genetic modulation of cellular calcium dynamics, neuronal excitability, neurotransmitter release from mouse brain slices, and brain activity in the mouse brain in vivo using the aforementioned Si materials. The entire procedure takes ~ 4-8 days in the hands of an experienced graduate student, depending on the specific biological targets. We anticipate that our

Real-world bioelectronics applications, including drug delivery systems, biosensing, and electrical modulation of tissues and organs, largely require biointerfaces at the macroscopic level. However, traditional macroscale bioelectronic electrodes usually exhibit invasive or power-inefficient architectures, inability to form uniform and subcellular interfaces, or faradaic reactions at electrode surfaces. Here, we develop a micelle-enabled self-assembly approach for a binder-free and carbon-based monolithic device, aimed at large-scale bioelectronic interfaces. The device incorporates a multiscale porous material architecture, an interdigitated microelectrode layout, and a supercapacitor-like performance. In cell training processes, we use the device to modulate the contraction rate of primary cardiomyocytes at the subcellular level to target frequency in vitro . We also achieve capacitive control of the electrophysiology in isolated hearts, retinal tissues, and sciatic nerves, as well as bioelectronic cardiac sensing. Our results support the exploration of device platforms already used in energy research to identify new opportunities in bioelectronics.

Conducting or semiconducting materials embedded in insulating polymeric substrates can be useful in biointerface applications; however, attainment of this composite configuration by direct chemical processes is challenging. Laser-assisted synthesis has evolved as a fast and inexpensive technique to prepare various materials, but its utility in the construction of biophysical tools or biomedical devices is less explored. Here, we use laser writing to convert portions of polydimethylsiloxane (PDMS) into nitrogen-doped cubic silicon carbide (3C-SiC). The dense 3C-SiC surface layer is connected to the PDMS matrix via a spongy graphite layer, facilitating electrochemical and photoelectrochemical activity. We demonstrate the fabrication of arbitrary two-dimensional (2D) SiC-based patterns in PDMS and freestanding 3D constructs. To establish the functionality of the laser-produced composite, we apply it as flexible electrodes for pacing isolated hearts and as photoelectrodes for local peroxide delivery to smooth muscle sheets.