Micropatterned Silk-Fibroin/Eumelanin Composite Films for Bioelectronic Applications

Abstract

There has been growing interest in the use of natural bionanomaterials and nanostructured systems for diverse biomedical applications. Such materials can confer unique functional properties as well as address concerns pertaining to sustainability in production. In this work, we propose the biofabrication of micropatterned silk fibroin/eumelanin composite thin films to be used in electroactive and bioactive applications in bioelectronics and biomedical engineering. Eumelanin is the most common form of melanin, naturally derived from the ink of cuttlefish, having antioxidant and electroactive properties. Another natural biomaterial, the protein silk fibroin, is modified with photoreactive chemical groups, which allows the formation of electroactive eumelanin thin films with different microstructures. The silk fibroin/eumelanin composites are fabricated to obtain thin films as well as electroactive microstructures using UV curing. Here, we report for the first time the preparation, characterization, and physical, electrochemical, and biological properties of these natural silk fibroin/eumelanin composite films. Higher concentrations of eumelanin incorporated into the films exhibit a higher charge storage capacity and good electroactivity even after 100 redox cycles. In addition, the microscale structure and the cellular activity of the fibroin/eumelanin films are assessed for understanding of the biological properties of the composite. The developed micropatterned fibroin/eumelanin films can be applied as natural electroactive substrates for bioapplications (e.g., bioelectronics, sensing, and theranostics) because of their biocompatible properties.

An Electrically Conductive Oleogel Paste for Edible Electronics

“…Melanin thin films and melanin nanoparticles-based composites exhibit a hybrid electronic and ionic conduction mechanism and were suggested as eatable electrodes. [37][38][39][40][41] Yet, edible hydrogels have ionic conductive properties that cannot sustain a constant electronic current in a circuit. Furthermore, the ionic conduction features depend on the environment because relying on hydration.…”

Quantitative Functionalization of the Tyrosine Residues in Silk Fibroin through an Amino‐Tyrosine Intermediate

“…[8] The only reactive amino acids present in greater than 1 mol% are serine (12 mol%), tyrosine (5.3 mol%), DOI: 10.1002/macp.202200119 and aspartic/glutamic acid (1.1 mol%), so these are the sites typically targeted for chemical modification to customize the protein for a desired application. [9] While serine residues are most abundant, the poor reactivity of alcohol groups in aqueous media require the use of organic or ionic liquid solvents, [10][11][12] highly basic [13] or strongly oxidizing conditions. [14] Carbodiimide-mediated reactions targeting the carboxylic acid residues have been more widely used as they can be carried out in mild, aqueous conditions.…”

Interfacial Self-Assembly of Silk Fibroin Polypeptides and α-NiCo(OH)2 Nanocrystals with Tunable Energy Storage Applications

“…Indeed, SF can be easily converted into several forms, such as films, fibers, hydrogels, and scaffolds. 2,3 Therefore, SF can be applied on a wide range of areas, including biomedical, 4 drug delivery, 5 optical devices, 6 and more recently in electronics. 7,8 Another exciting feature of SF and other polypeptides with a βsheet structure is the possibility of modulating the material's mechanical and electric properties by controlling its hierarchical structure at the mesoscale.…”

“…Among countless biological materials that possess this capacity, silk fibroin (SF) from silkworm Bombyx mori is extensively explored in the literature due to its remarkable characteristics, such as excellent biocompatibility, mechanical resistance, and facile processing. Indeed, SF can be easily converted into several forms, such as films, fibers, hydrogels, and scaffolds. , Therefore, SF can be applied on a wide range of areas, including biomedical, drug delivery, optical devices, and more recently in electronics. , Another exciting feature of SF and other polypeptides with a β-sheet structure is the possibility of modulating the material’s mechanical and electric properties by controlling its hierarchical structure at the mesoscale. , In that regard, the hierarchical structure of SF can be divided into four levels, from the nano- to the macroscopic scale. First, the secondary structure composed of β-sheet crystallites forms nanofibrils and amorphous regions of α-helix and random coil structures.…”