Naturally Derived Melanin Nanoparticle Composites with High Electrical Conductivity and Biodegradability

Abstract

The development of electronic devices from naturally derived materials is of enormous scientific interest. Melanin, a dark protective pigment ubiquitous in living creatures, may be particularly valuable because of its ability to conduct charges both electronically and ionically. However, device applications are severely hindered by its relatively poor electrical properties. Here, the facile preparation of conductive melanin composites is reported in which melanin nanoparticles (MNPs), directly extracted from squid inks, form electrically continuous junctions by tight clustering in a poly(vinyl alcohol) (PVA) matrix. Prepared as freestanding films and patterned microstructures by a series of precipitation, dry casting, and post‐thermal annealing steps, the percolated composites show electrical conductivities as high as 1.17 ± 0.13 S cm−1 at room temperature, which is the best performance yet obtained with biologically‐derived nanoparticles. Furthermore, the biodegradability of the MNP/PVA composites is confirmed through appetitive ingestion by Zophobas morios larvae (superworms). This discovery for preparing versatile biocomposites suggests new opportunities in functional material selections for the emerging applications of implantable, edible, green bioelectronics.

Personalized Healthcare for Dementia

“…However, several issues, including long-term biocompatibility and safety issues with new drugs, remain challenges. To overcome these challenges, various approaches such as bio-derived electronic materials [ 80 , 81 ], electronic material [ 82 , 83 ], biohybrid systems [ 84 ], and biomimetic designs [ 85 ] have been proposed; however, more breakthroughs are still needed in material development for the widespread use of advanced sensors.…”

Probing the heterogeneous structure of eumelanin using ultrafast vibrational fingerprinting

“…Very recently, eumelanin-based materials have attracted widespread interest for solar energy conversion, electrochemical energy storage, and biomedical applications 4 – 6 . Because it absorbs broadly from the UV to near-infrared spectrum and because of its ability to conduct 7 , 8 and store charge, eumelanin is receiving considerable attention for applications including photocatalysis, battery electrodes, and supercapacitors 5 .…”

Advances in applying C–H functionalization and naturally sourced building blocks in organic semiconductor synthesis

“…Shim et al achieved electrical conductivities as high as 1.17 AE 0.13 S cm À1 by preparing a composite with melanin nanoparticles in a poly(vinyl alcohol) matrix. 165 This was a huge improvement in contrast to the original conductivity of significantly hydrated melanin which was reported to be 10 À3 S cm À1 . 166 Meredith et al reported a novel metal (copper(II) ions) doping strategy to enhance and control the proton conductivity of melanin for OECT application.…”