Melanins are a ubiquitous class of functional biomacromolecules found throughout nature in many roles including photo-protection, pigmentation and free radical scavenging. Due to their hybrid ion-electron solid-state electrical conduction properties, synthetic melanins based upon poly-indolequinones have also emerged as a classic model for bioinspired optoelectronic materials in applications such as bioelectronics. It has been known for several years that the solid-state DC and AC electrical conductivity in melanin thin films and pellets is strongly modulated by adsorbed water which takes part in a local radical reaction known as the comproportionation equilibrium. The mechanism is likely generic in conducting biomaterials (and indeed certain synthetic polymers) which have ionisable groups with local pKas around neutrality. In addition, melanins show pronounced solid-state photoconductivity which is also linked to this mechanism – and in particular to the conversion between two distinct spin populations, a carbon centred radical and photo-induced semiquinone.<br/>In my talk I will describe the photo-physics and spin-related fundamentals of these processes and in particular discuss new work showing how the comproportionation equilibrium can be manipulated to modulate bulk electrical properties. This leads to the exciting possibility of melanin-based bioelectronic devices such as a new all-solid-state transistor capable of high fidelity transduction between electrons and protons.

Photophysical and spin properties of melanins: Towards bioelectronic interfaces

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.