Sustainable Production and Characterization of Eumelanin from Organically Cultivated Mucuna ceniza Seeds: A High-Performance Biomaterial for Optoelectronic Applications

TL;DR

This paper describes a sustainable method to produce high-quality eumelanin from Mucuna ceniza seeds for use in optoelectronic devices.

Contribution

A novel sustainable biotechnological process for high-yield eumelanin production from organically cultivated Mucuna ceniza seeds.

Findings

Eumelanin production rate reached 1526.23 mg L−1 h−1 with complete L-DOPA conversion.

Spectroscopic analysis confirmed the eumelanin's authentic structure and composition.

The produced eumelanin has practical utility in optoelectronic applications.

Abstract

Natural melanins represent an emerging class of bio-based materials with exceptional properties for advanced technological applications. This study presents a comprehensive analytical characterization of eumelanin produced from organically cultivated Mucuna ceniza seeds through sustainable biotechnological processes. A high-quality L-DOPA extract containing 56% w/w L-DOPA was first obtained using green extraction protocols with organic acids, followed by lyophilization. Then, optimized stirred-tank bioreactor conditions achieved remarkable melanin production rates of 1526.23 ± 10.78 mg L−1 h−1 with complete L-DOPA conversion, yielding 9.5 g/L of purified eumelanin. Spectroscopic characterization using UV-visible, FTIR, Raman, and NMR spectroscopy confirmed the authentic eumelanin structure, characterized by a characteristic absorption at 225 nm, diagnostic FTIR bands, Raman signatures at 1380 and 1580 cm−1, and NMR peaks. The elemental composition (C: 48.04%, H: 6.14%, N: 11.85%, O: 33.94%) classified the pigment as eumelanin, with an inferred empirical formula of C48H74N10O25. This melanin has already demonstrated practical utility in optoelectronic applications. By harnessing the unique biocatalytic potential of organically grown Mucuna ceniza, this study validates a green, high-yield production platform for eumelanin, paving the way for its commercially viable application in advanced functional materials.

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