The melanins are an important class of natural biopolymers of diverse nature and chemical composition that arise biogenetically from the oxidation of phenolic metabolites. In man and mammals two main groups of melanins account for the variety of cutaneous pigmentation, the black insoluble eumelanins and the reddish-brown, sulphur-containing pheomelanins. Both eumelanins and pheomelanins are produced within melanocytes by a biosynthetic pathway involving the tyrosinase-catalyzed oxidation of tyrosine. Besides the skin, hair and eyes, melanin pigments are also found in the in the inner ear and in the substantia nigra of the brain, though the latter appear to arise from catecholamine oxidation. Other pigments commonly referred to as melanins include cephalopod ink, the most convenient melanin source in Nature and the black pigments found in higher plants, fungi and bacteria.

The black variants eumelanins display a peculiar set of physico-chemical properties which include:
a) a broad-band monotonic absorption and the ability to absorb photons from the ultraviolet and visible parts of the solar spectrum, accounting for their black appearance;
b) more than 99.9% non-radiative dissipation of absorbed photons;
c) electrical conductivity and photoconductivity, as well as threshold and memory switching;
d) antioxidant and redox behaviour;
e) a persistent free radical character as indicated by the electron paramagnetic resonance (EPR) signal;
f) strong metal binding and drug binding properties.

Melanins and their pathways represent a unique source of bioavailable and biocompatible soft materials, metabolites and processes of considerable potential for health care and technological applications

A selection of recent patents on melanins

Applications of eumelanin-like synthetic polymers are increasingly found in patents. Melanin-type pigments have been added as active ingredients in cosmetics and functional sunscreen formulations. Black eumelanin-like pigments have also been incorporated as screening materials into optical plastics for the preparation of sunglass lenses. Melanin-related compounds may also be useful in a variety of medical applications.

Biodegradable electronic devices for biosensor used in environmental monitoring or biomedical in vivo device. Borenstein, Jeffrey T.; Bettinger, Chris; Langer, Robert; Kaplan, David. (Charles Stark Draper Laboratory, Inc., USA; Trustees of Tufts College; Massachusetts Institute of Technology). PCT Int. Appl. (2008)

Biologically photoconductive organic dispersion. Parker, Reginald; Edwards, Jesse. (USA). U.S. Pat. Appl. Publ. (2008)

Open air manufacturing process for producing biologically optimized photovoltaic cells. Parker, Reginald; O'Neal, Ray; Edwards, Jesse. (USA). U.S. Pat. Appl. Publ. (2008)

A laminated body for optical purposes that includes a melanin -containing layer and an optical product which includes the laminate. Kawai, Ryozo; Namiki, Masahiko; Aoki, Yoshiyuki; Miura, Mitsuo. (MGC Filsheet Co., Ltd., Japan). Eur. Pat. Appl. (2007)

Melanin nanoshells for protection against radiation and electronic pulses. Dadachova, Ekaterina; Casadevall, Arturo. (Albert Einstein College of Medicine of Yeshiva University, USA). U.S. Pat. Appl. Publ. (2007)

Polarizing plate with melanin. Sugimura, Hideyo; Qin, Xuzhi; Boulineau, Michael S. (Vision-Ease Lens, USA; Insight Equity A.P.X., L.P.). U.S. Pat. Appl. Publ. (2006)

Design of photovoltaic cells containing melanin and melanin -like biomolecules.
Meredith, Paul. (The University of Queensland, Australia). PCT Int. Appl. (2003)

Melanin polyvinyl alcohol plastic laminates for optical applications. Gallas, James; Eisner, Melvin. (USA). U.S. Pat. Appl. Publ. (2003)

Melanin cosmetic compositions. Cheetham, Peter Samuel James; Taylor, Charles Jefferson. (Zylepsis Limited, UK). PCT Int. Appl. (2002)

Last update: September 11, 2011

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