MELANINS
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)
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