Process for Absorbing Ultraviolet
Radiation Using Dispersed Melanin
"You take the blue pill and the story ends. You wake in your bed and you believe whatever you want to believe."
"You take the red pill and
you stay in Wonderland and I'll show you how deep the
rabbit-hole goes."
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United States Patent |
5,286,979 |
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Berliner , et al. |
February 15, 1994 |
http://164.195.100.11/netacgi/nph-Parser?Sect1=PTO1&Sect2=
HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l
=50&s1=5,286,979.WKU.&OS=PN/5,286,979&RS=PN/5,286,979
Abstract
This invention is a process for absorbing ultraviolet radiation in the atmosphere by dispersing melanin, its analogs, or derivatives into the atmosphere. By appropriate choice of melanin composition, size of melanin dispersoids, and their concentration, the melanin will absorb some quantity of ultraviolet radiation and thereby lessen its overall effect on the critters who would normally absorb such radiation.
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Inventors: |
Berliner; David L. (380 Selby La., Atherton, CA 94027); Leong; Helen (146 Atherton Ave., Atherton, CA 94027) |
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Appl. No.: |
073284 |
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Filed: |
June 7, 1993 |
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Current U.S. Class: |
250/515.1; 250/505.1; 359/358; 359/361 |
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Intern'l Class: |
G21K 003/00 |
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Field of Search: |
250/515.1,505.1 359/358,361 |
References Cited [Referenced By]
U.S. Patent Documents
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Dec., 1930 |
Oglesby et al. |
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Feb., 1962 |
Vonnegut |
239/2. |
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Apr., 1963 |
Hamilton et al. |
23/4. |
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Mar., 1964 |
Lohse |
239/14. |
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Feb., 1969 |
Jones |
239/2. |
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Jan., 1971 |
Crabtree et al. |
221/90. |
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Sep., 1971 |
Kooser |
239/2. |
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Sep., 1971 |
Kooser |
239/2. |
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Apr., 1974 |
Kuhne et al. |
239/2. |
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Jul., 1991 |
Gallas |
523/106. |
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Nov., 1983 |
Yates et al. |
239/171. |
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Aug., 1987 |
Eastlund |
361/231. |
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Oct., 1987 |
Gallas |
523/106. |
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Feb., 1989 |
Leong et al. |
424/487. |
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Aug., 1989 |
Leong et al. |
424/487. |
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Aug., 1990 |
Picot |
239/171. |
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Oct., 1990 |
Grollier |
8/423. |
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Mar., 1991 |
Chang et al. |
250/505. |
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Sep., 1991 |
Gallas |
359/361. |
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Other References
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Primary Examiner: Berman; Jack I.
Attorney, Agent or Firm: Morrison & Foerster
Parent Case Text
This application is a continuation of application Ser. No. 7/878,716,
filed May 4, 1992, now abandoned.
Claims
We claim as our invention:
1. A method for absorbing ultraviolet radiation in the atmosphere
comprising the step of introducing a dispersed composition comprising
melanins into the path of the ultraviolet radiation.
2. The method of claim 1 where the dispersed composition comprises
neat melanins.
3. The method of claim 1 where the dispersed composition comprises
melanin solution.
4. The method of claim 1 where the dispersed composition comprises a
melanin suspension.
5. The method of claim 1 where the dispersed composition comprises
particles containing melanin.
6. The method of claim 5 where the dispersed composition comprises a
polymeric particle comprising melanin.
7. The method of claim 1 where the dispersed composition comprises a
particle size of 0.5-100 microns.
8. The method of claim 6 where the polymeric particles are polymeric
beads having an average diameter between about 0.5 microns to 50
microns.
9. The method of claim 8 where the polymeric beads have an average
diameter in the range of 0.5 microns to 10 microns.
10. The method of claim 6 where the polymeric particles contain
melanin-comprised methylmethacrylate ethyleneglycol dimethacrylate
copolymer.
11. The method of claim 1 where the melanin is produced from melanin
precursors selected from the group of L-dopa, tyrosine, tryptophan,
and cysteine.
12. The method of claim 11 where the melanin precursor is L-dopa.
13. The method of claim 1 where the ultraviolet radiation has a
wavelength of 250-400 nanometers.
14. The method of claim 13 where the wavelength of the ultraviolet
radiation is 320-400 nanometers.
Description
FIELD OF THE INVENTION
This invention is a process for absorbing ultraviolet radiation in the
atmosphere by dispersing melanins, their analogs, or derivatives into
the atmosphere. By appropriate choice of melanin composition, size of
melanin dispersoids, and their concentration, the melanins will absorb
some quantity of ultraviolet radiation and thereby lessen its overall
effect on the inhabitants on the Earth's surface who would normally
encounter such radiation.
BACKGROUND OF THE INVENTION
This invention is a process for the introduction of melanins, neat,
solvated, suspended, encapsulated, or otherwise introduced as a fine
dispersion of melanin containing compositions to act as absorbers of
ultraviolet radiation. Depending upon melanin chosen and the method of
introducing it into the atmosphere, the melanin will absorb variously
UVA, UVB, or UVC ultraviolet radiation.
Ozone is a form of oxygen found in trace quantities throughout the
atmosphere; the highest concentrations are located in a layer of the
lower stratosphere found between the altitudes of 45,000 feet and
90,000 feet. Ozone found in the high atmosphere is typically produced
by the dissociation of molecular oxygen and at the lower atmosphere or
surface is produced by the dissociation of nitrogen oxides. The energy
for such dissociation is supplied by solar ultraviolet radiation.
At the earth's surface, ozone is a pollutant which can be harmful to
the respiratory system, hastens oxidation of paints, tires, and
whatever else may be found in its path. Ozone also plays an important
part in the formation of photochemical smog. In the upper atmosphere,
the trace amount of ozone absorbs much of the ultraviolet radiation
having a wavelength between 240 and 320 nanometers. This radiation is
lethal to such organisms as algae and bacteria and damages the surface
cells of higher plants and animals. It is responsible for the sunburn
of human skin and otherwise damages the DNA material of those cells.
High skin cancer incidence is also observed where the surface
intensities of ultraviolet light having a wavelength of 290 and 320
nanometers are found. These ultraviolet wavelengths are not completely
absorbed by the ozone layer.
Although the ozone layer in the upper atmosphere has been studies
since the early 1950s, the thinning of this protective layer was not
considered serious until a sudden decrease in the thickness in the
layer by 3% was discovered in the 1970s. There has been concern that
supersonic aircraft designed to fly in the lower stratosphere (such as
the Concorde) produce NO.sub.x in their engines by the thermal
decomposition and recombination of the nitrogen and oxygen in the air.
Initial computations suggested that the presence of this NO.sub.x
would result in significant depletion of stratospheric ozone. However,
later chemical studies have determined that supersonic aircraft have a
very much smaller effect on stratospheric ozone than originally
thought.
An additional concern has been voiced that the use of various Freons,
in particular CFCl.sub.3 and CF.sub.2 Cl.sub.2, cause depletion of
ozone through their decomposition (through contact with ultraviolet
light) and dissociation into lower chlorofluorocarbons and
monochlorine. The chlorine singlet reacts with the ozone to produce
oxygen. Freon chlorofluorocarbons are in the process of being phased
out but are currently used as refrigerants, as blowing or foaming
agents for plastic foams, and as aerosol can propellants. Some
computational chemical models predict that chlorofluoromethanes are
responsible for between 1% and 7% decrease in stratospheric ozone
concentration during the next few years.
Other causes may produce substantial effects in ozone production or
destruction; increases in CO.sub.2 due to combustion of fossil fuels
may lead to a cooling of the stratosphere and thus a decrease in the
rate of ozone destruction. But whatever the cause, significant
downward changes in the concentration of ozone in that layer will
increase the incidence of various ultraviolet light wavelengths at the
Earth's surface.
This invention is a method for at least a partial alleviation of some
of the consequences of that ozone layer depletion.
The use of melanin to protect human skin is known. Particularly, U.S.
Pat. Nos. 4,806,360 and 4,855,144, to Leong et al., show variously
melanin-containing compositions made of small polymeric particles and
methods of producing the particles. The resulting compositions may be
used as sunscreens in a variety of products such as sunscreen products
per se or as a component of cosmetic compositions.
U.S. Pat. No. 4,961,754 to Grollier, shows a powder containing very
small, inert, inorganic particles having on their surface melanin
pigments resulting from the oxidation of an indole dye of a specific
formula.
Other uses for melanin are in protecting human eyes from ultraviolet
radiation. For instance, U.S. Pat. Nos. 4,698,374; 5,036,115; and
5,047,447 all to Gallas, show a variety of devices, primarily optical
devices such as sun glasses using melanin incorporated in a layer of
the lens or device.
None of these disclosures suggests the use of finely dispersed melanin
in the atmosphere to protect those beneath the melanin dispersion or
cloud.
A variety of materials have been introduced into the atmosphere for an
equally wide variety of reasons. For instance, U.S. Pat. No. 3,608,810
and 3,608,820, both to Kooser, suggest the concept of dispensing
surfactants, salts, water-soluble poly-electrolytes, or mixtures
thereof to disperse fogs or to cause rain. Similarly, U.S. Pat. No.
3,802,624 to Kuhne et al., suggests the use of a combination of sugar
alcohols, saccharides, and polyvinyl alcohol in combination with low
melting point alkane-diols, triols, or polyols. The mixture is sprayed
into fog or clouds in a finely-dispersed form to either coalesce fog
or dispel clouds.
A classic silver iodide cloud seeding generator is shown in U.S. Pat.
No. 3,126,155 to Lohse. The device operates by using a method similar
to that found in a carburetor. A fluid under pressure is introduced
into a venturi. The air flowing through the venturi is accelerated and
disperses the silver iodide-containing solution into small droplets.
In Cicerone et al., "Reduced Ozone Depletions in a Model with
Hydrocarbon Injections", Science 254, pp.1191-1194 (1991), the concept
of introducing hydrocarbons into the upper atmosphere is found. This
is said to be a method for removing active chlorine from the
atmosphere. Chlorine singlets are believed to result in reaction of
ozone to form oxygen.
In Chang et al., U.S. Pat. No. 5,003,186, is described a process for
introducing Welsbach materials and metal oxides which have high
emissivities (and hence low reflectivities) into the atmosphere. Such
particles would absorb long wavelength energy and radiate it into
space.
Another venturi passage used for atmospheric seeding is shown in U.S.
Pat. No. 3,429,507 to Jones. Other known methods for dispersing
materials into the atmosphere include those shown in U.S. Pat. No.
4,412,654 to Yates et al., and 4,948,050 to Picot. The Yates patent
shows an airfoil-shaped body which has an open slot at the trailing
edge. Located within the interior of the airfoil is a distributor
having a series of small orifices which spray droplets toward the
trailing edge of the airfoil with its open slot. As the dispersed
liquid leaves the slot it is even further comminuted into much smaller
droplets.
The Picot patent shows a rotary liquid spray atomizer for aerial
spraying. The atomizer is driven by a variable speed motor which may
be driven by a variable speed AC generator.
None of the methods or devices suggested for dispersing materials into
the atmosphere suggests dispersing melanin for any purpose.
SUMMARY OF THE INVENTION
This invention is to a process for dispersing melanins incorporated
into microsize microspheres into the atmosphere at a level below the
ozone layer to absorb UV rays, particularly those having a wavelength
of 250-400 nanometers and more particularly those at 320-400
nanometers, coming through the ozone layer before they reach the
Earth's surface.
MELANINS
Melanins are a major class of broad-spectrum ultraviolet-absorbing
organic polymers found naturally in the human epidermis. For the
purposes of this invention they are defined and classified as in the
work Melanins by R.A. Nicolaus, 1968 (Paris, France). Melanins are
typically formed in the epidermis by the enzymatic conversion of
L-tyrosine into L-3,4-dihydroxyphenyl alanine, commonly referred to as
L-dopa. The L-dopa is then further converted into melanin by known
biologic pathways. The primary class of melanins produced in the human
epidermis is eumelanins. Members of this class are characterized by a
black-brown color which is derived from tyrosine. Pheomelanins are the
second class of melanins, characterized by reddish-brown color and
containing cysteine-derived units in addition to tyrosine-derived
units.
A third group of melanins, allomelanins (the word itself meaning
"other melanins"), are formed from nitrogen-free precursors, primarily
catechol, and 1,8-dihydroxynaphthalenes. Quinones are the usual
intermediates in allomelanin synthesis.
Melanins particularly suitable for use in the process of this
invention include any of the wide variety of black-brown and
reddish-brown polymers of indole 5,6-quinone and 5,6-dihydroxyindole
to carboxylic acid which occur naturally in the skin, hair, retina and
elsewhere in humans, as well as in a variety of other organisms. In
particular, eumelanins, which are black-brown polymers composed mainly
of tyrosine-derived units and a few pheomelanins, which are composed
of cysteine-derived units in addition to tyrosine-derived units are
each suitable. Melanin precursors may include but are not limited to
tyrosine, L-dopa, D-dopa, catechol, 5-hydroxyindole, tyramine,
dopamine, m-aminophenol, o-aminophenol, p-aminophenol,
4-aminocatechol, 2-hydroxyl-1,4-naphthaquinone, 4-metholcatechol,
3,4-dihydroxynaphthalene, gallic acid, resorcinol, 2-chloroaniline, p-chloroanisole,
2-amino-p-cresol, 4,5-dihydroxynaphthalene, 2,7-disulfonic acid,
o-cresol, m-cresol, p-cresol, and other related substances which are
capable of being oxidized to tan, brown or black compounds capable of
absorbing ultraviolet radiation. Combinations of precursors are also
suitable.
The melanins may be dispersed in pure form. However, several melanins
are somewhat viscous and hard to handle. If used without a solid
carrier, they are preferably dissolved in a suitable aqueous solvent
solution. They may also be suspended in a suitable liquid.
Since the preferred size of the melanin-containing particles
introduced into the atmosphere is between 0.5 and 100 microns,
preferably 0.5 to 50 microns and most preferably from 0.5 to 10
microns, the melanins may be incorporated in a solid carrier, either
resin-type or of a polymeric base. Processes for producing suitable
polymeric particles including melanin compositions are shown in U.S.
Pat. Nos. 4,806,360 and 4,855,140, to Leong et al., discussed above,
the entirety of which are incorporated by notice.
The 4,806,360 patent discloses a process for producing polymer beads
having average diameters from about 5 to about 100 microns. The
cross-linked polymer beads are produced either from polyethylenically
saturated monomers, i.e., those having at least two sites of
saturation, or from monoethylenically saturated monomers in the
presence of one or more polyethylenically unsaturated monomers. In the
latter case, the percentage of cross-linking is controlled by
balancing the relative amounts of monoethylenically unsaturated
monomer and polyethylenically unsaturated monomer. Though a variety of
polyolefinic polymer beads are suitable for encapsulating the melanins,
a particularly desirable polymer bead is formed by the
copolymerization of methyl methacrylate and ethyleneglycol dimethyl
methacrylate.
The 4,85,144 patent discloses the use of polymeric particles which
have rigid structures having a substantially non-collapsible pore
structure. The particles made according to this invention are
especially desirable in that the beads are very easy to handle and may
be dispensed and dispersed into the atmosphere with great ease. The
most desirable polymer bead is produced from copolymerization of
methyl methacrylate and ethylene glycol methyl methacrylate as was the
4,806,360 patent particle. Both 4,806,360 and 4,855,144 patents teach
processes for including the melanin into the polymeric beads.
Other appropriate physical forms for the melanin particles include
encapsulated melanins and vesicles or liposome-type particles. Methods
of producing these particles are well-known.
PROCESS
The melanin, solution or suspension of melanins, or polymer supported
melanins are dispersed at an appropriate altitude, e.g., 35,000 to
45,000 feet, using known methods of introducing the melanin containing
moiety into the atmosphere. The concentration of melanin-containing
materials need not be high since they are ideally introduced merely to
counteract the thinning of the ozone layer in a particular area. The
method of introducing these materials is not especially critical so
long as they are dispersed in the size range in which they will remain
in the atmosphere for significant periods of time. As noted above, the
use of particles in the range of 0.5 to 100 microns will assure such
suspension. Methods for producing particles of that size are discussed
above and the processes for distributing the melanins, be they neat
liquid, solvated liquid, in a suspension, or supported in the
polymeric materials discussed above are known. The processes for
distributing any of these compositions are known and suitable ones
were discussed above in the Background of the Invention.
The invention has been described in some detail by way of illustration
for the purposes of understanding its scope. However, it should be
apparent that certain changes within the scope of the appended claims
and their equivalents will be within the breadth of the invention as
described.