J. Biol. Macromol., 15 (1), 3-11 (2015)

Review
Utilization of Natural Polymers in Beauty Product Materials and Evaluation
Technology
Tomoyuki Kawasoe
Shiseido Research center
2-2-1, Hayabuchi Tsuzuki-ku, Yokohama, Kanagawa 224-8558 Japan
Received June 24, 2015; Accepted July 29, 2015
A variety of natural polymers such as biologically derived proteins, lipids, andfunctional polysaccharides are blended as materials for functionality and safety inbeauty products. Of these natural polymers, we developed the polysaccharide
curdlan (β-1, 3-glucan), which forms an irreversible gel through heating at a certain
temperature or higher, as a beauty product material that has a hairstyling functionof memorizing a hairstyle when heat from a dryer is applied. We also used a curdlan
gel obtained by heating and appropriately molding this curdlan as a substitute for
conductive adhesive paste that is generally used to secure electrodes for measuring
brain waves to the scalp. On the other hand, in the research and development ofbeauty products, efforts are also actively underway to develop a technique toobjectively evaluate the effectiveness and functionality of beauty products. We also
realized a simple, high precision method that uses keratin film fabricated from aprotein solution extracted from hair to detect initial hair degradation, which isordinarily difficult to measure with high precision due to variations such asindividual differences and damage history.
Key words: curdlan, β-1, 3-glucan, electrode, keratin film, initial hair degradation
Introduction
A variety of natural polymers are
blended as materials in beauty products
Corresponding
author:Tomoyuki
Kawasoe: +81-45-590-6038, E-mail:tomoyuki.kawasoe@to.shiseido.co.jp

including biologically derived proteins,
lipids, and functional polysaccharides. For
example, collagen and elastin, which are
the main components of skin, andhyaluronic
acid,
which
is
a

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Utilization of Natural Polymers in Beauty Productmucopolysaccharide present in joints areoften blended in skincare products forpurposes of skin protection and moistureretention. In addition, high molecularweightpolysaccharidessuchascarrageenan and xanthan gum, which arealso used as food additives, provide amoisture retention effect that retains
moisture in the skin and hair, and are also
blended as thickening agents to impart
thickness and viscosity to productformulations. In some cases, naturalpolymers are also used in techniques toobjectively evaluate the effectiveness,functionality, and safety of beauty
products.
For
example,athree-dimensionally cultured dermis
model fabricated using human skinfibroblast cells and collagen is used toevaluate the safety against cytotoxicity andother areas [1].
Of the various natural polymers used in
the research and development of beauty
products, in this paper, I introduce
development and applications of twonatural polymers in which I was involved.
Polysaccharide curdlan has a uniqueproperty of forming an irreversible gel
through heating at a certain temperature or
higher, and therefore it was developed as amaterial for beauty products that have ahair styling function. We also examined acurdlan gel obtained by heating andappropriately molding curdlan for using asa substitute of the conductive adhesive

paste that is generally used for securing
electrodes for measuring brain waves tothe scalp. Furthermore, we used a keratin
film fabricated from a keratin protein
solution extracted from hair to detect hairdegradation from everyday ultraviolet
light. This type of hair degradation isordinarily difficult to measure with a highprecision due to variations in individual
difference and damage history.
Curdlan as a Hairstyling Material [2]Curdlan, which is used as a food additive
such as gelling agent, stabilizer, andthickening agent, is a straight chain
β-1,3-glucan having a molecular weight ofabout 500,000 and β-1,3-linked glucose
residues (Fig.1). It is produced fromglucose in a culture medium using abacteriumofthemicroorganism

Fig. 1. Structures of curdlan
agrobacterium genus. The solubility of
curdlan in water is low in the neutral pH
range, and therefore an aqueous solutionof sodium hydroxide is added so that the
final concentration is 20 mM. After the
curdlan is uniformly dissolved under thealkaline condition, the solution is similarly
neutralized with a solution of hydrochloric
acid to fabricate a dispersed solution.

T. Kawasoe

When the curdlan dispersion solution is
exposed to a temperature of about 55°C, a
moisture retaining gel begins to form, andin the temperature range of 80°C or higher,
the gel exhibits temperature-dependent
strength. A low-set gel, which is formed
when the curdlan dispersion solution isheated to 55-65°C followed by cooling toambient temperature or lower, exhibits athermally-reversible property, while ahigh-set gel, which is formed when the
curdlan dispersion solution is heated to
80°C or higher, is stable with respect totemperature and exhibits an irreversible
property [3]. Figure 2 shows a 1% curdlan
dispersion solution and a curdlan gel
formed by heating at 90°C for 5 minutes.

Fig. 2. Ability for gelation of curdlan
A: 1% curdlan dispersion solution
B: curdlan gel formed by heating
The mechanism for curdlan gelation
through heating is presumed to be theformation of a triple helix structure by themolecular chain through the formation ofhydrogen bonds between the molecules.
Ineveryday
activities,
itisinconceivable that living organisms would
be exposed to temperatures of 80°C or
higher, but when hair is dried and styled
after being shampooed, it is heated to5temperatures of 80°C or higher using adryer. Therefore, it was expected that a
hairstyle will be immediately fixed
through the heat of the dryer by using
curdlan which promptly forms anirreversible gel through heating. Polymers
that are ordinarily blended in beauty
products for hair for providing a hairstyling function have often been
copolymers of vinyl pyrrolidone and vinyl
acetate, copolymers of methacrylic acidalkyl ester and acrylic acid alkyl ester, andother synthetic polymers. Each of thesesynthetic polymers provides a hard coating
after being dried, and therefore when used
as a beauty product for hair, they exhibit ahard setting force. On the other hand, aproblem with these polymers was that thehair becomes sticky when a coating isformed while the product is applied anddried, and the finished hair is hard andloses its natural texture. In contrast to theseconventional materials, a dried curdlan gel
film formed by heating at 80°C is flexible
and exhibits resistance against elongationstresses (Fig. 3). Moreover, a film formed

Fig. 3. Stress-strain curve of curdlan film●: curdlan film after heating■: curdlan film without heating◆: vinyl pyrrolidone / vinyl acetate

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Utilization of Natural Polymers in Beauty Productthrough heating is insoluble in water, andtherefore, an effect of maintaining ahairstyle under high humidity conditions
was also confirmed. Figure 4 shows thetest results [4] of evaluating curl holdstrength at a temperature of 30°C with
90% humidity both with and without
heating of the hair coated with curdlan.

Fig. 4. Curl setting retention of curdlan film●: curdlan film after heating■: curdlan film without heatingThis curdlan was actually blended in afoam type styling product and marketed asa product with a copy, “memorizing ahairstyle by dryer heat”, and became a
topic of conversation. While the productdoes have a disadvantage of not allowing
to be subject to a temperature of 55°C or
more in the manufacturing process at thefactory, it did successfully create a new
trend of sustaining a natural finish of hair.
Curdlan as a Material that Contacts the
Scalp for Brain Wave Measuring
Electrodes [5]The curdlan gel formed by applying

heat exhibits superior ultrasonic wave
characteristics and mechanical strength,
and therefore it have also been developed
as contact medium of high safety forprobes of ultrasonic diagnostic equipment[6]. Therefore, we focused on themoderate elasticity and electrolyteoriginated conductivity exhibited by the
curdlan gel obtained by heating a 5%
curdlan gel dispersion solution, andexamined use of the curdlan gel in place ofthe conductive adhesive paste that is used
to secure electrodes to the scalp whenmeasuring brain waves. Conventionally,
when brain waves are measured, anadhesive base called a paste is used tosecure the electrodes to the scalp (Fig. 5A),
but after the brain waves have beenmeasured, the paste must be washed off,
which is a nuisance. On the other hand, analternative method is known in which ahelmet is worn on the head to measurebrain waves without the use of the paste[7]. In this technique, a felt piece
impregnated with a saline solution or otherelectrolyte is used as the contact material
between the electrodes and the scalp, butwhen a helmet is worn for an extended
period of time, a headache attributable tothe hardness of the felt can occur, and thenormal saline solution impregnated in thefelt easily evaporates, resulting in adecrease in measurement precision.
Therefore, we examined use of the curdlan
gel in place of the felt by utilizing the

T. Kawasoe

7

wave measurements can be significantly
reduced. We were able to be involved inthis application research because we hadparticipated in the development of curdlan
as a hairstyling material.

Fig. 5. The illustration of electrode unit
for electroencephalography
A: conventional method using paste
B: alternative method without the useof paste
excellent moldability of the curdlan gel(Fig. 5B). As a result, we found that the
curdlan gel obtained by heating a 5％
curdlan dispersion solution at 80°C for 20
minutes had an elastic modulus of 7.8×105
Pa and an electrical resistivity of 3×104 Ω･m, no pain was generated by contacting
the gel with the scalp, and sufficient
conductivity for measuring brain waves
was obtained. By using curdlan as acontact material between the scalp andelectrodes, we found that the material“does not dry out even when used for an
extended period of time,” “pressure on thehead is minimal,” and the “contact surface
between the scalp and the electrodes isstable,” and thus burdens during brain

System for Evaluating Hair Damage
Using a Keratin Film
Keratin film is a sheet-shaped material(Fig. 6A) derived from hair protein andproduced by casting, to the bottom of aplastic dish. This protein solution isderived in a high concentration from thehuman hairs of numerous people using a
reducing agent solution characterized by
thiourea [8]. Like hair, the keratin film isconfigured by keratin and keratin related
proteins, and a fibrous structureaccompanied by a granular structure isFig. 6. Morphological observation of
keratin film
A: photography, B: SEM image
confirmed through an observation with ascanning electron microscope (Fig. 6B).
Because the film exhibiting the same
properties can be produced in a large
quantity, it was expected that slight hairdegradation due to exposure to daily
ultraviolet light could be stably measured

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Utilization of Natural Polymers in Beauty Productwith a high precision. Until now, detecting
this slight hair degradation was difficult
due to individual differences in hair and tovariations in the damage history.
Hair is a biological sample of which
physical properties can be easily measured,and it is suited for researches because it
can be easily sampled and can withstandstorages for a long period. Measurementsof the tensile strength of a sampled hair in
its axial direction are generally used todetect hair degradation, and hairdegradation due to hair coloring, perms,
and long-term continuous exposure toultraviolet radiation can be quantitatively
determined accordingly [9, 10]. However,hair degradation caused by sunlight
exposure through everyday activities
without a decrease in tensile strength wasdifficult to be detected using this technique.
In a prior research, we found that hairproteins are non-specifically carbonylated
in proportion to exposure time to daily
ultraviolet light, and that this phenomenon
can be quantitatively determined by using
a fluorescent reagent (fluorescein-5thio-semicarbazide, 5-FTSC) that bonds
specifically to carbonyl groups [11].
However, as a trade-off for thehigh-precisions measurement technique,variations in data due to individual
differences in hair and the damage history
are emphasized, and thus the problems ofindividual differences in hair, which is thetest substance, and the damage history

must be dealt with while maintaining thecharacteristics of hair such as the
production of carbonylated protein.
Therefore, we examined the applicationof a keratin film in place of hair samples todetect hair degradation from light
exposure during everyday activities. We
used a keratin film exposed to artificial
sunlight for a certain amount of time todetect the carbonylated proteins generated
in the film using 5-FTSC, and as a result,
we confirmed the increase in the
carbonylated proteins in proportion to theFig. 7. Fluorescence images of the keratin
films reacting with 5-FTSC after artificial
sunlight irradiation
light exposure time (Fig. 7). This indicatesthat the keratin film also undergoes thesame oxidation as hair. Moreover, when
the film was exposed to light for 10
minutes or longer, the fluorescenceintensity increased significantly comparedto that of a keratin film not exposed tolight (Fig. 8), suggesting a highly sensitive
measurements were possible [12]. In
contrast to hair of which characteristics
easily vary due to individual differences,
the keratin film is effective at improving
testing precision and reproducibility

T. Kawasoe

because the film shows a similar reaction
to hair, which produces carbonylated

9

Furthermore, the surface structure ofkeratin film is sensitive to oxidationreduction reactions, and its finemorphology changes to smooth whensubjected to a reducing agent treatment.
Then when an oxidation treatment isperformed, a fibrous structure which isaccompanied by a granular structure isrestored. This unique property of having

Fig. 8. Average of fluorescence intensity of
the keratin films reacting with 5-FTSC
after artificial sunlight irradiation
proteins, and the film with the same
properties can be produced in a large
quantity.
In addition to the light exposure test,
because the keratin film can reproduce thesame changes occurring to the hair protein
when subjected to bleaching, perm
applications, and the like with highsensitivity, it has been actively utilized todevelop materials to confirm changes due
to hair damages and minimize thedamages. With respect to the impact ofoxidation from bleach treatments, evenwith a slight oxidation condition, which
could not be confirmed with hair samples,
cysteic acid could be detected with FT-IR[13]. Moreover, in applications in perm
agent treatments, we confirmed that
proteins that are eluted during a reducing
agent treatment are keratin-related proteins,which suggests that they are indicators ofdamage due to perm agents [14].

Fig. 9. Morphological observation of the hairkeratin films treated with permanent wave
solutions
A: photography, B: SEM image

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Utilization of Natural Polymers in Beauty Productthe reversible structural change wasconfirmed (Fig. 9).
Recently, use of a keratin film toevaluate the frictional properties ofshampoo and conditioner has beenreported [15] Treatment effects ofshampoo and conditioner can be
confirmed by measuring a keratin film, towhich these products were applied, using afriction sensitivity tester (from Kato Tech
Co., Ltd.) Because absorption of siliconcompounds, similar to that of hair, can be
confirmed, the keratin film was effective
for examining conditioner formulations
and the tactile sensation of the shampoo.
While keratin film does not have a cuticle
structure, because an increase in cysteic
acid and carbonyl groups resulting fromdamage can be confirmed, keratin film isalso thought to be effective for examining
the adsorption of components that can
improve tactile sensation on damaged
hairs.
Conclusion
The research and development ofbeauty products consists of elemental
technologies from numerous different
academic fields. When the characteristics
of beauty products are considered, it
becomes necessary to integrate thesedifferent technologies to find effectivenessin the three areas: functionality, safety, andsensitivity. In utilization of naturalpolymers in beauty product materials andevaluation technologies, the polymers
should be considered not from cost or
quality stability perspective, but bepositioned as alternatives to biologicalsamples, which have unique functionalitythat cannot be realized with synthetic
polymers. We demonstrated in this paper;a new functionality of curdlan wasdeveloped by utilizing its unique property;
and a keratin film was applied in atechnique to objectively evaluate
functionality and sensitivity. Moreover,because curdlan that was developed as amaterial for beauty products can also be
used as the contact material of electrodes
for the scalp to measure brain waves, we
expect that the keratin film can be widelyused in a variety of fields in the future.
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Communicated by Mihara Hisaaki