203 Polyphenol-metal Complex With Dopamine
HAIR DYEING PRE-TREATMENT
Before hair coloring, commercial human white hair and human natural white hair samples
were soaked in commercial shampoo (Ruwei Cosmetics Co., RNW, Product Standard No.
GB/T 29679) and repeatedly rubbed for 5 minutes. After washing, the hair was rinsed with
water and left to dry naturally in the air.
POLYPHENOL SCREENING
0.035 g GA, TA, PA, PG, CH, RE, CA, and SA were dissolved in 30 mm and 5 mL Tris
solution to prepare polyphenol solution 0.035 g DA was dissolved in 30 mm, 5 mL Tris-
HCl solution to prepare DA solution 0.035 g DA was dissolved in 30 mm and 5 mL Tris
solution to prepare PDA solution. The above solution was mixed with 10 parts of ferrous
chloride tetrahydrate dissolved in 3 mL of water according to the ratio of polyphenols to
Fe(II) at a ratio of 1:5, and mixed with vortex vibration for 10 seconds, and then centrifuged
(2,000 g, 5 min) to remove the precipitate to prepare the polyphenol-Fe (II) solution. We
took 10 parts of 0.2 g commercial white hair and immersed it in polyphenol-Fe(II) solution
for 30 minutes. We then removed it and washed the residual solution with clean water and
dried it with absorbent paper. Next the samples were allowed to dry naturally. Finally, we
measured the color difference after natural drying, and screened the polyphenols with the
best dyeing effect.
In addition, we assisted in the screening of the best polyphenol materials by determining
the chelation rate of polyphenols and Fe(II). The first is to establish a standard curve. We
added 1 mL and 1 mg/mL of ferrous chloride tetrahydrate solutions, 0.1 mL hydroxylamine
hydrochloride (10%), 0.2 mL o-diazepine (0.15%), and 0.5 mL sodium acetate (1 mol/mL).
Water was added to 10 mL, and 0.1 mg/mL Fe(II) solution was prepared. The above 0.1 mg/
mL Fe(II) solution was prepared into Fe(II) standard solutions of 0.025 mg/mL, 0.05 mg/
mL, 0.07 mg/mL, 0.085 mg/mL, and 0.095 mg/mL, respectively. The absorbance of each
group of solutions was measured at a wavelength of 510 nm, and the concentration C (mg/
mL) of Fe(II) standard solution was used as the abscissa, and absorbance A (nm) was used
as the ordinate to establish a standard curve. We took 1 mL of the above polyphenol-Fe(II)
solution, added absolute ethanol to 10 mL, sonicated for 15 minutes, centrifuged (2,000 g,
5 min), and took two parts of 1 mL supernatant, numbers 1 and 2, respectively. Tube
1 added 0.1 mL of hydroxylamine hydrochloride, 0.2 mL of phenanthrene hydrochloride,
0.5 mL of sodium acetate, and added water to set the volume to 10 mL Tube 2 added
0.1 mL of hydroxylamine hydrochloride, 0.5 mL of sodium acetate, and added water to set
the volume to 10 mL. The absorbance at 510 nm wavelength was determined separately,
and the chelation rate of polyphenol-Fe(II) was calculated.
ETHANOLAMINE CONDITIONS WERE SCREENED WITH GA-FE(II) CONDITIONS
A single-factor test was employed to investigate the pH value, concentration, and
ethanolamine immersion time of natural gray hair after various ethanolamine soaking
durations. Subsequently, the hair was stained in a GA-Fe(II) solution with a molar ratio
of GA to Fe(II) of 1:5 and a pH range of 4–5 for 2 hours. After post-processing, the color
difference value was measured under different ethanolamine conditions to identify the
optimal conditions for staining natural gray hair with ethanol.

204 JOURNAL OF COSMETIC SCIENCE
Natural gray hair was treated in 20% ethanolamine solution at pH 9–10 for 1 hour, followed
by removal of excess liquid using absorbent paper and allowing it to dry naturally. In this
study, the single-factor test was conducted to access the dyeing time of GA-Fe(II)-stained
natural white hair, the pH of GA-Fe(II) solution, and the molar ratio of GA-Fe(II) to Fe(II).
The optimal dyeing conditions for GA-Fe(II)-stained natural white hair were determined
by measuring the color difference value of stained white hair.
ETHANOLAMINE EMULSION FOR UNFOLDING NATURAL WHITE HAIR SCALES
First, 2 mL of ethanolamine was added to 8 mL of water and mixed, and the pH was adjusted
to 9.2–9.4. Then, 0.8 mL of glycerol, 0.4 mL of Tween-80, 0.2 g of sodium dodecyl sulfate,
0.1 g of sodium sulfite, 0.2 g of sodium benzoate, 2 mL of propylene glycol, and 2.3 mL of
water were added to the ethanolamine solution and mixed at 65°C for 15 minutes to obtain
the aqueous phase solution. Additionally, 2 mL of isopropanol and 2 mL of oleic acid were
heated and stirred at 65°C for 15 minutes to create the oil phase solution. The oil phase
was added to the aqueous phase solution while heating and stirring at 65°C for 10 minutes,
resulting in the formation of the oil-in-water ethanolamine emulsion. The emulsion was
allowed to cool to room temperature, and 0.2 g of natural white hair was immersed in the
emulsion for 1 hour. Subsequently, the emulsion was removed, and the residual solution on
the white hair was wiped off with absorbent paper to be set aside.
GA-FE(II)+DA HAIR DYE FOR DYEING NATURAL WHITE HAIR
0.035 g GA was dissolved in 30 mm of 5 mL Tris solution to obtain GA solution. Next,
0.2088 g of ferrous chloride tetrahydrate was dissolved in 3 mL of water to create the Fe(II)
solution (with a molar ratio of GA to Fe(II) at 1:5). The two solutions were mixed by vortex
vibration for 10 seconds. Then, 0.035 g of DA was dissolved in the mixture, and the pH
was adjusted to 5.0–5.2. Afterward, it was centrifuged (2,000 g for 5 minutes) to remove
the precipitate, resulting in the preparation of the GA-Fe(II)+DA solution.
To prepare the aqueous phase solution, 2 mL of propylene glycol, 0.4 mL of Tween-80,
0.2 g of sodium dodecyl sulfate, 0.1 g of sodium thiosulfate, 0.1 g of sodium sulfite, 0.1 g
of ascorbic acid, 0.2 g of sodium benzoate, 0.8 mL of glycerol, and 3.8 mL of water at 65°C
with heating and stirring for 15 minutes. The GA-Fe(II)+DA solution was then added
under the same conditions and further heated and stirred for 10 minutes.
The oil phase solution was prepared by mixing 2 mL of isopropanol and 2 mL of oleic acid
at 65°C with heating and stirring for 15 minutes. The oil phase was added in a fine stream
to the aqueous phase solution while heating and stirring at 65°C, and the mixture was
stirred for an additional for 10 minutes to obtain the oil-in-water emulsion. The emulsion
was cooled to room temperature to yield GA-Fe(II)+DA hair dye. The natural white hair,
unfolded by ethanolamine, was dipped into the hair dye for 2 hours. Then the residual
solution was washed off with water and dried with a hair dryer.
MEASUREMENTS OF COLOR PARAMETERS
Color parameters, including L* (luminance), a* (red/green coordinates), and b* (yellow/blue
coordinates), were obtained using a colorimeter (HP-2136, Shanghai HanPat Optoelectronics