Biomimetics Through Bioconjugation of 16- Methylheptadecanoic Acid to Damaged Hair for Hair Barrier Recovery

doi:10.21203/rs.3.rs-4234806/v1

Download PDF

Article

Biomimetics Through Bioconjugation of 16- Methylheptadecanoic Acid to Damaged Hair for Hair Barrier Recovery

https://doi.org/10.21203/rs.3.rs-4234806/v1

This work is licensed under a CC BY 4.0 License

Journal Publication

published 09 Nov, 2024

Read the published version in Scientific Reports →

You are reading this latest preprint version

The primary component of the lipid barrier on human hair, which is essential for defense against aging and environmental stresses, is 18-methyleicosanoic acid (18-MEA), which provides hydrophobic properties and protective benefits. Since 18-MEA cannot be regenerated once damaged, it is critical to develop technology that can permanently bind alternativematerials to hair. Once it was determined that 18-MEA was removed from the hair using X-ray photoelectron spectroscopy (XPS), pentaerythritol tetraisoosterate (PTIS) was hydrolyzed and observed via gas chromatography/mass spectrometry (GC/MS)to confirm that mimic 18-MEA, 16-methylheptadecanoic acid (16-MHA) wasobtained at pH 4 or lower. The 16-MHA was bioconjugated to damaged hair from which 18-MEA was removed via a carbodiimide reaction using polycarbodiimide. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed that 16-MHA remained on the surface of bioconjugated hair even after washing. Observation of the endothermic reaction of moisture in the hair using a differential scanning calorimeter (DSC) and evaluation of the moisture content confirmed that the hair bioconjugated with 16-MHA exhibited similar physical properties to virgin hair. This biomimetic approach has been demonstrated to restore both external structural integrity and internal moisture homeostasis.

Physical sciences/Chemistry/Chemical biology

Physical sciences/Chemistry/Physical chemistry

Biological sciences/Chemical biology/Biophysical chemistry

Biological sciences/Chemical biology/Lipids

18-MEA

hair surface

biomimic

pentaerythritol tetraisosterate

16-methylheptadecanoic acid

Human hair's lipid barrier, crucial for resilience against aging and environmental stressors, relies on 18-methyleicosanoic acid (18-MEA) for hydrophobicity and protective function. 18-methyleicosanoic acid (18-MEA) is key to hair health, as it gives the hair hydrophobicity, making it smooth and shiny. 18-MEA is a covalently bound lipid approximately 1.1 nm thick that is located in the top layer of each cuticle, including the outermost cuticle of the hair.^1,2 Lipid study estimated 60% protein and 36% 18-MEA in the top 3 nm of fiber. Computational modeling studies have shown that 18-MEA is an ideal material that exhibits the highest hydrophobicity on the hair surface compared to other eicosanoic acids.³

18-MEA can be damaged by chemical processes such as dyeing or perming, resulting in weakening hair from external factors.⁴ The amount of 18-MEA in hair strands naturally reduces by more than 10% each year,⁵ and the overall amount of 18-MEA has been observed to decrease from the age of 50.⁶ Although 18-MEA is not completely removed by dyeing,⁷ through observation under an atomic force microscope, the surface of 18-MEA hair partially damaged by dyeing was found to exhibit changes in flatness and an increase in friction.⁸ The interaction and arrangement of 18-MEA molecules also affect the adsorption of hair conditioning molecules.⁹ Since 18-MEA is related to dehydrogenase, it is also relevant from a pathological perspective, as studies have shown that it is not found in the hair of patients with maple syrup urine disease.^10,11 Therefore, 18-MEA is an important lipid in the human body, and its recovery is meaningful from a cosmetic and health perspective.

There have been many attempts to recreate the cuticle surface, which has changed from hydrophilic to hydrophobic as a result of damage to 18-MEA. Polymers, oils, waxes, hydrolyzed amino acids, and cationic molecules used as conditioners provide hydrophobicity by lubricating the surface of the hair.¹² However, imparting hydrophobicity using cosmetics has the disadvantage of adding unnecessary texture, such as the stickiness of raw materials.

18-MEA has the disadvantage of being difficult to obtain naturally. There have been attempts to induce hydrophobicity in healthy hair through the adsorption of substances with as similar physical properties or structure to 18-MEA as possible. For example, the thioesterase activity of palmitoyl protein has been found to increase the hydrophobicity of hair.¹³ There have also been attempts to synthesize 18-MEA through enzymatic hydrolysis or to synthesize ceramide and make it adsorb to hair.^14,15 The use of cationic surfactants allows the conjugate of 18-MEA and stearoxypropyldimethylamine to adhere to human hair, enhancing hair conditioning and rejuvenating the hair’s damaged surface.^7,16 Meanwhile, other researchers attempted to attach various substances mimicking 18-MEA to hair and 19-methyleicosanoic acid (19-MEA).¹⁷ Using electrostatic and polar forces between proteins, it was possible to increase the hydrophobicity of the lipophilic layer by adsorbing protein lipids to the sulfonate of the 18-MEA layer.¹⁸

Many of these studies provided the damaged hair with hydrophobicity, but the adsorbed substances were easily washed away. To increase durability after washing, we aimed to covalently bind mimic 18-MEA to the surface of the hair to grant it hydrophobicity. This study was conducted with the goal of easily obtaining and efficiently covalently combining mock 18-MEA, which is difficult to synthesize.

2.1. 18-MEA damaged hair

18-MEA on the hair surface was removed using a 0.1 M potassium T-butoxide/T-butanol solution. To quantitatively compare the degree of damage to hair 18-MEA, the hair surface was observed using X-ray photoelectron spectroscopy (XPS). Two sulfur S2p peaks were observed as shown in Fig. 1(a). The peaks from virgin hair observed at 163 eV and 167 eV can be assigned to the disulfide of S2p(II) and the sulfonate of S2p(IV).¹⁹ When the hair was left in a potassium T-butoxide/T-butanol solution for 1 minute and 5 minutes, the disulfide peak gradually disappeared over time. The area/electron of the atom of S2p(II) decreased to 1.66 (virgin), 0.48 (1 min), and 0 (5 min). The area/electrons of S2p(II) atoms are observed to be lower at the hair tips, where the most damage occurs, than at the roots.²⁰ Therefore, a decrease in the S2p(II) peak indicates impaired binding of disulfide components that make up the hair, including 18-MEA.

The cuticle surfaces of the hair was evaluated using atomic force microscopy (AFM), as shown in Fig. 1(b). AFM scans were performed on the same hair at different treatment times. Cuticle height was evaluated as normal at 200-400nm,¹ and it was confirmed that there was no change in hair cuticle structure before and after 18-MEA damage.

Lateral force, which measures the force exerted along the lateral axis as the cantilever scans, represents friction. Red color means the lateral force microscope (LFM) has larger friction values, with values increasing significantly at the cuticle edge. LFM values at the filled triangular mark positions were 3.1 V, 4.7 V, and 5.2 V for virgin, 1 and 5 min, respectively. As the time for treating the potassium T-butoxide/T-butanol solution increased, the friction of the cuticle surface increased. A decrease in LFM indicates that changes are occurring on the hair surface.

The concentrations of non-covalently bound lipids were determined from the hair using gas chromatography/mass spectrometry (GC/MS). A detailed description of the methods for extraction and chromatogram is included in Figure S1. Since 68.5% of total fatty acids are myristic acid (C14), palmitic acid (C16), and stearic acid (C18),¹ these lipids were used as representative lipids in Fig. 1(c). There was no statistically significant difference in hair lipid concentration before and after 5 minutes after immersing the hair in the solution. The concentration of hair lipids after incubation for 30 minutes decreased significantly. This supports that hair treated for 5 minutes had no effect on other lipids except 18-MEA.

The results in Fig. 1 show that 18-MEA on the surface of hair treated with a potassium T-butoxide/T-butanol solution for 5 minutes was sufficiently removed. Further experiment was conducted under the assumption that the internal lipids of the hair prepared was the same.

2.2. Obtaining 16-MHA from PTIS via hydrolysis

18-MEA and 16-methylheptadecanoic acid (16-MHA) are similar in that they contain carboxylic acids and are hydrophobic. If 16-MHA were bound to the outermost surface of the hair, it would be expected to have a similar arrangement and physical properties to 18-MEA. Pentaerythritol tetraisoosterate (PTIS), which is used as a moisturizer, viscosity modifier, and dispersant, contains four 16-MHA. The following experiment was conducted to obtain 16-MHA by hydrolyzing PTIS, which is already widely used in personal care products.

Figure 2 shows the GC/MS results of PTIS dissolved in isopropyl alcohol (IPA) and hydrolyzed at various pH conditions. In the GC spectrum, a peak for 16-MHA appeared at 30.2 min (Fig. 2(a)). Figure S2 shows the mass spectrum evaluated for 16-MHA at 30.2 min. The 30.2 min-peak was observed at pH 1.5 and pH 4 conditions as shown in Fig. 2(a). Addition of PTIS to ethanol resulted in aggregation due to transesterification. When PTIS was dissolved in t-butanol, no 16-MHA was produced, as shown in Figure S3. Instead, butyloctadecanoate was generated at 32.5 min. Since n-butanol is a linear chain, the highly reactive n-Butyl octadecanoate appeared to be generated between the linear chains.

Figure 2(b) shows the intensity of the 30.2 min peak evaluated at various pH conditions. The peak was not observed above pH 6, indicating that 16-MHA was hydrolyzed below pH 4. pH 1.5 is highly acidic and not suitable for use in personal care products. Therefore, pH 4 in IPA was set as a condition for hydrolyzing PTIS to obtain 16-MHA.

2.3. Bioconjugation of 16-MHA on damaged hair

The reaction of 16-MHA obtained from the results in Fig. 2 was performed by reacting with the primary amine of hair amino acid. The carbodiimide reaction produces urea as a by-product and binds 16-MHA to the hair as shown in Fig. 3. A reaction occurred in which carboxylic acid components and the primary amine in the hair were combined. 16-MHA obtained from PTIS undergoes a reaction with polycarbodiimide (PCI), resulting in the formation of primary amine and amide bonds within the hair structure. Structurally similar covalent bonds are formed compared to the disulfide bond present in 18-MEA from virgin hair.

After bioconjugation, to confirm whether 16-MHA actually remained in washed hair, the hair surface was analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Figure 4(a) shows a TOF-SIMS spectra for virgin hair, bioconjugated hair with 16-MHA and PCI, and hair with only 16-MHA applied without bioconjugation. The 18-MEA peak was expected to appear at m/z 341 (reverse triangle), but was not present in the results of this experiment. This is consistent with the disulfide peak reduction results in Fig. 1, indicating that 18-MEA was successfully removed.

The 16-MHA on the hair surface is detected as the negative molecular ion peak at m/z 312.3 (filled circle). A 16-MHA peak was observed in hair bioconjugated with 16-MHA. The 16-MHA peak did not appear in hair that had not bioconjugated to the damaged hair.

Figure 4(b) shows the TOF-SIMS images of 16-MHA for the hair samples. 16-MHA was detected uniformly in the bioconjugated hair, but in the hair with only 16-MHA applied, all of the 16-MHA was removed and was almost undetectable in the imaging analysis. This indicates that non-bioconjugated 16-MHA can be easily washed away.

When the hair surface is damaged, phenomena such as increased friction, increased breakage due to combing, and loss of shine occur. There is also a change in physical properties change to hydrophilicity, which is observed as a change in contact angle. A contact angle experiment was conducted to measure the change in hydrophobicity of hair when 16-MHA obtained from hydrolyzed PTIS was treated on the surface of the hair.

The best linear fit (line) with contact angle changing over time has been plotted in Fig. 5(a). The contact angle slope for the hair without bioconjugation decreased significantly from − 0.26 before washing to -1.89 after washing. On the other hand, for hair bioconjugated with 16-MHA, the slope before and after washing was − 0.43, showing no difference.

Figure 5(b) shows the contact angles at 15 seconds. The contact angle of virgin hair was obtained as 95.75° at 15 s. For hair without 18-MEA, the moment a water drop was placed on the hair, the droplet lost its shape, making it impossible to measure. The contact angle of the hair in which 16-MHA covalently bound to 18-MEA damaged hair was 90.19°, with no difference before and after washing.

When only 16-MHA was applied to 18-MEA damaged hair, the hair without bioconjugation showed 62.98° at 15 s. When washed with surfactant, the contact angle was reduced to 51.65°, which was significantly lower than the contact angle of bio-conjugated hair. Once washed, the contact angle decreased rapidly over time, probably due to the disappearance of 16-MHA. It can be seen that water droplets on the surface of hair bioconjugated with 16-MHA maintain their shape as in the virgin hair. Therefore, the durability of bioconjugation after washing was confirmed.

After absorbing water equivalent to 1.2 times its own weight, the hair was horizontally shaked at 90 rpm to release the water between hair fibers (Fig. 6). As the water between the hairs released, the volume of the hair tress increased as shown in Fig. 6(a). As a result of measuring the weight of hair after water release, the water release rate of the 18-MEA damaged hair was slower than that of virgin hair (Fig. 6(b)). The hair bioconjugated with 16-MHA showed similar rate to virgin hair at 90 min.

2.4. Recovery of lipid barrier

By bioconjugationing 16-MHA, recovery of the hair's lipid barrier was observed based on moisture content. Moisture content is an important indicator of hair health.²¹ According to the contact angle results, bioconjugated 16-MHA remains on the surface of the hair even after washing. After recovery of the hydrophobicity of the hair surface with 16-MHA, the effect of strengthening the hair barrier was shown in Figs. 7 and 8 through moisture behavior evaluation.

The moisture binding capacity and moisture behavior of hair covalently bound to 16-MHA were evaluated using differential scanning calorimeter (DSC), as shown in Fig. 7. The first reaction peak around 110°C was responsible for the reaction of moisture molecules inside the hair.²² The peak that occurred around 230°C was a result of the bonds in the decomposition of α-helix protein.²³

Virgin hair produced a moisture peak at around 118°C. However, the maximum moisture peak value of hair damaged by 18-MEA occurred at 108°C. The lower reaction temperature of the maximum moisture peak is consistent with the lower moisture response values of bleached hair.²⁴ The maximum moisture peak for hair bioconjugated with 16-MHA to 18-MEA damaged hair reacted at 115°C. Treating hair with hyaluronate increased the hair moisture peak reaction temperature of DSC.²⁵ The temperature at the maximum peak and the enthalpy for moisture endothermic reaction increased to the level of virgin hair, meaning that the moisture content inside the hair was also at the level of virgin hair.

The changes in the moisture content inside the hair were observed as shown in Fig. 8(a). The change in moisture content occurs when hair is heated to a certain temperature. Since hair protein reacts at around 230°C,²³ the change in mass reacting at the heating temperature below 165°C used in this experiment can be attributed to moisture.

During the heating process, the moisture inside the hair evaporates over time, but after approximately 20 minutes of heating, the moisture content reaches its maximum without changing. Figure 8(b) shows the final moisture contents obtained after 20 min of heating and after equilibrium was reached. It was found that the moisture content of hair from which 18-MEA was removed was lower than that of virgin hair. At a heating temperature of 75°C, the moisture content of virgin hair was 10.13%, but the moisture content of hair damaged by 18-MEA was as low at 8.19%. The hair bioconjugated with 16-MHA showed 9.98% moisture content at a heating temperature of 75°C, which was similar to that of virgin hair. Hair damaged and bioconjugated with 16-MHA to 18-MEA exhibited moisture content similar to that of virgin hair over the entire heating temperature range. Hair whose surface was rejuvenated with 16-MHA appeared to have increased and maintained moisture binding inside the hair. The amount of releasing water did not follow an exponential function but decreased linearly. However, after 120 minutes, it showed a similar weight to damaged hair.

The content of 18-MEA varies even in healthy hair depending on the individual's environment and personal history. 18-MEA is not completely damaged even when oxidized.⁷ Since it is difficult to make and test hair with the same amount of residual 18-MEA, we decided to completely remove 18-MEA by damaging virgin hair with chemicals.

There is a method that involves using liquid chromatography/mass spectrometry (LC/MS) to measure the amount of 18-MEA, but it is time consuming and requires complete elution of hair lipids from hair.²⁶ Other researchers have used TOF-SIMS to detect 18-MEA in hair.^27–30 However, because we focused on quantitative comparisons, we chose XPS over TOF-SIMS for superior quantitative analysis.³¹

In the XPS experiment, as the treatment time for hair damage increased, the area representing disulfide decreased significantly, while the SO₃⁻ area slightly increased. As the disulfides on the hair surface break, the sulfur undergoes several reactions, some of which are converted to sulfonates. Therefore, as the degree of damage increased, the disulfide peak decreased, while the area of sulfonate increased slightly. Comparing hair before and after bleaching using atomic force microscopy (AFM) revealed that nonionic spaces existed at intervals of 10 to 30 nm in the area where 18-MEA was removed.³² This means that not all 18-MEA is converted to sulfonate when it is removed from the surface of the hair.

It has yet to be determined exactly where the sulfur in 18-MEA is bound to the hair. Since the sulfur of 18-MEA binds to hair protein, it is assumed that it is most likely a thiol bond that can bind to the sulfur of 18-MEA. Therefore, the disulfide detected at 163 eV would represent the bond between the sulfur of 18-MEA and cystine on the hair surface. In other words, the disappearance of the disulfide peak in Fig. 1 indicates that the disulfide bond in the hair protein has been removed, suggesting that almost all of the 18-MEA has been removed. Considering the 1–2 nm thickness of the 18-MEA layer,² reduced disulfide signal in XPS is closely related to 18-MEA damage on the surface of the hair.

We attempted to achieve a permanent bond by bioconjugating 16-MHA to hair through a carbodiimide reaction. The carbodiimide reaction is nontoxic and one of the few that can be used under mild conditions in household products that react with water.³³ On the basis of this carbodiimide chemistry, it is assumed that carboxylic acids form a cross-linkage with the amine compounds of the hair, as depicted in Fig. 3. They can be toxic due to their high reactivity, but the irritant toxicity has been reduced by using PCI. Hair is composed of 18 amino acids, and all amino acids except proline contain primary amines, so there is a high possibility that carbodiimide reaction will occur.

Through evaluation of the internal binding force of hair, it was confirmed that a PCI concentration of at least 0.4% or higher was required for bioconjugation (in Figure S4). In the TOF-SIMS spectrum, the peak at m/z 312.3, representing 16-MHA, appeared only in bioconjugated hair. When the hair treated with only 16-MHA was washed, no 16-MHA peak was observed, indicating that the bioconjugation attempted in this study was successful.

The contact angle of hair bioconjugated with 16-MHA was similar to that of virgin hair, unlike the contact angle of 18-MEA-damaged hair. The contact angle was measured to show that the bioconjugation has high durability against washing. The covalently bonding of the bioconjugated hair was stable, but the measured contact angle slightly decreased over time. A decrease in contact angle over time was also observed in virgin hair, while a slightly greater decrease was observed in bioconjugated hair. This appears to be due not to loss of hydrophobicity from broken bioconjugation, but to uneven distribution of charge on the hair surface.³² Even after washing, the hydrophobicity of the hair did not change significantly over time, indicating that covalent bonds were maintained.

The DSC results showed that the enthalpy of the moisture reaction peak inside the hair where 16-MHA was bioconjugated was higher, meaning that the moisture inside the hair was more strongly bound. As the 18-MEA on the hair surface was removed, the moisture binding pattern inside the hair changed due to SLES (sodium lauryl ether sulfate) penetrating the hair during washing. In fact, washing with surfactants caused a loss of lipoproteins inside the hair.^34,35 Additionally, pores appeared inside hair washed with surfactants.³⁶ The enthalpy of the hair moisture reaction peak increased when 16-MHA was bioconjugated because the hair surface, which had its hydrophobicity restored, prevented internal penetration of surfactants during washing. Water molecules penetrating into the hair disrupt internal structure of hair.³⁴

Once the hair surface was restored to hydrophobicity, the penetration of moisture or surfactants from the external environment during the washing process reduced. It appears that the change in moisture binding by making the hair surface hydrophobic with 16-MHA prevented the hair structural perturbation when the hair was washed with surfactant.

In Fig. 6, the hydrophobicity of the 16-MHA bioconjugated hair was confirmed once again. The water content of the 16-MHA bioconjugated hair initially decreased to that of virgin hair, but later remained at the similar level as damaged hair. The failure of the exponential to remove water between the hairs also causes the 16-MHA to not align properly. It has a methyl group at position 18, so it is well aligned on the hair surface.³⁷ Structurally speaking, 18-MEA is the optimal lipid for the hair surface. Future studies are needed to properly align 16-MHA to the hair surface.

4.1. Materials

For polycarbodiimide (PCI), a Picassian XL-742 from Stahl (Netherlands) was used. Pentaerythritol tetraisosterate (PTIS) was obtained from Croda (US). T-butoxide, T-butanol, Hydrochloric acid solution, ammonium hydroxide, and isopropyl alcohol (IPA) were purchased from Daejung Chemicals (Siheung, Korea). Sodium laureth sulfate (SLES) was obtained from LG Household and Healthcare (Seoul, Korea). Myristic acid, palmitic acid, stearic acid, and o-Terphenyl were purchased from Sigma-Aldrich (US). Oleic acid was obtained from Nippon oil&Fats (Japan).

4.2. Remove of 18-MEA

Hair swatches were purchased from Happy Call (Seoul, Korea). The swatches were washed with SLES for 1 min and rinsed with water for 2 min. After washing, 10 g of hair was weighed and weighed into two tresses of 5 g each. To induce 18-MEA damage, one of the samples was soaked in 50 mL of 0.1 M potassium T-butoxide/T-butanol solution at room temperature. After sufficient exposure to ethanol, it was washed with SLES for 2 minutes at a flow rate of 35 ml/s and then dried with a hair dryer.

4.3. Surface analysis with XPS and AFM

X-ray photoelectron spectroscopy (XPS, Thermo VG Scientific, UK) was used to examine the 18-MEA at KAIST Analysis Center for Research Advancement (KARA).

The topography of the hair and the friction at the cuticle were evaluated via atomic force microscopy (AFM, XE-100, Park Systems, Suwon, Republic of Korea) using a LFMR cantilever (Nanosensors, Neuchatel, Switzerland) with a typical spring constant of 0.2 N·m^− 1 and resonant frequency of 23 kHz. A lateral force microscope (LFM) was utilized when AFM was scanned in contact mode. No flattening was performed. XEI software (ver. 5.2.4) was used for the analysis.

4.4. Lipid extraction and analysis

A hair swatch was cut to a length of less than 1 mm with a mass of 250 mg, and the hair residue was transferred to a 50 mL vial filled with extraction solvents of chloroform, methanol, and water, for 30 h. For the gas chromatography/mass spectrometry (GC/MS), samples were analyzed on an Agilent (7890A GC System, US) gas chromatograph coupled to an Agilent detector (5975C MSD System, US). Separation was performed on an HP-5ms UI column (30 m × 0.25 mm × 0.25 µm) using helium as the carrier gas. It was programmed to maintain an initial column temperature of 80°C for 1 min, then change to 320°C at a rate of 6°C min^-1 and hold for 20 min at this temperature. See SI Materials and Methods for further details.

4.5. PTIS hydrolysis and analysis

To obtain 16-MHA 1% PTIS was added to IPA and suspended at 80°C for 1 h. Tert-butanol reaches its melting point at room temperature, making it difficult to handle, so n-butanol, which has a low melting point, was used.

16-MHA was confirmed through GC/MS at Yonsei University. The samples were analyzed on an Agilent (8890A GC System, US) gas chromatograph coupled to an Agilent detector (5977B MSD System, US). The injector temperature was maintained at 230°C during the analysis while the ion source temperature and interface temperature were 80 and 270°C, respectively. Separation was performed on an HP-5MS UI column (30 m × 250 µm × 0.25 µm) using helium as the carrier gas. It was programmed to maintain an initial column temperature of 80°C for 1 min then increase to 270°C at a rate of 6°C min^-1 and maintain this temperature for 20 min.

4.6. Bioconjugation

For the carbodiimide reaction, hair was coated with the first agent, the solution of 16-MHA, for 10 minutes at room temperature and then transferred to the second liquid agent, an aqueous solution of 0.4% PCI (w/w), at 40°C for 1 hour. Carbodiimide-responsive hair was washed five times with SLES. The unwashed hair was gently patted with a paper towel and left to dry naturally.

4.7. Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

TOF-SIMS measurements were obtained at the Korea Advanced Institute of Science and Technology using a TOFSIMS.5 (IONTOF GmbH, Münster, Germany) operated under high vacuum (10^− 9 mbar). The hair samples were analyzed using Cs⁺ sputtering and Bi³⁺ analysis conditions of 500 eV and 30 keV, respectively.

4.8. Hydrophobicity Measurements

Contact angle measurements were recorded and analyzed at room temperature using a Sanyo camera with FTA 32 (Ver 2.0). Five strands of hair were tightly fixed in a home-made jig and set on a surface analyzer, DSA-100 (Krüss, Germany). An empty space below the hair fibers in the center of the jig prevented the hair from touching any surfaces. Next, 0.3 µL of water was placed on the hair using a syringe, and measurements were taken immediately. When water droplets are dropped on hydrophilic hair, they spread and flow into the hair, making it difficult to measure the contact angle on the hair. Even if the hair is hydrophobic, the surface of the hair is round, so the area where water droplet comes into contact with the hair is relatively large compared to the diameter of the hair. As time passes, the water droplets become unstable and the contact angle decreases. Therefore, the contact angles were compared based on 15 seconds, the middle time of the experiment.

After absorbing 1.2 times the weight of the hair in water, the hair tress was suspended in a home-built device that vibrated along a horizontal axis. Hair samples were stored in a constant temperature and humidity room at 25 ℃ and RH = 45% for more than 24 hours. After operating the device equipped with the sample, the weight of the hair was measured at regular time intervals and the condition of the hair was observed.

4.9. DSC

To understand the internal structure of hair resulting from the endothermic reaction according to heat supply, it was evaluated using differential scanning calorimetry (DSC, DSC204 F1 Phoenix, Netzsch, Germany). One gram of chopped hair was measured in drying mode at 10°C per minute. The thermal open fan cover (SML-PE19378) was purchased from Shinko M&T (Korea). To prevent oxidation reaction due to temperature, the experiment was conducted by flowing nitrogen gas through the area in which the sample container was located. All hair used in the experiment was washed with SLES 5 times.

4.10. Moisture Analyzers

The moisture content was analyzed using a halogen moisture analyzer (HX204, Mettler-Toledo, Greifensee, Switzerland). The hair tresses were left overnight in a humidity room at constant temperature, 25°C, and 50% relative humidity. Individual tresses were cut into small pieces, and 0.5 g of hair was placed on the balance of the device. Heating was performed for 60 minutes, and fresh samples were used for each measurement.

Acknowledgments: The authors thank Yeonsoo Son in KARA of KAIST for his assistance with the XPS and Jieun Kim at Yonsei university for assisting with the GC/MS experiment (PTIS). The authors thank Young Hoon Kim in Sunkyunkwan university who measured GC/MS (hair lipid). The authors thank Yunjeong Jang in KIST (Korea Institute of Science and Technology) for helping with the TOF-SIMS measurements. The authors also wish to thank our researcher, Daehyun Kim, for assisting with the contact angle measurement. S.-H.S. thanks Dr. Jonghyun Lim for the kind discussion.

Author Contributions: S.-H.S. wrote the manuscript, and conducted the experiments. P.H.S. participated in GC/MS experiment and carbodiimide reaction. B.T.L treatred hair samples, and measured moisture analysis. K.S.S. participated in the data analysis.

Conflicts of Interest: All authors are employed by LG H & H, Ltd.

Data Availability: The data that support the finding of this study are available on request from the corresponding author.

Robbins, C. R. Chemical and Physical Behavior of Human Hair. 5th edn, 1-93 (Springer, 2012).
Natarajan, U. & Robbins, C. The thickness of 18-MEA on an ultra-high-sulfur protein surface by molecular modeling. Journal of cosmetic science 61, 467-477 (2010).
Cheong, D. W., Lim, F. C. H. & Zhang, L. Insights into the Structure of Covalently Bound Fatty Acid Monolayers on a Simplified Model of the Hair Epicuticle from Molecular Dynamics Simulations. Langmuir 28, 13008-13017, doi:10.1021/la302161x (2012).
Yasuda, M. Hand combing sensation and stiffness of hair, and science of hair surface. J. Hair Sci. 95, 7-12 (2004).
Thibaut, S. et al. Chronological ageing of human hair keratin fibres. International Journal of Cosmetic Science 32, 422-434, doi:https://doi.org/10.1111/j.1468-2494.2009.00570.x (2010).
Takahashi, T., Mamada, A., Breakspear, S., Itou, T. & Tanji, N. Age-dependent changes in damage processes of hair cuticle. Journal of cosmetic dermatology 14, 2-8, doi:10.1111/jocd.12129 (2015).
Tokunaga, S., Tanamachi, H. & Ishikawa, K. Degradation of Hair Surface: Importance of 18-MEA and Epicuticle. Cosmetics 6 (2019).
Breakspear, S., Smith, J. R. & Luengo, G. Effect of the covalently linked fatty acid 18-MEA on the nanotribology of hair’s outermost surface. Journal of Structural Biology 149, 235-242, doi:https://doi.org/10.1016/j.jsb.2004.10.003 (2005).
Efremenko, I., Zach, R. & Zeiri, Y. Adsorption of Explosive Molecules on Human Hair Surfaces. The Journal of Physical Chemistry C 111, 11903-11911, doi:10.1021/jp071616e (2007).
Smith, J. R. & Swift, J. A. Maple syrup urine disease hair reveals the importance of 18-methyleicosanoic acid in cuticular delamination. Micron (Oxford, England : 1993) 36, 261-266, doi:10.1016/j.micron.2004.11.004 (2005).
Jones, L. N., Peet, D. J., Danks, D. M., Negri, A. P. & Rivett, D. E. Hairs from Patients with Maple Syrup Urine Disease Show a Structural Defect in the Fiber Cuticle. Journal of Investigative Dermatology 106, 461-464, doi:https://doi.org/10.1111/1523-1747.ep12343618 (1996).
Gavazzoni Dias, M. F. Hair cosmetics: an overview. International journal of trichology 7, 2-15, doi:10.4103/0974-7753.153450 (2015).
Hutchinson, S., Evans, D., Corino, G. & Kattenbelt, J. An evaluation of the action of thioesterases on the surface of wool. Enzyme and Microbial Technology 40, 1794-1800, doi:https://doi.org/10.1016/j.enzmictec.2007.01.016 (2007).
Ganske, F., Meyer, H. H., Deutz, H. & Bornscheuer, U. Enzyme-catalyzed hydrolysis of 18-methyl eicosanoic acid-cysteine thioester. European Journal of Lipid Science and Technology 105, 627-632, doi:https://doi.org/10.1002/ejlt.200300800 (2003).
Philippe, M. et al. Synthesis of 2-N-oleoylamino-octadecane-1,3-diol: a new ceramide highly effective for the treatment of skin and hair. Int J Cosmet Sci 17, 133-146, doi:10.1111/j.1467-2494.1995.tb00116.x (1995).
Tanamachi, H. et al. A role of the anteiso branch of 18-MEA in 18-MEA/SPDA to form a persistent hydrophobicity to alkaline-color-treated weathered hair. Journal of cosmetic science 60, 509-518 (2009).
Liljeblad, J. F. D. et al. Self-assembly of long chain fatty acids: effect of a methyl branch. Physical Chemistry Chemical Physics 16, 17869-17882, doi:10.1039/C4CP00512K (2014).
Wiesche, E. S., Körner, A., Schäfer, K. & Wortmann, F. J. Prevention of hair surface aging. Journal of cosmetic science 62, 237-249 (2011).
Okamoto, M., Ishikawa, K., Tanji, N. & Aoyagi, S. Investigation of the damage on the outermost hair surface using ToF-SIMS and XPS. Surface and Interface Analysis 44, 736-739, doi:https://doi.org/10.1002/sia.3878 (2012).
Robbins, C. & Bahl, M. Analysis of hair by electron spectroscopy for chemical analysis. J. Soc. Cosmet. Chem. 35, 379-390 (1984).
Breakspear, S. et al. Learning from hair moisture sorption and hysteresis. International Journal of Cosmetic Science 44, 555-568, doi:https://doi.org/10.1111/ics.12806 (2022).
Cao, J. & Leroy, F. Depression of the melting temperature by moisture for α-form crystallites in human hair keratin. Biopolymers 77, 38-43, doi:https://doi.org/10.1002/bip.20186 (2005).
Popescu, C. & Gummer, C. DSC of human hair: a tool for claim support or incorrect data analysis? Int J Cosmet Sci 38, 433-439, doi:10.1111/ics.12306 (2016).
Fernandes, M. & Cavaco-Paulo, A. Protein disulphide isomerase-mediated grafting of cysteine-containing peptides onto over-bleached hair. Biocatalysis and Biotransformation 30, 10-19, doi:10.3109/10242422.2012.644436 (2012).
Qu, W. et al. Improving the Mechanical Properties of Damaged Hair Using Low-Molecular Weight Hyaluronate. Molecules 27 (2022).
Masukawa, Y., Tsujimura, H. & Imokawa, G. A systematic method for the sensitive and specific determination of hair lipids in combination with chromatography. Journal of Chromatography B 823, 131-142, doi:https://doi.org/10.1016/j.jchromb.2005.06.014 (2005).
Mall, J. K., Sims, P. & Carr, C. M. Surface Chemical Analysis of Lipase Enzyme Treatments on Wool and Mohair. The Journal of The Textile Institute 93, 43-51, doi:10.1080/00405000208630551 (2002).
Volooj, S., Carr, C. M., Mitchell, R. & Vickerman, J. C. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of the bleaching of keratin fibres and the application of cationic alkyl protein softeners to bleached cashmere. Surface and Interface Analysis 29, 422-430, doi:https://doi.org/10.1002/1096-9918(200007)29:7<422::AID-SIA885>3.0.CO;2-2 (2000).
Habe, T. et al. ToF-SIMS characterization of the lipid layer on the hair surface. I: the damage caused by chemical treatments and UV radiation. Surface and Interface Analysis 43, 410-412, doi:https://doi.org/10.1002/sia.3407 (2011).
Poleunis, C., Everaert, E. P., Delcorte, A. & Bertrand, P. Characterisation of human hair surfaces by means of static ToF-SIMS: A comparison between Ga+ and C60+ primary ions. Applied Surface Science 252, 6761-6764, doi:https://doi.org/10.1016/j.apsusc.2006.02.174 (2006).
Briggs, D., Brewis, D. M., Dahm, R. H. & Fletcher, I. W. Analysis of the surface chemistry of oxidized polyethylene: comparison of XPS and ToF-SIMS. Surface and Interface Analysis 35, 156-167, doi:https://doi.org/10.1002/sia.1515 (2003).
Korte, M. et al. Distribution and Localization of Hydrophobic and Ionic Chemical Groups at the Surface of Bleached Human Hair Fibers. Langmuir 30, 12124-12129, doi:10.1021/la500461y (2014).
Scheffel, D. L. et al. Transdentinal cytotoxicity of carbodiimide (EDC) and glutaraldehyde on odontoblast-like cells. Oper. Dent. 40, 44-54, doi:10.2341/13-338-L (2015).
Song, S.-H. et al. Prevention of lipid loss from hair by surface and internal modification. Scientific Reports 9, 9834, doi:10.1038/s41598-019-46370-x (2019).
de Cássia Comis Wagner, R. & Joekes, I. Hair protein removal by sodium dodecyl sulfate. Colloids and Surfaces B: Biointerfaces 41, 7-14, doi:https://doi.org/10.1016/j.colsurfb.2004.10.023 (2005).
Song, S.-H., Park, H.-S., Jeon, J., Son, S. K. & Kang, N.-G. Hair Pores Caused by Surfactants via the Cell Membrane Complex and a Prevention Strategy through the Use of Cuticle Sealing. Cosmetics 10 (2023).
McMullen, R. L. & Kelty, S. P. Molecular Dynamic Simulations of Eicosanoic Acid and 18-Methyleicosanoic Acid Langmuir Monolayers. The Journal of Physical Chemistry B 111, 10849-10852, doi:10.1021/jp073697k (2007).

Competing interest reported. All authors are employed by LG Household & Health Care, Ltd.

SMBiomimeticsThroughBioconjugationof16MethylheptadecanoicAcidtoDamagedHairforHairBarrierRecovery.docx

Download PDF

Journal Publication

published 09 Nov, 2024

Read the published version in Scientific Reports →

Editorial decision: Revision requested
12 Sep, 2024
Reviews received at journal
07 Aug, 2024
Reviewers agreed at journal
25 Jul, 2024
Reviewers agreed at journal
22 Jul, 2024
Reviews received at journal
18 Jul, 2024
Reviewers agreed at journal
09 Jul, 2024
Reviewers invited by journal
28 Jun, 2024
Editor assigned by journal
26 Jun, 2024
Editor invited by journal
17 Apr, 2024
Submission checks completed at journal
17 Apr, 2024
First submitted to journal
08 Apr, 2024

You are reading this latest preprint version

Biomimetics Through Bioconjugation of 16- Methylheptadecanoic Acid to Damaged Hair for Hair Barrier Recovery

Status:

Journal Publication

Version 1

Abstract

Figures

1. Introduction

2. Results

2.1. 18-MEA damaged hair

2.2. Obtaining 16-MHA from PTIS via hydrolysis

2.3. Bioconjugation of 16-MHA on damaged hair

2.4. Recovery of lipid barrier

3. Discussion

4. Methods

4.1. Materials

4.2. Remove of 18-MEA

4.3. Surface analysis with XPS and AFM

4.4. Lipid extraction and analysis

4.5. PTIS hydrolysis and analysis

4.6. Bioconjugation

4.7. Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

4.8. Hydrophobicity Measurements

4.9. DSC

4.10. Moisture Analyzers

Declarations

References

Additional Declarations

Supplementary Files

Status:

Journal Publication

Version 1