Simultaneous 3D visualization of hair microstructure and damage using FIB-SEM
Podium 25
Presented by: Yasunori Okuma
Introduction
In order to develop an effective hair care product, it is important to elucidate the details of hair damage.
Recently, it has been reported to acquire three-dimensional (3D) images of damaged parts in hair using devices such as X-ray CT. However, these observed only one part of hair such as voids from damage and are still lacking in comprehensiveness.
Therefore, in this study, we tried to make the microstructure in the hair and the voids from damage into 3D at the same time, and confirmed which part in the hair and how much damage occurred. Furthermore, we searched for ingredients that prevent hair damage.
Materials and Methods
Hair samples were collected from same woman with no history of chemical treatment. Hair tresses were bleached at room temperature for 20 minutes.
The microstructure of hair was directly imaged by FIB-SEM without any staining. We sputtered the surface of the specimen with gallium ion beam, and observed the new exposed surface by backscattered electron imaging with SEM, and repeated the process of sputtering and observation until obtained 300 slice images. Image stacks were aligned after processed by denoising, removal of ion beam milling artefacts and removal of local charge imbalance. Finally, we reconstructed the 3D structure by stacking the images of serial section series.
In the screening of ingredients that prevent hair damage, hair tresses were immersed into each sample at room temperature for 20 minutes. Next, each hair tresses were bleached at room temperature for 20 minutes. After wash, there were immersed in water at 40℃ for 24hr, and outflow of hair protein was measured.
Results and discussion
By using FIB-SEM, we succeeded in simultaneous 3D conversion of microstructures such as melanin and CMC and damaged parts such as voids in bleached hair. As a result, bleached hair had significantly more voids than non-chemical treated hair. Especially it was confirmed that the size of voids in CMC was biggest than voids of near melanin.
Following screening of ingredients that prevent hair damage, S-Sulfokeratein showed a high prevent effect. The FIB-SEM measurements showed S-Sulfokeratein suppresses the generation of voids.
FIB-SEM (Focused Ion Beam Scanning Electron Microscopes) refers to a composite machine that combines an SEM lens barrel capable of high-resolution observation and an FIB lens barrel capable of cross-sectional processing of a small area. 2 beams, electrons and ions are focused on one coincident point. With gallium ion beam, some nanometers of the surface are removed, and the remaining block-face is imaged with the electron beam in a repetitive manner. This method provides many serial sections, thereby enabling 3-D structure reconstruction.
For observing the hair damage, a transmission electron microscope (TEM) has been mainly employed. From the result of TEM observation, it has been reported that damage causes voids around melanin and CMC inside the hair. However, it is difficult to evaluate the size of voids and microstructures in hair from 2D images. Although it has been reported that X-ray CT could also present 3-D data, these could only observe voids. On the other hand, our novel method revealed the inside of the hair, indicated the positional relationship and morphology information of voids and microstructures. From this observation result, the tendency for voids formation by hair bleach was clearly seen, such as the size of voids in CMC was biggest than that of voids near melanin.
Hair bleach is a global beauty habit that is very popular with people who change their original hair color. However, bleaching processes can be cleave disulfide bond, occur protein elution and increase porosity. S-Sulfokeratein has a disulfide bond within the molecule, and it hypothesized that it bonds by an SS/SH interchange reaction with the thiol group of disulfide bond decomposed inside the hair. Based on the above, it seems that S-Sulfokeratein acts as an anti-damaging agent.
Conclusion
In this study, we obtained 3D images of microstructures and voids in hair at the same time with the aid of FIB-SEM. The 3-D information help in interpreting the structures correctly, allowing that how much damage is in which part in hair to be validated.
This method is undoubtedly a promising tool for elucidate the details of hair damage and develop an effective hair care product.
In order to develop an effective hair care product, it is important to elucidate the details of hair damage.
Recently, it has been reported to acquire three-dimensional (3D) images of damaged parts in hair using devices such as X-ray CT. However, these observed only one part of hair such as voids from damage and are still lacking in comprehensiveness.
Therefore, in this study, we tried to make the microstructure in the hair and the voids from damage into 3D at the same time, and confirmed which part in the hair and how much damage occurred. Furthermore, we searched for ingredients that prevent hair damage.
Materials and Methods
Hair samples were collected from same woman with no history of chemical treatment. Hair tresses were bleached at room temperature for 20 minutes.
The microstructure of hair was directly imaged by FIB-SEM without any staining. We sputtered the surface of the specimen with gallium ion beam, and observed the new exposed surface by backscattered electron imaging with SEM, and repeated the process of sputtering and observation until obtained 300 slice images. Image stacks were aligned after processed by denoising, removal of ion beam milling artefacts and removal of local charge imbalance. Finally, we reconstructed the 3D structure by stacking the images of serial section series.
In the screening of ingredients that prevent hair damage, hair tresses were immersed into each sample at room temperature for 20 minutes. Next, each hair tresses were bleached at room temperature for 20 minutes. After wash, there were immersed in water at 40℃ for 24hr, and outflow of hair protein was measured.
Results and discussion
By using FIB-SEM, we succeeded in simultaneous 3D conversion of microstructures such as melanin and CMC and damaged parts such as voids in bleached hair. As a result, bleached hair had significantly more voids than non-chemical treated hair. Especially it was confirmed that the size of voids in CMC was biggest than voids of near melanin.
Following screening of ingredients that prevent hair damage, S-Sulfokeratein showed a high prevent effect. The FIB-SEM measurements showed S-Sulfokeratein suppresses the generation of voids.
FIB-SEM (Focused Ion Beam Scanning Electron Microscopes) refers to a composite machine that combines an SEM lens barrel capable of high-resolution observation and an FIB lens barrel capable of cross-sectional processing of a small area. 2 beams, electrons and ions are focused on one coincident point. With gallium ion beam, some nanometers of the surface are removed, and the remaining block-face is imaged with the electron beam in a repetitive manner. This method provides many serial sections, thereby enabling 3-D structure reconstruction.
For observing the hair damage, a transmission electron microscope (TEM) has been mainly employed. From the result of TEM observation, it has been reported that damage causes voids around melanin and CMC inside the hair. However, it is difficult to evaluate the size of voids and microstructures in hair from 2D images. Although it has been reported that X-ray CT could also present 3-D data, these could only observe voids. On the other hand, our novel method revealed the inside of the hair, indicated the positional relationship and morphology information of voids and microstructures. From this observation result, the tendency for voids formation by hair bleach was clearly seen, such as the size of voids in CMC was biggest than that of voids near melanin.
Hair bleach is a global beauty habit that is very popular with people who change their original hair color. However, bleaching processes can be cleave disulfide bond, occur protein elution and increase porosity. S-Sulfokeratein has a disulfide bond within the molecule, and it hypothesized that it bonds by an SS/SH interchange reaction with the thiol group of disulfide bond decomposed inside the hair. Based on the above, it seems that S-Sulfokeratein acts as an anti-damaging agent.
Conclusion
In this study, we obtained 3D images of microstructures and voids in hair at the same time with the aid of FIB-SEM. The 3-D information help in interpreting the structures correctly, allowing that how much damage is in which part in hair to be validated.
This method is undoubtedly a promising tool for elucidate the details of hair damage and develop an effective hair care product.