Expanding the Frontiers of nail product evaluation: Novel application of differential scanning calorimetry (DSC) for assessing crosslinking density and predicting nail brittleness and flexibility

OBJECTIVE

While modern industry advancements have expanded nail beautification options, scientific literature primarily focuses on nail biology and medicine, with limited attention on cosmetic treatments. This study aimed to investigate human nail denaturation properties, including gender impact, blending nails to enlarge the sample pool, nail sensitization through bleaching, and active effectiveness testing. The objective was to understand the DSC and bending fatigue relationship, and define the consumer relevance of the DSC test.

METHODS

Nail clippings were collected from adult female and male volunteers. The wet DSC was employed to validate sample preparation, explore the effects of gender, and assess the potential of using blended nails for claims substantiation testing. Nails were sensitized through bleaching using hydrogen peroxide. The effects were confirmed through DSC and nail flexure tests. Furthermore, the ability of actives to address concerns related to nail softness and brittleness was assessed using these techniques.

RESULTS

The results confirmed the viability of equilibrating nails in water for up to 14 h as a standardized testing method. The denaturation temperature results were independent of gender and suitable for claims substantiation testing. Blending nails from different sources did not yield significant variations in denaturation properties. A preliminary study suggested that cadaver nails should be used with caution because they exhibited differences in denaturation temperature, influenced by the sampling location. Bending fatigue tests highlighted the significance of humidity, with higher humidity conditions (80%) enhancing nail flexibility and providing better resolution for claims substantiation. Sensitizing the nails with hydrogen peroxide induced alterations in both DSC and bending fatigue results. Proof-of-principle studies demonstrated an elevation in denaturation temperature and a decrease in the number of cycles to break, indicating a nail-hardening effect when formaldehyde was applied. The use of a nail softener led to an enhancement in nail fatigue resistance due to a notable reduction in nail crosslinking density.

CONCLUSIONS

The measurement of crosslinking density proved to be a sensitive tool for assessing the effects of cosmetic treatments on nails, particularly in predicting outcomes related to nail brittleness and flexibility.

Effects of chemical straighteners on the hair shaft and scalp: a review

Background

The effects of chemical straighteners on the scalp and hair shaft are not fully known, although such substances are widely used. Hair straightening became popular in Brazil with the use of formaldehyde and its derivatives, despite the prohibition by the current legislation.

Objective

To identify changes in hair shaft and scalp caused by the use of chemical straighteners.

Methods

A search was performed using keywords in three databases from 03/16/2020 to 05/20/2020, with publications between the years 2000 to 2020. After applying the inclusion and exclusion criteria, 33 articles were selected for review.

Results

In some studies, hair relaxers were associated with eczema, desquamation, pain, burns, and inflammation in the scalp. Hair loss, damage to the shaft, alteration in the color of the hairs and in the composition of their amino acids were observed. Findings are variable across the studies.

Study limitations

The search was restricted to three databases, in two languages, different study designs were accepted.

Conclusions

Straightening techniques can have side effects, including scalp inflammation, damage to the shaft, and hair loss. Its long-term effects remain unknown and further studies are necessary.

Psoriasiform skin reaction due to Brazilian keratin treatment: A clinical-dermatoscopic study of 43 patients

Introduction:

Hair straightening products like the Brazilian Keratin Treatment (BKT) contain high concentrations of formaldehyde, and its use is associated with adverse effects. In 2016, seven cases of eczema-like psoriasiform skin reaction secondary to BKT were described for the first time. We aim to investigate the clinical characteristics and dermatoscopic findings of patients with psoriasiform skin reactions due to BKT.

Materials and Methods:

A cross-sectional study was performed from October 2017 to June 2020. Patients who developed erythema and scales on the scalp following the use of BKT were included. Age, sex, number of BKTs, time elapsed between BKT and the skin reaction, pull test, and dermatoscopic findings were investigated. Descriptive and inferential statistics were used.

Results:

We found 43 patients with a mean age of 35 ± 10 years, predominantly females in 42 (98%) cases. The mean number of BKTs was 2 ± 2. The mean length of time elapsed to present the reaction was 12 ± 17 months and this was related to the number of BKTs (P = 0.01). The pull test was positive in 37 (86%) patients. The most frequent dermatoscopic findings were perifollicular scales in 42 (98%), red patches in 35 (81%), and peripilar desquamation resembling the outer skin of an onion bulb in 32 (74%).

Conclusion:

Hair straightening products are widely used and the psoriasiform skin reaction that develops afterward might be underdiagnosed. It is important to investigate the background of BKT in conjunction with the clinical and dermatoscopic findings suggestive of this cutaneous reaction.

Antioxidant extracts from Dicerocaryum senecioides as active ingredients in semi-permanents and hair conditioners

BACKGROUND

Different hair types respond differently to cosmetic treatments; hence, many options ought to be availed to the consumer. The purpose of this study was to evaluate the use of antioxidant extract from Dicerocaryum senecioides as active alternatives in hair semi-permanent waving and hair conditioning.

METHODS

The antioxidant phytochemicals were first identified and isolated by thin-layer chromatography (TLC) and spraying with revealing agents. The antioxidant potency was determined by DPPH antiradical scavenging and ferric reducing power methods. The extract was incorporated in two different formulations to make the extract perm (bio-semi-permanent) and the antioxidant hair conditioner (AC). The formulations had their performance examined for hair curling and conditioning on Asian and African hair types. Hair damage was assessed by scanning the surface of treated samples on an attenuated total reflectance-Fourier transform infrared spectrometer (ATR-FTIR) and by quantifying lost protein on ultraviolet visible (UV-Vis) spectrophotometer.

RESULTS

The extract antioxidant had an IC₅₀ of 26.54 ± 0.34 µg/ml exhibiting greater antioxidant potency compared to the controls quercetin (38.84 ± 0.12 µg/ml) and ascorbic acid (35.22 ± 0.07 µg/ml). The extract perm had a lower curling ability indicated by a perm set of 85.10 ± 3.92% and 81.35 ± 2.35% for Asian and African hairs, respectively, while commercial product, ammonium thioglycolate (ATG) had 96.05 ± 1.70% and 93.60 ± 2.21% for the same. The curling of hair with extract perm resulted in less oxidative damage with oxidative peak areas of 3.37 ± 0.09 and 3.71 ± 0.03 as well as lower protein losses of 4.72 ± 0.71 µg/mg and 5.62 ± 0.70 µg/mg on Asian and African hair samples, respectively. The application of AC reduced the oxidative damage peak areas of ATG and extract perm treated Asian hair samples by 1.15 and 0.48 units, respectively. AC was also effective in reducing damage caused by UV radiation on ATG-treated samples by 1.06 units (African hair) and 1.09 units on Asian hair.

CONCLUSION

The results show antioxidant extracts from Dicerocryum senecioides as a promising and safer alternative for hair conditioning and semi-permanent curling.

Straight to the Point: What Do We Know So Far on Hair Straightening?

Background

Hair represents a valued aspect of human individuality. The possibility of having an easy to handle hairstyle and changing it from time to time promoted an increasing search for chemical hair transformations, including hair straightening. Hair straightening is the process used to convert curly into straight hair.

Aims

This review aims to discuss hair straightening, addressing techniques, products, methods of application, consequences to hair shafts, recommendations on this topic, and the risks involving the safety of both the user and the performing professional.

Methods and Results

The terms "straightening" AND "hair," "straightening" AND "alopecia," and "straightening" AND "human hair" were used to perform a literature search in MEDLINE through PubMed until July 15, 2020. We limited the search to articles available in English, considering those mentioning alternatives to straighten the hair. We had a total of 33 relevant articles.

Conclusions

This article will help dermatologists to advise their patients, providing a more suitable orientation on how to get the best outcome without risking one's safety.

The evolving mechanical response of curly hair fibres subject to fatigue testing

Cyclic testing of human hair reveals important details about the behaviour of fibres over many cycles of loading. Phenomena which are observed under static tensile tests give important clues about the form and behaviour of hair fibres, but these do not necessarily remain constant on the inevitable march to failure. In previous work, we demonstrated that curly fibres exhibited a toe-region during tensile tests. The form of curly fibres could be altered by mechanical manipulation but the curl could be recovered upon immersion in water. In this study, where straight and curly fibres are subject to cyclic loading, this characteristic toe-region was shown to be present in the first cycle of loading (for curly fibres). As the number of cycles increased (and the curly fibres progressively became straighter), the stress-strain response of curly fibres started to resemble that of straight fibres. This observation supports our previous hypothesis, which states that the toe-region can be attributed to the presence of a hydrogen bonding mechanism, which is present in curly fibres only, and can be altered by mechanical force. Interestingly, the alteration in load-bearing pattern in curly fibres did not necessarily translate to increased endurance, demonstrating that the relationship between fatigue and strength is a complex one in hair fibres.