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Letter

Determination of the pH Gradient in Hair Follicles of Human Volunteers Using pH-Sensitive Melamine Formaldehyde-Pyranine Nile Blue Microparticles

1
Surflay Nanotec GmbH, 12489 Berlin, Germany
2
Charité–Universitätsmedizin Berlin, Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology (CCP), 10117 Berlin, Germany
*
Author to whom correspondence should be addressed.
Sensors 2020, 20(18), 5243; https://doi.org/10.3390/s20185243
Received: 6 August 2020 / Revised: 8 September 2020 / Accepted: 10 September 2020 / Published: 14 September 2020
(This article belongs to the Collection Biomedical Optical Nanosensors)
Nanoparticles can be applied to the hair follicles, which can serve as reservoirs for triggered drug release. A valid measurement method for the determination of the pH within the hair follicle in vivo has not been shown yet. Here, melamine formaldehyde particles up to 9 µm in size were applied on 40 freshly plucked scalp hairs of eight individuals to determine the pH along the hair shaft down to the root area of the hair. For fluorescent pH indicators, pyranine and Nile blue were incorporated into the particles. Measurements were conducted using confocal laser scanning microscopy. A pH decay gradient could be found from the hair sheath towards the external hair shaft (p = 0.012) with pH values at the hair sheath of 6.63 ± 0.09, at the hair sheath end at 6.33 ± 0.11, and at the external hair shaft at 6.17 ± 0.09 (mean ± SE). The pH difference between the hair sheath end and the external hair shaft was found to be significant (p = 0.036). The results might be comparable with the pH within the hair follicle in vivo indicating a pH increase towards the hair root. View Full-Text
Keywords: triggered drug release; follicular penetration; skin barrier; skin acidity triggered drug release; follicular penetration; skin barrier; skin acidity
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MDPI and ACS Style

Kaden, D.; Dähne, L.; Knorr, F.; Richter, H.; Lademann, J.; Meinke, M.C.; Patzelt, A.; Darvin, M.E.; Jung, S. Determination of the pH Gradient in Hair Follicles of Human Volunteers Using pH-Sensitive Melamine Formaldehyde-Pyranine Nile Blue Microparticles. Sensors 2020, 20, 5243. https://doi.org/10.3390/s20185243

AMA Style

Kaden D, Dähne L, Knorr F, Richter H, Lademann J, Meinke MC, Patzelt A, Darvin ME, Jung S. Determination of the pH Gradient in Hair Follicles of Human Volunteers Using pH-Sensitive Melamine Formaldehyde-Pyranine Nile Blue Microparticles. Sensors. 2020; 20(18):5243. https://doi.org/10.3390/s20185243

Chicago/Turabian Style

Kaden, Dennis, Lars Dähne, Fanny Knorr, Heike Richter, Jürgen Lademann, Martina C. Meinke, Alexa Patzelt, Maxim E. Darvin, and Sora Jung. 2020. "Determination of the pH Gradient in Hair Follicles of Human Volunteers Using pH-Sensitive Melamine Formaldehyde-Pyranine Nile Blue Microparticles" Sensors 20, no. 18: 5243. https://doi.org/10.3390/s20185243

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