Determination of the pH Gradient in Hair Follicles of Human Volunteers Using pH-Sensitive Melamine Formaldehyde-Pyranine Nile Blue Microparticles
Dennis Kaden,
Lars Dähne,
Fanny Knorr,
Heike Richter,
Jürgen Lademann,
Martina C. Meinke,
Alexa Patzelt,
Maxim E. Darvin,
Sora Jung
Affiliations
Dennis Kaden
Surflay Nanotec GmbH, 12489 Berlin, Germany
Lars Dähne
Surflay Nanotec GmbH, 12489 Berlin, Germany
Fanny Knorr
Charité–Universitätsmedizin Berlin, Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology (CCP), 10117 Berlin, Germany
Heike Richter
Charité–Universitätsmedizin Berlin, Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology (CCP), 10117 Berlin, Germany
Jürgen Lademann
Charité–Universitätsmedizin Berlin, Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology (CCP), 10117 Berlin, Germany
Martina C. Meinke
Charité–Universitätsmedizin Berlin, Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology (CCP), 10117 Berlin, Germany
Alexa Patzelt
Charité–Universitätsmedizin Berlin, Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology (CCP), 10117 Berlin, Germany
Maxim E. Darvin
Charité–Universitätsmedizin Berlin, Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology (CCP), 10117 Berlin, Germany
Sora Jung
Charité–Universitätsmedizin Berlin, Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology (CCP), 10117 Berlin, Germany
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.
