title: Synthesis and Validation of Functional Nanogels as pH-Sensors in the Hair Follicle.
abstract: In the present study, a pH responsive dendritic polyglycerol nanogel (dPG-NG) is developed to measure the pH values inside the hair follicle (HF) using an ex vivo porcine ear model. The macromolecular precursors are labeled with a pH sensitive indodicarbocyanine dye (pH-IDCC) and a control dye (indocarbocyanine dye: ICC) and crosslinked via a mild and surfactant-free Thiol-Michael reaction using an inverse nanoprecipitation method. With this method, it is possible to prepare tailor-made particles in the range of 100 nm to 1 µm with a narrow polydispersity. The dPG-NGs are characterized using dynamic light scattering, nanoparticle tracking analysis, and atomic force microscopy. Systematic analysis of confocal microscope images of histological sections of the skin enables accurate determination of the pH gradient inside the HF. The results show that these novel pH-nanosensors deeply penetrate the skin via the follicular pathway and the pH of the pig hair follicles increase from 6.5 at the surface of the skin to 7.4 in deeper areas of the HF. The pH-nanosensor shows no toxicity potentials.
authors.affiliation: Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, Berlin, 14195, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Dimde
authors.affiliation: Center of Experimental and Applied Cutaneous Physiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, Berlin, 10117, Germany.
authors.forename: Fitsum Feleke
authors.initials: FF
authors.lastname: Sahle
authors.affiliation: Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, Berlin, 14195, Germany.
authors.forename: Virginia
authors.initials: V
authors.lastname: Wycisk
authors.affiliation: Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, Berlin, 14195, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Steinhilber
authors.affiliation: Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, Berlin, 14195, Germany.
authors.forename: Luis Cuellar
authors.initials: LC
authors.lastname: Camacho
authors.affiliation: Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, Berlin, 14195, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Licha
authors.affiliation: Center of Experimental and Applied Cutaneous Physiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, Berlin, 10117, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Lademann
authors.affiliation: Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, Berlin, 14195, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Haag
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D002232:Carbocyanines / Q000737:chemistry; D004396:Coloring Agents / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000737:chemistry; D004423:Ear / Q000033:anatomy & histology; D005782:Gels; D005990:Glycerol / Q000737:chemistry*; D018859:Hair Follicle / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D049329:Nanostructures / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013552:Swine; D046509:Tissue Culture Techniques
chemical_list: D002232:Carbocyanines; D004396:Coloring Agents; D003432:Cross-Linking Reagents; D005782:Gels; D011108:Polymers; C043941:polyglycerol; D005990:Glycerol
keywords: hair follicle; nanoprecipitation; pH nanosensor; polyglycerol nanogels; surfactant-free