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Witting, Madeleine Yvonne (2016): Local and targeted delivery of proteins. Dissertation, LMU München: Faculty of Chemistry and Pharmacy



Local and targeted delivery of labile biomacromolecules, such as proteins, peptides, and enzymes, is of high interest and needs to take the well-known instability and delivery problems of these APIs into account. To offer new options for local and targeted intraepidermal and dermal drug delivery, the goal of the thesis was the development, investigation and characterization of promising delivery devices and vehicles. Efficient protein delivery into the skin may enable a substitution therapy approach of skin diseases like atopic dermatitis which come along with a lack of certain structural proteins. For the first time, dPG-based nanogels were investigated for their suitability to encapsulate and release proteins. Using two different types of release trigger mechanisms, we succeeded in developing biocompatible dPG nanogels with high protein load. Acidic-cleavable and thermoresponsive nanogels offered mild encapsulation conditions, where proteins were kept intact without activity loss during manufacturing and after the triggered release. Furthermore, the thermoresponsive PNIPAM-dPG nanogels were able to deliver TGase1 locally to the epidermis of TGase-1-deficient skin models. Here, the restoration of a normal skin barrier function was observed, which verifies their feasibility in delivering therapeutically relevant concentrations into diseased skin. The very versatile polysaccharide HA was investigated for its beneficial effects on the enhanced dermal delivery of low molecular weight drugs in the past. Successful topical delivery of biomacromolecules using HA gels was demonstrated using FRET-FLIM and FT-IR analysis. Substantiating literature findings on HA skin penetration, we observed enhanced BSA delivery to intact skin with 5 kDa HA, presumably as a result of protein-HA co-transport supported by SC hydration as well as keratin and lipid structure interactions. In barrier-disrupted skin, we observed a localized penetration confinement of the protein to the epidermis, which could not be unraveled so far, but demonstrates the supposedly great potential of HA in dermal drug delivery. Finally, solid stainless steel MN arrays were characterized and analyzed for their feasibility to locally deliver proteins. 300 ìm long MN arrays were coated with an optimized aqueous protein formulation and technique to yield up to 68 % of the protein payload (8.0 ± 1.4 mg per skin model / 4.7 ± 0.8 mg/cm²) in the skin tissue after dissolution. The coated protein was stable up to 3 month storage without loss of activity and integrity. Following MN repeated insertions, reconstructed skin showed minor increases in interleukin levels, which indicates a slight but not critical skin irritation.