Mechanical Properties of Healthy and ex vivo Onychomycosis Nails and the Influence of a Porphyrin-propylene Glycol Antifungal Formulation

Abstract

Aims: To investigate nail penetration enhancing effectiveness of a novel drug formulation and ingredients, 40% propylene glycol (PG) and 40 µM multifunctional photosensitizer (MFPS). Proposed formulation was proven effective in photodynamic treatment (PDT) of ex vivo fungal infections of human nails (onychomycoses) and indirectly also to weaken nail's strength. Study Design: To directly proof the effect of the novel formulation on nail's hardness Atomic Force Microscopy (AFM) was employed to measure small-distance forces. Based on indentations Young's moduli of healthy and ex vivo onychomycosis nails were calculated before and after treatment with the novel formulation. Changes in young's modulus can be related to changes in nail's strength and thus formulation effectiveness. Additionally, AFM imaging was employed to study topographical / roughness changes resulting from the treatments to both nail types. Trichophyton mentagrophytes, representative for clinical onychomycosis, was chosen to induce nail infections.

Microstructural alterations in the onychomycotic and psoriatic nail: Relevance in drug delivery

“…Whilst these findings could appear in contradiction to ours the same authors reported that infected nails from patients (as those used in this work) presented a smoother topography than nails infected ex vivo, a difference apparently explained by the location where the infection originates. In ex vivo T. mentagrophytes-induced onychomycosis, the infection starts from the outer surface of the nail plate whereas in vivo, the infection infiltrates the internal side of the nail plate from the nail root and the eponychium [29,30]. This is consistent with our SEM microphotography of naturally infected specimens that showed hyphen in the ventral but not in de dorsal surface of the plate.…”