Vibrational microscopy and imaging of skin: from single cells to intact tissue

Vibrational microscopy and imaging offer several advantages for a variety of dermatological applications, ranging from studies of isolated single cells (corneocytes) to characterization of endogenous components in intact tissue. Two applications are described to illustrate the power of these techniques for skin research. First, the feasibility of tracking structural alterations in the components of individual corneocytes is demonstrated. Two solvents, DMSO and chloroform/methanol, commonly used in dermatological research, are shown to induce large reversible alterations (α-helix to β-sheet) in the secondary structure of keratin in isolated corneocytes. Second, factor analysis of image planes acquired with confocal Raman microscopy to a depth of 70 μm in intact pigskin, demonstrates the delineation of specific skin regions. Two particular components that are difficult to identify by other means were observed in the epidermis. One small region was formed from a conformationally ordered lipid phase containing cholesterol. In addition, the presence of nucleated cells in the tissue (most likely keratinocytes) was revealed by the spectral signatures of the phosphodiester and cytosine moieties of cellular DNA

Transdermal delivery of diclofenac sodium through rat skin from various formulations

The aim of this study was to evaluate and compare the in vitro and in vivo transdermal potential of w/o microemulsion (M) and gel (G) bases for diclofenac sodium (DS). The effect of dimethyl sulfoxide (DMSO) as a penetration enhancer was also examined when it was added to the M formulation. To study the in vitro potential of these formulations, permeation studies were performed with Franz diffusion cells using excised dorsal rat skin. To investigate their in vivo performance, a carrageenan-induced rat paw edema model was used. The commercial formulation of DS (C) was used as a reference formulation. The results of the in vitro permeation studies and the paw edema tests were analyzed by repeated-measures analysis of variance. The in vitro permeation studies found that M was superior to G and C and that adding DMSO to M increased the permeation rate. The permeability coefficients (Kp) of DS from M and M+DMSO were higher (Kp=4.9×10−3±3.6×10−4 cm/h and 5.3×10−3±1.2×10−3 cm/h, respectively) than the Kp of DS from C (Kp=2.7×10−3±7.3×10−4 cm/h) and G (Kp=4.5×10−3±4.5×10−5 cm/h). In the paw edema test, M showed the best permeation and effectiveness, and M+DMSO had nearly the same effect as M. The in vitro and in vivo studies showed that M could be a new, alternative dosage form for effective therapy